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1 //! The renderer-agnostic half of the make-family design system.
2 //!
3 //! <!-- wiki: makeover-layout -->
4 //!
5 //! `makeover` answers *what colour*, and varies by theme. `makeover-geometry`
6 //! answers *how much space*, and varies by density and surface. This crate
7 //! answers *what the thing is*, and varies by nothing.
8 //!
9 //! # The deferral rule
10 //!
11 //! A description names intents and relationships, never values. Say
12 //! [`Fill::Raised`], never `#D9DDF4`. Say `Gap::Peer`, never `6px`. What is
13 //! left once colour and spacing are deferred is **composition**: which edges
14 //! are lit, what inverts on press, what nests in what.
15 //!
16 //! The constraint that shapes all of it: a renderer that can only paint
17 //! rectangles has to be able to express the result. egui has no
18 //! `box-shadow: inset` and one stroke per widget with no per-side control; a
19 //! terminal has box-drawing characters and one cell of resolution, and cannot
20 //! draw a two-tone lit edge at all. A description that assumes per-side edges
21 //! is a CSS description wearing a neutral name. So this crate names the
22 //! *intent* — this region is a well — and each renderer chooses an expression
23 //! it can actually produce, including dropping half of one.
24 //!
25 //! # Scope
26 //!
27 //! Depth came first: the bevel and the surfaces it shapes. That much was
28 //! settled the hard way — the vocabulary here was read off audiofiles'
29 //! `ui::theme` and `ui::widgets`, which are the only implementation written
30 //! by a consumer with no CSS, then checked against both webview apps. All
31 //! three agreed once Balanced Breakfast's fills were corrected.
32 //!
33 //! 0.2.0 adds the rest of the description, each member drawn the same way,
34 //! from what the three apps already hand-write rather than from a taxonomy:
35 //!
36 //! - Components. [`Token`] (badge against chip), [`Notice`] (toast against
37 //! banner), [`RowPart`], [`Heading`], [`Selector`], [`Readiness`], and
38 //! [`Tone`], which is the one intent family they share.
39 //! - Schemas. [`Field`] for forms and [`Column`] for lists and tables.
40 //! - Structure. [`Region`] for the parts of a screen, [`Arrangement`] for how
41 //! a screen is put together.
42 //!
43 //! **Validation** was absent on purpose here, on the grounds that neither app
44 //! had a shared story. That reasoning is retired — see 0.11.0 below, which is
45 //! where the constraints arrived and why the argument did not survive contact
46 //! with what the apps were measured to do.
47 //!
48 //! 0.3.0 closes a gap the first real adoption found, which is what adopting
49 //! against goingson first was for. [`Selector`] described only the *chosen*
50 //! option, so an unchosen one fell through to [`Depth::Flat`] and no renderer
51 //! drew it; goingson's tab strip recesses its unchosen tabs by hand and could
52 //! not delete the line, because being recessed is *why* the chosen tab reads as
53 //! coming forward. So [`Selector::unchosen`] joins `chosen`, and saying it
54 //! needed [`Fill::Sunken`] and [`Depth::Sunken`]: a surface set back by colour
55 //! with no edge, which is neither a well nor level-with.
56 //!
57 //! 0.7.0 adds [`State`], the interaction axis, closing the gap that adopting
58 //! against three apps rather than one made visible. The description named
59 //! rest and, through [`Depth::pressed`], pressed. It named neither focus nor
60 //! disabled, so `makeover-webview` emitted a hover rule and stopped, and each
61 //! consumer completed the primitive from outside by out-specifying a rule it
62 //! did not own: 19 such rules in goingson, 21 in the MNW server, a further set
63 //! in Balanced Breakfast, and three focus rings that do not match. The axis is
64 //! deliberately two members wide, because hover and pressed belong where they
65 //! already are. [`State`]'s own docs carry that argument.
66 //!
67 //! 0.8.0 finishes [`Field`], which described a field well enough to label it and
68 //! not well enough to draw it. Writing `makeover-webview`'s form emitter found
69 //! three things missing and the renderer supplied all three from outside: the
70 //! current value, a select's options, and the placeholder. Two of those move
71 //! here and one does not.
72 //!
73 //! - [`Field::placeholder`] is user-facing text sitting beside `label` and
74 //! `hint`. There was never a reading on which it was renderer state; it was
75 //! outside only because adding a field to a published struct is breaking.
76 //! - [`Field::options`] moves because every renderer needs them and each was
77 //! going to invent its own shape. [`Choice`] is the shape `makeover-webview`
78 //! already arrived at, taken as-is rather than redesigned.
79 //! - The current value stays renderer-side and is not coming here. It is the
80 //! one of the three that is genuinely state: a webview reads it out of the
81 //! DOM, an immediate-mode renderer holds a `&mut` to the app's own field, and
82 //! a description that carried it would be a form model.
83 //!
84 //! 0.9.0 opens [`RowPart`], which was the last closed enum in the vocabulary,
85 //! and adds [`RowPart::Tokens`]. Both halves come from the same finding, made
86 //! by the first two real screens described through the router rather than by
87 //! reading a stylesheet.
88 //!
89 //! A goingson project card carries two trailing badges, a type and a toned
90 //! status; a contact card carries a primary email *and* a strip of tags. `Meta`
91 //! is one slot and one string, so both ports joined their facts with a
92 //! separator and lost what the second one was: a status reads as text where it
93 //! used to read as colour. [`Token`] already says exactly the right thing — a
94 //! small labelled thing with a kind, a tone and an optional action — and could
95 //! only ever be a node in its own right, never inside a row.
96 //!
97 //! So the missing thing was permission rather than a concept. `Tokens` is that
98 //! permission, and `#[non_exhaustive]` arrives with it so the next member is not
99 //! a lockstep event across three renderers. The pairing is the point: this
100 //! enum's own consumer in `makeover-webview` carried a comment predicting it
101 //! would stop compiling one day, which is a lockstep break written down and
102 //! waited for rather than prevented.
103 //!
104 //! Balanced Breakfast was checked before the member was added, because one
105 //! consumer wanting something is not evidence. It packs a count and two icon
106 //! buttons into the same single `Meta` slot while leaving `Actions` empty, so
107 //! the slot was already straining under a second consumer for a different
108 //! reason.
109 //!
110 //! 0.10.0 adds [`Meter`], a proportion carried as a pair rather than as a
111 //! percentage. Its own docs carry the argument; the short form is that the
112 //! percentage shape had already been tried in goingson and had already needed a
113 //! companion flag to recover what rounding and clamping threw away.
114 //!
115 //! 0.11.0 is four members from the quasi proving ground, batched into one
116 //! release because pre-1.0 a minor is breaking and a cascade is nine repos.
117 //! Three findings that arrived with them turned out not to belong here at all:
118 //! this crate has no notion of an action, a route or a destination, so anything
119 //! asking what a control *calls* was never the vocabulary's to say.
120 //!
121 //! - [`Figure`], a value with a caption. goingson had five of them across five
122 //! screens with five class vocabularies for the one shape, which is the
123 //! divergence this crate exists to end, sitting in plain sight and counted for
124 //! the first time.
125 //! - [`RowPart::Proportion`], so a [`Meter`] can sit in a row. `Meter` reached
126 //! two of its seven sites at 0.10.0 and the other five are row-shaped. Exactly
127 //! [`RowPart::Tokens`]'s problem with a different payload, and it takes
128 //! `Tokens`' answer: the part carries the description of a bar, not a node.
129 //! - [`Field::max_length`], [`Field::min`] and [`Field::max`], joining
130 //! [`Field::required`], which had been sitting here as the sole constraint
131 //! while the header above claimed there were none. The set stops before
132 //! `pattern`, which fails the renderer test and is one site in one app.
133 //! - [`FieldKind::File`]. Every host has an honest answer — a native picker, an
134 //! `<input type="file">`, a path prompt, an argument — and it carries no
135 //! accepted-types list because `accept` appears at zero sites in either app.
136 //!
137 //! The evidence rule changed under these, and it is worth recording because four
138 //! earlier decisions were made under the old one. The two-app test said a shape
139 //! earns a word once a second app wants it. It is backwards: a rule that
140 //! withholds a word until a second app has duplicated the code guarantees the
141 //! duplication, and app three writes it a third time. The bar is now generic
142 //! against bespoke — is this furniture any app would have, or is it this app's
143 //! own? Bespoke keeps [`Region::Bespoke`], which already carries a completion
144 //! heatmap and is the right answer for a calendar nobody will build twice.
145 //!
146 //! 0.12.0 is two more from the same proving ground, and the same sorting
147 //! happened first: six findings came out of a measurement of goingson's whole
148 //! frontend, and four of them turned out to be asking what a control *calls*,
149 //! which this crate cannot say. The two that were really here:
150 //!
151 //! - [`Readiness`] grows from two states to four. It named `Ready` and
152 //! `Pending` and stopped, so a screen whose list came back empty had nothing
153 //! to say about it; goingson draws an empty state at 27 sites and Balanced
154 //! Breakfast at 9. `Empty` and `Failed` are the same axis rather than a new
155 //! member beside it, because a region shows one of the four and never two.
156 //! `#[non_exhaustive]` arrives with them, the pairing [`RowPart`] made at
157 //! 0.9.0 and for the same reason.
158 //! - [`Column::sortable`], [`Column::sorted`] and [`Sort`]. The one finding in
159 //! the set that completes a member rather than adding one: `Column` shipped
160 //! with a width and a priority and could not say that a table is ordered by a
161 //! column, so a described table could draw no caret and offer no reordering.
162 //!
163 //! 0.14.0 is two additive members on two `#[non_exhaustive]` enums, released
164 //! together because publishing twice for that is waste and the cascade below
165 //! this crate is nine repos.
166 //!
167 //! - [`Depth::Overlay`]. The enum could say raised, well, sunken and flat, and
168 //! could not say that a surface sits *over* the page. Every renderer already
169 //! had the surface — `makeover-tui`'s `Palette::overlay`,
170 //! `makeover-immediate`'s `Palette::elevation`, `makeover-webview`'s
171 //! `--elevation-overlay` — and none of them could be reached from a
172 //! description. buckets_of_money has 16 modals waiting on it.
173 //! - [`CellPart`], which is [`RowPart`] for tables. A row's parts have carried
174 //! their own content intent since 0.2.0, so `.row-actions` inherits rather
175 //! than taking a text colour; a table cell had no such vocabulary and
176 //! `makeover-webview` emitted one undifferentiated `.cell`, so a button in a
177 //! cell was painted as text. The four members are the four things quasi's
178 //! `Cell` was measured to hold, and the count is in that crate's history
179 //! rather than assumed here.
180 //!
181 //! 0.15.0 adds [`FieldKind::Date`] and [`FieldKind::DateTime`], on the argument
182 //! [`FieldKind::Email`] was admitted on: a webview emits a different `type=`,
183 //! which is a native picker, the platform's validation and a different keyboard
184 //! on a touch device. Described as text with a "YYYY-MM-DD" hint, all three are
185 //! lost.
186 //!
187 //! Two members and not one or five, from a count rather than from symmetry: 13
188 //! sites of `date` and 13 of `datetime-local` across the MNW server and
189 //! goingson, and zero of `time`, `month` or `week`. The wire format each takes
190 //! is named here as [`DATE_FORMAT`] and [`DATETIME_FORMAT`], because a host
191 //! left to pick its own would disagree with a server silently, and
192 //! [`FieldKind::temporal`] is the pair asked about once rather than at each
193 //! renderer. `FieldKind`'s own comment claiming `radio` was the last HTML input
194 //! type missing was already false when 0.8.1 wrote it; these are what it was
195 //! missing.
196 //!
197 //! What each of the 0.12.0 findings deliberately leaves out is the address — what pressing a
198 //! header calls, and where an empty state's "Add your first project" button
199 //! goes. That is the boundary this crate is defined by, and four findings moved
200 //! across it rather than being answered here.
201 //!
202 //! 0.19.0 narrows [`State`] to [`State::Disabled`] alone. `State::Focus` is
203 //! gone: a description never states what has focus, because what focus *is*
204 //! differs per host and every renderer had already decided for itself — the
205 //! webview draws it from `:focus-visible`, egui refused the variant outright,
206 //! and quasi-tui honoured it once at startup and overrode it thereafter.
207 //!
208 //! 0.20.0 adds [`Region::Widget`], the third tier, and `#[non_exhaustive]` to
209 //! [`Region`] with it. Every vocabulary finding until now had two answers
210 //! available — grow the primitive set, or [`Region::Bespoke`] — and a whole
211 //! class of thing is wrong for both. A carousel is not a primitive, because a
212 //! terminal has none and that is the test `Node::Html` failed. It is not
213 //! bespoke either, because bespoke is what one app owns and every part of a
214 //! carousel is furniture plus members this crate already has.
215 //!
216 //! The cost of the binary was that refusing a primitive was expensive: the app
217 //! hand-rolls the thing forever, so the pressure always ran toward growing the
218 //! primitive set with one host's idioms. A named assembly changes what "no"
219 //! costs without changing what the vocabulary can say.
220 //!
221 //! MNW's carousel is the first consumer and was the finding that started it: one
222 //! partial, three pages, an ordered set of frames with a position, prev/next and
223 //! a dot strip, all of it sayable already and none of it nameable. See wiki
224 //! `widget-tier` for the ownership model, which is why this member carries a
225 //! name a renderer may decline to know.
226 //!
227 //! 0.21.0 adds [`Image`] and [`Fit`], found by trying to describe MNW's
228 //! carousel under 0.20.0's widget tier and getting one step in. Nothing named a
229 //! picture. The vocabulary could say a number with a caption, a badge, a meter
230 //! and a table, and could not say the thing three of MNW's public pages are
231 //! mostly made of.
232 //!
233 //! It reads as an oversight and is a measurement: 24 `<img>` sites across 22
234 //! MNW templates, against one in goingson and none in Balanced Breakfast or
235 //! audiofiles. A picture is furniture a *content platform* has, and MNW is the
236 //! only one in the tree, so the evidence never arrived from the two-app
237 //! direction the earlier rule looked in. Under the generic-against-bespoke bar
238 //! it is not close: a picture is not one app's own.
239 //!
240 //! A primitive rather than a widget, which is worth stating now that the tier
241 //! makes it a real question. A widget is an assembly of things already sayable
242 //! and a picture is a leaf, assembled from nothing. It also passes the test
243 //! `Node::Html` failed — every host has an honest answer, including a terminal,
244 //! which has a graphics protocol or has [`Image::alt`].
245 //!
246 //! [`Image`] carries no source, the split [`Act`] already makes: an address is
247 //! not this crate's to hold. See its own docs, which is where the argument is.
248 //!
249 //! 0.22.0 finishes [`Image`], which 0.21.0 shipped unable to say how much room
250 //! a picture needs. Without that a renderer cannot reserve space, so a picture
251 //! occupies nothing until its bytes arrive and then takes its full height at
252 //! once. Measured on MNW's landing page: a 478px jump per frame and a
253 //! cumulative layout shift of 0.087 for the page.
254 //!
255 //! - [`Image::intrinsic`], the picture's own dimensions, carried as [`Extent`].
256 //! A fact about the asset rather than a display size, which is what keeps it
257 //! on this side of the deferral rule: 5120x3412 is what the file *is*, and no
258 //! renderer can learn it without fetching the bytes.
259 //! - [`Loading`], and the default flips to [`Loading::Eager`]. 0.21.0 emitted
260 //! the webview's `loading="lazy"` for every picture, which read one
261 //! consumer's habit as a rule. Deferring a picture that is on screen at first
262 //! paint saves nothing and makes its shift land later. The carousel is the
263 //! case that proves this cannot be one renderer-wide setting: its first frame
264 //! is on screen and its others are not, in one widget, at one moment.
265 //!
266 //! 0.23.0 adds [`Showing`], which is three open findings collapsing into one
267 //! member. A tab group could not say which tab was open, a carousel could not
268 //! say which frame was up, and a disclosure could not say whether its child was
269 //! showing. All three are the same missing sentence, and while it was missing a
270 //! renderer had two moves: match on a widget name, or draw every child.
271 //!
272 //! So the widget tier was taking the blame for a gap one level below it. With
273 //! this a renderer derives its chrome from the description — labels get a strip,
274 //! no labels get previous/position/next — once, for every widget there will ever
275 //! be, and [`Region::Widget`]'s name goes back to being app vocabulary a
276 //! renderer may decline to know.
277 //!
278 //! Only the kind lives here. Which child is up, and what each child is called,
279 //! sit with whatever holds the regions, the same split [`Selector`] already made
280 //! against `Node::Select`.
281 //!
282 //! 0.27.0 adds [`Region::Group`], which closes a gap this crate had carried
283 //! since 0.2.0 without noticing: [`Heading::Section`] is documented as naming a
284 //! block within the screen, and there was no block. A section heading is a leaf
285 //! beside the things it names, so the description could say a section had
286 //! *started* and never that one had ended.
287 //!
288 //! Found by asking how a screen distinguishes groups of settings by colour, and
289 //! the answer turned out to be two findings rather than one. This is the first
290 //! and it is the precondition: there is nothing to tint until there is a
291 //! container. The second — every renderer already resolves `category.one`
292 //! through `category.six` and no description can reach any of them — is filed
293 //! and not shipped here.
294 //!
295 //! What the colour question settled anyway, because it shapes this member: the
296 //! group carries no colour and no ordinal. A renderer distinguishing sibling
297 //! groups derives the assignment from their order, which is
298 //! [`Region::Columns`]' reasoning about counts applied to colour — the children
299 //! say, and a value here would be a second source for something the description
300 //! already states by containing them.
301 //!
302 //! 0.28.0 is what audiofiles' forms port found it could not say, three findings
303 //! filed against a working conversion rather than guessed at in advance. All
304 //! three are about a *question* rather than about a control, which is the line
305 //! this crate keeps having to redraw.
306 //!
307 //! - [`FieldKind::Range`] and [`Field::step`]. A bounded number the user drags
308 //! across, where both ends being on screen is what the question means. The
309 //! reading to resist is that this is [`FieldKind::Number`] with bounds, and it
310 //! is [`FieldKind::Radio`]'s argument again: a validated number can be out of
311 //! range and a slider cannot, so the bounds stop being a rule and become the
312 //! control's extent. [`Field::bounded`] is the check a renderer asks, since a
313 //! range missing an end has nothing to draw.
314 //! - [`Choice::unavailable`]. An option that is real, worth showing, and cannot
315 //! be picked yet. Without it an app either drops the option — and the user
316 //! never learns it is there — or hand-rolls the control outside the
317 //! description, which is what audiofiles' instrument panel did: a permanently
318 //! disabled radio plus a hand-written line saying what would enable it.
319 //! `#[non_exhaustive]` arrives on [`Choice`] in the same release, so this is
320 //! the last breaking addition to it.
321 //! - Not a member at all: [`Field::placeholder`] on a chooser. It was sayable
322 //! already and no renderer read it, so a select with nothing chosen showed an
323 //! empty box and the instruction lived on a disabled button elsewhere. The
324 //! renderers moved, not the description.
325 //!
326 //! 0.29.1 adds [`Awaiting`], which is the sentence [`Readiness`] could say about
327 //! a region and could not say about a control. A described screen could state
328 //! that a list was on its way and could not state that the button just pressed
329 //! is doing the thing it was pressed for, so every renderer's in-flight
330 //! treatment was the app's to hand-write. The MNW server hand-writes it 57 times
331 //! and hand-writes the guard against a second press twice, which is the half
332 //! that matters going missing on a codebase that sells things.
333 //!
334 //! The mark is the fact that something outstanding will complete, once, in
335 //! expected finite time. Deliberately not remoteness, since a heavy local query
336 //! waits too, and deliberately not slowness, which is a judgement rather than a
337 //! property. It carries an optional amount, stated only when the amount is
338 //! measured, and it carries no duration at all: a renderer draws what is done
339 //! over what there is plus the time so far, and never an estimate of what is
340 //! left.
341 //!
342 //! One mark and two readings, which is what keeps a slow region from being
343 //! hand-split into its own route the way MNW's payout summary is: a pressed
344 //! control goes busy and locks, a region fed by an awaiting call stands in as
345 //! [`Readiness::Pending`] and fills when it lands.
346 //!
347 //! A patch release for a new member, which is the 0.27.5 precedent rather than a
348 //! new rule: nothing existing changed shape, so every consumer already asking
349 //! for 0.29 keeps resolving and the suite below this crate does not have to move
350 //! for a type only quasi reads. The minor releases above were minor because they
351 //! also narrowed something.
352 //!
353 //! 0.30.0 is two members batched into one release, which is 0.11.0's precedent
354 //! and its reasoning: pre-1.0 a minor is breaking, the cascade below this crate
355 //! is seven repos, and paying that twice in a week for two unrelated words is
356 //! the tax the batching exists to avoid.
357 //!
358 //! - [`FieldKind::Rich`], a field whose value is markdown source. The editing
359 //! counterpart of prose already carried as markdown, and it is renderable
360 //! everywhere for the reason the carrying is: editing markdown is editing
361 //! text. It buys a renderer permission to offer a preview or a syntax pass and
362 //! buys a host reading the value back the knowledge of what it holds; a
363 //! renderer with neither draws a textarea. It says nothing about when the
364 //! value is saved, because autosave is a clock. Measured against four MNW
365 //! section editors that are one shape written four times.
366 //! [`FieldKind::multiline`] arrives with it, since the pair is now two members
367 //! every renderer has to ask about.
368 //! - [`Facet`], [`Selecting`], [`FacetValue`] and [`Standing`]: a named
369 //! dimension a set is narrowed by. MNW's discover page filters six ways
370 //! through six mechanisms, and its filter rows carry a tick box *and* a
371 //! chevron only because a tag's selection and a tag's browse position were
372 //! held separately. One word covers all six, and [`Selecting::Subtree`] is the
373 //! member that made it an enum rather than a bool: a tree's selection is
374 //! branches taken and branches pruned, which no flat mode can express, and
375 //! making one gesture do browsing and filtering together is what lets the
376 //! second mechanism go. [`Standing`] has four members rather than a bool for
377 //! the tree's sake — a value in force because an ancestor is, is not a value
378 //! somebody picked. [`FacetValue`] splits an identifier from a label for
379 //! [`Choice`]'s reason and one of its own: two leaves under different parents
380 //! are legitimately both called "Ambient", and the path is what tells them
381 //! apart and what nearest-ancestor-wins resolves over. Deliberately wider than
382 //! that one page: audiofiles' library browser and goingson's filters are the
383 //! same shape.
384 //!
385 //! 0.38.0 describes the theme picker. [`FieldKind::Theme`], [`ThemeChoice`],
386 //! [`ThemeVariant`], [`Contrast`], [`Field::themes`] and [`Field::follows`] are
387 //! one screen's control named as furniture. Ruled by Max 2026-08-28
388 //! (`70028e00`), against the grouped option list that was the obvious answer.
389 //!
390 //! - **The measurement is what rejected `Choice::group`.** `optgroup` appears
391 //! at exactly one live site in the tree, in the one app not yet ported, and
392 //! the non-theme grouping count is zero. Two apps' grouped pickers were
393 //! deleted by their ports and both described replacements dropped the
394 //! grouping on purpose. So the thing that recurs is not option lists that
395 //! group; it is this picker, hand-written three times.
396 //! - **Two of the four facts cannot come from an app.** A theme's group and its
397 //! measured contrast tier come off the resolved theme, so the layer that
398 //! loaded it is the only party holding them. `Choice::new(id, "{name}
399 //! ({variant})")` is what all three apps wrote, and it turns structure into
400 //! prose and drops the tier entirely.
401 //! - **The order is the grouping**, rather than a returned list of groups. A
402 //! renderer that draws headings walks the run of one variant; one that cannot
403 //! still gets the useful order, and neither shape is made to flatten the
404 //! other's.
405 //! - **[`ThemeVariant`] is spelled twice on purpose.** This crate takes no
406 //! dependencies, so it cannot name `makeover::Variant`, and a renderer that
407 //! groups needs the groups as values. The adopter converts, in a three-arm
408 //! match.
409 //! - **The cost is stated rather than found later.** This is the first member
410 //! here that names a subject instead of a shape of answer. It stays narrow: a
411 //! theme picker, not a general host-resolved list. A second such list is when
412 //! the generalisation gets measured.
413 //!
414 //! 0.35.0 gives a suggestion its second line. [`Candidate`] is the entry in a
415 //! field's suggestion list: a value, a label, and the [`detail`] that orients
416 //! it. Ruled by Max 2026-08-21 (`1fcf2e9b`) after the combobox member shipped
417 //! and was then held against the two sites it was designed from, which is an
418 //! order worth not repeating.
419 //!
420 //! - **A candidate is not a [`Choice`], and the difference is in the reading
421 //! rather than the writing.** Both submit one string and read as another. An
422 //! option is picked out of a set the user can see whole; a candidate is
423 //! offered out of a set nobody can see, so it has to say what tells it from
424 //! its neighbours. Both measured sites draw that second string today, by
425 //! hand, in a second span.
426 //! - **It is its own type rather than a member on [`Choice`].** `Choice` is the
427 //! most-consumed struct in the vocabulary and the member would have landed on
428 //! every option list in the tree the day it shipped, including the ones with
429 //! nowhere to draw it.
430 //! - **[`Candidate`] is `#[non_exhaustive]` from birth**, which is the whole of
431 //! what 0.28.0 cost and is not being paid twice.
432 //! - No `unavailable`. A suggestion that cannot be picked is a row a route
433 //! should not have offered.
434 //!
435 //! [`detail`]: Candidate::detail
436 //!
437 //! 0.34.0 gives an interval a description. [`FieldKind::Interval`] and
438 //! [`Field::upper_name`] say that two values are one question with two ends.
439 //! Ruled by Max 2026-08-21 against audiofiles' six filter axes and the MNW
440 //! server's price pair, which is HTML saying the grouping in an ARIA
441 //! `role="group"` and nowhere else.
442 //!
443 //! - **The ends constrain each other, and nothing else in the vocabulary could
444 //! say so.** Two [`FieldKind::Number`] fields are two questions: a renderer
445 //! draws two labels with no relationship, and [`Field::error`] attaches to one
446 //! side of a fault that belongs to both.
447 //! - **It is not [`FieldKind::Range`]**, which is the reading to resist and the
448 //! same resistance `Range` needed against `Number`. A range is one value
449 //! inside an extent; this is two, and the extent is a bound on each rather
450 //! than the question's meaning.
451 //! - **Both names are stated rather than derived.** Measured the same day, the
452 //! two sites disagree about affix order -- `bpm_min`/`bpm_max` against
453 //! `min_price`/`max_price` -- so any rule renames one of them. One member
454 //! instead of a naming convention this crate would own forever, and which
455 //! member a name sits in is what says which end it is.
456 //! - The crossing rule is not enforced, exactly as [`Field::min`] is not. What
457 //! the description buys is one place to report the fault rather than two.
458 //!
459 //! [`Field::upper_name`] is a member on a struct that is not
460 //! `#[non_exhaustive]`, so this is a formal break for crates.io and zero
461 //! call-site edits in the tree: every literal builds on a constructor.
462 //!
463 //! 0.33.0 gives a number its unit. [`Field::unit`] carries what the value is
464 //! measured in, and [`FieldKind::measurable`] says which kinds read it. Decided
465 //! by Max 2026-08-21 (`32215e21`) against eight sites across four audiofiles
466 //! files that had each independently put the unit in parentheses at the end of
467 //! the label -- three of them written while the gap was a known open question.
468 //!
469 //! - **A unit is a fact about the value, not part of the question's name.** The
470 //! two readings come apart the moment anything reads a field back rather than
471 //! drawing it, which is the argument that decided it.
472 //! - **The convention it replaces froze the worst placement.** A label is the
473 //! sentence above the control, so unit-in-label was the same answer on every
474 //! host -- including the host that had somewhere better, since egui's slider
475 //! already draws a suffix beside the readout, which is what these controls did
476 //! before they were described.
477 //! - A string rather than a closed family, which is [`Curve`]'s argument
478 //! inverted and correctly so: a curve is a mapping this crate computes, and a
479 //! unit is a symbol it only carries. The measured set is `GiB`, `dBFS`, `s`
480 //! and `ms`, and this crate does not know what the next consumer measures in.
481 //!
482 //! Additive: absent is what every field meant before.
483 //!
484 //! 0.32.0 is the slider's real shape. **The data of a slider is a fraction and
485 //! a function taking numbers to numbers** (Max, 2026-08-21), so [`Curve`]
486 //! arrives and [`Field::curve`] with it. [`Field::min`] and [`Field::max`] were
487 //! never the control's extent: a slider's extent is always 0 to 1, and the
488 //! bounds are `f(0)` and `f(1)`. Linear is the constant-slope case, which is
489 //! why the mapping was invisible — under it the extent and the bounds coincide
490 //! numerically — and why four renderers each hard-coded it without anyone
491 //! deciding to.
492 //!
493 //! - It is not a scale flag on a range. The question this replaced asked
494 //! whether to name a decoration; what was unnamed is half of what a slider
495 //! *is*, which is why the member is a mapping and not an adjective.
496 //! - **The step spacing rides on the curve.** Max, in the same breath: if the
497 //! family is prescriptive anyway, the granularity belongs in it. On a slider
498 //! the two are one decision, and holding them apart is what let a 0-to-1
499 //! threshold ship as a two-position control. [`Field::step`] narrows to the
500 //! *typed* kinds, where there is no mapping to decide with.
501 //! - A closed family rather than `fn(f64) -> f64`, which is the literal reading
502 //! and does not cross the description boundary: a fn pointer cannot be
503 //! emitted into a browser and cannot be compared or hashed meaningfully,
504 //! which [`Field`] needs. Nothing measured wants an arbitrary function — one
505 //! non-linear shape across five controls, and no second shape.
506 //! - The mapping computes here rather than in each renderer
507 //! ([`Curve::value_at`], [`Curve::position_of`]), so a terminal's bar, an
508 //! egui slider and a browser's input cannot disagree about where a value
509 //! sits. This crate otherwise describes rather than computes; four copies of
510 //! two formulas is the cost of holding that line here.
511 //!
512 //! Additive: [`Curve::Linear`] with no step is what every range meant before,
513 //! so no existing site changes meaning. Consumers: audiofiles' ADSR envelope
514 //! (three logarithmic times) and its storage cap picker.
515 //!
516 //! 0.31.0 finishes the file field. [`FieldKind::File`] arrived at 0.11.0
517 //! carrying neither an accepted-types list nor a multiplicity flag, and said so
518 //! in its own doc: `accept` appeared at zero sites in either app, and a member
519 //! added for a case nobody has is a member designed against nothing. That count
520 //! was taken over goingson and Balanced Breakfast, and the MNW server is a third
521 //! consumer with 14 `accept` lists across 10 templates and 4 of its 16 file
522 //! inputs marked `multiple`. The reasoning was right and the measurement went
523 //! stale, so [`Field::accept`] and [`Field::multiple`] arrive now.
524 //!
525 //! - [`Accepted`] is an enum rather than the comma-joined string the templates
526 //! hold, because the list is read twice and only one of the readings is
527 //! filtering. The other is which disclosure to offer — a preview, a duration,
528 //! a waveform — and a renderer deciding that from raw strings is three
529 //! renderers each writing a media-type parser. [`Accepted::family`] answers it
530 //! once. All three shapes are in the measured sites and none can be dropped:
531 //! `image/*` is a [`Family`], `image/jpeg` and `text/csv` are a
532 //! [`Type`](Accepted::Type), and `.zip`, `.tar.gz` and `.clap` are a
533 //! [`Suffix`](Accepted::Suffix). One site carries `.csv,text/csv`, which is
534 //! both in one list.
535 //! - A suffix carries no family and this crate will not infer one. `.mp3` is
536 //! audio in fact, and a table here saying so is a mapping that rots in a
537 //! published crate and is wrong for the first container format someone hands
538 //! it. A call site that wants the disclosure writes the family or the media
539 //! type, which is what the sites offering previews already do.
540 //! - There is one upload shape, not one per type. What a media upload shows
541 //! beyond a plain one is disclosure layered on this shape, which is why the
542 //! accept list is load-bearing beyond validation and why nothing here names a
543 //! media upload as its own kind.
544 //! - Progress is not a member and needs none. An upload in flight is a control
545 //! in flight with a number attached, so it is [`Awaiting`] with the file's
546 //! length as its [`amount`](Awaiting::amount) — the case that type's own doc
547 //! names. Where the bytes go is an address, and this crate holds none; that is
548 //! the router's [`Action`], which the field already points at when it writes
549 //! on its own.
550 //!
551 //! # Reach, focus and the focus ring
552 //!
553 //! Three terms, and no others, for what 0.19.0 moved out of the description.
554 //! **Reach** is which things can take focus and in what order; a browser reads
555 //! it off the document, a TUI derives it from draw order, egui from its own id
556 //! stack. **Focus** is which reached thing has the keyboard right now: the
557 //! renderer's, live, never described and never round-tripped through a
558 //! description. The **focus ring** is the visible cue; the token (`focus-ring`,
559 //! derived by `makeover` from the action colour) is the one shared artifact and
560 //! the drawing is the renderer's. Retired as names for any of this: "focus
561 //! stroke", "focus cue", "wants focus". "Caret" is a different thing — the text
562 //! cursor inside a field — and keeps its name.
563 //!
564 //! # The three tones, and what a colour claims
565 //!
566 //! One rule, settled 2026-08-16, for how colour says whether a thing can be
567 //! used. Every renderer answers to it, and it is stated here because the
568 //! description is what names the intents.
569 //!
570 //! | the thing | intent |
571 //! |-----------|--------|
572 //! | active, emphasised, the thing itself | `content` |
573 //! | inactive but usable: it still answers a press | `content-secondary` |
574 //! | inert: disabled, or not a control at all | `content-muted` |
575 //!
576 //! `content-muted` is the one with a claim in it. [`State::Disabled`] resolves
577 //! to it, so a live control wearing it is telling the user it will not answer —
578 //! and being wrong about that is worse than being quiet, because the user's
579 //! response is to stop trying. A sortable column heading that was never sorted,
580 //! and every unchosen option in a radio group, both read as dead lists that way;
581 //! those are the two this rule was written out of. What is legitimately muted is
582 //! a caption, a hint, a placeholder, a meter's reading, an axis label: text that
583 //! was never going to answer anything.
584 //!
585 //! The three are one ramp and not three colours. `makeover`'s `Emphasis` derives
586 //! the quieter two from the ink, so "one step back" means the same distance in
587 //! every theme and a renderer cannot land between them by picking its own.
588 //!
589 //! # First paint is final paint
590 //!
591 //! One rule, settled 2026-08-16. Nothing may change size or position after it is
592 //! first drawn, and nothing may stand in for content that has not arrived yet.
593 //! Both halves are absolute.
594 //!
595 //! It is stated here, rather than left to each renderer, because a renderer can
596 //! only reserve space the description gave it enough to size. A member whose
597 //! size depends on its content therefore owes whatever makes it sizeable while
598 //! the content is still absent, and that is the second admission test for a new
599 //! member: not only does it compose something this crate already names, it can
600 //! be laid out before it is filled.
601 //!
602 //! The mechanism is a reservation, and [`Sort`]'s caret is the worked example.
603 //! The caret is drawn into a box its own width whether or not the column is
604 //! sorted, so pressing a heading cannot reflow the row it sits in. The box names
605 //! no magnitude, which is what keeps it out of `makeover-geometry`'s territory.
606 //! Reserve from what is known; never discover geometry from what has not
607 //! arrived.
608 //!
609 //! The trap is an `Option` that means "not yet". [`Readiness::Pending`] is the
610 //! honest way to say a region is still waiting. An optional *measurement* is
611 //! not: a count that shows up later widens the text that prints it and moves
612 //! everything beside it, which is the reflow this rule exists to forbid. So an
613 //! `Option` on a measurement means the host will never know it — a property of
614 //! the query, fixed for the life of the screen — and a renderer sizes for the
615 //! answer it was handed rather than for the one it hopes is coming.
616 //!
617 //! # Any width, one answer
618 //!
619 //! The sibling of the rule above, and settled the same day. That one is
620 //! independence from *when*; this one is independence from *how you got here*.
621 //!
622 //! A rendering is a pure function of the description and the viewport. The same
623 //! description at the same width is the same output, whatever widths came
624 //! before it. No renderer may carry geometry across frames, and none may narrow
625 //! by counting.
626 //!
627 //! The failure this forbids is ordinary enough to be the default everywhere
628 //! else: a page that hides its sidebar below some width, remembers that it hid
629 //! it, and does not bring it back the same way. Layout there is a function of
630 //! `(width, history)`, so dragging a window to 900 wide is a different screen
631 //! depending on whether you came from 1400 or from 600. Nobody chose that; it
632 //! is what measuring and remembering produce.
633 //!
634 //! The mechanism is [`Width`] for what grows and [`Priority`] for what drops.
635 //! Both are declared, both are read off the description, and neither needs a
636 //! measurement. A renderer narrows by raising a cutoff over a total order,
637 //! never by counting what fits and stopping — `makeover-tui`'s table states
638 //! that as its own rule and tests it, and `makeover-webview` reaches the same
639 //! place with `@media` and `display: none`, which is path-independent by
640 //! construction because CSS has nowhere to keep the previous width.
641 //!
642 //! Two things follow for anything new. A member that would need last frame's
643 //! size to lay out this frame is refused, the same way a member that cannot be
644 //! sized before it is filled is refused. And a fact about what disappears
645 //! belongs in the description, because a host that has to infer it can only
646 //! infer it from a measurement.
647 //!
648 //! # Where the description stops
649 //!
650 //! The rule is that a member is added when an app needs a fact the vocabulary
651 //! cannot state, and refused when what it wants is presentation it should be
652 //! asking a renderer for. That is the whole test. It is not a quota, and the
653 //! goal is every screen described.
654 //!
655 //! ## What the timeline refusal got wrong, 2026-08-15
656 //!
657 //! This section used to read "a day-plan timeline, a kanban board and a
658 //! calendar are not describable here and will not become describable", and it
659 //! propagated: 12 files across three apps, three libraries and the design wiki
660 //! cited it, including audiofiles and the MNW server, neither of which has a
661 //! timeline. It is withdrawn, and [`Track`] is the member it was refusing.
662 //!
663 //! The error was pricing. The argument assumed a timeline needs a component
664 //! library's worth of vocabulary, and nobody measured it. Held against
665 //! goingson's `day-planning-render.js`, the members it actually needed and
666 //! could not get were two integers: where a thing starts, and how long it
667 //! lasts. Labels, gridlines, item bodies and tones were all furniture this
668 //! crate already named. A refusal that expensive should have carried a
669 //! measurement, and did not.
670 //!
671 //! The reasoning underneath it survives and is still the test: slot heights,
672 //! gridline colour, how overlapping things stack, which hour scrolls into view.
673 //! Those are presentation, they stay the renderer's, and [`Track`] carries none
674 //! of them. What changed is the conclusion, not the principle.
675 //!
676 //! ## The other two, measured 2026-08-15
677 //!
678 //! The same sentence refused a kanban board and a calendar. Both were counted
679 //! the way the timeline should have been, and neither came out where the
680 //! refusal put it.
681 //!
682 //! **Kanban: one member, and it is [`Region::Columns`].** Held against
683 //! goingson's `tasks-kanban.js`, every card fact was already sayable — title,
684 //! project, due date, the blocked and unblocks badges, subtask progress, the
685 //! open action and the context menu are `Row`'s existing parts. A column is a
686 //! heading, a count and a list. What nothing could say was that the columns are
687 //! *peers*: [`Arrangement`] offers list-detail and sidebar-content, and a board
688 //! described as either is a lie about the screen. Dragging a card between
689 //! columns never entered into it — a drop's effect is "set status", a discrete
690 //! action `Row`'s menu already carries, and the drag itself is affordance.
691 //!
692 //! **Calendar: no members, no consumer, and a sharper reason (Max,
693 //! 2026-08-15).** The month grid's primacy in calendar apps is an artifact of
694 //! paper: paper cannot be queried, so it has to show every day at once as a
695 //! fallback index. Routes, search and ranking do that job better, which is the
696 //! argument `events-calendar.js` already lost to a segmented list on
697 //! 2026-08-11.
698 //!
699 //! Three jobs survive that reasoning, and only one of them needs a grid:
700 //!
701 //! 1. **Spans across days** — a stretch of leave, a trip, a sprint. You cannot
702 //! see "away the 3rd to the 17th" in a list without diffing dates. This is
703 //! [`Track`] with [`Unit::Days`], not a calendar, and
704 //! [`Track::days`] is it.
705 //! 2. **Density at a glance** — which weeks were heavy. That is a heatmap, and
706 //! goingson describes both of its heatmaps as lists already.
707 //! 3. **Weekday periodicity** — "every other Tuesday", "the 15th is a
708 //! Saturday". This is the only job that needs the seven-column wrap, because
709 //! alignment is the whole of what makes it visible.
710 //!
711 //! So the open question is not "is a calendar describable" but "is job 3 worth
712 //! a member", and nothing in the tree asks for job 3 yet. GoingsOn
713 //! quasicoherent `4a1237b6`.
714 //!
715 //! A month grid renders today as a
716 //! [`Table`](crate::Column): seven weekday columns, weeks as rows, blanks for
717 //! the offset. goingson's monthly review reached this conclusion before this
718 //! note did and describes its month as a list of days that had something on
719 //! them, marking today with an ordinary badge. What the tree actually contains
720 //! is two completion heatmaps — one scalar per day — and no calendar at all:
721 //! `events-calendar.js` was deleted 2026-08-11 in favour of a segmented list,
722 //! and no MNW template mentions one. So the refusal was defending a screen
723 //! nobody has. If one is built, measure again; the facts already fit and only
724 //! the grid's shape would be in question.
725 //!
726 //! The pattern worth keeping from all three: one sentence refused three things
727 //! for one reason, and the reason was wrong three different ways. Count the
728 //! members.
729 //!
730 //! [`Region::Bespoke`] remains for the genuinely app-owned, and its
731 //! justification does not depend on the withdrawn claim. The
732 //! description names the *place* and the app owns the contents, so a screen
733 //! containing a timeline is still a whole screen and still routable. Without
734 //! it, the four goingson screens that make the app worth using would need a
735 //! second, undescribed path beside the router, and two paths is how a
736 //! vocabulary starts drifting from its app again.
737 //!
738 //! [`Region::Widget`] sits between that limit and the primitives, and it does
739 //! not move the limit. A widget is an assembly of members this crate *already*
740 //! has, under a name a renderer may or may not recognise. Anything that needs a
741 //! member the vocabulary does not have is still a finding about the vocabulary
742 //! or still bespoke; naming an assembly buys no new expressive power, which is
743 //! exactly why it is safe to let the set grow outside this crate.
744
745 #![forbid(unsafe_code)]
746
747 /// A colour intent this crate refers to but never resolves.
748 ///
749 /// The string is the token name `makeover` publishes, so a renderer can look
750 /// it up without this crate knowing what colour came back.
751 pub trait Intent {
752 /// The `makeover` intent token this resolves against.
753 fn token(self) -> &'static str;
754 }
755
756 /// Which way the light falls across a two-tone edge.
757 ///
758 /// The whole content of a bevel, once colour and thickness are deferred. The
759 /// light is always assumed to come from the top left: every consumer measured
760 /// agreed on that and none of them ever varied it, so it is an invariant here
761 /// rather than a parameter.
762 ///
763 /// # The two corners that belong to both edges
764 ///
765 /// Top-right and bottom-left are where the lit run meets the shaded one, and
766 /// the description's claim is that they belong to *both*. How a renderer says
767 /// that is its own business, because the answer is bounded by resolution and
768 /// not by taste:
769 ///
770 /// - A terminal cell is roughly 8x17 device pixels, so giving the whole corner
771 /// to one tone thickens that edge by a cell and reads as one run overrunning
772 /// the other. A half-cell glyph divides the cell already, so `makeover-tui`
773 /// splits it and recovers real information. Its box-drawing fallback cannot:
774 /// a single stroke has no half to give, so there both corners go to dark.
775 /// - A pixel bevel is a one-point stroke by default, which makes the corner a
776 /// one-point square. There is nothing to divide — a diagonal seam across one
777 /// point is sub-pixel, and antialiasing renders it as the blend a mitred join
778 /// already produces. So `makeover-immediate` mitres and is *not* diverging;
779 /// it is the same rule at a resolution where the split degenerates.
780 ///
781 /// Stated here so the difference reads as a decision rather than as drift. A
782 /// renderer with room to divide the corner should; one without should mitre or
783 /// pick the shaded tone, and neither is a bug.
784 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
785 pub enum Bevel {
786 /// Lit from the top left: light on top and left, dark on bottom and right.
787 Raised,
788 /// The same edge inverted, which is also the pressed state of anything
789 /// that draws itself [`Bevel::Raised`].
790 Inset,
791 }
792
793 impl Bevel {
794 /// The edge intents, as `(top_left, bottom_right)`.
795 ///
796 /// Split out from any painting because the inversion *is* the idea, and
797 /// it is the one part every renderer implements identically.
798 #[must_use]
799 pub const fn edges(self) -> (Edge, Edge) {
800 match self {
801 Self::Raised => (Edge::Light, Edge::Dark),
802 Self::Inset => (Edge::Dark, Edge::Light),
803 }
804 }
805
806 /// Pressing inverts. A raised control reads as inset while held.
807 ///
808 /// Stated here rather than left to each consumer because a cascade can
809 /// carry a pressed state and an immediate-mode renderer cannot: audiofiles
810 /// resolves this per call site, eighteen times.
811 #[must_use]
812 pub const fn pressed(self) -> Self {
813 match self {
814 Self::Raised => Self::Inset,
815 Self::Inset => Self::Raised,
816 }
817 }
818 }
819
820 /// One side of a bevel, named by the intent it takes.
821 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
822 pub enum Edge {
823 /// The lit side.
824 Light,
825 /// The shadowed side.
826 Dark,
827 }
828
829 impl Intent for Edge {
830 fn token(self) -> &'static str {
831 match self {
832 Self::Light => "bevel-light",
833 Self::Dark => "bevel-dark",
834 }
835 }
836 }
837
838 /// A surface intent a region is filled with.
839 ///
840 /// `#[non_exhaustive]`, so a renderer must carry a wildcard arm and a new
841 /// member is additive rather than breaking. Added 0.4.0, after [`Sunken`]
842 /// (an additive member, 0.3.0) hard-broke `makeover-tui` and
843 /// `makeover-immediate` at compile time and left neither able to move until
844 /// both published. The vocabulary exists to grow and the renderers exist to
845 /// disagree about how much of it they answer, so growth must not be a
846 /// lockstep event. The renderer's wildcard is not a hole: [`Fill`] is
847 /// resolved through a fallible lookup, and a missing intent is answered with
848 /// structure rather than with a substituted colour.
849 ///
850 /// [`Sunken`]: Fill::Sunken
851 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
852 #[non_exhaustive]
853 pub enum Fill {
854 /// The page behind everything.
855 Page,
856 /// A surface lifted off the page: cards, controls, menus, toasts.
857 Raised,
858 /// A surface floating above the page rather than resting on it.
859 Overlay,
860 /// The inside of a well.
861 Well,
862 /// A surface set back from the one it sits on, by colour and nothing else.
863 ///
864 /// Not a well. A well is a hole with an edge, and the two are authored in
865 /// opposite directions: `makeover` derives `surface-well` by inverting
866 /// against the theme's own content colour, while `surface-sunken` is
867 /// authored and free to sit darker than raised (goingson's does). Naming
868 /// only the well left the recessed-with-no-edge surface unsayable, which is
869 /// what an unchosen tab is: it recedes so the chosen one can come forward,
870 /// and it carries no bevel of its own.
871 ///
872 /// Added 0.3.0, from goingson's tab strip, which hand-writes exactly this
873 /// and could not delete the line because no member described it.
874 Sunken,
875 }
876
877 // No `fallback` here, deliberately. An earlier cut had `Fill::Well` fall back
878 // to `Fill::Page` so a consumer on makeover 2.2.0, which has no `surface-well`,
879 // had something to paint. makeover-tui found that wrong within a day: page is
880 // the surface a well is usually cut into, so on a terminal that substitution
881 // produces exactly the invisibility it was meant to prevent, and the right
882 // answer there is a drawn edge rather than a different colour.
883 //
884 // Substituting one intent for another is renderer policy. The description says
885 // what the region is and stops.
886
887 impl Intent for Fill {
888 fn token(self) -> &'static str {
889 match self {
890 Self::Page => "surface-page",
891 Self::Raised => "surface-raised",
892 Self::Overlay => "surface-overlay",
893 Self::Well => "surface-well",
894 Self::Sunken => "surface-sunken",
895 }
896 }
897 }
898
899 /// How a region sits relative to the surface behind it.
900 ///
901 /// Fill and bevel are named together because naming them apart is what let
902 /// them disagree. Every consumer measured had at least one region carrying a
903 /// raised bevel over a recessed fill: audiofiles fixed it in `raised_frame`
904 /// and recorded the bug in its doc comment, and Balanced Breakfast still had
905 /// twelve of them a year later. A single name for the pair makes that
906 /// unrepresentable.
907 /// `#[non_exhaustive]` for the same reason as [`Fill`], and in the same
908 /// release: a depth this renderer has no drawing for should cost it a
909 /// wildcard arm, not a compile error and a wait on someone else's publish.
910 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
911 #[non_exhaustive]
912 pub enum Depth {
913 /// Level with its surroundings. No edge.
914 Flat,
915 /// A card laid on the panel it sits in.
916 Raised,
917 /// A hole in the panel, with content down inside it. For anything the
918 /// user looks *into*: a table body, a tag tree, a text field.
919 Well,
920 /// Set back from what it sits on, by colour alone. No edge.
921 ///
922 /// The one member carrying a fill without a bevel, so a renderer cannot
923 /// assume the two arrive together. That is deliberate and it is still the
924 /// pairing rule: both halves come off the same `Depth`, so they cannot
925 /// disagree, and here one half is legitimately absent.
926 ///
927 /// Distinct from [`Depth::Flat`], which has no fill either and inherits.
928 /// Recessed and level-with are different claims, and only one of them
929 /// needs a colour.
930 Sunken,
931 /// A surface sitting *over* the page rather than in it. A modal, a popover,
932 /// a menu.
933 ///
934 /// Takes elevation and no bevel: a surface overlaying the page is lifted
935 /// off it, and a surface in the page is cut into it. That is the same
936 /// pairing rule the rest of the enum holds, applied to the one case where
937 /// the separation is not an edge at all — the lift and the scrim behind it
938 /// are already saying where the surface is.
939 ///
940 /// Every renderer had the surface before it had this variant.
941 /// `makeover-tui` carries `Palette::overlay`, `makeover-immediate` gained
942 /// `Palette::elevation` at 0.10.0, and `makeover-webview` emits
943 /// `--elevation-overlay`. What was missing was the route from a description
944 /// to any of them, which is why this is one variant rather than a feature.
945 Overlay,
946 }
947
948 impl Depth {
949 /// The edge this depth is drawn with, if it has one.
950 #[must_use]
951 pub const fn bevel(self) -> Option<Bevel> {
952 match self {
953 // Sunken joins Flat here, for the opposite reason: Flat has no edge
954 // because nothing separates it from its surroundings, and Sunken has
955 // none because its colour is already doing the separating.
956 Self::Flat | Self::Sunken => None,
957 // A third reason to have no edge, which is why it gets its own arm
958 // rather than joining the two above: an overlay is separated by the
959 // lift and by the scrim behind it, so an edge would be a second
960 // answer to a question already answered.
961 Self::Overlay => None,
962 Self::Raised => Some(Bevel::Raised),
963 Self::Well => Some(Bevel::Inset),
964 }
965 }
966
967 /// The surface this depth is filled with.
968 ///
969 /// [`Depth::Flat`] has no fill of its own: it inherits whatever it sits on,
970 /// which is the difference between level-with and painted-the-same-colour.
971 #[must_use]
972 pub const fn fill(self) -> Option<Fill> {
973 match self {
974 Self::Flat => None,
975 Self::Raised => Some(Fill::Raised),
976 Self::Well => Some(Fill::Well),
977 Self::Sunken => Some(Fill::Sunken),
978 Self::Overlay => Some(Fill::Overlay),
979 }
980 }
981
982 /// Pressing a raised region reads as a well, and nothing else moves.
983 ///
984 /// [`Depth::Overlay`] is untouched along with the rest: an overlay is a
985 /// surface, not a control, so there is nothing there to press.
986 #[must_use]
987 pub const fn pressed(self) -> Self {
988 match self {
989 Self::Raised => Self::Well,
990 other => other,
991 }
992 }
993 }
994
995 /// An interaction state a region can be in, beside whatever [`Depth`] it is.
996 ///
997 /// Orthogonal to depth on purpose. A disabled button is still [`Depth::Raised`]
998 /// and a disabled field is still a [`Depth::Well`], so folding either member
999 /// into `Depth` would make [`Depth::bevel`] and [`Depth::fill`] answer for
1000 /// something that is not a depth, and would leave disabled-button and
1001 /// disabled-field sharing one variant that cannot tell them apart.
1002 ///
1003 /// # Why hover and pressed are not members
1004 ///
1005 /// The line is whether every renderer has the state to express, not whether CSS
1006 /// does. Hover is renderer policy and `makeover-webview` says so in its own
1007 /// header: a terminal and an immediate-mode painter have no pointer hovering
1008 /// over anything, and pressed already arrives through [`Bevel::pressed`] and
1009 /// [`Depth::pressed`], where it belongs, because pressing is a depth inversion
1010 /// rather than a separate condition.
1011 ///
1012 /// Focus and disabled are different in kind. A TUI has a focused widget and a
1013 /// greyed-out one; so does egui. Both were unsayable here, so all three webview
1014 /// consumers supplied them from outside the primitive by out-specifying rules
1015 /// they did not own: goingson alone carries 19 of them, and the MNW server
1016 /// another 21. That is the divergence this crate exists to end, arriving one
1017 /// layer down.
1018 ///
1019 /// # The principle this encodes
1020 ///
1021 /// A primitive owns every state it implies. A renderer that emits a hover rule
1022 /// for a thing owes disabled and the capability answer for that same thing,
1023 /// because anything less exports the completion work to N consumers who will
1024 /// each do it differently.
1025 ///
1026 /// Focus is not on that list and was removed from this axis in 0.19.0. It is
1027 /// the renderer's, decided after the description; see the crate header, "Reach,
1028 /// focus and the focus ring", for the three terms and who owns each.
1029 ///
1030 /// `#[non_exhaustive]` for the reason [`Fill`] and [`Depth`] carry it: growth
1031 /// must not be a lockstep event across the three renderers.
1032 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1033 #[non_exhaustive]
1034 pub enum State {
1035 /// Present, visible, and not answering.
1036 ///
1037 /// Not the same as absent, and deliberately not a [`Fill`]: a disabled
1038 /// control keeps the surface it always had and stops responding, so what
1039 /// changes is its content and its interactivity rather than what it is.
1040 Disabled,
1041 }
1042
1043 impl State {
1044 /// Whether a region in this state stops answering the pointer.
1045 ///
1046 /// Stated in the description rather than left to each renderer, on the same
1047 /// reasoning as [`Bevel::pressed`]: a cascade carries it for free and an
1048 /// immediate-mode renderer resolves it per call site, so leaving it unsaid
1049 /// means resolving it once per consumer and disagreeing.
1050 #[must_use]
1051 pub const fn suppresses_interaction(self) -> bool {
1052 // A match rather than a bare `true`, so a member added to this
1053 // `#[non_exhaustive]` axis has to answer the question rather than
1054 // inheriting an answer.
1055 match self {
1056 Self::Disabled => true,
1057 }
1058 }
1059 }
1060
1061 impl Intent for State {
1062 fn token(self) -> &'static str {
1063 match self {
1064 // Reusing the muted content intent rather than minting a
1065 // `disabled` colour. Disabled is a reduction and not a status, and
1066 // `makeover-webview`'s progress rules already record the reading
1067 // that `content-muted` is what disabled looks like.
1068 Self::Disabled => "content-muted",
1069 }
1070 }
1071 }
1072
1073 /// What a region is saying, when it is saying something.
1074 ///
1075 /// The one intent family shared by badges, notices and nothing else. Kept
1076 /// separate from [`Fill`] because a surface is where a thing sits and a tone is
1077 /// what it means, and the three apps agree on the four statuses:
1078 /// `info_banner` / `warning_banner` in audiofiles, `.toast-info` /
1079 /// `.toast-success` / `.toast-error` in goingson, `.toast.success` /
1080 /// `.toast.error` in Balanced Breakfast.
1081 ///
1082 /// The per-tag palette (`category-one` through `category-six`) is deliberately
1083 /// not here. Which colour a *particular* tag takes is app domain, and both
1084 /// webview apps already carry it as a `data-color` attribute.
1085 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1086 pub enum Tone {
1087 /// No status.
1088 ///
1089 /// Ordinary content, at full weight. It does not also mean muted: a
1090 /// badge reads quiet because [`Token::Badge`] answers no click, which is
1091 /// the renderer's knowledge and not this axis's. A renderer wanting a
1092 /// muted badge reaches for [`Token::interactive`] itself rather than
1093 /// expecting `Neutral` to have muted it.
1094 Neutral,
1095 /// Something worth knowing and nothing to do about it.
1096 Info,
1097 /// Something finished and it worked.
1098 Success,
1099 /// Something the user should look at before continuing.
1100 Warning,
1101 /// Something broken, or something about to be destroyed.
1102 Danger,
1103 }
1104
1105 impl Intent for Tone {
1106 fn token(self) -> &'static str {
1107 match self {
1108 // Neutral has no status token of its own, so it takes the plain
1109 // content intent. It used to answer `content-muted`, which read
1110 // "no status" as "de-emphasised" and muted every figure value in
1111 // the webview. Muting is a renderer's call about a particular
1112 // token, not something the status axis knows.
1113 Self::Neutral => "content",
1114 Self::Info => "info",
1115 Self::Success => "success",
1116 Self::Warning => "warning",
1117 Self::Danger => "danger",
1118 }
1119 }
1120 }
1121
1122 /// A small labelled thing that sits inside something else.
1123 ///
1124 /// Two members, because the three apps drew three taxonomies and only one line
1125 /// runs through all of them: does it answer a click. audiofiles has
1126 /// `classification_badge` (a label) against `tag_chip`, `tag_chip_removable`
1127 /// and `selectable_tag` (all of which do). Balanced Breakfast has `.tag` and
1128 /// `.badge` against `.tag-chip`. goingson is the one that has to move: its
1129 /// `.tag` and `.badge` are a single CSS rule, so every call site has to be read
1130 /// to decide which of the two it always was.
1131 ///
1132 /// The evidence that a chip is a real concept rather than a badge with a
1133 /// cursor: audiofiles inverts its bevel on press and Balanced Breakfast latches
1134 /// `.tag-chip.active` with the inset bevel. Two independent arrivals at "a chip
1135 /// holds itself down", which is exactly what [`Depth::pressed`] already says.
1136 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1137 pub enum Token {
1138 /// Non-interactive status or count. Answers no click.
1139 Badge,
1140 /// An interactive or removable token. Answers a click, and latches if it
1141 /// stands for a filter that is either on or off.
1142 Chip {
1143 /// Whether it carries its own remove affordance.
1144 removable: bool,
1145 },
1146 }
1147
1148 impl Token {
1149 /// Whether this answers a click.
1150 ///
1151 /// The whole difference between the two members, and the reason a renderer
1152 /// with no hover (a touch surface, a terminal) can still tell them apart.
1153 #[must_use]
1154 pub const fn interactive(self) -> bool {
1155 matches!(self, Self::Chip { .. })
1156 }
1157
1158 /// How it sits, given whether it is currently latched down.
1159 ///
1160 /// A badge is flat: it is a label, and giving it an edge would say it can
1161 /// be pressed. A chip is raised, and inset while latched.
1162 #[must_use]
1163 pub const fn depth(self, latched: bool) -> Depth {
1164 match self {
1165 Self::Badge => Depth::Flat,
1166 Self::Chip { .. } if latched => Depth::Well,
1167 Self::Chip { .. } => Depth::Raised,
1168 }
1169 }
1170 }
1171
1172 /// Something the app is telling the user, unprompted.
1173 ///
1174 /// Two concepts, not one with a placement. They differ in more than where they
1175 /// sit: a toast is transient, stacked and self-dismissing, and a banner is
1176 /// persistent, in flow, one per region, and dismissed by fixing the condition
1177 /// it reports. Folding them into one member with a placement parameter would
1178 /// make lifetime, stacking and dismissal all placement-dependent, which is the
1179 /// description leaking renderer policy.
1180 ///
1181 /// All three apps have banners: `info_banner` and `warning_banner` in
1182 /// audiofiles, five of them in goingson (sync, sync-result, vacation-day,
1183 /// timer-active, past-review), `.update-banner` in Balanced Breakfast. The two
1184 /// webview apps also have toasts. So neither member is speculative, and no app
1185 /// gains a concept it lacks except audiofiles, whose renderer may legitimately
1186 /// decline to draw a toast at all.
1187 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1188 pub enum Notice {
1189 /// Transient, stacked, dismisses itself.
1190 Toast,
1191 /// Persistent, in flow, one per region, dismissed by fixing the cause.
1192 Banner,
1193 }
1194
1195 impl Notice {
1196 /// Whether it goes away on its own.
1197 #[must_use]
1198 pub const fn transient(self) -> bool {
1199 matches!(self, Self::Toast)
1200 }
1201
1202 /// How it sits.
1203 ///
1204 /// A toast floats above the page rather than resting on it, which is
1205 /// [`Fill::Overlay`]'s whole reason to exist. A banner is a card in the
1206 /// flow. Both are raised, and they are raised off different things.
1207 #[must_use]
1208 pub const fn fill(self) -> Fill {
1209 match self {
1210 Self::Toast => Fill::Overlay,
1211 Self::Banner => Fill::Raised,
1212 }
1213 }
1214 }
1215
1216 /// The parts of a list row.
1217 ///
1218 /// Four to begin with, taken from Balanced Breakfast, which was the only
1219 /// consumer that had all of them (`row-primary`, `row-secondary`, `row-meta`,
1220 /// `row-actions`). audiofiles has two and no slot structure at all, so it gains
1221 /// meta and actions as real work rather than a rename; goingson moves off
1222 /// `task-row` / `task-cell`.
1223 ///
1224 /// [`Tokens`](Self::Tokens) joined at 0.9.0, and `#[non_exhaustive]` with it.
1225 /// See the crate header for why the two arrived together.
1226 ///
1227 /// # Meta against Tokens
1228 ///
1229 /// The line is whether the thing has its own standing. `Meta` is one short
1230 /// trailing fact about the row, written as text: a count, a size, a date.
1231 /// `Tokens` is a set of small labelled things, each of which can be toned and
1232 /// can answer a click. "3 files" is meta. A status badge that is amber, and a
1233 /// tag you can click to filter by, are tokens.
1234 ///
1235 /// Keeping them apart is what a single widened slot would have foreclosed. A
1236 /// renderer can right-align one string and cannot usefully do the same to a
1237 /// strip of chips, and a fact that is not clickable should not be drawn as
1238 /// though it were.
1239 /// How much vertical room a part's text may take.
1240 ///
1241 /// A row is an inline run and every part in it is a leaf, so a part's text has
1242 /// always been drawn on one line and no description could say otherwise. Two
1243 /// apps say otherwise in their own stylesheets, both to the same number and
1244 /// both with a comment explaining it: Balanced Breakfast clamps a feed row's
1245 /// title to two lines (`.row--article .row-primary`, whose comment reads
1246 /// "overrides .row-primary's single flex line"), and goingson clamps a
1247 /// problem's body to two ("two lines is enough to recognize one, and the full
1248 /// text is in the task once promoted").
1249 ///
1250 /// Two named tiers rather than a line count, and the count is what the measured
1251 /// demand argues against. Both sites want exactly one tier past the default,
1252 /// and a number invites a row whose primary is a paragraph, which is a block
1253 /// and has no business in a run. A third tier is a decision, made here, rather
1254 /// than something a call site can reach for.
1255 ///
1256 /// What a renderer owes it: `Tight` is what a run already does and needs no
1257 /// answer. `Relaxed` is at most two lines and then truncation, however that
1258 /// renderer truncates -- a webview clamps, a terminal wraps into two rows of
1259 /// cells, an immediate-mode renderer caps the galley. A renderer that cannot
1260 /// give two lines may draw one; what it may not do is grow without bound,
1261 /// because the run is a line and the row's neighbours are relying on that.
1262 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
1263 #[non_exhaustive]
1264 pub enum Flow {
1265 /// One line. What every part did before this type existed.
1266 #[default]
1267 Tight,
1268 /// Up to two lines, then truncated.
1269 Relaxed,
1270 }
1271
1272 impl Flow {
1273 /// How many lines the part may take.
1274 ///
1275 /// A number here rather than in the enum, because a renderer needs one and
1276 /// a call site does not. That asymmetry is the whole argument for the
1277 /// tiers: the description says how much room the thing deserves and this
1278 /// says what that costs, so a third tier changes one line rather than every
1279 /// consumer's arithmetic.
1280 #[must_use]
1281 pub const fn lines(self) -> u8 {
1282 match self {
1283 Self::Relaxed => 2,
1284 // Including any tier added later: one line is the safe reading of
1285 // an unknown flow, since it is what the run guaranteed before flows
1286 // existed.
1287 _ => 1,
1288 }
1289 }
1290 }
1291
1292 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1293 #[non_exhaustive]
1294 pub enum RowPart {
1295 /// The thing itself. What the row is called.
1296 Primary,
1297 /// Supporting text under the primary.
1298 Secondary,
1299 /// A short trailing fact: a count, a size, a date.
1300 Meta,
1301 /// Controls that act on this row.
1302 Actions,
1303 /// Small labelled things belonging to the row: badges, chips, tags.
1304 ///
1305 /// Each carries its own [`Token`] kind and [`Tone`], so a renderer with no
1306 /// colour still has the kind to work with, and one with no chips still has
1307 /// the label. That is the constrained-consumer test this vocabulary exists
1308 /// to pass, and it is why the tone lives on the token rather than on the
1309 /// part.
1310 Tokens,
1311 /// How much of a set the row's thing has done: a [`Meter`] in the row.
1312 ///
1313 /// Added 0.11.0, `da5666ae`, and it is [`Tokens`](Self::Tokens)'s problem
1314 /// again with a different payload. [`Meter`] arrived at 0.10.0 and closed
1315 /// two of the seven sites that asked for it; the other five sit in rows, and
1316 /// a row holds no nodes by the ruling that a row part may not carry an
1317 /// arbitrary node — the door through which a description becomes a
1318 /// templating language. So the part carries the *description of a bar*
1319 /// rather than a node, exactly as `Tokens` carries tags rather than nodes.
1320 ///
1321 /// Without it a row flattens the proportion into [`Meta`](Self::Meta) as
1322 /// "3/7 subtasks", which keeps both numbers and loses the reading, the same
1323 /// way a toned status badge read as prose before `Tokens`.
1324 Proportion,
1325 }
1326
1327 impl RowPart {
1328 /// What the part is worth when the run does not fit.
1329 ///
1330 /// The default only. A part may say otherwise, and a renderer reads the
1331 /// part rather than the role; this is what a description that has never
1332 /// heard of [`Priority`] means, which is every description written before
1333 /// the field existed.
1334 ///
1335 /// Deriving it from the role is the thing this vocabulary has otherwise
1336 /// been moving away from, and it is right here for one reason: the roles
1337 /// already encode this ranking and every consumer already assumes it.
1338 /// [`Primary`](Self::Primary) is what the row is called, and
1339 /// [`Priority::Essential`]'s own doc was written about exactly that --
1340 /// "without it the row does not identify itself".
1341 ///
1342 /// [`Actions`](Self::Actions) is `Essential` and it is the interesting one.
1343 /// A control is not a fact, so dropping it does not cost the reader a
1344 /// detail; it costs them the only way to act on the row, and in a terminal
1345 /// it silently removes something focus had already been claimed for. A
1346 /// renderer that needs room takes it from what the row *says*, never from
1347 /// what it *offers*.
1348 ///
1349 /// An unknown member reads as [`Priority::Secondary`]: droppable, but not
1350 /// first, since guessing `Optional` for something this crate has not been
1351 /// taught would make a new member the first thing to vanish.
1352 #[must_use]
1353 pub const fn priority(self) -> Priority {
1354 match self {
1355 Self::Primary | Self::Actions => Priority::Essential,
1356 Self::Meta | Self::Proportion => Priority::Optional,
1357 _ => Priority::Secondary,
1358 }
1359 }
1360
1361 /// The content intent the part takes.
1362 #[must_use]
1363 pub const fn intent(self) -> &'static str {
1364 match self {
1365 Self::Primary => "content",
1366 Self::Secondary => "content-secondary",
1367 Self::Meta => "content-muted",
1368 // Actions carry controls rather than text, so they inherit.
1369 Self::Actions => "content",
1370 // So do tokens: each one carries its own tone, and a part-level
1371 // intent underneath it would fight the token that sits on it.
1372 Self::Tokens => "content",
1373 // And so does a proportion, for the same reason: the meter carries
1374 // the tone, and it is about the ratio rather than about the row.
1375 Self::Proportion => "content",
1376 }
1377 }
1378 }
1379
1380 /// How far down the heading tree a title sits.
1381 ///
1382 /// Three, and only the three that are actually headings. The bands those used
1383 /// to be filed with (goingson's `.page-header`, Balanced Breakfast's `.header`
1384 /// and `.detail-header`) are arrangement, not type, and live at
1385 /// [`Region::Band`]. One of them contains no text at all.
1386 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1387 pub enum Heading {
1388 /// Names the whole screen. One per screen.
1389 Page,
1390 /// Names a block within the screen.
1391 Section,
1392 /// Names a sub-block inside an already-named section.
1393 Subsection,
1394 }
1395
1396 impl Heading {
1397 /// Whether a rule follows the heading.
1398 ///
1399 /// audiofiles' `section_header` draws a separator and its
1400 /// `subsection_label` deliberately does not, which is the only thing
1401 /// distinguishing the two once weight and colour are deferred.
1402 #[must_use]
1403 pub const fn separated(self) -> bool {
1404 matches!(self, Self::Section)
1405 }
1406 }
1407
1408 /// A control that picks between things.
1409 ///
1410 /// Three, because three distinct behaviours are in play and collapsing any two
1411 /// loses something. A segmented control picks a value; a tab picks a pane; a
1412 /// toggle picks nothing and simply holds itself on or off.
1413 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1414 pub enum Selector {
1415 /// Exactly one of N, and the options abut.
1416 Segmented,
1417 /// Independent on or off, on its own.
1418 Toggle,
1419 /// Navigation between panes. The folder semantic.
1420 Tabs,
1421 }
1422
1423 impl Selector {
1424 /// How the chosen option sits.
1425 ///
1426 /// Held in for a segmented control and a toggle, which is the same shape
1427 /// pressing produces and the whole economy of the idiom: one appearance,
1428 /// two reasons to wear it. A tab is the exception, because the selected
1429 /// folder tab comes *forward* to join the pane it opens.
1430 #[must_use]
1431 pub const fn chosen(self) -> Depth {
1432 match self {
1433 Self::Segmented | Self::Toggle => Depth::Well,
1434 Self::Tabs => Depth::Raised,
1435 }
1436 }
1437
1438 /// How the options that were *not* picked sit.
1439 ///
1440 /// Added 0.3.0. Describing only [`Selector::chosen`] left the unchosen
1441 /// option falling through to [`Depth::Flat`], which says it is level with
1442 /// the strip it sits in, and no renderer emitted anything for it. That is
1443 /// wrong in both directions and goingson proved it: its unchosen tabs are
1444 /// recessed by hand, and being recessed is *why* the chosen one reads as
1445 /// coming forward. Against a flat strip, a raised chosen tab is a bevel
1446 /// drawn on the strip's own colour, which is a much weaker folder effect
1447 /// than the contrast the idiom is named after.
1448 ///
1449 /// Each member is the inverse of its chosen state, which is the whole
1450 /// content of "picked" once colour is deferred:
1451 ///
1452 /// - Tabs recede, so the chosen one comes forward.
1453 /// - A segment and a toggle stand up, so the chosen one is held in.
1454 #[must_use]
1455 pub const fn unchosen(self) -> Depth {
1456 match self {
1457 Self::Tabs => Depth::Sunken,
1458 Self::Segmented | Self::Toggle => Depth::Raised,
1459 }
1460 }
1461
1462 /// Whether the options touch.
1463 ///
1464 /// The gap is the entire difference between a segmented control and a row
1465 /// of buttons that happen to sit near each other, which is what audiofiles'
1466 /// `segmented_control` says in its own comment and why it zeroes the
1467 /// spacing by hand.
1468 #[must_use]
1469 pub const fn abutting(self) -> bool {
1470 matches!(self, Self::Segmented | Self::Tabs)
1471 }
1472 }
1473
1474 /// What is in a region right now.
1475 ///
1476 /// The state, not the shimmer. Whether pending paints a skeleton, a spinner or
1477 /// nothing at all is renderer policy, the same class of decision that got
1478 /// `Fill::fallback` deleted from this crate. goingson and Balanced Breakfast
1479 /// each grew a skeleton with differently-named parts; both keep them, as the
1480 /// webview renderer's expression of [`Readiness::Pending`]. audiofiles has none
1481 /// and needs none, because an immediate-mode renderer simply repaints.
1482 ///
1483 /// # Four states and not two, as of 0.12.0
1484 ///
1485 /// `703f4cd2`. It named `Ready` and `Pending` and stopped, so a described screen
1486 /// whose list came back empty had to render an empty region or invent its own
1487 /// placeholder text, and neither says what it is. goingson draws one at 27 sites
1488 /// across 12 files and Balanced Breakfast at 9, with a class family that had
1489 /// already drifted into `empty-state`, `empty-state--error`, `error-state` and
1490 /// six more.
1491 ///
1492 /// The four are one axis because they are mutually exclusive: a region shows its
1493 /// content, or a sign that it is coming, or a sign that there is none, or a sign
1494 /// that it broke. Never two. That is the test for one enum against several
1495 /// fields, and it is why this grew rather than a new member arriving beside it.
1496 ///
1497 /// # What is not here
1498 ///
1499 /// **The message.** "No projects yet" is content, and this names a state. It
1500 /// lives with whatever holds the region — in quasi's case a `Slot` — alongside
1501 /// the action that leads out of the emptiness, since an address is the one thing
1502 /// this crate never names.
1503 ///
1504 /// **How much room it gets.** goingson's `--compact`, `--dashboard` and
1505 /// `--padded` are the same state at three sizes, and a size is
1506 /// `makeover-geometry`'s question. Naming them here would be this crate stating
1507 /// values again.
1508 ///
1509 /// **The icon.** Presentation, and each host has its own answer or none.
1510 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1511 #[non_exhaustive]
1512 pub enum Readiness {
1513 /// The content is here.
1514 Ready,
1515 /// The content is on its way.
1516 ///
1517 /// For a region that changes *after* the first paint, and never for the
1518 /// first paint itself: see "First paint is final paint" in the crate header.
1519 /// A host that renders once, with its data already in hand, has nothing to
1520 /// say this about, and a screen arriving in this state is describing a
1521 /// moment its host should not have been in.
1522 ///
1523 /// What stands in occupies the geometry the content will occupy. A stand-in
1524 /// sized to itself rather than to what replaces it is the reflow the rule
1525 /// forbids, arriving one repaint later.
1526 Pending,
1527 /// The content arrived and there is none of it.
1528 ///
1529 /// Not a failure. An empty list is the normal state of a new install, and a
1530 /// renderer that drew it in a danger tone would be reporting a fault where
1531 /// there is none.
1532 Empty,
1533 /// The content did not arrive.
1534 Failed,
1535 }
1536
1537 impl Readiness {
1538 /// Whether the region draws its own content, or something standing in for
1539 /// it.
1540 ///
1541 /// The question every renderer asks first, so it is answered once here
1542 /// rather than by a `matches!` in each. A state added later is a stand-in
1543 /// until proven otherwise: falling back to drawing content that may not be
1544 /// there is the worse of the two mistakes.
1545 #[must_use]
1546 pub const fn shows_content(self) -> bool {
1547 matches!(self, Self::Ready)
1548 }
1549
1550 /// What the state means, for a renderer choosing a colour.
1551 ///
1552 /// Derived rather than carried, which is the opposite of [`Meter`] and
1553 /// [`Figure`], and the difference is worth stating: a proportion's meaning
1554 /// depends on what is being counted and only the app knows it, while
1555 /// "nothing here yet" and "this broke" mean the same thing in every app that
1556 /// will ever have them.
1557 #[must_use]
1558 pub const fn tone(self) -> Tone {
1559 match self {
1560 Self::Failed => Tone::Danger,
1561 _ => Tone::Neutral,
1562 }
1563 }
1564 }
1565
1566 /// An action is waiting on something that resolves once, in expected finite
1567 /// time.
1568 ///
1569 /// The control-side sibling of [`Readiness`]. That enum names four states for a
1570 /// region and named nothing at all for the button that is currently doing what
1571 /// it was clicked for, so the in-flight treatment is hand-written wherever it
1572 /// exists: the MNW server carries 57 in-flight indicators against 2 guards
1573 /// against a second press, which is the spinner mostly present and the guard
1574 /// mostly absent, on a codebase whose money path is a purchase button.
1575 ///
1576 /// # What is described here, and what is not
1577 ///
1578 /// The fact is that there is an outstanding thing which will complete. Not that
1579 /// the address is remote: a heavy local query waits too, and a server calling a
1580 /// payment provider is not the browser leaving the app. Not that the call is
1581 /// slow either, which is a judgement about a call rather than a property of one.
1582 ///
1583 /// Resolving **once** is the boundary, and it is what separates this from a
1584 /// screen that keeps changing. A live screen never resolves and has no name in
1585 /// this crate yet.
1586 ///
1587 /// # One mark, two renderings
1588 ///
1589 /// | what reads it | what it does |
1590 /// |---|---|
1591 /// | a control that was pressed | goes busy and refuses a second press until it resolves |
1592 /// | a region fed by it | stands in as [`Readiness::Pending`], then fills |
1593 ///
1594 /// The two were on the table separately and both were taken. Controls alone
1595 /// leaves a slow region hand-split into its own route, which is what MNW's user
1596 /// dashboard does with its payout summary; regions alone leaves the purchase
1597 /// button unguarded.
1598 ///
1599 /// # A quantity when it is measured, never a duration
1600 ///
1601 /// [`amount`](Self::amount) is stated only when it is a measured fact about the
1602 /// payload. An upload's file length, yes; a round trip to a payment provider,
1603 /// [`None`]. A duration is described nowhere, and a renderer may not manufacture
1604 /// one from the amount either: a determinate bar shows what is done over what
1605 /// there is, plus the time it has taken so far, and never a remaining time, an
1606 /// arrival time or a rate extrapolated forwards. A prediction is wrong the
1607 /// moment the transfer stalls, and being confidently wrong is worse than being
1608 /// honestly indeterminate.
1609 ///
1610 /// This is why the crate refuses to say how long an undo stays offered and
1611 /// accepts a byte count here. The refusal is about naming a decision that
1612 /// belongs to the renderer; a file's length is not a decision, nobody chose it.
1613 ///
1614 /// # Not [`Meter`]
1615 ///
1616 /// [`Meter`] is how much of a set is done, and its own docs refuse the progress
1617 /// of an operation on the grounds that a description is built once and dropped
1618 /// while an operation runs between renders. That refusal stands. This names the
1619 /// operation and its size, which is all that is known before it starts; how much
1620 /// of it has gone through is the renderer's to observe live, and nothing round
1621 /// trips through a description to say so.
1622 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
1623 #[non_exhaustive]
1624 pub struct Awaiting {
1625 /// Total work to get through, when it is a measured fact about the payload.
1626 ///
1627 /// `None` when the wait has no countable size, which is the common case and
1628 /// the default.
1629 ///
1630 /// Unit-agnostic on purpose. Bytes for an upload, rows for an import; what
1631 /// is being counted is the app's business and a renderer draws a proportion
1632 /// either way.
1633 pub amount: Option<u64>,
1634 }
1635
1636 impl Awaiting {
1637 /// A wait with no countable size.
1638 #[must_use]
1639 pub const fn unmeasured() -> Self {
1640 Self { amount: None }
1641 }
1642
1643 /// A wait whose size is known.
1644 ///
1645 /// Reach for it only with a measured figure. An estimate written in here is
1646 /// a prediction wearing a fact's clothes, and the renderer has no way to
1647 /// tell the two apart.
1648 #[must_use]
1649 pub const fn of(amount: u64) -> Self {
1650 Self {
1651 amount: Some(amount),
1652 }
1653 }
1654
1655 /// Whether there is a proportion to draw.
1656 ///
1657 /// The question every renderer asks first, answered once here rather than by
1658 /// a `matches!` in each. False means indeterminate, which is the honest
1659 /// drawing when nothing countable was measured.
1660 #[must_use]
1661 pub const fn is_determinate(self) -> bool {
1662 self.amount.is_some()
1663 }
1664 }
1665
1666 /// How much of a set is done.
1667 ///
1668 /// Added 0.10.0. Nine sites across the two webview apps drew a bar and nothing
1669 /// here named one, so every described screen concatenated the two numbers into
1670 /// its heading text instead: "Subtasks 3/7", "Time Tracking 45m tracked / 30m
1671 /// est, over". Every fact survives that and the reading does not, which is the
1672 /// same loss `RowPart::Tokens` closed when a toned status badge became prose.
1673 ///
1674 /// # Why a pair and not a percentage
1675 ///
1676 /// Both numbers, not the percentage the apps compute from them. The percentage
1677 /// was the obvious shape and it had already been tried: goingson's
1678 /// `Task::time_progress` divides, rounds, and then clamps to 100, which throws
1679 /// away the one case the bar exists to show — 45 minutes tracked against a
1680 /// 30-minute estimate. It carries a separate `is_over_estimate` boolean beside
1681 /// it to recover the fact the clamp dropped. A pair keeps the over-run without a
1682 /// companion flag, and [`percent`](Meter::percent) is still one call away for a
1683 /// renderer that wants it.
1684 ///
1685 /// The pair is also what the apps already have at every site. All seven
1686 /// determinate bars write the ratio into the accessible layer and never the
1687 /// percentage: `title="3/7 subtasks"`, `aria-label="3 of 7 subtasks completed"`,
1688 /// a milestone's own `3/7` span. Given 43 nothing can recover "3 of 7", so a
1689 /// percentage member would have made [`label`](Meter::label) mandatory at every
1690 /// call site, which is the concatenated text this member removes, moved one
1691 /// layer down.
1692 ///
1693 /// # What this is not
1694 ///
1695 /// The progress of an *operation*. Two of the nine sites are that — goingson's
1696 /// focus timer, Balanced Breakfast's feed fetch — and they get nothing here, on
1697 /// purpose. Both are imperative controllers over a live handle, driven by a tick
1698 /// or an event stream, and a description is built once and dropped. Holding one
1699 /// would mean growing a way to update a description between renders, which is a
1700 /// different feature. [`Readiness::Pending`] and a [`Notice::Toast`] carry the
1701 /// honest part.
1702 ///
1703 /// The two cases are distinguishable in the markup rather than by taste: every
1704 /// determinate bar in both apps carries a tone, and neither operation bar
1705 /// carries one. Two codebases drew that line the same way without coordinating.
1706 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1707 pub struct Meter<'a> {
1708 /// How much is done. May exceed [`total`](Self::total), and that is the
1709 /// case worth drawing.
1710 pub done: u32,
1711 /// How much there is to do. Zero means there is no set, not that the set is
1712 /// complete.
1713 pub total: u32,
1714 /// What the proportion means right now.
1715 ///
1716 /// Carried rather than derived, because no renderer can work it out. The
1717 /// same 90% is [`Tone::Success`] on a subtask rollup and [`Tone::Danger`] on
1718 /// a time estimate, and goingson picks between them from `is_over_estimate`,
1719 /// a fact about the data and not about the number.
1720 pub tone: Tone,
1721 /// What is being counted, if the bar says so: "subtasks", "tasks".
1722 ///
1723 /// The noun, not the ratio. A renderer builds "3 of 7 subtasks" from this
1724 /// and the two numbers; handing it the assembled string would put the
1725 /// sentence order in the description, where a terminal at one line and a
1726 /// tooltip want different ones.
1727 pub label: Option<&'a str>,
1728 }
1729
1730 impl<'a> Meter<'a> {
1731 /// A proportion with no tone and no label.
1732 #[must_use]
1733 pub const fn new(done: u32, total: u32) -> Self {
1734 Self {
1735 done,
1736 total,
1737 tone: Tone::Neutral,
1738 label: None,
1739 }
1740 }
1741
1742 /// What the proportion means.
1743 #[must_use]
1744 pub const fn tone(mut self, tone: Tone) -> Self {
1745 self.tone = tone;
1746 self
1747 }
1748
1749 /// What is being counted.
1750 #[must_use]
1751 pub const fn label(mut self, label: &'a str) -> Self {
1752 self.label = Some(label);
1753 self
1754 }
1755
1756 /// How full the bar is, 0 to 100, clamped.
1757 ///
1758 /// For drawing, which is the only thing a clamped number is good for. Ask
1759 /// [`overflowing`](Self::overflowing) before reporting it as a fact, or this
1760 /// is `time_progress`'s bug again with the clamp moved.
1761 ///
1762 /// An empty set reads as 0. Nothing is done, because there is nothing to do
1763 /// and no bar to fill; the apps guard on the count before drawing at all.
1764 #[must_use]
1765 pub const fn percent(&self) -> u8 {
1766 if self.total == 0 {
1767 return 0;
1768 }
1769 let scaled = (self.done as u64 * 100) / self.total as u64;
1770 if scaled > 100 { 100 } else { scaled as u8 }
1771 }
1772
1773 /// Whether more is done than there was to do.
1774 ///
1775 /// The fact [`percent`](Self::percent) destroys, kept reachable so a
1776 /// renderer can mark the over-run rather than drawing a full bar and
1777 /// implying it landed exactly.
1778 #[must_use]
1779 pub const fn overflowing(&self) -> bool {
1780 self.done > self.total
1781 }
1782
1783 /// Whether there is a set at all.
1784 ///
1785 /// A meter over nothing is sayable on purpose, for the same reason a field
1786 /// with no options is: it is what an app with an unloaded count actually
1787 /// has, and a renderer that shows an empty bar says so on screen rather than
1788 /// dividing by zero.
1789 #[must_use]
1790 pub const fn is_empty(&self) -> bool {
1791 self.total == 0
1792 }
1793 }
1794
1795 /// One figure with a caption: a number and what it counts.
1796 ///
1797 /// The dashboard shape. A large value over a small caption, several of them in a
1798 /// strip: a current streak, a completion rate, a total. Added 0.11.0,
1799 /// `93c6a174`, after goingson turned out to have five of them across five
1800 /// screens with five class vocabularies for the one shape — `task-overview-stat`,
1801 /// `stat-box`, `month-stat-item`, `contact-summary-stat`, `sync-stat`. Four put
1802 /// the value above the caption and one inverts it, which is drift inside the
1803 /// shape rather than a second shape.
1804 ///
1805 /// # Why the value is text
1806 ///
1807 /// "17", "84%", "12/30", "3d". A figure is whatever the app computed, already
1808 /// formatted, and the formatting is the app's because only it knows whether the
1809 /// number is a percentage, a duration or a ratio. This carries none of the
1810 /// arithmetic [`Meter`] carries, and that is the difference between them: a
1811 /// meter is a proportion a renderer draws, and a figure is a fact a renderer
1812 /// sets in type.
1813 ///
1814 /// # Tone is carried, for [`Meter`]'s reason
1815 ///
1816 /// Three of the five sites tone the figure by their own means — `red`/`blue` on
1817 /// the weekly review, a `${type}` class on the monthly one, `sync-stat-warn` on
1818 /// sync. So tone is carried at every site that needs it and derived at none, and
1819 /// no renderer can work out that a streak of zero is worth colouring.
1820 ///
1821 /// # What is not here
1822 ///
1823 /// Whether the figure answers a click. One of the five is a control — sync's
1824 /// "Not Applied: 3" opens the list — and an action is not something this crate
1825 /// can name: nothing here knows what a route is. That belongs beside the figure
1826 /// in whatever layer holds the actions, the same way a row's activation sits
1827 /// beside its parts rather than inside them.
1828 ///
1829 /// The arrangement is not here either. Several figures in a strip is a set, and
1830 /// a renderer given them one at a time cannot tell it is looking at one; the
1831 /// layer that holds the tree is where the set gets said.
1832 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1833 pub struct Figure<'a> {
1834 /// The number, formatted the way the app means it to read.
1835 pub value: &'a str,
1836 /// What it counts. The caption under the value.
1837 pub caption: &'a str,
1838 /// How the value has moved, if the app is tracking that.
1839 ///
1840 /// Added 0.13.0. Text, for [`value`](Self::value)'s reason: only the app
1841 /// knows whether a move reads as `+12.5%`, `+3` or `2x`, and a renderer
1842 /// handed a number would have to guess.
1843 ///
1844 /// This is what [`tone`](Self::tone) was for and had no consumer of. The MNW
1845 /// server has four screens whose stat card is a label, a value and a delta,
1846 /// and the delta is the toned part: the figure itself is an ordinary fact
1847 /// and it is the movement that reads as good or bad. Without this the delta
1848 /// has to be folded into the caption, which loses the tone and reads as a
1849 /// longer caption rather than as a second, smaller line.
1850 pub change: Option<&'a str>,
1851 /// What the figure means right now. [`Tone::Neutral`] is an ordinary fact.
1852 ///
1853 /// Applies to [`change`](Self::change) where there is one, since that is the
1854 /// part that carries the judgement, and to the value where there is not.
1855 pub tone: Tone,
1856 }
1857
1858 impl<'a> Figure<'a> {
1859 /// A figure that is an ordinary fact.
1860 #[must_use]
1861 pub const fn new(value: &'a str, caption: &'a str) -> Self {
1862 Self {
1863 value,
1864 caption,
1865 change: None,
1866 tone: Tone::Neutral,
1867 }
1868 }
1869
1870 /// How the value has moved.
1871 #[must_use]
1872 pub const fn change(mut self, change: &'a str) -> Self {
1873 self.change = Some(change);
1874 self
1875 }
1876
1877 /// What the figure means.
1878 #[must_use]
1879 pub const fn tone(mut self, tone: Tone) -> Self {
1880 self.tone = tone;
1881 self
1882 }
1883 }
1884
1885 /// Something the user can do, and what it costs to say so.
1886 ///
1887 /// Added 0.17.0, out of `quasi-tui`: the terminal renderer had drawn one of
1888 /// these for months and every other consumer that wanted a button had written
1889 /// its own, because this layer named [`RowPart::Actions`] as a *slot* and never
1890 /// named the thing that goes in it. Beside [`Meter`] and [`Figure`] for the
1891 /// reason those are here: a renderer that is handed the parts has to decide how
1892 /// to say them, and a renderer that is handed a finished string has already had
1893 /// the decision made for it.
1894 ///
1895 /// No address. Where a control goes is the app's business and every host
1896 /// follows it differently — an `hx-get`, a protocol URL, a function call — so
1897 /// the description says what the control *is* and the caller keeps what it
1898 /// does. That is the same split [`Choice`] makes.
1899 ///
1900 /// No confirmation flag either, and that one is a finding rather than an
1901 /// omission: a question asked *after* a control is pressed belongs to whatever
1902 /// is holding the interaction, and a renderer that drew it would be asking
1903 /// before there was anything to answer.
1904 /// How a picture sits in the box it is given.
1905 ///
1906 /// An intent rather than a value, so a renderer picks the expression it has:
1907 /// `object-fit` in a webview, a texture's UV rect in egui, and in a terminal a
1908 /// choice about how many cells the blit gets. Named because MNW already makes
1909 /// the distinction deliberately at 17 sites and makes it three different ways,
1910 /// which is a policy the app decided rather than one a shared crate would be
1911 /// picking by accident.
1912 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
1913 #[non_exhaustive]
1914 pub enum Fit {
1915 /// The picture's own proportions, and the box takes the height they imply.
1916 ///
1917 /// The default because it is the only one that shows the whole picture at
1918 /// its own shape, so a renderer that ignores this enum entirely is still
1919 /// right about the common case. A screenshot wants this; the shipped MNW
1920 /// carousel sets no `object-fit` at all, which is this.
1921 #[default]
1922 Natural,
1923 /// Fill the box and crop whatever does not fit.
1924 ///
1925 /// For a picture in a slot whose shape the layout fixed: a thumbnail, an
1926 /// avatar, cover art. 15 of MNW's 17 sites.
1927 Cover,
1928 /// Fit inside the box whole, leaving space on two sides.
1929 ///
1930 /// The letterbox. For when the whole picture matters more than filling the
1931 /// space, and the space is not the picture's shape.
1932 Contain,
1933 }
1934
1935 /// A picture, and what it says to someone who is not looking at it.
1936 ///
1937 /// # No source
1938 ///
1939 /// [`Act`]'s split, for [`Act`]'s reason. A source is an address, and this
1940 /// crate has no notion of an address: it says what a thing *is* and the caller
1941 /// keeps what it points at. The three findings dropped from 0.11.0 were all
1942 /// this same shape.
1943 ///
1944 /// It matters more here than it does for a control, because a picture is the
1945 /// one member where the address is most of what a webview needs and *none* of
1946 /// what the description knows. `quasi_router::Node::Image` carries the URL, the
1947 /// way it carries an `Action` for a control.
1948 ///
1949 /// # Why [`alt`](Self::alt) is not optional
1950 ///
1951 /// Every other host has to draw something, and for two of the three the alt
1952 /// text is not a fallback but the whole rendering: a terminal without a
1953 /// graphics protocol has the words and nothing else. Making it optional would
1954 /// make "this picture is invisible on a terminal" the default, and the
1955 /// description would be carrying a webview assumption in its shape.
1956 ///
1957 /// An image that genuinely says nothing — a rule, a spacer, a decoration
1958 /// repeating what the text beside it already said — is an empty `alt`, which is
1959 /// the same thing HTML means by it and is a claim rather than an oversight.
1960 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1961 pub struct Image<'a> {
1962 /// What the picture says, for anything not showing it.
1963 ///
1964 /// Empty means the picture is decorative and adds nothing to the text
1965 /// around it. See the type's own docs on why this is not an `Option`.
1966 pub alt: &'a str,
1967 /// A visible line under the picture, where the app wants one.
1968 ///
1969 /// Distinct from [`alt`](Self::alt) and the difference is who it is for: a
1970 /// caption is content everybody reads, alt text is what stands in for the
1971 /// picture. A screenshot captioned "The library view" still needs alt text
1972 /// describing what is in the shot.
1973 pub caption: Option<&'a str>,
1974 /// How it sits in the box it is given.
1975 pub fit: Fit,
1976 /// The picture's own dimensions, where the app knows them.
1977 ///
1978 /// **Not a display size**, and that distinction is what makes this belong
1979 /// here rather than fall foul of the deferral rule. Saying a picture should
1980 /// be 320 points wide is a layout value and is not the description's to
1981 /// give. Saying the file is 5120x3412 is a fact *about the picture*, the
1982 /// same kind of fact [`alt`](Self::alt) is, and no renderer can find it out
1983 /// without fetching the bytes.
1984 ///
1985 /// # What it is for, and it is not decoration
1986 ///
1987 /// Without it a renderer cannot reserve room, so the picture occupies
1988 /// nothing until it arrives and then takes its full height at once,
1989 /// shoving everything below it down the screen. Measured on MNW's landing
1990 /// page 2026-08-14: a 478px jump per frame, and a cumulative layout shift
1991 /// of 0.087 for the page, which is most of the way to the 0.1 that counts
1992 /// as bad.
1993 ///
1994 /// Every host wants it and none can derive it. A webview writes `width` and
1995 /// `height` so the browser holds the space; egui sizes a texture; a
1996 /// terminal with a graphics protocol scales a blit into cells. This was
1997 /// missing from 0.21.0, which is the release that added [`Image`], and its
1998 /// absence is the defect rather than an omission.
1999 ///
2000 /// `None` is honest and common: a creator-uploaded image whose dimensions
2001 /// the app never recorded genuinely does not know. It means the renderer
2002 /// cannot reserve, not that the picture has no size.
2003 pub intrinsic: Option<Extent>,
2004 /// Whether the picture is needed with the screen, or can arrive later.
2005 pub loading: Loading,
2006 }
2007
2008 /// A picture's own pixel dimensions.
2009 ///
2010 /// Deliberately not [`makeover_geometry`]'s business. Geometry answers *how
2011 /// much space a thing should get*, which is a scale question with the same
2012 /// answer on every screen. This is the intrinsic size of one asset, which is a
2013 /// fact about that asset and varies per picture.
2014 ///
2015 /// [`makeover_geometry`]: https://docs.rs/makeover-geometry
2016 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
2017 pub struct Extent {
2018 /// Width in the picture's own pixels.
2019 pub width: u32,
2020 /// Height in the picture's own pixels.
2021 pub height: u32,
2022 }
2023
2024 impl Extent {
2025 /// A picture's dimensions.
2026 #[must_use]
2027 pub const fn new(width: u32, height: u32) -> Self {
2028 Self { width, height }
2029 }
2030
2031 /// Width over height, or `None` if either side is zero.
2032 ///
2033 /// The form a renderer actually reserves space with: a box that knows its
2034 /// proportion holds the right height at any width, which is what a
2035 /// responsive picture needs and what a fixed pixel height cannot give.
2036 #[must_use]
2037 pub fn ratio(self) -> Option<f32> {
2038 (self.width > 0 && self.height > 0).then(|| self.width as f32 / self.height as f32)
2039 }
2040 }
2041
2042 /// When a picture is needed.
2043 ///
2044 /// A claim about *importance and position* rather than a fetch mechanism, which
2045 /// is why it is the description's to make: only the app knows whether a picture
2046 /// is the first thing on the screen or the fortieth thing down a list.
2047 ///
2048 /// # Eager is the default, and that is a correctness choice
2049 ///
2050 /// 0.21.0 emitted the webview's `loading="lazy"` for every picture, on the
2051 /// evidence that the one consumer measured wrote it. That was reading a habit
2052 /// as a rule. Deferring a picture that is on screen at first paint does not
2053 /// save anything -- it is needed immediately either way -- and it delays the
2054 /// arrival, so the space it eventually takes is claimed later and the shift is
2055 /// more visible, not less.
2056 ///
2057 /// So the safe answer is the default and the optimisation is opted into. A
2058 /// carousel is the case that proves the two cannot be one setting for the
2059 /// renderer to choose: its first frame is on screen and its other frames are
2060 /// not, in the same widget, at the same moment.
2061 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
2062 #[non_exhaustive]
2063 pub enum Loading {
2064 /// Needed with the screen. Fetch it now.
2065 #[default]
2066 Eager,
2067 /// Not on screen yet. It can wait until it is near.
2068 Lazy,
2069 }
2070
2071 impl<'a> Image<'a> {
2072 /// A picture that carries its own proportions.
2073 #[must_use]
2074 pub const fn new(alt: &'a str) -> Self {
2075 Self {
2076 alt,
2077 caption: None,
2078 fit: Fit::Natural,
2079 intrinsic: None,
2080 loading: Loading::Eager,
2081 }
2082 }
2083
2084 /// The picture's own dimensions, so a renderer can hold its place.
2085 #[must_use]
2086 pub const fn intrinsic(mut self, width: u32, height: u32) -> Self {
2087 self.intrinsic = Some(Extent::new(width, height));
2088 self
2089 }
2090
2091 /// This picture is not on screen yet; it can arrive when it is near.
2092 #[must_use]
2093 pub const fn lazy(mut self) -> Self {
2094 self.loading = Loading::Lazy;
2095 self
2096 }
2097
2098 /// A visible line under it.
2099 #[must_use]
2100 pub const fn caption(mut self, caption: &'a str) -> Self {
2101 self.caption = Some(caption);
2102 self
2103 }
2104
2105 /// How it sits in its box.
2106 #[must_use]
2107 pub const fn fit(mut self, fit: Fit) -> Self {
2108 self.fit = fit;
2109 self
2110 }
2111
2112 /// Whether the picture adds anything for someone not looking at it.
2113 ///
2114 /// A renderer with no way to show a picture uses this to decide between
2115 /// drawing the alt text and drawing nothing at all. Both are correct and
2116 /// the difference is this flag: standing in for a decorative rule with the
2117 /// word "decoration" is worse than leaving the space empty.
2118 #[must_use]
2119 pub const fn speaks(self) -> bool {
2120 !self.alt.is_empty()
2121 }
2122 }
2123
2124 /// What a [`Track`]'s integers count.
2125 ///
2126 /// `Track::fraction` never needed this -- the arithmetic is the same whatever
2127 /// the numbers mean -- which is exactly how the ruler came to assume minutes
2128 /// and print `00:00` over a month. A renderer drawing an axis has to write a
2129 /// label, and it cannot derive the unit from the numbers.
2130 ///
2131 /// Added 2026-08-15, after a probe put a fifteen-day span on a
2132 /// thirty-one-slot track and got correct geometry under a wall clock.
2133 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
2134 #[non_exhaustive]
2135 pub enum Unit {
2136 /// Minutes from the start of a day. A day view.
2137 #[default]
2138 Minutes,
2139 /// Whole days. A month strip, a sprint, a stretch of leave.
2140 ///
2141 /// A day-granularity axis is a *strip*, not a calendar: one line with
2142 /// spans laid along it. What it deliberately does not do is wrap into
2143 /// weeks, which is the shape that makes weekday periodicity visible and
2144 /// the one job of a month grid that a strip cannot take over. See the
2145 /// crate header.
2146 Days,
2147 }
2148
2149 /// A window on an axis, in whatever [`Unit`] its [`Track`] counts.
2150 ///
2151 /// The axis a [`Track`] draws. Offsets rather than instants, because a
2152 /// description carrying a `DateTime` would carry a timezone with it and the
2153 /// vocabulary has no business holding one. The app knows which day or month
2154 /// this is; the description says how far along it a thing sits.
2155 ///
2156 /// `to` is exclusive and may exceed the natural period, which is how a span
2157 /// running past the end is said without a second date: under
2158 /// [`Unit::Minutes`], `Span::new(1320, 1560)` is 22:00 to 02:00.
2159 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
2160 pub struct Span {
2161 from: u16,
2162 to: u16,
2163 }
2164
2165 impl Span {
2166 /// Midnight to midnight, the ordinary day.
2167 pub const DAY: Self = Self { from: 0, to: 1440 };
2168
2169 /// A span, clamped to a sane one.
2170 ///
2171 /// An empty or backwards span is a caller bug that should not cost a
2172 /// renderer a division by zero, so `to` is forced at least one minute past
2173 /// `from` rather than returning an error nobody can act on. Same reasoning
2174 /// as [`Share::percent`], which clamps rather than refuses.
2175 #[must_use]
2176 pub const fn new(from: u16, to: u16) -> Self {
2177 Self {
2178 from,
2179 to: if to > from { to } else { from + 1 },
2180 }
2181 }
2182
2183 /// The first minute on the axis.
2184 #[must_use]
2185 pub const fn from(self) -> u16 {
2186 self.from
2187 }
2188
2189 /// One past the last minute on the axis.
2190 #[must_use]
2191 pub const fn to(self) -> u16 {
2192 self.to
2193 }
2194
2195 /// How much the axis covers, in its track's unit. Never zero.
2196 #[must_use]
2197 pub const fn length(self) -> u16 {
2198 self.to - self.from
2199 }
2200
2201 /// Whether an offset falls on this axis.
2202 #[must_use]
2203 pub const fn holds(self, minute: u16) -> bool {
2204 minute >= self.from && minute < self.to
2205 }
2206 }
2207
2208 impl Default for Span {
2209 fn default() -> Self {
2210 Self::DAY
2211 }
2212 }
2213
2214 /// Where a thing sits on a [`Track`], and for how long.
2215 ///
2216 /// The one fact a list cannot carry and the whole reason this primitive exists.
2217 /// A list says what order things come in; a track says a thing starts 135
2218 /// minutes along and lasts 45, which is a different claim and not derivable
2219 /// from the first.
2220 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
2221 pub struct Placement {
2222 at: u16,
2223 length: u16,
2224 }
2225
2226 impl Placement {
2227 /// A placement, clamped to a drawable one.
2228 ///
2229 /// Zero length becomes one for the same reason [`Span::new`] clamps: a
2230 /// zero-height thing is invisible rather than expressive, and every
2231 /// renderer would need its own guard.
2232 #[must_use]
2233 pub const fn new(at: u16, length: u16) -> Self {
2234 Self {
2235 at,
2236 length: if length == 0 { 1 } else { length },
2237 }
2238 }
2239
2240 /// Offset from the axis origin, matching [`Span`]'s.
2241 #[must_use]
2242 pub const fn at(self) -> u16 {
2243 self.at
2244 }
2245
2246 /// How long it lasts, in its track's unit. Never zero.
2247 #[must_use]
2248 pub const fn length(self) -> u16 {
2249 self.length
2250 }
2251
2252 /// One past its last minute.
2253 #[must_use]
2254 pub const fn end(self) -> u16 {
2255 self.at + self.length
2256 }
2257
2258 /// Whether two placements cover any of the same time.
2259 ///
2260 /// Geometry, and deliberately not a described field. Whether an overlap is
2261 /// a *conflict* is the app's judgment -- a meeting inside a block of free
2262 /// time overlaps and is fine -- and that judgment travels the way every
2263 /// other judgment does, as a [`Tone`] on the thing itself. What a renderer
2264 /// needs in order to lay two things side by side instead of on top of each
2265 /// other is this, and it can compute it.
2266 ///
2267 /// The alternative was a `conflicts: bool` on each entry, which is state
2268 /// that can disagree with the times beside it. Two sources for one fact is
2269 /// how a screen starts rendering a conflict badge on a thing that no longer
2270 /// conflicts.
2271 #[must_use]
2272 pub const fn overlaps(self, other: Self) -> bool {
2273 self.at < other.end() && other.at < self.end()
2274 }
2275 }
2276
2277 /// A time axis: things placed by when they happen, rather than flowed.
2278 ///
2279 /// # Why this is a primitive
2280 ///
2281 /// This crate refused to name it until 2026-08-15, on the argument that a
2282 /// description expressive enough to draw a timeline is a component library
2283 /// wearing a description's name. The refusal is withdrawn, and it is worth
2284 /// being precise about what was wrong with it, because the reasoning it used
2285 /// applies to real cases and should not be discarded with it.
2286 ///
2287 /// What a timeline needs that a [`List`](Region::Pane) does not is **one**
2288 /// thing: placement. Where a thing sits is a fact about the thing, the way a
2289 /// row's primary text is, and it is not derivable from order. Everything else a
2290 /// day view draws -- the labels, the gridlines, the item bodies, the tones --
2291 /// is furniture this vocabulary already names. Measured against goingson's
2292 /// `day-planning-render.js`, the only members it needed and could not get were
2293 /// `at` and `minutes`.
2294 ///
2295 /// So the timeline was never a component library's worth of vocabulary. It was
2296 /// two integers, and the refusal was priced as though it were the whole widget.
2297 /// The test that matters is not "does this shape look complicated" but "how
2298 /// many members does it actually add, and are they facts or presentation".
2299 /// Slot heights, gridline colour, how overlaps stack and which hour scrolls
2300 /// into view on open are all presentation and all stay the renderer's, which is
2301 /// why they are absent here.
2302 ///
2303 /// # What it does not carry
2304 ///
2305 /// No pixel measure, no scroll offset, no drag affordance. A renderer draws the
2306 /// span at whatever density its host uses; `makeover-geometry` owns that the
2307 /// way it owns everything else measured in pixels.
2308 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
2309 pub struct Track {
2310 /// The window the axis covers.
2311 pub span: Span,
2312 /// The granularity a thing can be placed on, in minutes.
2313 ///
2314 /// goingson's day view is 15, giving 96 slots across a day. A renderer uses
2315 /// it to decide where gridlines fall and what a drop lands on; it does not
2316 /// constrain [`Placement`], because data arriving from a calendar does not
2317 /// respect anyone's grid.
2318 pub slot: u16,
2319 /// How often the axis labels itself, in its own unit.
2320 ///
2321 /// 60 gives an hourly ruler over a 15-minute grid, which is the common
2322 /// shape and the reason this is separate from `slot`. Zero means an
2323 /// unlabelled axis.
2324 pub tick: u16,
2325 /// What `span`, `slot`, `tick` and every [`Placement`] on it count.
2326 ///
2327 /// The one field here a renderer cannot derive, and the reason it exists:
2328 /// [`fraction`](Self::fraction) is unit-agnostic, so a day-granularity
2329 /// track produced correct geometry under an hours-and-minutes ruler until
2330 /// this was added. Geometry never needed it; a label always did.
2331 pub unit: Unit,
2332 }
2333
2334 impl Track {
2335 /// An ordinary day: midnight to midnight, quarter-hour slots, hourly ticks.
2336 pub const DAY: Self = Self {
2337 span: Span::DAY,
2338 slot: 15,
2339 tick: 60,
2340 unit: Unit::Minutes,
2341 };
2342
2343 /// A track over `span`, with the day's usual granularity.
2344 #[must_use]
2345 pub const fn over(span: Span) -> Self {
2346 Self {
2347 span,
2348 slot: 15,
2349 tick: 60,
2350 unit: Unit::Minutes,
2351 }
2352 }
2353
2354 /// A strip of whole days: one slot a day, a label a week.
2355 ///
2356 /// The shape a stretch of leave or a sprint is drawn on. Not a calendar --
2357 /// it does not wrap into weeks, and the crate header says why that
2358 /// distinction is the whole of what a month grid still has over this.
2359 #[must_use]
2360 pub const fn days(span: Span) -> Self {
2361 Self {
2362 span,
2363 slot: 1,
2364 tick: 7,
2365 unit: Unit::Days,
2366 }
2367 }
2368
2369 /// How many slots the axis holds.
2370 ///
2371 /// Rounded up, so a span that does not divide evenly by `slot` still has a
2372 /// slot covering its tail rather than dropping it. Never zero: `slot` of 0
2373 /// reads as one slot spanning the whole axis rather than a division by
2374 /// zero, since a renderer asking this question has already committed to
2375 /// drawing something.
2376 #[must_use]
2377 pub const fn slots(self) -> u16 {
2378 if self.slot == 0 {
2379 1
2380 } else {
2381 self.span.length().div_ceil(self.slot)
2382 }
2383 }
2384
2385 /// Where a placement sits on the axis, as a fraction from 0.0 to 1.0.
2386 ///
2387 /// The one calculation every renderer would otherwise write itself, and the
2388 /// place the three would drift apart. Clamped, so a placement outside the
2389 /// span draws at the edge rather than off it -- an event running past
2390 /// midnight is a real thing and truncating it is better than either
2391 /// panicking or drawing it somewhere impossible.
2392 #[must_use]
2393 pub fn fraction(self, minute: u16) -> f32 {
2394 let span = f32::from(self.span.length());
2395 let offset = f32::from(minute.saturating_sub(self.span.from()));
2396 (offset / span).clamp(0.0, 1.0)
2397 }
2398 }
2399
2400 impl Default for Track {
2401 fn default() -> Self {
2402 Self::DAY
2403 }
2404 }
2405
2406 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
2407 pub struct Act<'a> {
2408 /// What the control says.
2409 pub label: &'a str,
2410 /// The key that reaches it where a host has keys.
2411 ///
2412 /// The one member written for a terminal before there was one. A webview
2413 /// hangs it off `accesskey` or ignores it; a terminal has nothing else to
2414 /// offer, so this is the whole of how a control is reached there.
2415 pub key: Option<&'a str>,
2416 /// What pressing it means. [`Tone::Danger`] is the destructive one.
2417 pub tone: Tone,
2418 /// Disabled, or nothing said.
2419 ///
2420 /// [`State::Disabled`] is what changes what a renderer may do: see
2421 /// [`State::suppresses_interaction`], which is what says a disabled control
2422 /// is drawn and not reachable. It has been the only member since 0.19.0,
2423 /// and a control's focus is not sayable here at all — see the crate header,
2424 /// "Reach, focus and the focus ring".
2425 pub state: Option<State>,
2426 }
2427
2428 impl<'a> Act<'a> {
2429 /// An ordinary control, reachable, with no key.
2430 #[must_use]
2431 pub const fn new(label: &'a str) -> Self {
2432 Self {
2433 label,
2434 key: None,
2435 tone: Tone::Neutral,
2436 state: None,
2437 }
2438 }
2439
2440 /// The key that reaches it.
2441 #[must_use]
2442 pub const fn key(mut self, key: &'a str) -> Self {
2443 self.key = Some(key);
2444 self
2445 }
2446
2447 /// What pressing it means.
2448 #[must_use]
2449 pub const fn tone(mut self, tone: Tone) -> Self {
2450 self.tone = tone;
2451 self
2452 }
2453
2454 /// Focus, or disabled.
2455 #[must_use]
2456 pub const fn state(mut self, state: State) -> Self {
2457 self.state = Some(state);
2458 self
2459 }
2460
2461 /// Whether the control is drawn and does not answer.
2462 #[must_use]
2463 pub fn disabled(&self) -> bool {
2464 self.state.is_some_and(State::suppresses_interaction)
2465 }
2466 }
2467
2468 /// A named part of a screen.
2469 ///
2470 /// The thing `makeover-geometry` deliberately does not name: it names the space
2471 /// *between* things by relationship, and nothing named the things. Six named
2472 /// members, taken from what the two webview apps actually use, plus
2473 /// [`Region::Bespoke`] for the parts no description should reach. Both apps'
2474 /// `layout.css` currently names exactly two things, `.raised` and `.well`, so
2475 /// this layer is absent rather than divergent, which makes it the cheapest of
2476 /// the schemas to add and the easiest to over-build.
2477 ///
2478 /// `#[non_exhaustive]` arrives with [`Region::Widget`], the pairing [`RowPart`]
2479 /// made at 0.9.0 and [`Readiness`] at 0.12.0, and for the same reason: the
2480 /// member after this one should not be a lockstep event across three renderers.
2481 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
2482 #[non_exhaustive]
2483 pub enum Region<'a> {
2484 /// A full-width strip with a title slot and an actions cluster, either of
2485 /// which may be empty. goingson's `.page-header`, Balanced Breakfast's
2486 /// `.header` and `.detail-header` are all this, differing only in which
2487 /// slots they fill.
2488 Band,
2489 /// A persistent column beside the content, holding navigation.
2490 Sidebar,
2491 /// A region of content with its own scroll.
2492 Pane,
2493 /// Things that belong together, and nothing else.
2494 ///
2495 /// The block [`Heading::Section`] has been naming since 0.2.0 without the
2496 /// vocabulary being able to contain it. A section heading is a leaf sitting
2497 /// *beside* the things it names, so nothing said where a section started or
2498 /// ended and a renderer learned one had ended only because the next heading
2499 /// arrived.
2500 ///
2501 /// # The measurement
2502 ///
2503 /// 41 [`Heading::Section`] sites across the ten screens described through
2504 /// the router, not one of them contained. audiofiles' settings screen is the
2505 /// clearest: one pane holding a heading, a field, a heading, two toggles, a
2506 /// heading, a toggle and a heading, which is four sections and no
2507 /// containers. Under the hand-written CSS the ports are replacing the same
2508 /// block is spelled `.settings-section` in goingson, `.form-section` and
2509 /// `.content-section` in the MNW server, `.help-section` in Balanced
2510 /// Breakfast: three apps, four names, one shape.
2511 ///
2512 /// # Why the existing members were the wrong answer
2513 ///
2514 /// [`Pane`](Self::Pane) is what apps reached for, and it is 28 of the 45
2515 /// regions in the described screens. It claims a scroll of its own and
2516 /// [`Depth::Well`], so four settings groups inside a pane are four wells
2517 /// inside a well and four scroll contexts. Neither claim is true of a group.
2518 ///
2519 /// [`Widget`](Self::Widget) is wrong from the other side. Its own docs say a
2520 /// widget is never how a primitive gets added by the back door, and a run of
2521 /// related controls under a heading is furniture any app would have, which
2522 /// is the generic-against-bespoke bar a primitive has to clear.
2523 ///
2524 /// # What it does not carry
2525 ///
2526 /// **A heading.** A group usually has one and it is an ordinary node in the
2527 /// body, the way it already was. A group of related toggles with no heading
2528 /// is a real thing and a mandatory slot would forbid it.
2529 ///
2530 /// **A depth.** [`Depth::Flat`], on [`Bespoke`](Self::Bespoke)'s reasoning:
2531 /// it inherits, and an app that wants its group in a well puts it in a
2532 /// [`Pane`](Self::Pane), which composes rather than adding a knob here.
2533 ///
2534 /// **A colour.** Distinguishing sibling groups by colour is the thing this
2535 /// member was asked for and it is deliberately not stated here. The
2536 /// description says these things belong together; which of the theme's
2537 /// categorical colours a renderer reaches for, and whether it reaches for
2538 /// one at all, is derived from sibling order at the renderer. A terminal
2539 /// that tints nothing and separates with a rule is honouring this.
2540 Group,
2541 /// Two panes side by side, where the left chooses what the right shows.
2542 Split,
2543 /// Peer regions across, all of them equals.
2544 ///
2545 /// A kanban board's columns, and the shape [`Split`](Self::Split) is not:
2546 /// a split's two panes stand in a master-detail relationship, where the
2547 /// left chooses what the right shows. These choose nothing about each
2548 /// other. Each is a whole region and the set is the arrangement.
2549 ///
2550 /// # What it does not carry
2551 ///
2552 /// **How many.** The children say, and a count here would be a second
2553 /// source for something the description already states by containing them.
2554 ///
2555 /// **How wide.** Peers are equal by definition, so there is no [`Share`] to
2556 /// state. A board whose columns wanted different widths would be a
2557 /// different member, and no app has one.
2558 ///
2559 /// **What happens when there is no room.** Scroll across, wrap, or collapse
2560 /// to one column at a time: all three are right on some host, none is
2561 /// derivable from the description, and every one of them is presentation.
2562 /// A terminal that stacks them vertically is honouring this, not degrading
2563 /// it.
2564 ///
2565 /// # Why it is not an `Arrangement`
2566 ///
2567 /// [`Arrangement`] is the page's shape, and a board is usually a region
2568 /// *inside* a page that also has a band over it. Naming it here composes;
2569 /// naming it there would make a screen either a board or a list-detail and
2570 /// never a band above a board. It also keeps [`Arrangement::share`]
2571 /// meaningful, which a peer arrangement has no answer for.
2572 Columns,
2573 /// A set of panes, one visible at a time, and a [`Selector::Tabs`] that
2574 /// chooses between them.
2575 ///
2576 /// Says nothing about where the strip sits. A row over the panes, a column
2577 /// beside them, a wrapped run of links under them: all three are the same
2578 /// member drawn by a renderer that knows its host, the way the strip's
2579 /// overflow is.
2580 TabGroup,
2581 /// Content over a scrim, taking input until dismissed.
2582 Modal,
2583 /// A region this crate names the *place* of and nothing else. The app owns
2584 /// what goes in it.
2585 ///
2586 /// The escape hatch, and the thing that keeps the description honest about
2587 /// its own limits. A day-plan timeline, a kanban board, a calendar and the
2588 /// paint interaction over the timeline are not describable here and are not
2589 /// going to become describable: a description expressive enough to produce
2590 /// a timeline is a widget library wearing a description's name.
2591 ///
2592 /// But a screen containing one still has to be a screen. Without this
2593 /// member the description covers only the boring screens, and the four that
2594 /// make goingson worth using would need a second, undescribed path beside
2595 /// the router. Two paths is how the vocabulary starts drifting from the app
2596 /// again, which is the exact failure this crate exists to end.
2597 ///
2598 /// So the description says "a thing called `day-plan` goes here" and stops.
2599 /// The name is opaque: this crate never interprets it, and no renderer is
2600 /// expected to know what it means beyond handing the space over.
2601 Bespoke {
2602 /// What the app calls it. Never interpreted here.
2603 name: &'a str,
2604 },
2605 /// A named assembly of things the vocabulary already says.
2606 ///
2607 /// The third tier, between a primitive and [`Bespoke`](Self::Bespoke).
2608 /// Stated by Max 2026-08-12 answering the carousel: "something in between a
2609 /// primitive and a bespoke interface, like a widget, which is just an
2610 /// assembly of primitives." Full note: wiki `widget-tier`.
2611 ///
2612 /// # What separates it from the two members either side
2613 ///
2614 /// A primitive is a thing every renderer draws from scratch, and the test
2615 /// it has to pass is that every host has an honest answer. A carousel fails
2616 /// that test — a terminal has no carousel — which is the same refusal
2617 /// `Node::Html` got and is why the carousel sat unsayable for months.
2618 ///
2619 /// [`Bespoke`](Self::Bespoke) fails it from the other side. Bespoke is for
2620 /// what one app owns and nobody will build twice, and it carries *no*
2621 /// contents: the description names the place and stops. A carousel is
2622 /// furniture any app would have, and every part of it — an ordered set of
2623 /// frames, a position, prev and next, a strip of position indicators — is
2624 /// already sayable. Only the assembly had no name.
2625 ///
2626 /// So this member is the pair the other two are not: a name **and**
2627 /// contents. The contents are the assembly, in the region's own body, said
2628 /// in members that already exist.
2629 ///
2630 /// # Why the name does not have to be understood
2631 ///
2632 /// A renderer that recognises the name draws it the way its host does it: a
2633 /// carousel in a webview, a pager with a count in a terminal, a selector in
2634 /// egui. A renderer that does not recognise it walks the body, which is
2635 /// primitives all the way down and which it can already draw.
2636 ///
2637 /// That is what lets the widget set be **open** without every renderer
2638 /// knowing every widget. An unrecognised widget degrades to its assembly
2639 /// instead of failing, so a second or third party can name one without
2640 /// three renderers releasing in lockstep to accept it. Contrast
2641 /// [`Bespoke`](Self::Bespoke), which no renderer can degrade: there is
2642 /// nothing under it to fall back to.
2643 ///
2644 /// # What it does not do
2645 ///
2646 /// A widget is an assembly of things the vocabulary *already* says, so it
2647 /// buys no expressive power. Anything needing a member the vocabulary does
2648 /// not have is a finding about the vocabulary, and the answer to a finding
2649 /// is to add the member. A widget is never the way a primitive gets added
2650 /// by the back door.
2651 ///
2652 /// This used to say "it does not make a timeline describable, and the
2653 /// refusal in the crate header stands unchanged". The timeline is
2654 /// describable as of 2026-08-15 -- see [`Track`] -- and it got there the
2655 /// way the paragraph above says it should have: by adding the two members
2656 /// that were missing, not by dressing the screen up as an assembly.
2657 Widget {
2658 /// What the assembly is called. This crate never interprets it, and a
2659 /// renderer is free not to know it.
2660 name: &'a str,
2661 },
2662 }
2663
2664 impl<'a> Region<'a> {
2665 /// How the region sits on what is behind it.
2666 #[must_use]
2667 pub const fn depth(self) -> Depth {
2668 match self {
2669 Self::Band | Self::Sidebar | Self::Split | Self::TabGroup => Depth::Flat,
2670 // Flat, and it inherits. A group says its contents belong together
2671 // and says nothing about the surface they sit on, so a group in a
2672 // pane is in a well and a group on the page is on the page. An app
2673 // wanting one lifted puts it in a `Pane`.
2674 Self::Group => Depth::Flat,
2675 // Flat, and it is the container rather than the columns. Each
2676 // column is its own region and brings its own depth; a well here
2677 // would put a second edge around a row of wells.
2678 Self::Columns => Depth::Flat,
2679 // A pane is looked into, the same as a table body or a tag tree.
2680 Self::Pane => Depth::Well,
2681 Self::Modal => Depth::Raised,
2682 // Flat because it inherits: a bespoke region takes the depth of
2683 // whatever frames it. An app that wants its timeline in a well puts
2684 // it in a `Pane`, which composes rather than adding a knob here.
2685 //
2686 // A widget inherits for the same reason and it matters more here,
2687 // because a widget is drawn by whichever renderer recognises it. A
2688 // depth set here would be this crate deciding that a carousel is
2689 // raised on every host, which is the kind of value the deferral
2690 // rule exists to refuse.
2691 Self::Bespoke { .. } | Self::Widget { .. } => Depth::Flat,
2692 }
2693 }
2694
2695 /// Whether this crate can say anything about the region's contents.
2696 ///
2697 /// A renderer walks the description and hands every region it understands
2698 /// to the right drawing code. This is how it tells the two apart, and the
2699 /// reason it is a method rather than a `matches!` at each renderer: there
2700 /// is exactly one opaque member and there should stay exactly one.
2701 ///
2702 /// [`Widget`](Self::Widget) is described, and that is the whole of what
2703 /// separates it from [`Bespoke`](Self::Bespoke) here. Both carry a name
2704 /// this crate never interprets; only one of them carries contents under it.
2705 /// A renderer that does not recognise a widget's name still walks its body,
2706 /// so there is nothing for it to hand over and nothing it cannot draw.
2707 #[must_use]
2708 pub const fn described(self) -> bool {
2709 !matches!(self, Self::Bespoke { .. })
2710 }
2711
2712 /// The name an app gave this region, if it gave one.
2713 ///
2714 /// [`Bespoke`](Self::Bespoke) and [`Widget`](Self::Widget) are the two
2715 /// members that carry a name, for two different purposes: one says what the
2716 /// app will fill the space with, the other says what the assembly under it
2717 /// is called. A renderer dispatching on either wants the string without
2718 /// caring which member it came from, and writing that `matches!` at each
2719 /// renderer is how the two drift apart.
2720 #[must_use]
2721 pub const fn name(self) -> Option<&'a str> {
2722 match self {
2723 Self::Bespoke { name } | Self::Widget { name } => Some(name),
2724 // Spelled out rather than a wildcard, so a member added later has
2725 // to answer whether it carries a name instead of inheriting `None`
2726 // by sitting under a `_`.
2727 Self::Band
2728 | Self::Sidebar
2729 | Self::Pane
2730 | Self::Group
2731 | Self::Split
2732 | Self::Columns
2733 | Self::TabGroup
2734 | Self::Modal => None,
2735 }
2736 }
2737 }
2738
2739 /// How many of a region's children are visible at once.
2740 ///
2741 /// `4dcd241b`. Three findings turned out to be one sentence the vocabulary
2742 /// could not say: *this region holds several children and shows some of them,
2743 /// and the reader can change which.* [`Region::TabGroup`] existed with nothing
2744 /// saying which tab was open, a carousel had nothing saying which frame was up,
2745 /// and a disclosure had nothing saying whether its one child was showing at all.
2746 ///
2747 /// Because the fact lived nowhere, a renderer had two moves: hardcode a widget
2748 /// name, or draw every child. That is what put per-widget code in renderers, and
2749 /// it was the missing member rather than the widget tier that put it there.
2750 ///
2751 /// # What is here and what is not
2752 ///
2753 /// The *kind*, and only the kind. Which child is currently up is the current
2754 /// answer, and a layer that defers every address does not hold the current
2755 /// answer either — the split [`Selector`] already makes, where this crate says
2756 /// what kind of chooser a thing is and the router says which option is picked.
2757 /// So a holder of regions carries the index and the per-child label beside this.
2758 ///
2759 /// # What a renderer does with it
2760 ///
2761 /// Derives its chrome, once, for every widget rather than per name:
2762 ///
2763 /// - Children carrying labels get a strip of the labels, the current one marked.
2764 /// - Children carrying none get previous, position, next.
2765 /// - [`AtMostOne`](Self::AtMostOne) over one child gets a summary line that
2766 /// opens.
2767 ///
2768 /// The name on [`Region::Widget`] survives as app vocabulary, for a renderer
2769 /// that wants to do something *special* with one, which is what it should have
2770 /// been from the start.
2771 ///
2772 /// Degradation runs the way it already did: a renderer ignoring this draws every
2773 /// child, which is more content rather than less.
2774 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
2775 #[non_exhaustive]
2776 pub enum Showing {
2777 /// Every child, in order. What every region did before this existed.
2778 #[default]
2779 All,
2780 /// Exactly one. A carousel, a tab group.
2781 One,
2782 /// One, or none. A disclosure, which is closed until it is opened.
2783 AtMostOne,
2784 }
2785
2786 impl Showing {
2787 /// Whether the reader can change which child is up.
2788 ///
2789 /// The question every renderer's region arm asks before deriving any
2790 /// chrome, and a method rather than a `matches!` at each renderer for
2791 /// [`Region::name`]'s reason: three renderers writing the same comparison is
2792 /// how they come to disagree about a member added later.
2793 #[must_use]
2794 pub const fn selective(self) -> bool {
2795 !matches!(self, Self::All)
2796 }
2797
2798 /// Whether showing nothing is a legal state.
2799 ///
2800 /// True only for [`AtMostOne`](Self::AtMostOne). A renderer needs this to
2801 /// know whether its control closes as well as moves: a carousel's row moves
2802 /// between frames and never reaches empty, and a disclosure's summary line
2803 /// is the same control wearing its closed state.
2804 #[must_use]
2805 pub const fn dismissible(self) -> bool {
2806 matches!(self, Self::AtMostOne)
2807 }
2808 }
2809
2810 /// A window onto a sequence: where it starts, how much it covers, and how long
2811 /// the sequence is when that is known.
2812 ///
2813 /// The mechanism under two things the vocabulary deliberately keeps apart. A
2814 /// carousel is a window of one frame over children that are all present; a
2815 /// paged list is a window of a page over rows most of which were never fetched.
2816 /// Those are different facts and they stay different types — [`Showing`] says
2817 /// which child is up, [`Paging`] says where a reader is in a query — but the
2818 /// arithmetic underneath is one piece of code, so a terminal and a browser
2819 /// cannot come to disagree about which frame is last.
2820 ///
2821 /// # Why `of` is optional and `count` is not
2822 ///
2823 /// `count` is what is on screen and is therefore always known. `of` is the
2824 /// length of the thing being windowed, and a host that cannot count says so by
2825 /// leaving it empty **for the life of the screen**. It is never "not counted
2826 /// yet": see "First paint is final paint" in the crate header. A total that
2827 /// turns up on a later pass widens the text that prints it.
2828 ///
2829 /// # Clamping
2830 ///
2831 /// Every derivation clamps rather than refusing, and a zero `count` answers
2832 /// `None` rather than dividing. A window past the end is a bug in the host, and
2833 /// a renderer that answered it by drawing nothing would report a region that
2834 /// vanished, which is the hardest kind of bug to find from what is on screen.
2835 /// [`Share::percent`] clamps for the same reason.
2836 #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
2837 pub struct Window {
2838 /// The index into the sequence where the window starts.
2839 pub from: usize,
2840 /// How many the window covers. One, for a carousel.
2841 pub count: usize,
2842 /// How long the sequence is, when the host can say.
2843 pub of: Option<usize>,
2844 }
2845
2846 impl Window {
2847 /// A window of `count`, starting at `from`, over a sequence of unknown
2848 /// length.
2849 #[must_use]
2850 pub const fn new(from: usize, count: usize) -> Self {
2851 Self {
2852 from,
2853 count,
2854 of: None,
2855 }
2856 }
2857
2858 /// How long the sequence is.
2859 #[must_use]
2860 pub const fn of(mut self, of: usize) -> Self {
2861 self.of = Some(of);
2862 self
2863 }
2864
2865 /// One item of a sequence whose length is known. A carousel frame.
2866 #[must_use]
2867 pub const fn frame(at: usize, of: usize) -> Self {
2868 Self {
2869 from: at,
2870 count: 1,
2871 of: Some(of),
2872 }
2873 }
2874
2875 /// Which window this is, counting from zero.
2876 ///
2877 /// `None` when `count` is zero, which is the only input with no answer
2878 /// rather than a clamped one.
2879 #[must_use]
2880 pub const fn index(self) -> Option<usize> {
2881 if self.count == 0 {
2882 return None;
2883 }
2884 Some(self.from / self.count)
2885 }
2886
2887 /// How many windows the sequence holds.
2888 ///
2889 /// `None` unless both the length and a non-zero `count` are known. A
2890 /// partial answer here would be a renderer drawing "of 0".
2891 #[must_use]
2892 pub const fn windows(self) -> Option<usize> {
2893 match self.of {
2894 Some(of) if self.count > 0 => Some(of.div_ceil(self.count)),
2895 _ => None,
2896 }
2897 }
2898
2899 /// Whether anything sits before this window.
2900 #[must_use]
2901 pub const fn has_before(self) -> bool {
2902 self.from > 0
2903 }
2904
2905 /// How many sit after this window, when the length is known.
2906 ///
2907 /// Here rather than in each renderer for [`Showing::selective`]'s reason:
2908 /// three of them writing the same subtraction is how they come to disagree,
2909 /// and this one has an underflow in it for whoever writes it fourth.
2910 #[must_use]
2911 pub const fn after(self) -> Option<usize> {
2912 match self.of {
2913 Some(of) => Some(of.saturating_sub(self.from.saturating_add(self.count))),
2914 None => None,
2915 }
2916 }
2917
2918 /// Whether anything sits after it.
2919 ///
2920 /// `true` when the length is unknown: a host that cannot count cannot rule
2921 /// out more, and offering a way forward that turns out to be empty is the
2922 /// cheaper of the two mistakes.
2923 #[must_use]
2924 pub const fn has_after(self) -> bool {
2925 match self.of {
2926 Some(of) => self.from.saturating_add(self.count) < of,
2927 None => true,
2928 }
2929 }
2930
2931 /// The window with `from` brought inside the sequence.
2932 ///
2933 /// A no-op when the length is unknown, since there is nothing to clamp
2934 /// against.
2935 #[must_use]
2936 pub const fn clamped(mut self) -> Self {
2937 if let Some(of) = self.of
2938 && self.from >= of
2939 {
2940 // `max(1)` by hand: `Ord::max` is not const yet, and a zero-count
2941 // window would otherwise clamp onto the end rather than inside it.
2942 let step = if self.count == 0 { 1 } else { self.count };
2943 self.from = of.saturating_sub(step);
2944 }
2945 self
2946 }
2947 }
2948
2949 /// Where a reader is in a set that arrived in parts.
2950 ///
2951 /// A [`Window`] wearing the paged reading of itself. Distinct from a carousel's
2952 /// window at the top level on purpose, because the intent differs and a call
2953 /// site should say which one it means, while the arithmetic below is shared so
2954 /// the two cannot drift apart.
2955 ///
2956 /// # The two idioms, and which one a renderer may draw
2957 ///
2958 /// Load-more and numbered pages are both this type. Which is honest is
2959 /// [`paged`](Self::paged): a set whose page size is known can be drawn as
2960 /// "Page 3 of 8", and one without can only be drawn as "150 of 400" and a way
2961 /// forward. Saying it here rather than letting each renderer guess is the point
2962 /// — three renderers inferring it from the numbers is how they come to disagree.
2963 ///
2964 /// # What it does not carry
2965 ///
2966 /// No addresses. `makeover-layout` cannot name an action, and the way to ask for
2967 /// the next part is the host's: `quasi_router` pairs this with the addresses the
2968 /// same way `Row` pairs its parts with `Row::activate`. That split is the reason
2969 /// this type is reusable by a carousel, which has nothing to ask.
2970 #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
2971 pub struct Paging {
2972 /// The window onto the set.
2973 pub window: Window,
2974 /// Whether the parts are a fixed size, and so whether pages are countable.
2975 ///
2976 /// `false` for load-more, where the window simply grew and "page 2" would
2977 /// name nothing.
2978 pub paged: bool,
2979 }
2980
2981 impl Paging {
2982 /// A page of `per`, starting at `from`.
2983 #[must_use]
2984 pub const fn pages(from: usize, per: usize) -> Self {
2985 Self {
2986 window: Window::new(from, per),
2987 paged: true,
2988 }
2989 }
2990
2991 /// The first `shown`, with more behind them.
2992 ///
2993 /// The load-more shape: the window starts at the beginning and grows, so
2994 /// there is no page to number.
2995 #[must_use]
2996 pub const fn more(shown: usize) -> Self {
2997 Self {
2998 window: Window::new(0, shown),
2999 paged: false,
3000 }
3001 }
3002
3003 /// How many there are altogether.
3004 ///
3005 /// Left unsaid by a host that cannot count, and left unsaid **for good**:
3006 /// a total arriving later widens whatever prints it. See "First paint is
3007 /// final paint" in the crate header.
3008 #[must_use]
3009 pub const fn of(mut self, of: usize) -> Self {
3010 self.window = self.window.of(of);
3011 self
3012 }
3013
3014 /// Which page this is, counting from one, when pages are countable.
3015 ///
3016 /// One-based because it is read aloud. [`Window::index`] is the zero-based
3017 /// form for anyone indexing with it.
3018 #[must_use]
3019 pub const fn page(self) -> Option<usize> {
3020 if !self.paged {
3021 return None;
3022 }
3023 match self.window.index() {
3024 Some(index) => Some(index + 1),
3025 None => None,
3026 }
3027 }
3028
3029 /// How many pages there are, when that is countable.
3030 #[must_use]
3031 pub const fn pages_total(self) -> Option<usize> {
3032 if !self.paged {
3033 return None;
3034 }
3035 self.window.windows()
3036 }
3037
3038 /// How many are on screen.
3039 #[must_use]
3040 pub const fn shown(self) -> usize {
3041 self.window.count
3042 }
3043
3044 /// How many there are, when the host counted.
3045 #[must_use]
3046 pub const fn total(self) -> Option<usize> {
3047 self.window.of
3048 }
3049
3050 /// How many are not shown yet, when the host counted.
3051 ///
3052 /// The figure a load-more control puts in its label. `None` is the honest
3053 /// and common case: a set that cannot say how many more there are still has
3054 /// a way to ask for them.
3055 #[must_use]
3056 pub const fn remaining(self) -> Option<usize> {
3057 self.window.after()
3058 }
3059
3060 /// Whether there is anything further on.
3061 #[must_use]
3062 pub const fn has_more(self) -> bool {
3063 self.window.has_after()
3064 }
3065
3066 /// Whether there is anything back the other way.
3067 #[must_use]
3068 pub const fn has_previous(self) -> bool {
3069 self.window.has_before()
3070 }
3071 }
3072
3073 /// How much of the width an arrangement's first region takes.
3074 ///
3075 /// `e0fd485e`. Nothing said how much room a region got, so every renderer
3076 /// invented its own number and two hosts showing one screen disagreed about
3077 /// its proportions. A webview never noticed, because the stylesheet answered
3078 /// once for every consumer; a terminal has no stylesheet to inherit from, so
3079 /// `quasi-tui` picked 24 columns for a sidebar and 40% for a list pane and
3080 /// neither had anything behind it.
3081 ///
3082 /// # A proportion, never a unit
3083 ///
3084 /// Held as a percentage, and that is the only form it comes in. A description
3085 /// carrying columns would be describing a terminal and one carrying pixels a
3086 /// webview, and the whole point is that both honour the same fact: a terminal
3087 /// resolves it against a column count, a webview writes it into a grid, and
3088 /// neither has to know what the other did.
3089 ///
3090 /// It is not [`makeover_geometry::Ratio`]'s job either, which was the first
3091 /// guess. Geometry is scales that answer the same for every screen and takes
3092 /// no input that would let a sidebar screen differ from a list-detail one.
3093 ///
3094 /// [`makeover_geometry::Ratio`]: https://docs.rs/makeover-geometry
3095 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
3096 pub struct Share(u8);
3097
3098 impl Share {
3099 /// What a sidebar takes, when nobody says otherwise.
3100 ///
3101 /// A quarter. `quasi-tui` drew 24 columns, which is a quarter of a
3102 /// 96-column terminal and about a fifth of a wide one; a quarter is that
3103 /// number said in the form a webview can honour too.
3104 pub const SIDEBAR: Self = Self(25);
3105
3106 /// What the list side of a list-detail takes, when nobody says otherwise.
3107 ///
3108 /// `quasi-tui`'s 40%, which was already a proportion and is the one number
3109 /// this member did not have to invent.
3110 pub const LIST: Self = Self(40);
3111
3112 /// A share of the width, as a percentage.
3113 ///
3114 /// Clamped to 5..=95 rather than refused. A description that asked for a
3115 /// region of nothing is a bug in the app, and a renderer drawing a region
3116 /// zero cells wide reports it as a region that vanished, which is the
3117 /// hardest kind of bug to find from what is on the screen.
3118 #[must_use]
3119 pub const fn percent(percent: u8) -> Self {
3120 Self(if percent < 5 {
3121 5
3122 } else if percent > 95 {
3123 95
3124 } else {
3125 percent
3126 })
3127 }
3128
3129 /// The share as a percentage.
3130 #[must_use]
3131 pub const fn as_percent(self) -> u8 {
3132 self.0
3133 }
3134
3135 /// This share of a width, rounded to the nearest whole unit.
3136 ///
3137 /// What a terminal calls to turn the proportion into columns. At least one,
3138 /// because a region the description named should be visible: a screen
3139 /// 3 columns wide is unusable either way, and a sidebar that is there is a
3140 /// truer picture of the description than a sidebar that is not.
3141 #[must_use]
3142 pub const fn of(self, whole: u16) -> u16 {
3143 let taken = (whole as u32 * self.0 as u32).div_ceil(100);
3144 if taken == 0 { 1 } else { taken as u16 }
3145 }
3146 }
3147
3148 /// How a screen is laid out.
3149 ///
3150 /// Two, and the second is not a variant of the first. goingson is list-detail,
3151 /// Balanced Breakfast is sidebar plus content, and neither app has a third.
3152 /// The tab group is a modifier rather than a member, because goingson uses it
3153 /// *inside* the same content region rather than instead of one.
3154 ///
3155 /// This exists at all because the router has to be able to express a screen
3156 /// rather than only a control. Discovering the arrangement layer missing after
3157 /// the renderers exist is a redesign; naming two now is a morning.
3158 ///
3159 /// # Why the share rides here
3160 ///
3161 /// `e0fd485e`. A share is per-arrangement: how much a sidebar takes and how
3162 /// much a list side takes are different questions, and this enum is the only
3163 /// thing that knows which one is being asked. Geometry would have had to invent
3164 /// a channel to be told.
3165 ///
3166 /// [`list_detail`](Self::list_detail) and
3167 /// [`sidebar_content`](Self::sidebar_content) build these with the default
3168 /// shares, so a screen that has no opinion does not have to have one.
3169 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
3170 pub enum Arrangement {
3171 /// A list that chooses what the detail beside it shows.
3172 ListDetail {
3173 /// Whether the detail side is a [`Region::TabGroup`].
3174 tabbed: bool,
3175 /// How much of the width the list side takes.
3176 share: Share,
3177 },
3178 /// Navigation down the side, content filling the rest.
3179 SidebarContent {
3180 /// How much of the width the sidebar takes.
3181 share: Share,
3182 },
3183 }
3184
3185 impl Arrangement {
3186 /// A list and a detail beside it, at the default share.
3187 #[must_use]
3188 pub const fn list_detail(tabbed: bool) -> Self {
3189 Self::ListDetail {
3190 tabbed,
3191 share: Share::LIST,
3192 }
3193 }
3194
3195 /// A sidebar and content beside it, at the default share.
3196 #[must_use]
3197 pub const fn sidebar_content() -> Self {
3198 Self::SidebarContent {
3199 share: Share::SIDEBAR,
3200 }
3201 }
3202
3203 /// How much of the width the first region takes.
3204 #[must_use]
3205 pub const fn share(self) -> Share {
3206 match self {
3207 Self::ListDetail { share, .. } | Self::SidebarContent { share } => share,
3208 }
3209 }
3210
3211 /// The same arrangement, at this share.
3212 #[must_use]
3213 pub const fn with_share(self, share: Share) -> Self {
3214 match self {
3215 Self::ListDetail { tabbed, .. } => Self::ListDetail { tabbed, share },
3216 Self::SidebarContent { .. } => Self::SidebarContent { share },
3217 }
3218 }
3219 }
3220
3221 /// How wide the content of a whole screen runs.
3222 ///
3223 /// `0eccff0d`, and [`Share`]'s sibling one level up: that one says how a
3224 /// screen's width is divided between regions, this says how much of the window
3225 /// the screen uses in the first place. Both are the description's, which is
3226 /// what answering the two together settled.
3227 ///
3228 /// Measured in the MNW server, where 69 of 72 templates carry exactly one of
3229 /// three mutually exclusive classes and the choice is per screen. GoingsOn
3230 /// reaches for `max-width` 56 times and Balanced Breakfast 12, neither with a
3231 /// token for it, so three apps were solving one thing by hand.
3232 ///
3233 /// # Named for the measure, not for MNW's classes
3234 ///
3235 /// A renderer that is not a browser has to answer this too, and `padded-page`
3236 /// tells a terminal nothing. The three say how wide the text runs, which is a
3237 /// question every renderer can answer: a webview with a `max-width`, a terminal
3238 /// with gutters, an immediate-mode frame with its own width.
3239 ///
3240 /// `#[non_exhaustive]` for [`Fill`]'s reason. The set is closed today because
3241 /// the measurement found three, and a fourth arriving should not be a lockstep
3242 /// release across nine repos.
3243 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
3244 #[non_exhaustive]
3245 pub enum Measure {
3246 /// The whole width, with gutters. The default, and 53 of the 69.
3247 ///
3248 /// What a dashboard, a table and a settings screen want: the content is
3249 /// wide because the content *is* wide, and constraining it would waste the
3250 /// window.
3251 #[default]
3252 Wide,
3253 /// Capped at a comfortable page width, centred. 13 of the 69.
3254 ///
3255 /// A form, a sign-in, a purchase. Content that does not get better by
3256 /// getting wider, but is not prose either.
3257 Contained,
3258 /// Capped at a line length that reads well. 3 of the 69.
3259 ///
3260 /// Prose. The narrowest of the three, and the one with a reason outside
3261 /// taste: a line of text past roughly 75 characters costs the reader the
3262 /// return sweep.
3263 Reading,
3264 }
3265
3266 impl Measure {
3267 /// A stable name, for a renderer that needs to spell it.
3268 ///
3269 /// Here rather than in each renderer for [`Sort::as_str`]'s reason: three
3270 /// renderers spelling one enum is three chances to spell it differently.
3271 #[must_use]
3272 pub const fn as_str(self) -> &'static str {
3273 match self {
3274 Self::Wide => "wide",
3275 Self::Contained => "contained",
3276 Self::Reading => "reading",
3277 }
3278 }
3279 }
3280
3281 /// What kind of value a form field takes.
3282 ///
3283 /// The union of the two vocabularies that diverged, which is what triggered
3284 /// this crate. They have since converged on their own: both apps now have a
3285 /// `renderFormField` emitting the same anatomy, and what is left differing is
3286 /// the kind set, the error shape, and whether the return is a string or a node.
3287 ///
3288 /// Validation is deliberately absent. Neither app has a shared story (goingson
3289 /// validates after collecting the form data, with per-field transform hooks;
3290 /// Balanced Breakfast has `required` and nothing else), and a schema that
3291 /// describes fields but not constraints acquires a constraint layer per app,
3292 /// which is exactly how the current divergence started. Naming it absent is a
3293 /// decision; leaving it unmentioned would not be.
3294 /// `#[non_exhaustive]` for the reason [`Fill`] is: renderers match on this and
3295 /// the set keeps growing, so growth must not be a lockstep event. Email, Url
3296 /// and Tel arriving in 0.5.0 is the second growth in two releases.
3297 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
3298 #[non_exhaustive]
3299 pub enum FieldKind {
3300 /// A single line of text.
3301 Text,
3302 /// A single line of text that must never be echoed, logged or round-tripped
3303 /// through anything that might persist it.
3304 Secret,
3305 /// A number.
3306 Number,
3307 /// A number inside bounds the user drags across, where the range being
3308 /// visible is the point.
3309 ///
3310 /// Not [`Number`](Self::Number) with [`min`](Field::min) and
3311 /// [`max`](Field::max), which is the reading to resist and is the same
3312 /// resistance [`Radio`](Self::Radio) needed against `Select`. A bounded
3313 /// number and a validated number are different *questions*. A validated
3314 /// number is typed and can be wrong: the bounds are a rule the answer is
3315 /// checked against, and being told "must be at least 1" afterwards is the
3316 /// normal course of it. A range cannot be out of range at all, because the
3317 /// bounds are the control's extent rather than a rule, and the two ends are
3318 /// what the question means — audiofiles asks for a classifier threshold
3319 /// between 0 and 1, where 0 is never and 1 is only-on-certainty, and a typed
3320 /// 0.72 says nothing without both ends on screen beside it.
3321 ///
3322 /// A renderer cannot infer which one is meant from `min`/`max` alone, which
3323 /// is why this is a kind and not an inference: goingson's `min="1"` duration
3324 /// is a validated number and would become a slider.
3325 ///
3326 /// The membership test passes without stretching: a webview emits
3327 /// `<input type="range">`, egui has `Slider`, a terminal draws a bar and
3328 /// takes arrow keys, a CLI takes a bounded argument.
3329 ///
3330 /// # It owes its bounds
3331 ///
3332 /// [`min`](Field::min) and [`max`](Field::max) are `Option` for every other
3333 /// kind and are **required** here, in the sense the description can require
3334 /// anything: [`Field::bounded`] is the check, and a range missing one has no
3335 /// extent for a renderer to draw. What a renderer does with an unbounded
3336 /// range is its own call and both answers are honest — fall back to a typed
3337 /// number, or pick a host default — so this is stated rather than enforced,
3338 /// the way every other constraint here is.
3339 ///
3340 /// [`Field::step`] is the third fact and is genuinely optional: absent, the
3341 /// host's own granularity stands.
3342 ///
3343 /// Added 0.28.0, from audiofiles' classifier thresholds and storage cap
3344 /// picker (`fb93426b`), where four sliders were hand-rolled against a
3345 /// vocabulary that could not say what they were.
3346 Range,
3347 /// One question with two ends: a lower value and an upper one, submitted
3348 /// under two names.
3349 ///
3350 /// "Show me samples between 90 and 130 BPM" has a single answer with two
3351 /// ends, and the ends constrain each other: a minimum above the maximum is
3352 /// not a wrong value, it is an empty result nobody asked for. Described as
3353 /// two [`Number`](Self::Number) fields that is unsayable — nothing says they
3354 /// are one question, so a renderer draws two controls with two labels and no
3355 /// relationship, and [`Field::error`] can only be attached to one side of a
3356 /// fault that belongs to both.
3357 ///
3358 /// Not [`Range`](Self::Range), which was the reading to resist and the
3359 /// resistance is the same one `Range` itself needed against `Number`. A
3360 /// range describes *one* value inside an extent; this describes two, and the
3361 /// extent is a bound on each rather than the question's meaning. The two
3362 /// come apart in the answer: a range has a value, an interval has a pair,
3363 /// and either end may be absent while the other stands.
3364 ///
3365 /// # It states both names
3366 ///
3367 /// [`Field::name`] is the lower end and [`Field::upper_name`] is the upper
3368 /// one, stated rather than derived. Measured 2026-08-21, the two sites in
3369 /// this tree disagree about affix order — audiofiles submits `bpm_min` /
3370 /// `bpm_max` and the MNW server submits `min_price` / `max_price` — so any
3371 /// derived rule picks one and renames the other's parameters. One member
3372 /// instead of a naming convention this crate would then own forever.
3373 ///
3374 /// Direction is carried by which member the name sits in, so nothing
3375 /// separate says which end is which.
3376 ///
3377 /// # What it does not enforce
3378 ///
3379 /// The crossing rule. A lower end above the upper one is describable here
3380 /// and always was, exactly as an out-of-[`min`](Field::min) number is: this
3381 /// crate carries constraints and never checks them, and deciding a value is
3382 /// wrong stays with whoever validated. What the description buys is that the
3383 /// fault now has one place to be reported rather than two.
3384 ///
3385 /// # Both ends take the same facts
3386 ///
3387 /// [`min`](Field::min), [`max`](Field::max), [`step`](Field::step) and
3388 /// [`unit`](Field::unit) describe the axis rather than one end of it, so
3389 /// they are read once and applied to both. Six of audiofiles' filter axes
3390 /// are exactly this: one extent, one unit, one granularity, two ends.
3391 ///
3392 /// The bounds are optional here, unlike `Range`. They are a rule the answer
3393 /// is checked against rather than the control's extent, which is
3394 /// [`Number`](Self::Number)'s arrangement and not a slider's.
3395 ///
3396 /// Added 0.34.0, ruled by Max 2026-08-21, from audiofiles' six filter axes
3397 /// and the MNW server's price pair.
3398 Interval,
3399 /// An email address.
3400 ///
3401 /// Distinct from [`Text`](Self::Text) because the distinction is not
3402 /// decoration: a webview renderer emits `type="email"`, which on a touch
3403 /// device changes the keyboard that appears and turns on the platform's own
3404 /// validation. goingson ships to iOS, so collapsing this into text costs a
3405 /// keyboard with no `@` on it.
3406 ///
3407 /// Added 0.5.0, from goingson's contact form.
3408 Email,
3409 /// A URL. Same reasoning as [`Email`](Self::Email).
3410 ///
3411 /// Added 0.5.0, from goingson's contact-social and contact-feed forms.
3412 Url,
3413 /// A telephone number. Same reasoning as [`Email`](Self::Email), and the
3414 /// clearest case of it: the keyboard is a numeric pad rather than letters.
3415 ///
3416 /// Added 0.5.0, from goingson's contact-phone form.
3417 Tel,
3418 /// A calendar day, with no time of day in it.
3419 ///
3420 /// [`Email`](Self::Email)'s argument, and it carries further: a webview
3421 /// emits `type="date"`, which is a native picker, the platform's own
3422 /// validation, and on a touch device the date keyboard. Described as
3423 /// [`Text`](Self::Text) with a hint reading "YYYY-MM-DD", all three are
3424 /// lost and the hint is doing the platform's job in prose.
3425 ///
3426 /// The membership test passes on every host without stretching: a webview
3427 /// and a Tauri app emit the input, egui has a date picker, a terminal
3428 /// prompts for a day and can validate it, a CLI takes an argument.
3429 ///
3430 /// # The value is ISO 8601, `YYYY-MM-DD`
3431 ///
3432 /// Named here rather than left to each host, because a host that picks
3433 /// differently sends a server something it parses differently, and the
3434 /// failure is silent and per-host. It is `<input type="date">`'s own wire
3435 /// format, so the webview renderer owes nothing to honour it and the other
3436 /// hosts have one spelling to meet. [`DATE_FORMAT`] is the constant, and a
3437 /// test asserts this doc and that constant agree.
3438 ///
3439 /// Added 0.15.0, from the MNW server's git access-token expiry
3440 /// (`user_ssh_keys_tab.html`) and six further sites across the server and
3441 /// goingson.
3442 Date,
3443 /// A calendar day and a time of day together.
3444 ///
3445 /// Apart from [`Date`](Self::Date) because the question is different rather
3446 /// than more precise: "which day does this expire" and "at what moment does
3447 /// this publish" are asked by different screens and answered by different
3448 /// controls. A webview emits `type="datetime-local"` for one and
3449 /// `type="date"` for the other, and a host that collapsed them would ask
3450 /// half the tree for a precision it does not want.
3451 ///
3452 /// Both arrived together on measurement rather than on symmetry: 13 sites
3453 /// of each across the MNW server and goingson, and **zero** of `time`,
3454 /// `month` or `week`, which is why those are not here. A member added for a
3455 /// case nobody has is a member designed against nothing, which is
3456 /// [`File`](Self::File)'s reasoning about `accept` applied to a whole
3457 /// member.
3458 ///
3459 /// # The value is `YYYY-MM-DDTHH:MM`, local, with no zone
3460 ///
3461 /// `<input type="datetime-local">`'s own format, and the "local" is the
3462 /// load-bearing half: the value carries no offset and no `Z`, so the moment
3463 /// it names is only fixed once something supplies a zone. That is the app's
3464 /// business and not the description's. Seconds are absent, which is the
3465 /// browser's own default and is left as the rule rather than restated as a
3466 /// constraint. [`DATETIME_FORMAT`] is the constant.
3467 ///
3468 /// [`Field::min`] and [`Field::max`] already take "the host's own spelling
3469 /// of a bound", so a floor of *not in the past* needs nothing new here: it
3470 /// is a string in this same format.
3471 ///
3472 /// Added 0.15.0, from goingson's snooze picker and day planner and the MNW
3473 /// server's publish-at fields.
3474 DateTime,
3475 /// Several lines of text.
3476 Textarea,
3477 /// Several lines of text the user writes markdown in.
3478 ///
3479 /// The editing counterpart of prose a description carries as markdown
3480 /// source, and the reason it can exist at all is the same one that lets the
3481 /// source be carried: editing markdown is editing text, so a terminal, an
3482 /// immediate-mode host and a webview all have an honest answer, and none of
3483 /// them has to refuse. A kind that meant "rich text" in the WYSIWYG sense
3484 /// would have been a document model, and two of the three hosts would have
3485 /// had to draw something they cannot.
3486 ///
3487 /// What the mark buys over [`Textarea`](Self::Textarea) is that a renderer
3488 /// may offer the affordances markdown has and plain text does not — a
3489 /// preview, a syntax pass, a monospaced face for the source — and that a
3490 /// host reading the value back knows what it is holding. A renderer with
3491 /// none of that draws a textarea, which is why this is additive rather than
3492 /// a second control.
3493 ///
3494 /// It says nothing about **when** the value is saved. Autosave is a clock,
3495 /// clocks are not described here, and the four MNW editors this was measured
3496 /// against each keep their own.
3497 ///
3498 /// Sanitising stays where it already is for markdown that is only displayed:
3499 /// with the renderer, at the point markup is produced. Being described is
3500 /// not a safety property, and a host with its own sanitiser and its own
3501 /// content-security posture still owns both.
3502 ///
3503 /// Added 0.30.0, `f8ad0b32`, from four hand-written MNW section editors —
3504 /// `project-sections.js`, `blog-editor.js`, `partial-item-text-editor.js`
3505 /// and `wizard-item-sections.js` — which are one shape written four times.
3506 Rich,
3507 /// One of a fixed set, offered behind a control that shows one at a time.
3508 Select,
3509 /// One of a fixed set, with every option on screen at once.
3510 ///
3511 /// Not a presentation of [`Select`](Self::Select), which is the reading to
3512 /// resist: what differs is a property of the *question*. A choice that is
3513 /// consequential or irreversible has to be readable without opening
3514 /// anything, because a closed control shows one option and hides the rest,
3515 /// and the one it shows is whichever was current before the user had read
3516 /// the alternatives. audiofiles asks whether a library copies samples into
3517 /// its store or references them where they lie — which cannot be changed
3518 /// afterwards — and had already promoted that out of a checkbox by hand,
3519 /// with a comment giving this reason, before the description could say it.
3520 ///
3521 /// It was described here at 0.8.1 as "the one HTML input type this enum was
3522 /// missing", which was not true then and is not true now: `file` arrived at
3523 /// 0.11.0 and `date` and `datetime-local` at 0.15.0. Everything here is
3524 /// still an `<input type=...>`, a `<select>` or a `<textarea>`, and the way
3525 /// this enum grows is by a site being measured rather than by a list being
3526 /// completed, so "the last one" is not a claim it should make again.
3527 ///
3528 /// Added 0.8.1, from audiofiles' Add Library form.
3529 Radio,
3530 /// On or off.
3531 Checkbox,
3532 /// A file the user picks from wherever the host keeps files.
3533 ///
3534 /// Added 0.11.0, `844b5ae0`, from goingson's project-dashboard attachments
3535 /// column. It was filed as a router finding — a control whose destination is
3536 /// a host capability rather than an address — and splitting it is what made
3537 /// it two answers instead of one member satisfying neither. *Opening* a file
3538 /// is a one-way handoff and needs no new API. *Picking* one returns a value
3539 /// into a write, which is a form concern, which is this.
3540 ///
3541 /// The membership test passes on every host and not by a stretch: a Tauri
3542 /// app opens a native picker, a server renders `<input type="file">`, a
3543 /// terminal prompts for a path, a CLI takes an argument. That is closer to
3544 /// [`Email`](Self::Email), which exists because it changes the keyboard,
3545 /// than to anything bespoke.
3546 ///
3547 /// # The four things an upload says, and where each of them lives
3548 ///
3549 /// | axis | where |
3550 /// |---|---|
3551 /// | what it accepts | [`Field::accept`] |
3552 /// | one file or several | [`Field::multiple`] |
3553 /// | where the bytes go | the router's action, not here |
3554 /// | how far along it is | [`Awaiting`] on that action |
3555 ///
3556 /// Only the first two are this crate's, and that split is the answer to
3557 /// "describe an upload in full" rather than a gap in it. A destination is an
3558 /// address and this crate holds no addresses; progress is a live number and
3559 /// a description is built once, so the number is the renderer's to observe
3560 /// against the size [`Awaiting::amount`] carried before the transfer began.
3561 ///
3562 /// # How the file is handed over is the host's
3563 ///
3564 /// A drop area, a button opening a native picker, a path typed at a prompt:
3565 /// all three are the same field, and every measured site has the first. It
3566 /// is not described for the reason no gesture is — this crate owns no
3567 /// coordinates and no pointer, and a terminal that cannot be dropped on
3568 /// would be refusing a description it can otherwise honour completely.
3569 ///
3570 /// The first two were absent until 0.31.0, and the doc here said why: they
3571 /// were measured rather than deferred, `accept` appearing at zero sites in
3572 /// either app. The count was taken over goingson and Balanced Breakfast, and
3573 /// the MNW server is a third consumer with 14 of them. A member designed
3574 /// against nothing is still the rule; the measurement is what changed.
3575 File,
3576 /// Which theme the app wears.
3577 ///
3578 /// The one member here that names a *subject* rather than a shape of
3579 /// answer, and it is worth saying why that is not the door it looks like.
3580 /// Every other kind is a question a screen might ask about anything; this
3581 /// one is a specific question every app in the family asks, once, on its
3582 /// settings screen, and three of them wrote the same control by hand.
3583 ///
3584 /// # It is furniture, and the measurement is what says so
3585 ///
3586 /// The reading to resist is that this is [`Select`](Self::Select) with a
3587 /// grouped option list, and the grouped select is what was rejected to get
3588 /// here (`70028e00`, ruled by Max 2026-08-28). Grouping was measured across
3589 /// the tree first: `optgroup` appears at exactly **one** live site, in the
3590 /// one app not yet ported, and the non-theme grouping count is **zero**.
3591 /// So the recurring thing was never "option lists that group". It was this
3592 /// picker.
3593 ///
3594 /// # What it carries that a select cannot
3595 ///
3596 /// [`Field::themes`] rather than [`Field::options`], because a theme is
3597 /// four facts and an option is two. The two extra facts are the ones no
3598 /// app can supply without redoing work the theme layer has already done:
3599 /// which [`ThemeVariant`] group a theme is in, and how legible its muted
3600 /// text measured. `Choice::new(id, format!("{name} ({variant})"))` is what
3601 /// the three apps had, and it flattens the group into prose and loses the
3602 /// tier entirely.
3603 ///
3604 /// [`Field::follows`] carries the entry that is not a theme.
3605 ///
3606 /// # The cost, stated rather than discovered later
3607 ///
3608 /// This puts one screen's shape into a vocabulary that otherwise holds
3609 /// none, which was the objection raised against it and accepted going in.
3610 /// The mitigation is narrowness: this describes a theme picker, not a
3611 /// general "list the host resolved" mechanism. A second host-resolved list
3612 /// is when that generalisation gets measured, and not before.
3613 ///
3614 /// A renderer that has not heard of it draws a select over
3615 /// [`Field::themes`]' names and loses the grouping, which is the state
3616 /// every app was in before this member. Degrading to the status quo ante
3617 /// is the floor the member is designed against.
3618 ///
3619 /// Added 0.38.0.
3620 Theme,
3621 /// Carried through the form and never shown.
3622 Hidden,
3623 }
3624
3625 /// The wire format a [`FieldKind::Date`] value takes: ISO 8601, `YYYY-MM-DD`.
3626 ///
3627 /// A constant rather than a sentence in a doc comment, because the reason to
3628 /// name the format at all is that a host picking its own would fail silently
3629 /// against a server parsing another. A host that cannot emit the native control
3630 /// still has one spelling to meet, and can say which one it meant.
3631 pub const DATE_FORMAT: &str = "%Y-%m-%d";
3632
3633 /// The wire format a [`FieldKind::DateTime`] value takes: `YYYY-MM-DDTHH:MM`,
3634 /// local, carrying no zone and no seconds.
3635 ///
3636 /// [`DATE_FORMAT`]'s sibling and there for its reason. The absent zone is a
3637 /// property of the value rather than an omission: the moment is not fixed until
3638 /// something outside the description supplies one.
3639 pub const DATETIME_FORMAT: &str = "%Y-%m-%dT%H:%M";
3640
3641 impl FieldKind {
3642 /// Whether the value the kind takes is a moment rather than a string.
3643 ///
3644 /// Named once here for the reason [`offers_options`](Self::offers_options)
3645 /// is: two kinds answer yes, and a host that has to parse or format a value
3646 /// needs to ask without spelling the pair out at each renderer. A third
3647 /// temporal kind should land here and nowhere else.
3648 ///
3649 /// The format each one takes is [`DATE_FORMAT`] and [`DATETIME_FORMAT`].
3650 #[must_use]
3651 pub const fn temporal(self) -> bool {
3652 matches!(self, Self::Date | Self::DateTime)
3653 }
3654
3655 /// Whether the field is drawn at all.
3656 #[must_use]
3657 pub const fn visible(self) -> bool {
3658 !matches!(self, Self::Hidden)
3659 }
3660
3661 /// Whether the value must be kept out of logs and diagnostics.
3662 #[must_use]
3663 pub const fn confidential(self) -> bool {
3664 matches!(self, Self::Secret)
3665 }
3666
3667 /// Where the field's own label sits.
3668 ///
3669 /// A checkbox labels itself on the right of the box; everything else takes
3670 /// a label above. Both webview apps already do this and both special-case
3671 /// it inline, which is the tell that it belongs in the description.
3672 ///
3673 /// A [`Radio`](Self::Radio) is not one of them, and the near-miss is worth
3674 /// naming: its *options* each label themselves, but the field still asks a
3675 /// question above them, so the group takes a label like everything else.
3676 #[must_use]
3677 pub const fn labels_itself(self) -> bool {
3678 matches!(self, Self::Checkbox)
3679 }
3680
3681 /// Whether the kind reads [`Field::options`].
3682 ///
3683 /// Two kinds do, so the pair is named once here rather than spelled out at
3684 /// each renderer and again in [`Field::options`]' own doc, where "every
3685 /// kind but `Select`" was true for exactly one release. A third
3686 /// option-taking kind should land here and nowhere else.
3687 #[must_use]
3688 pub const fn offers_options(self) -> bool {
3689 matches!(self, Self::Select | Self::Radio)
3690 }
3691
3692 /// Whether the kind reads [`Field::themes`] and [`Field::follows`].
3693 ///
3694 /// One member answers yes, and it gets a name for
3695 /// [`takes_files`](Self::takes_files)'s reason rather than in spite of
3696 /// being alone: four renderers ask it before they read either member, and
3697 /// a `matches!` per renderer is where the next one goes missing.
3698 ///
3699 /// Deliberately not folded into
3700 /// [`offers_options`](Self::offers_options). A theme picker offers no
3701 /// [`Choice`]es at all, so a renderer walking `options` for it walks an
3702 /// empty slice and draws an empty control.
3703 ///
3704 /// Added 0.38.0.
3705 #[must_use]
3706 pub const fn offers_themes(self) -> bool {
3707 matches!(self, Self::Theme)
3708 }
3709
3710 /// Whether the value runs to more than one line.
3711 ///
3712 /// Named once here for [`temporal`](Self::temporal)'s reason: two kinds
3713 /// answer yes, every renderer has to ask it before it can size anything,
3714 /// and a `matches!` per renderer is the pair drifting apart one member at a
3715 /// time. What a host does with the markdown, if anything, it reads from the
3716 /// kind itself; this is only whether one line is enough.
3717 #[must_use]
3718 pub const fn multiline(self) -> bool {
3719 matches!(self, Self::Textarea | Self::Rich)
3720 }
3721
3722 /// Whether the value is a file the host picks rather than a string typed
3723 /// into a box.
3724 ///
3725 /// One member answers yes, which is [`visible`](Self::visible)'s and
3726 /// [`confidential`](Self::confidential)'s footing rather than a departure
3727 /// from it: the question gets a name because three renderers ask it before
3728 /// they can read [`Field::accept`] or [`Field::multiple`], and a `matches!`
3729 /// per renderer is where a second file-taking kind would go missing.
3730 #[must_use]
3731 pub const fn takes_files(self) -> bool {
3732 matches!(self, Self::File)
3733 }
3734
3735 /// Whether the value is a quantity, so [`Field::unit`] means something.
3736 ///
3737 /// The numeric kinds and nothing else. A date is a quantity in the sense
3738 /// that it is ordered, and it is not one in the sense that matters here:
3739 /// its unit is fixed by the kind, so `Date` carrying `days` would be the
3740 /// description restating what [`kind`](Field::kind) already said.
3741 ///
3742 /// [`takes_files`](Self::takes_files)'s footing, and for its reason: the
3743 /// renderers ask this before they decide where a unit goes, and a
3744 /// `matches!` per renderer is where the next measurable kind goes missing.
3745 ///
3746 /// Added 0.33.0 with [`Field::unit`]. [`Interval`](Self::Interval) joined at
3747 /// 0.34.0: an axis is measured in something and both its ends are in it.
3748 #[must_use]
3749 pub const fn measurable(self) -> bool {
3750 matches!(self, Self::Number | Self::Range | Self::Interval)
3751 }
3752 }
3753
3754 /// A family of media a file can belong to.
3755 ///
3756 /// Three members, because three is what a media type's own first segment offers
3757 /// that a renderer can do anything with. `text` and `application` are families
3758 /// too and neither buys a disclosure — there is no preview of an
3759 /// `application/octet-stream` — so naming them would be a member added for a
3760 /// case nobody has.
3761 ///
3762 /// It is the answer to "which disclosure", not a validation rule.
3763 /// [`Field::accept`] is what a host filters on.
3764 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
3765 #[non_exhaustive]
3766 pub enum Family {
3767 /// A still picture.
3768 Image,
3769 /// Sound.
3770 Audio,
3771 /// Moving pictures, with or without sound.
3772 Video,
3773 }
3774
3775 impl Family {
3776 /// The wildcard media type that means the whole family.
3777 ///
3778 /// `image/*` and its two siblings, which is what the measured sites write
3779 /// and what a webview puts in an `accept` attribute. Named here so the three
3780 /// renderers do not each spell the star.
3781 #[must_use]
3782 pub const fn wildcard(self) -> &'static str {
3783 match self {
3784 Self::Image => "image/*",
3785 Self::Audio => "audio/*",
3786 Self::Video => "video/*",
3787 }
3788 }
3789
3790 /// The family a media type's first segment names, if it is one of these.
3791 ///
3792 /// Case-insensitive on the segment, because a media type is
3793 /// case-insensitive and half the tree writes them lowercase by habit rather
3794 /// than by rule.
3795 #[must_use]
3796 pub fn of_type(media_type: &str) -> Option<Self> {
3797 let (top, _) = media_type.split_once('/')?;
3798 if top.eq_ignore_ascii_case("image") {
3799 Some(Self::Image)
3800 } else if top.eq_ignore_ascii_case("audio") {
3801 Some(Self::Audio)
3802 } else if top.eq_ignore_ascii_case("video") {
3803 Some(Self::Video)
3804 } else {
3805 None
3806 }
3807 }
3808 }
3809
3810 /// One entry in a file field's accept list.
3811 ///
3812 /// Three shapes rather than a string, and all three are in the measured sites:
3813 /// the MNW server writes `image/*`, `image/jpeg,image/png,image/webp`,
3814 /// `.zip,.dmg,.exe,.appimage,.deb,.tar.gz,.clap,.vst3` and, in one place,
3815 /// `.csv,text/csv`. A single string would carry all of them and answer nothing
3816 /// about any of them.
3817 ///
3818 /// # Why the list is not just a filter
3819 ///
3820 /// It is read twice. Once to decide what the picker offers, which any of the
3821 /// three shapes serves, and once to decide **which disclosure** the field gets:
3822 /// a preview for a picture, a duration or a waveform for a sound. There is one
3823 /// upload shape and a media upload is that shape with more of it shown, so the
3824 /// accept list is what says which more. [`family`](Self::family) is that
3825 /// question answered once here instead of a media-type parser in each renderer.
3826 ///
3827 /// # A suffix names no family, on purpose
3828 ///
3829 /// `.mp3` is audio in fact, and nothing here says so. A suffix-to-family table
3830 /// in a published crate is a mapping that goes stale, disagrees with the host's
3831 /// own idea of what a file is, and is wrong the first time somebody hands it a
3832 /// container. A call site that wants a picture's preview writes
3833 /// [`Family::Image`] or `image/jpeg`; a call site listing installer suffixes
3834 /// wants no disclosure anyway, which is the measured case.
3835 ///
3836 /// Added 0.31.0, `f7261a5a`.
3837 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
3838 #[non_exhaustive]
3839 pub enum Accepted<'a> {
3840 /// Every file of a family: `image/*` and its siblings.
3841 Family(Family),
3842 /// One media type, written the way a media type is written:
3843 /// `image/jpeg`, `text/csv`.
3844 Type(&'a str),
3845 /// One file-name suffix, written with its leading dot: `.zip`, `.tar.gz`.
3846 ///
3847 /// A suffix and not an extension, because `.tar.gz` is a measured site and
3848 /// is two dots.
3849 Suffix(&'a str),
3850 }
3851
3852 impl<'a> Accepted<'a> {
3853 /// The family this entry belongs to, when it names one.
3854 ///
3855 /// [`None`] for a [`Suffix`](Self::Suffix) and for any media type outside
3856 /// the three families, which is the honest answer rather than a missing
3857 /// one: the description did not say.
3858 #[must_use]
3859 pub fn family(self) -> Option<Family> {
3860 match self {
3861 Self::Family(family) => Some(family),
3862 Self::Type(media_type) => Family::of_type(media_type),
3863 Self::Suffix(_) => None,
3864 }
3865 }
3866
3867 /// How a host that wants one string writes this entry.
3868 ///
3869 /// A webview's `accept` attribute takes exactly these spellings, and a
3870 /// terminal listing what it will take reads the same words.
3871 #[must_use]
3872 pub const fn as_str(self) -> &'a str {
3873 match self {
3874 Self::Family(family) => family.wildcard(),
3875 Self::Type(text) | Self::Suffix(text) => text,
3876 }
3877 }
3878 }
3879
3880 /// One option offered by a field [`FieldKind::offers_options`] accepts.
3881 ///
3882 /// Two strings, because the submitted value and the read label are different
3883 /// facts and every renderer that has tried to collapse them has had to
3884 /// un-collapse them later. `makeover-webview` invented this shape writing its
3885 /// form emitter and it is taken here unchanged; moving it down rather than
3886 /// re-deriving it is the point, since the second and third renderers were each
3887 /// going to arrive at a near-miss of it.
3888 /// `#[non_exhaustive]` as of 0.28.0, which every other type here that a
3889 /// renderer matches or builds has carried for releases. It was the omission
3890 /// that made [`unavailable`](Self::unavailable) a breaking change across 40
3891 /// literal sites in six repos, and it arrives with that member so the price is
3892 /// paid once and never again.
3893 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
3894 #[non_exhaustive]
3895 pub struct Choice<'a> {
3896 /// What is submitted.
3897 pub value: &'a str,
3898 /// What is read.
3899 pub label: &'a str,
3900 /// Why it cannot be picked right now, when it cannot.
3901 ///
3902 /// One member rather than an `available: bool` beside a reason, and the
3903 /// conflation is the point: an option greyed out with no explanation is a
3904 /// dead end the user cannot act on, and it is exactly the state the app
3905 /// that found this gap had to patch by hand with a line of prose under the
3906 /// control. Making the reason mandatory means the description cannot say
3907 /// the useless half.
3908 ///
3909 /// The option stays in the list. Dropping it is what an app does today, and
3910 /// it costs the user the knowledge that the thing exists at all —
3911 /// audiofiles' multi-sample mode appears on its own once a second sample is
3912 /// dropped, so a user who never sees it never learns what to drop.
3913 ///
3914 /// **Not [`Field::error`], and not [`Field::hint`].** An error is about the
3915 /// answer and a hint is standing help for the whole question; this is about
3916 /// one option among several, which is the level neither of those reaches.
3917 ///
3918 /// **Not disabled-the-state.** `State::Disabled` is about a whole field
3919 /// refusing to answer. This says the field is live and one of its answers
3920 /// is not available yet, which is a different sentence and the reason the
3921 /// tone rule matters here: the *other* options are still usable.
3922 ///
3923 /// Added 0.28.0, from audiofiles' instrument mode selector (`e761833e`).
3924 pub unavailable: Option<&'a str>,
3925 }
3926
3927 impl<'a> Choice<'a> {
3928 /// An option whose submitted value is also its label.
3929 #[must_use]
3930 pub const fn plain(value: &'a str) -> Self {
3931 Self::new(value, value)
3932 }
3933
3934 /// An option that submits one string and reads as another.
3935 ///
3936 /// A constructor rather than a literal, which is what `#[non_exhaustive]`
3937 /// costs and buys: outside this crate the struct cannot be built by naming
3938 /// its members, so every call site goes through here and the next member
3939 /// added breaks none of them.
3940 #[must_use]
3941 pub const fn new(value: &'a str, label: &'a str) -> Self {
3942 Self {
3943 value,
3944 label,
3945 unavailable: None,
3946 }
3947 }
3948
3949 /// The same option, not pickable yet, and why.
3950 ///
3951 /// Builder-shaped because the reason is the rare case: 39 of the 40 option
3952 /// sites measured across the tree do not have one.
3953 #[must_use]
3954 pub const fn unless(mut self, reason: &'a str) -> Self {
3955 self.unavailable = Some(reason);
3956 self
3957 }
3958
3959 /// Whether the option can be picked right now.
3960 ///
3961 /// The predicate a renderer branches on, so that "unavailable" is read as
3962 /// one condition in one place rather than as `unavailable.is_some()` at
3963 /// three renderers, one of which will invert it.
3964 #[must_use]
3965 pub const fn available(&self) -> bool {
3966 self.unavailable.is_none()
3967 }
3968 }
3969
3970 /// One entry in a field's suggestion list.
3971 ///
3972 /// A suggestion-only type rather than a fourth member on [`Choice`], ruled by
3973 /// Max 2026-08-21 (`1fcf2e9b`). The two are near-identical and that is the
3974 /// drift risk the ruling accepted, so the mitigation is written here: **an
3975 /// option and a candidate are submitted the same way and read differently.**
3976 /// An option is a thing you pick from a known set, and the set is the whole of
3977 /// what there is. A candidate is a thing you are being *oriented* toward out of
3978 /// a set nobody can see, which is why it carries [`detail`](Self::detail) and
3979 /// an option does not.
3980 ///
3981 /// This reverses a position quasi-router stated in its own doc, that a
3982 /// candidate is [`Choice`] "because a candidate is submitted under one string
3983 /// and read under another, which is what an option is". True and not
3984 /// sufficient: how a thing is submitted was never the half that differed.
3985 ///
3986 /// # Why the second string is not folded into the label
3987 ///
3988 /// Because every renderer wants it separately, and the two measured sites both
3989 /// draw it by hand today. The MNW server's tag box computes its context as the
3990 /// parent path -- "the parent path orients an otherwise ambiguous leaf:
3991 /// 'Format' appears under audio, software, writing, and video" -- and a list of
3992 /// four identical rows reading "Format" is not a usable list. In a webview the
3993 /// second string is styled differently, in a terminal it wants the remaining
3994 /// columns rather than a dash, and in neither is it part of what the typed
3995 /// value matches against. `Choice::new(slug, format!("{label} - {context}"))`
3996 /// loses all three of those facts, which is the condition this type exists to
3997 /// end.
3998 ///
3999 /// # No `unavailable`
4000 ///
4001 /// [`Choice::unavailable`] has no counterpart here, and the omission is the
4002 /// implementer's call recorded rather than an oversight. A suggestion that
4003 /// cannot be picked is arguably not a suggestion: an option list is a fixed set
4004 /// a user is owed an explanation about, and a candidate list is whatever a
4005 /// route decided to offer, so a route with nothing to say simply does not offer
4006 /// the row. Add it if a measured site ever wants it.
4007 ///
4008 /// # What it does not carry, and where that lives
4009 ///
4010 /// What *happens* when a candidate is picked. Picking is local by default -- it
4011 /// writes [`value`](Self::value) into the field that owns the list -- and a
4012 /// candidate that does something else says so with an action. An action is not
4013 /// a word this crate has, exactly as [`Field`] here has no `suggests` member,
4014 /// so both live on the router's owned mirror of this type. Ruled the same day
4015 /// (`ed1fa86f`).
4016 ///
4017 /// `#[non_exhaustive]` from birth. Non-negotiable and the reason is on the
4018 /// sibling: [`Choice`] took it at 0.28.0 only after `unavailable` broke 40
4019 /// literal sites in six repos, and a new type repeating that would be the third
4020 /// time the tree learned it.
4021 ///
4022 /// Added 0.35.0.
4023 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
4024 #[non_exhaustive]
4025 pub struct Candidate<'a> {
4026 /// What is submitted, and what picking writes into the field.
4027 pub value: &'a str,
4028 /// What is read.
4029 pub label: &'a str,
4030 /// The second line: what orients this candidate among rows that read alike.
4031 ///
4032 /// Optional because a candidate list whose labels are already distinct
4033 /// wants nothing here, and a renderer given [`None`] draws one line rather
4034 /// than an empty second one.
4035 pub detail: Option<&'a str>,
4036 }
4037
4038 impl<'a> Candidate<'a> {
4039 /// A candidate whose submitted value is also its label.
4040 #[must_use]
4041 pub const fn plain(value: &'a str) -> Self {
4042 Self::new(value, value)
4043 }
4044
4045 /// A candidate that submits one string and reads as another.
4046 ///
4047 /// A constructor rather than a literal, which is what `#[non_exhaustive]`
4048 /// costs and buys: outside this crate the struct cannot be built by naming
4049 /// its members, so every call site goes through here and the next member
4050 /// added breaks none of them.
4051 #[must_use]
4052 pub const fn new(value: &'a str, label: &'a str) -> Self {
4053 Self {
4054 value,
4055 label,
4056 detail: None,
4057 }
4058 }
4059
4060 /// The same candidate, with the line that tells it from its neighbours.
4061 #[must_use]
4062 pub const fn detailed(mut self, detail: &'a str) -> Self {
4063 self.detail = Some(detail);
4064 self
4065 }
4066 }
4067
4068 /// Which ambient mode a theme is written for.
4069 ///
4070 /// The vocabulary's own spelling of what `makeover` calls a theme's variant,
4071 /// and the duplication is deliberate rather than an oversight. This crate has
4072 /// no dependencies by charter — it emits nothing, reads nothing and resolves
4073 /// nothing — so it cannot take the crate that owns the file format, and a
4074 /// renderer that must group a picker needs the three groups as values.
4075 ///
4076 /// The two are kept in step by the app that converts between them, which is a
4077 /// three-arm `match` at each adopter and the price of the layering. If a fourth
4078 /// mode is ever authored, this enum and `makeover::Variant` move together.
4079 ///
4080 /// Three, not two: one shipped theme is high contrast, and an app matching on
4081 /// light-or-dark alone files it under the wrong one.
4082 ///
4083 /// Added 0.38.0.
4084 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
4085 #[non_exhaustive]
4086 pub enum ThemeVariant {
4087 /// Written for a light ambient mode.
4088 Light,
4089 /// Written for a dark ambient mode.
4090 Dark,
4091 /// Written to be legible before it is pretty.
4092 HighContrast,
4093 }
4094
4095 impl ThemeVariant {
4096 /// The machine spelling, matching the theme file's own `meta.variant`.
4097 ///
4098 /// A data attribute, a stored value, a test assertion. Not a heading: what
4099 /// a group is *called* on screen is [`heading`](Self::heading).
4100 #[must_use]
4101 pub const fn as_str(self) -> &'static str {
4102 match self {
4103 ThemeVariant::Light => "light",
4104 ThemeVariant::Dark => "dark",
4105 ThemeVariant::HighContrast => "high-contrast",
4106 }
4107 }
4108
4109 /// What the group of themes in this variant is called on screen.
4110 ///
4111 /// Here rather than at each renderer, which is the whole argument for the
4112 /// member existing: three renderers picking their own headings is one
4113 /// picker reading three ways, and the spellings below are the ones
4114 /// goingson's shipped picker used before it was described.
4115 #[must_use]
4116 pub const fn heading(self) -> &'static str {
4117 match self {
4118 ThemeVariant::Light => "Light",
4119 ThemeVariant::Dark => "Dark",
4120 ThemeVariant::HighContrast => "High Contrast",
4121 }
4122 }
4123 }
4124
4125 impl std::fmt::Display for ThemeVariant {
4126 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
4127 f.write_str(self.as_str())
4128 }
4129 }
4130
4131 /// How legible a theme measured, as a picker reports it.
4132 ///
4133 /// A measurement carried into the description, which is unusual here and is the
4134 /// one case that earns it: the number comes off the theme's resolved colours,
4135 /// so the layer that loaded the theme is the only party that has it, and an app
4136 /// re-deriving it would be parsing every theme file a second time to learn what
4137 /// was already known. What a renderer does with it is a badge beside the name.
4138 ///
4139 /// Ordered worst-first, matching `makeover::ContrastTier`, so the two sort the
4140 /// same way and an adopter's `match` cannot invert an ordering by accident.
4141 ///
4142 /// Added 0.38.0.
4143 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
4144 #[non_exhaustive]
4145 pub enum Contrast {
4146 /// Muted text below the 3:1 floor for large text and UI parts.
4147 Low,
4148 /// Muted text clears 3:1 but not the 4.5:1 bar for normal text.
4149 Standard,
4150 /// Muted text meets WCAG AA on every panel ground.
4151 High,
4152 }
4153
4154 impl Contrast {
4155 /// The machine spelling, for a data attribute or a test.
4156 #[must_use]
4157 pub const fn as_str(self) -> &'static str {
4158 match self {
4159 Contrast::Low => "low",
4160 Contrast::Standard => "standard",
4161 Contrast::High => "high",
4162 }
4163 }
4164
4165 /// The short mark shown beside a theme's name.
4166 ///
4167 /// One spelling for the tree, for [`ThemeVariant::heading`]'s reason. These
4168 /// are the marks audiofiles shipped before its picker was described, which
4169 /// is the only implementation that ever drew them.
4170 ///
4171 /// [`Standard`](Self::Standard) is not the absence of a mark: a reader
4172 /// scanning a column of badges learns more from three marks than from two
4173 /// and a gap, and "OK" is the honest reading of a theme that clears the UI
4174 /// floor and misses the text one.
4175 #[must_use]
4176 pub const fn badge(self) -> &'static str {
4177 match self {
4178 Contrast::Low => "low",
4179 Contrast::Standard => "OK",
4180 Contrast::High => "AA",
4181 }
4182 }
4183 }
4184
4185 impl std::fmt::Display for Contrast {
4186 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
4187 f.write_str(self.as_str())
4188 }
4189 }
4190
4191 /// One theme, as a picker offers it.
4192 ///
4193 /// Four facts where a [`Choice`] has two, and the two extra ones are why this
4194 /// is its own type rather than options with the variant folded into the label.
4195 /// Both are facts the theme layer resolved and neither survives being written
4196 /// into a string: a group is structure and a badge is a second column.
4197 ///
4198 /// # No `unavailable`
4199 ///
4200 /// [`Choice::unavailable`]'s counterpart is absent for its own sibling's
4201 /// reason. A theme that is installed can be picked, and a theme that is not
4202 /// installed is not in the list. There is no third state for a reason to
4203 /// explain.
4204 ///
4205 /// `#[non_exhaustive]` from birth, which is the whole of what 0.28.0 cost the
4206 /// tree and is not being paid a third time.
4207 ///
4208 /// Added 0.38.0.
4209 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
4210 #[non_exhaustive]
4211 pub struct ThemeChoice<'a> {
4212 /// What is submitted, and what the app stores.
4213 pub id: &'a str,
4214 /// What is read.
4215 pub name: &'a str,
4216 /// Which group it belongs to.
4217 pub variant: ThemeVariant,
4218 /// How legible its muted text measured.
4219 pub contrast: Contrast,
4220 }
4221
4222 impl<'a> ThemeChoice<'a> {
4223 /// A theme, with everything a picker needs to place and mark it.
4224 ///
4225 /// Every fact is an argument and none is a builder, which is the opposite
4226 /// of [`Choice`]'s arrangement and is deliberate: a theme missing its
4227 /// variant has no group to sit in and a theme missing its tier has no badge
4228 /// to draw, so both are the control rather than embellishments on it. The
4229 /// same reasoning [`Field::range`] applies to its bounds.
4230 #[must_use]
4231 pub const fn new(
4232 id: &'a str,
4233 name: &'a str,
4234 variant: ThemeVariant,
4235 contrast: Contrast,
4236 ) -> Self {
4237 Self {
4238 id,
4239 name,
4240 variant,
4241 contrast,
4242 }
4243 }
4244 }
4245
4246 /// One field of a form.
4247 ///
4248 /// Borrowed rather than owned: a description is built, read once by a renderer,
4249 /// and dropped. Nothing here outlives the screen it describes.
4250 ///
4251 /// # What it carries, and what it does not
4252 ///
4253 /// Stated here so the next renderer does not re-ask, which is what the first
4254 /// two both did. It carries everything a renderer needs to *draw* the field:
4255 /// its kind, what it is called, what it is asked for, its standing help, what
4256 /// is wrong with it now, whether it is compulsory, whether it hides behind a
4257 /// disclosure, its ghost text, and the options it offers.
4258 ///
4259 /// It does not carry the **current value**, and it is not going to. That is the
4260 /// one thing here that is genuinely renderer state: a webview reads it back out
4261 /// of the DOM, an immediate-mode renderer holds a `&mut` to the app's own field
4262 /// and writes through it, and a terminal keeps an edit buffer. A description
4263 /// that carried the value would have to carry a way to write it back, at which
4264 /// point it is a form model and no longer a description.
4265 ///
4266 /// **Constraints** are here and enforcement is not, which is one line rather
4267 /// than two. [`required`], [`max_length`], [`min`] and [`max`] are facts about
4268 /// the *question*, so a renderer can emit its host's idiom for each — an HTML
4269 /// attribute, a marked label, a clamped spinner — and the platform helps the
4270 /// user before anything is submitted. Deciding that a value is wrong stays with
4271 /// whoever validated, and [`error`] is that decision arriving back.
4272 ///
4273 /// The set stops before `pattern`, and stops there on both tests at once. A
4274 /// regex has an honest answer in a webview and none anywhere else: egui would
4275 /// have to run it per keystroke and decide what a half-typed value means, which
4276 /// is enforcement wearing description's clothes. And it is one site in goingson
4277 /// and none in Balanced Breakfast, against 8 and 1 for `maxlength`. Measured
4278 /// 2026-08-09, `2cbad3e2`.
4279 ///
4280 /// [`error`]: Field::error
4281 /// [`required`]: Field::required
4282 /// [`max_length`]: Field::max_length
4283 /// [`min`]: Field::min
4284 /// [`max`]: Field::max
4285 /// How a slider's position becomes its value, and how finely it moves.
4286 ///
4287 /// **The data of a slider is a fraction and a function taking numbers to
4288 /// numbers.** Stated by Max 2026-08-21, and it corrects a reading this crate
4289 /// had carried since [`FieldKind::Range`] arrived at 0.28.0:
4290 /// [`min`](Field::min) and [`max`](Field::max) were never the control's extent.
4291 /// A slider's extent is always 0 to 1 — a thumb at 40% of a track — and the
4292 /// bounds are `f(0)` and `f(1)`. Linear is the constant-slope case, which is
4293 /// exactly why nobody noticed the function was there: when `f` is
4294 /// `min + t * (max - min)` the extent and the bounds coincide numerically and
4295 /// the mapping is invisible.
4296 ///
4297 /// So this is not a scale flag bolted onto a range. Every range described
4298 /// before it had a mapping, and four renderers each hard-coded the same one.
4299 ///
4300 /// # Why a closed family and not a function
4301 ///
4302 /// `fn(f64) -> f64` is the literal reading and it does not survive the
4303 /// description boundary. A fn pointer cannot be emitted into a browser, and it
4304 /// cannot be compared or hashed in a way that means anything, which this struct
4305 /// needs. A named family is the same semantics with arbitrary closures given
4306 /// up, and nothing measured wants one: the tree has a single non-linear shape
4307 /// across five controls and no second shape at all.
4308 ///
4309 /// # Why the step is here
4310 ///
4311 /// Max, in the same breath: if the family is prescriptive anyway, the step
4312 /// spacing belongs in it. On a slider the granularity and the mapping are one
4313 /// decision — a curve chosen without saying how finely it moves is half an
4314 /// answer — and holding them apart is what let a 0-to-1 threshold ship as a
4315 /// two-position control, since the host default of 1 was applied to a mapping
4316 /// nobody had named. It also un-overloads [`Field::step`], which stays as it
4317 /// was for a *typed* value, where there is no mapping and the granularity is a
4318 /// plain fact about the number.
4319 ///
4320 /// A future curve carrying a fact of its own — an exponent, an inflection —
4321 /// puts it in its own variant rather than on the struct, which is the second
4322 /// reason this shape is right.
4323 ///
4324 /// **The step is in the value's own units under every curve.** What a curve
4325 /// changes is the mapping, not the units the granularity is measured in: a step
4326 /// of `0.001` on an envelope time is three decimals whether the track is
4327 /// logarithmic or not, and a renderer that reads the step for display precision
4328 /// keeps reading it the same way.
4329 ///
4330 /// Added 0.32.0, from audiofiles' ADSR envelope and its storage cap picker.
4331 #[non_exhaustive]
4332 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
4333 pub enum Curve<'a> {
4334 /// Constant slope: `f(t) = min + t * (max - min)`.
4335 ///
4336 /// What every described range meant before this enum existed, and the
4337 /// default, so a site that says nothing is correct unchanged.
4338 Linear {
4339 /// The granularity, in the value's own units. `None` is the host's own.
4340 step: Option<&'a str>,
4341 },
4342 /// Constant ratio: `f(t) = min * (max / min).powf(t)`.
4343 ///
4344 /// The mapping for a question whose extent spans orders of magnitude and
4345 /// whose interesting half is the small end. audiofiles' envelope times run
4346 /// 0.001 to 5 seconds, where a 5 ms attack and a 50 ms attack are audibly
4347 /// different instruments and a linear track puts both inside its first one
4348 /// percent.
4349 ///
4350 /// # It needs positive bounds
4351 ///
4352 /// A constant ratio is undefined across zero, so this asks for `min > 0`.
4353 /// A range that does not have that is mapped [`Linear`](Self::Linear)ly
4354 /// instead — see [`value_at`](Self::value_at). Stated rather than enforced,
4355 /// the way every other constraint in this crate is, and it is not a
4356 /// hypothetical: an envelope's sustain is a 0-to-1 level and is linear for
4357 /// this reason rather than by oversight.
4358 Logarithmic {
4359 /// The granularity, in the value's own units. `None` is the host's own.
4360 step: Option<&'a str>,
4361 },
4362 }
4363
4364 impl Default for Curve<'_> {
4365 fn default() -> Self {
4366 Self::Linear { step: None }
4367 }
4368 }
4369
4370 impl<'a> Curve<'a> {
4371 /// The granularity this curve moves in, whichever curve it is.
4372 ///
4373 /// Every variant carries one, so reading it does not need a match at each
4374 /// of the four renderers.
4375 #[must_use]
4376 pub const fn step(self) -> Option<&'a str> {
4377 // No wildcard: `#[non_exhaustive]` binds downstream, not here, so a
4378 // curve added later has to answer this rather than fall through to a
4379 // granularity nobody chose.
4380 match self {
4381 Self::Linear { step } | Self::Logarithmic { step } => step,
4382 }
4383 }
4384
4385 /// Whether this curve maps as a constant ratio *given these bounds*.
4386 ///
4387 /// The bounds are the argument because [`Logarithmic`](Self::Logarithmic)
4388 /// is a request rather than a guarantee: it needs `0 < min < max`, and a
4389 /// range that does not have that is drawn linearly. A renderer asks this
4390 /// instead of matching on the variant, so the fallback is decided in one
4391 /// place rather than four.
4392 #[must_use]
4393 pub fn is_ratio(self, min: f64, max: f64) -> bool {
4394 matches!(self, Self::Logarithmic { .. }) && min > 0.0 && max > min
4395 }
4396
4397 /// The value at a position along the track, where `position` is 0 to 1.
4398 ///
4399 /// `f`. The whole point of the type, and it lives here rather than in each
4400 /// renderer so that a terminal's bar, an egui slider and a browser's input
4401 /// cannot disagree about where a value sits.
4402 ///
4403 /// A position outside 0 to 1 is clamped, and bounds that are equal or
4404 /// inverted give `min` back: a track with no extent has one value on it.
4405 #[must_use]
4406 pub fn value_at(self, position: f64, min: f64, max: f64) -> f64 {
4407 let position = position.clamp(0.0, 1.0);
4408 // NaN named rather than fallen through: `max <= min` is false for a NaN
4409 // bound, so without it a track with no numbers on it would be mapped as
4410 // if it had two.
4411 if max <= min || min.is_nan() || max.is_nan() {
4412 return min;
4413 }
4414 if self.is_ratio(min, max) {
4415 min * (max / min).powf(position)
4416 } else {
4417 position.mul_add(max - min, min)
4418 }
4419 }
4420
4421 /// The position a value sits at, where the answer is 0 to 1.
4422 ///
4423 /// `f` inverted, which is what a renderer needs to *draw* a value it was
4424 /// handed. Same clamping and the same degenerate answer as
4425 /// [`value_at`](Self::value_at).
4426 #[must_use]
4427 pub fn position_of(self, value: f64, min: f64, max: f64) -> f64 {
4428 if max <= min || min.is_nan() || max.is_nan() {
4429 return 0.0;
4430 }
4431 let value = value.clamp(min, max);
4432 let position = if self.is_ratio(min, max) {
4433 (value / min).ln() / (max / min).ln()
4434 } else {
4435 (value - min) / (max - min)
4436 };
4437 position.clamp(0.0, 1.0)
4438 }
4439 }
4440
4441 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
4442 pub struct Field<'a> {
4443 /// What kind of value it takes.
4444 pub kind: FieldKind,
4445 /// The name the value is submitted under.
4446 ///
4447 /// The *lower* end's name for a [`FieldKind::Interval`], whose upper end is
4448 /// [`upper_name`](Self::upper_name). Every other kind submits one value and
4449 /// this is the whole of it.
4450 pub name: &'a str,
4451 /// The name a [`FieldKind::Interval`]'s upper end is submitted under.
4452 ///
4453 /// [`None`] for every other kind, and sayable-and-ignored there the way
4454 /// [`options`](Self::options) is on a kind that offers none.
4455 ///
4456 /// Stated rather than derived from [`name`](Self::name), and
4457 /// [`FieldKind::Interval`] carries the measurement that decided it: the two
4458 /// sites in this tree disagree about affix order, so a derived rule would
4459 /// rename one of them. Which member a name sits in is also what says which
4460 /// end it is, so nothing separate carries the direction.
4461 ///
4462 /// An interval missing it is an interval with one end that can be submitted,
4463 /// which is a description a renderer may draw honestly and no better than
4464 /// that. [`Field::interval`] is what makes forgetting it unsayable, on the
4465 /// same footing as [`Field::range`] and its bounds.
4466 ///
4467 /// Added 0.34.0.
4468 pub upper_name: Option<&'a str>,
4469 /// What the user is asked for.
4470 pub label: &'a str,
4471 /// Standing help, shown whether or not anything is wrong.
4472 pub hint: Option<&'a str>,
4473 /// What is currently wrong with the value.
4474 pub error: Option<&'a str>,
4475 /// A consequence of the answer the user has given, carrying its own tone.
4476 ///
4477 /// The third message channel, between [`hint`](Self::hint) and
4478 /// [`error`](Self::error) and overlapping neither. A hint is standing help
4479 /// that does not depend on the value; an error says the value is not
4480 /// acceptable. A note is the case in the middle: the value is perfectly
4481 /// acceptable and choosing it costs something the user should know about.
4482 ///
4483 /// The first consumer is audiofiles' export Format field, where choosing
4484 /// WAV or AIFF over Original re-encodes and silently drops embedded BWF,
4485 /// iXML, loop points, cue markers and ID3. That is not a validation
4486 /// failure and it is not standing help — it is true of one answer to one
4487 /// question — and it was hand-drawn in the app's own draw callback for
4488 /// want of anywhere to say it.
4489 ///
4490 /// The tone is carried rather than fixed at [`Tone::Warning`] because the
4491 /// channel is not only for warnings: the same slot says "this is the
4492 /// recommended one" ([`Tone::Success`]) and "this is what that setting
4493 /// implies" ([`Tone::Info`]). A renderer gets the announcement behaviour
4494 /// off the tone for free — makeover-webview emits `data-tone` and treats
4495 /// Warning and Danger as assertive for `aria-live`.
4496 ///
4497 /// It does **not** make the field invalid. [`invalid`](Self::invalid) stays
4498 /// `error.is_some()`, so a note never marks the group as a problem.
4499 ///
4500 /// # Precedence, for a renderer with room for one
4501 ///
4502 /// Error, then note, then hint. A renderer that shows every message shows
4503 /// them in that order too. makeover-tui is the one with room for exactly
4504 /// one line, and it is why the order is decided here rather than three
4505 /// times: what is wrong outranks what it costs, which outranks how it
4506 /// works.
4507 ///
4508 /// Added 0.36.0.
4509 pub note: Option<(Tone, &'a str)>,
4510 /// Ghost text shown while the field is empty.
4511 ///
4512 /// User-facing text, and it sits with `label` and `hint` rather than with
4513 /// the value because it is a property of the *question* and not of the
4514 /// answer. It lived renderer-side in `makeover-webview` until 0.8.0 for one
4515 /// reason and it was not a reading on where it belonged: adding a field to
4516 /// a published struct is a breaking change.
4517 ///
4518 /// Not a substitute for a label. A field labelled only by its placeholder
4519 /// loses its label the moment anything is typed, and no renderer here can
4520 /// make that not happen, so the description keeps both.
4521 pub placeholder: Option<&'a str>,
4522 /// The options offered, in the order they are offered.
4523 ///
4524 /// Empty for every kind [`FieldKind::offers_options`] rejects. A field
4525 /// described with no options is sayable on purpose: it is what an app with
4526 /// an unfinished-loading option list actually has, and a renderer showing
4527 /// an empty control says so on screen rather than in a log.
4528 ///
4529 /// Which option is *current* is not here. That is the value, and the value
4530 /// is renderer state.
4531 pub options: &'a [Choice<'a>],
4532 /// The themes offered, in the order they are offered.
4533 ///
4534 /// Empty for every kind [`FieldKind::offers_themes`] rejects, and sayable
4535 /// as empty for the one that accepts it: an app whose theme directories
4536 /// hold nothing has a picker offering only [`follows`](Self::follows),
4537 /// which is a true description of that machine.
4538 ///
4539 /// **The order is the grouping.** Entries arrive sorted by
4540 /// [`ThemeVariant`] and then by [`Contrast`] within each variant, so a
4541 /// renderer that draws headings walks the run of one variant and a renderer
4542 /// that cannot still gets the useful order. Handing back groups would force
4543 /// the second renderer to flatten what the first wanted.
4544 ///
4545 /// Nothing here sorts. The description carries the order it was given, and
4546 /// the sort belongs with whoever measured the tiers — `makeover::theme_options`
4547 /// is what produces it, and re-sorting here would be this crate deciding a
4548 /// question it cannot see the inputs to.
4549 ///
4550 /// Which theme is *current* is not here. That is the value, and the value
4551 /// is renderer state, exactly as it is for [`options`](Self::options).
4552 ///
4553 /// Added 0.38.0.
4554 pub themes: &'a [ThemeChoice<'a>],
4555 /// The entry that follows the ambient mode instead of naming a theme.
4556 ///
4557 /// [`None`] for a picker that does not offer one, which is a real answer:
4558 /// an app whose host has no ambient mode to follow should not offer a row
4559 /// that does nothing.
4560 ///
4561 /// A [`Choice`] rather than a bare label, because the *value* is the app's.
4562 /// Every store in the family spells it `system` today and none of them is
4563 /// obliged to; a description that hardcoded the spelling would be this
4564 /// crate holding a fact about somebody else's config table.
4565 ///
4566 /// It is not a [`ThemeChoice`] with an absent variant. Following is a
4567 /// standing instruction that resolves differently as the desktop flips, and
4568 /// a theme id is an answer that does not — which is the distinction
4569 /// `makeover::ThemeSelection` exists to hold, carried here rather than
4570 /// blurred.
4571 ///
4572 /// Added 0.38.0.
4573 pub follows: Option<Choice<'a>>,
4574 /// What a file field takes, in the order a host offering the list shows it.
4575 ///
4576 /// Empty for every kind [`FieldKind::takes_files`] rejects, and empty is
4577 /// also a real answer for one that accepts it: a field that takes any file
4578 /// says so by listing nothing, which is what an `<input type="file">` with
4579 /// no `accept` does and what most of the measured sites are.
4580 ///
4581 /// It is a filter and it is the disclosure cue, and [`Accepted`]'s doc
4582 /// carries which reading is which. Nothing here validates: a host may hand
4583 /// back a file the list does not cover, exactly as a browser does when the
4584 /// user switches the picker to "All Files", and deciding a value is wrong
4585 /// stays with whoever validated.
4586 ///
4587 /// Added 0.31.0, `f7261a5a`.
4588 pub accept: &'a [Accepted<'a>],
4589 /// Whether more than one file may be picked at once.
4590 ///
4591 /// Only [`FieldKind::takes_files`] reads it. A multi-valued answer to any
4592 /// other question is a different shape — a set of options, a repeated
4593 /// group — and neither is this flag with a different kind beside it.
4594 ///
4595 /// False is the common case: 4 of the MNW server's 16 file inputs carry it.
4596 ///
4597 /// Added 0.31.0, `f7261a5a`.
4598 pub multiple: bool,
4599 /// Whether the form refuses to submit without it.
4600 pub required: bool,
4601 /// The longest the value may be, in characters.
4602 ///
4603 /// Added 0.11.0 with [`min`](Self::min) and [`max`](Self::max), joining
4604 /// [`required`](Self::required), which had been the only constraint here
4605 /// since before the crate wrote down that it carried none.
4606 pub max_length: Option<u32>,
4607 /// The lowest value accepted, as the host would write it.
4608 ///
4609 /// Text rather than a number, because the bound is only a number for some
4610 /// of the kinds that take one. goingson's own sites are `min="1"` on a
4611 /// duration and `min="2026-08-09T14:30"` on a datetime, and a numeric member
4612 /// could say the first and not the second. The [`kind`](Self::kind) already
4613 /// says how to read it, the same way it does for the value.
4614 pub min: Option<&'a str>,
4615 /// The highest value accepted, as the host would write it. See
4616 /// [`min`](Self::min).
4617 pub max: Option<&'a str>,
4618 /// The granularity the value moves in, as the host would write it.
4619 ///
4620 /// Text for [`min`](Self::min)'s reason, and it earns it twice over: the
4621 /// step of a date is a day and the step of a threshold is 0.01, and a
4622 /// numeric member could say one of them.
4623 ///
4624 /// Absent means the host's own granularity, which is the honest default
4625 /// rather than a missing value: a webview's `<input>` steps by 1 unless told
4626 /// otherwise, and that is the browser's rule and not this crate's to
4627 /// restate.
4628 ///
4629 /// # It is the granularity of a *typed* value
4630 ///
4631 /// [`FieldKind::Range`] reads its own from [`curve`](Self::curve) and
4632 /// ignores this, as of 0.32.0. Until then this member served both, and
4633 /// serving both is what the split fixes: on a slider the granularity and
4634 /// the mapping are one decision, and on a typed number there is no mapping
4635 /// to decide with. See [`Curve`], "Why the step is here".
4636 ///
4637 /// Added 0.28.0 with [`FieldKind::Range`], and narrowed away from it at
4638 /// 0.32.0.
4639 pub step: Option<&'a str>,
4640 /// How a slider's position becomes its value, and how finely it moves.
4641 ///
4642 /// [`FieldKind::Range`]'s, and nothing else reads it: a typed number has a
4643 /// granularity but no mapping, and takes [`step`](Self::step) instead.
4644 ///
4645 /// Defaults to [`Curve::Linear`] with no step, which is what every range
4646 /// described before 0.32.0 meant, so this member is additive and no
4647 /// existing site changes meaning.
4648 ///
4649 /// Added 0.32.0.
4650 pub curve: Curve<'a>,
4651 /// What the number is measured in: `s`, `ms`, `dB`, `GiB`.
4652 ///
4653 /// A fact about the value, not part of the question's name, and that
4654 /// distinction is the whole reason it is a member. The two readings come
4655 /// apart the moment anything reads a field back rather than drawing it: a
4656 /// [`max`](Self::max) of `-96` and a bound of `-96 dBFS` are the same number
4657 /// and not the same answer, and under the convention this replaces the unit
4658 /// could only be recovered by parsing it back out of a label.
4659 ///
4660 /// # Where a renderer draws it
4661 ///
4662 /// Beside the value, wherever that host puts a value. Not in the label: the
4663 /// label is the sentence above the control and that is the one place the
4664 /// convention could put it, which is why it read the same on every host and
4665 /// was wrong on the one host that had somewhere better. egui puts it inside
4666 /// the slider where the readout already is, a terminal appends it to the
4667 /// value in the edit line, a webview sets it adjacent to the input.
4668 ///
4669 /// # Which kinds read it
4670 ///
4671 /// [`FieldKind::measurable`] answers, and it is
4672 /// [`takes_files`](FieldKind::takes_files)'s footing: three renderers ask
4673 /// before they can decide whether to draw this, and a `matches!` per
4674 /// renderer is where the next measurable kind goes missing. A unit on a kind
4675 /// that rejects it is sayable and ignored, the same way
4676 /// [`options`](Self::options) is on a kind that offers none.
4677 ///
4678 /// # Why a string
4679 ///
4680 /// The measured sites are `GiB`, `dBFS`, `s` and `ms`. An enum would have to
4681 /// grow a member for every unit any consumer ever wants, and this crate does
4682 /// not know them; it knows that a number has one.
4683 ///
4684 /// Written as the symbol alone, with no brackets and no leading space. The
4685 /// spacing is the renderer's, because a slider's readout and a sentence want
4686 /// different answers.
4687 ///
4688 /// Added 0.33.0, `32215e21`, on eight sites across four files that had each
4689 /// arrived at "Attack (s)" separately.
4690 pub unit: Option<&'a str>,
4691 /// Whether the field lives behind a "more options" disclosure.
4692 pub extended: bool,
4693 /// Whether this local wall-clock value is submitted as an absolute instant.
4694 ///
4695 /// [`FieldKind::DateTime`] asks for a time the way a person says one --
4696 /// "the 14th at half past two" -- and that names a different moment in
4697 /// Denver than it does in Berlin. A route that stores an instant needs the
4698 /// moment, so somebody has to convert. This member says the description
4699 /// wants that conversion; it does not say how.
4700 ///
4701 /// # The conversion belongs to the renderer
4702 ///
4703 /// Because the renderer is the only party that knows what "your computer's
4704 /// time zone" means for its host. A browser has one and the user is sitting
4705 /// in it; a TUI reads the host clock; an egui app reads the same clock a
4706 /// different way. Nothing above the renderer can answer it, and the
4707 /// alternatives all try: a hidden IANA-zone field needs a host capability
4708 /// for reading the zone that three hosts answer differently, plus a kind
4709 /// that does not exist, plus a wire-contract change; a timezone on the
4710 /// user's profile is a product decision wearing a bug's clothes. Say it
4711 /// here, and the next reader does not propose them again.
4712 ///
4713 /// # What a renderer does
4714 ///
4715 /// Draws the same control it always did -- the flag changes what is
4716 /// *submitted*, not what is shown -- and converts the local value to an
4717 /// absolute instant on the way out. A renderer that cannot convert submits
4718 /// the local value unchanged, which is what every renderer did before this
4719 /// existed.
4720 ///
4721 /// No wire contract moves when a site adopts it: the route was already
4722 /// receiving an instant. What changes is who computed it.
4723 ///
4724 /// # Which kinds read it
4725 ///
4726 /// [`FieldKind::DateTime`]'s. `Date` and `Time` are each half a moment and
4727 /// cannot name one on their own, so the flag is sayable and ignored there,
4728 /// the way [`options`](Self::options) is on a kind that offers none.
4729 ///
4730 /// Added 0.37.0, retiring the MNW server's `data-config="publish-at-iso"`
4731 /// -- the last site of a private per-app vocabulary that this crate exists
4732 /// to replace.
4733 pub as_instant: bool,
4734 }
4735
4736 impl<'a> Field<'a> {
4737 /// A plain required-nothing field of the given kind.
4738 #[must_use]
4739 pub const fn new(kind: FieldKind, name: &'a str, label: &'a str) -> Self {
4740 Self {
4741 kind,
4742 name,
4743 upper_name: None,
4744 label,
4745 hint: None,
4746 error: None,
4747 note: None,
4748 placeholder: None,
4749 options: &[],
4750 themes: &[],
4751 follows: None,
4752 accept: &[],
4753 multiple: false,
4754 required: false,
4755 max_length: None,
4756 min: None,
4757 max: None,
4758 step: None,
4759 curve: Curve::Linear { step: None },
4760 unit: None,
4761 extended: false,
4762 as_instant: false,
4763 }
4764 }
4765
4766 /// A bounded number the user drags across its whole extent.
4767 ///
4768 /// The third under-described kind, and it gets a constructor for
4769 /// [`select`](Self::select)'s reason: a range is the one kind whose bounds
4770 /// are not a rule but the control itself, so a call site that forgot them
4771 /// has a slider with nothing to slide across. Taking them as arguments is
4772 /// what makes that unsayable.
4773 ///
4774 /// The granularity stays a field rather than a fourth argument, and since
4775 /// 0.32.0 it is [`curve`](Self::curve)'s: it is genuinely optional — the
4776 /// host's own is a real answer — and the two bounds are not.
4777 #[must_use]
4778 pub const fn range(name: &'a str, label: &'a str, min: &'a str, max: &'a str) -> Self {
4779 Self {
4780 min: Some(min),
4781 max: Some(max),
4782 ..Self::new(FieldKind::Range, name, label)
4783 }
4784 }
4785
4786 /// One question with two ends, taking the name each end submits under.
4787 ///
4788 /// A constructor for [`range`](Self::range)'s reason inverted: a range's
4789 /// bounds are what a call site cannot forget, and an interval's second name
4790 /// is. An interval built through [`new`](Self::new) has an upper end with
4791 /// nowhere to be submitted, and nothing downstream can invent one, so taking
4792 /// it as an argument is what makes that unsayable.
4793 ///
4794 /// The extent, the granularity and the unit stay members. They describe the
4795 /// axis rather than either end and they are genuinely optional, which is
4796 /// [`FieldKind::Number`]'s arrangement and the one an interval takes.
4797 #[must_use]
4798 pub const fn interval(name: &'a str, upper_name: &'a str, label: &'a str) -> Self {
4799 Self {
4800 upper_name: Some(upper_name),
4801 ..Self::new(FieldKind::Interval, name, label)
4802 }
4803 }
4804
4805 /// A file field, taking the given accept list.
4806 ///
4807 /// The fourth under-described kind and it gets a constructor for
4808 /// [`range`](Self::range)'s reason rather than [`select`](Self::select)'s:
4809 /// a file field with no accept list is not broken, it is a field that takes
4810 /// anything, and the hazard is the opposite one. A call site that meant to
4811 /// restrict and forgot has a picker offering every file on the machine and
4812 /// a server refusing the upload afterwards, which is the failure the list
4813 /// exists to move forward. Taking it as an argument is what makes an
4814 /// accidental omission a deliberate `&[]`.
4815 ///
4816 /// [`multiple`](Self::multiple) stays a field. One file is the common case
4817 /// and the honest default; several is the thing worth saying.
4818 #[must_use]
4819 pub const fn upload(name: &'a str, label: &'a str, accept: &'a [Accepted<'a>]) -> Self {
4820 Self {
4821 accept,
4822 ..Self::new(FieldKind::File, name, label)
4823 }
4824 }
4825
4826 /// A select offering the given options.
4827 ///
4828 /// One of the two kinds under-described by [`Field::new`], so it gets a
4829 /// constructor rather than leaving every call site to remember that a
4830 /// select with an empty `options` renders as an empty select.
4831 #[must_use]
4832 pub const fn select(name: &'a str, label: &'a str, options: &'a [Choice<'a>]) -> Self {
4833 Self::offering(FieldKind::Select, name, label, options)
4834 }
4835
4836 /// A radio group offering the given options.
4837 ///
4838 /// The other. Same hazard as [`select`](Self::select) and a worse one: a
4839 /// radio group with no options draws nothing at all, so a call site that
4840 /// forgot them has an empty rectangle rather than a visibly empty control.
4841 #[must_use]
4842 pub const fn radio(name: &'a str, label: &'a str, options: &'a [Choice<'a>]) -> Self {
4843 Self::offering(FieldKind::Radio, name, label, options)
4844 }
4845
4846 /// A theme picker over the themes the host resolved.
4847 ///
4848 /// A constructor for [`select`](Self::select)'s reason and one of its own.
4849 /// The shared reason: a theme picker built through [`new`](Self::new) has
4850 /// an empty [`themes`](Self::themes) list and draws an empty control. Its
4851 /// own: the list is the *only* thing this kind takes that a call site
4852 /// cannot get wrong by omission and can get wrong by substitution, since
4853 /// [`options`](Self::options) is right there and reads as if it would work.
4854 ///
4855 /// [`following`](Self::following) is the builder rather than a fourth
4856 /// argument, because a picker with no follow-the-system row is a real
4857 /// picker and every renderer draws it honestly.
4858 #[must_use]
4859 pub const fn theme(name: &'a str, label: &'a str, themes: &'a [ThemeChoice<'a>]) -> Self {
4860 Self {
4861 themes,
4862 ..Self::new(FieldKind::Theme, name, label)
4863 }
4864 }
4865
4866 /// The same picker, offering a row that tracks the ambient mode.
4867 ///
4868 /// The [`Choice`] carries the value the app's own store spells it with.
4869 #[must_use]
4870 pub const fn following(mut self, follow: Choice<'a>) -> Self {
4871 self.follows = Some(follow);
4872 self
4873 }
4874
4875 /// The shared body of the two constructors that take options.
4876 ///
4877 /// Private, and keyed on the kind rather than exposed, because the two
4878 /// public names are the point: a call site says which question it is
4879 /// asking, not which flag it is setting.
4880 const fn offering(
4881 kind: FieldKind,
4882 name: &'a str,
4883 label: &'a str,
4884 options: &'a [Choice<'a>],
4885 ) -> Self {
4886 Self {
4887 options,
4888 ..Self::new(kind, name, label)
4889 }
4890 }
4891
4892 /// Whether the field is currently reporting a problem.
4893 ///
4894 /// Read this rather than testing `error.is_some()` at each renderer: the
4895 /// error state has to mark the field's whole group and not only the
4896 /// message, because a renderer with no descendant selectors (egui, a
4897 /// terminal) cannot find the group from the message. goingson already marks
4898 /// the group and Balanced Breakfast does not, so goingson's shape is the
4899 /// one taken here.
4900 ///
4901 /// [`note`](Self::note) is deliberately not consulted. A note says the
4902 /// answer costs something, not that it is unacceptable, and a field the
4903 /// user may submit as it stands is not invalid.
4904 #[must_use]
4905 pub const fn invalid(&self) -> bool {
4906 self.error.is_some()
4907 }
4908
4909 /// Whether the field carries both ends of its extent.
4910 ///
4911 /// Only [`FieldKind::Range`] owes them, and it owes them absolutely: a
4912 /// slider with one end missing has no extent to draw. Named here rather
4913 /// than left to each renderer to test `min.is_some() && max.is_some()`,
4914 /// which is three renderers arriving at the same condition and one of them
4915 /// getting it wrong, and named as a question about the *field* rather than
4916 /// about the kind because the kind cannot see the bounds.
4917 ///
4918 /// It is a check and not a guarantee. Nothing here refuses to build an
4919 /// unbounded range — [`Field::range`] is what makes the bounded one easy —
4920 /// so a renderer asks this and falls back to whatever its host does
4921 /// honestly with a number.
4922 #[must_use]
4923 pub const fn bounded(&self) -> bool {
4924 self.min.is_some() && self.max.is_some()
4925 }
4926
4927 /// Whether anything in [`accept`](Self::accept) names a media family.
4928 ///
4929 /// The question a renderer asks before it decides to keep room for a
4930 /// preview, and it is deliberately the *whole list* rather than one entry:
4931 /// the media dropzone this was measured against takes `image/*,video/*`, so
4932 /// there is no single family to return and there is still a disclosure to
4933 /// offer. Which one it turns out to be is known once a file is picked, which
4934 /// is renderer-side and after the description is gone.
4935 ///
4936 /// False for an empty list, for a list of suffixes, and for `text/csv`. A
4937 /// renderer that wants the family of a particular entry reads
4938 /// [`Accepted::family`].
4939 #[must_use]
4940 pub fn accepts_media(&self) -> bool {
4941 self.accept.iter().any(|one| one.family().is_some())
4942 }
4943 }
4944
4945 /// How much room a placement asks for.
4946 ///
4947 /// A column says it, and so does a [`Field`]. An intent, so the actual floor
4948 /// stays with `makeover-geometry`. goingson's task table spells these as
4949 /// `minmax(200px, 1fr)`, `140px` and content-sized; only the first three words
4950 /// of that survive deferral.
4951 /// `#[non_exhaustive]`, for the reason [`Fill`] and [`FieldKind`] are: a
4952 /// renderer matches on this and a vocabulary that grows must not break every
4953 /// renderer when it does.
4954 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
4955 #[non_exhaustive]
4956 pub enum Width {
4957 /// Takes what it needs and no more.
4958 Content,
4959 /// A fixed share, the same at every width.
4960 Fixed,
4961 /// Absorbs whatever is left over.
4962 ///
4963 /// **Several fills divide what is left equally.** Stated because it would
4964 /// otherwise be undefined and each renderer would invent something, and
4965 /// stated this way because equal division is the only sharing rule that
4966 /// answers to "Any width, one answer" without a tiebreak: allocating in
4967 /// declaration order makes the result depend on the order the description
4968 /// was written in, which is a fact about the source file and not about the
4969 /// screen. It documents what both renderers already do — CSS grid gives
4970 /// `1fr 1fr`, ratatui gives each a `Constraint::Fill(1)` — rather than
4971 /// changing anything.
4972 ///
4973 /// So a row of fills is a legal thing to describe, and there is no rule
4974 /// against it. Measured 2026-08-16, every table in the tree uses exactly
4975 /// one, which is the discipline this would otherwise have had to forbid.
4976 Fill,
4977 }
4978
4979 /// What a member is worth when there is not room for all of them.
4980 ///
4981 /// Written for table columns and no longer only theirs. Three shapes ask the
4982 /// same question and this answers all three: a table too narrow for its
4983 /// columns, a row too narrow for its parts (see [`RowPart::priority`]), and a
4984 /// group of regions sharing one run of room -- goingson's tab strip and the
4985 /// [`Region::Band`] beside it, which is the case wiki `layout-room-and-fallback`
4986 /// was ruled on. It is what any member of a group is worth, not a table
4987 /// concept, and [`Fallback::Shed`] is what reads it.
4988 ///
4989 /// The doc below is the column argument, which is where the type was measured;
4990 /// the sentence that gave it away is [`Priority::Essential`]'s, which was
4991 /// already written about a row.
4992 ///
4993 /// Ordered: [`Priority::Optional`] drops first, [`Priority::Essential`] never
4994 /// drops. This replaces addressing columns by position, which is what both
4995 /// webview apps do today and is a live bug rather than only verbosity. goingson
4996 /// hides mobile columns with `nth-child(n+5)` against a seven-column table, so
4997 /// inserting a column silently hides the wrong one.
4998 /// `#[non_exhaustive]`, same reasoning as [`Width`]. Note the ordering is the
4999 /// whole point of the type, so a new tier has to be declared in its place in
5000 /// the sequence rather than appended.
5001 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
5002 #[non_exhaustive]
5003 pub enum Priority {
5004 /// Dropped first.
5005 Optional,
5006 /// Dropped once the optional members are gone.
5007 Secondary,
5008 /// Never dropped. Without it the group does not identify itself.
5009 Essential,
5010 }
5011
5012 /// How much room a group has, measured against its own allocation.
5013 ///
5014 /// Never authored. A renderer computes it from what the group was given and
5015 /// what the group's own contents ask for, in that renderer's units: a webview
5016 /// from `min-content` under a container query, a terminal from cell widths,
5017 /// egui from the galley. Nothing in the description says a number, which is the
5018 /// point -- an authored breakpoint rots and this cannot.
5019 ///
5020 /// # Why not [`Depth`]-style two members and no more
5021 ///
5022 /// Two is what the measurement supports. The goingson case that produced this
5023 /// type is a window 913px wide -- makeover-geometry's `SizeClass::Expanded` --
5024 /// holding a group that has run out of room. A third tier would be a guess
5025 /// about a shape nothing in the tree has yet.
5026 ///
5027 /// # Why it is not `SizeClass`
5028 ///
5029 /// Because 913 is exactly the case that proves they are different facts. The
5030 /// window is roomy and the group is not, so a type that answered for both would
5031 /// have to be wrong about one of them. Sharing the name would also invite
5032 /// `@media` thinking straight back in, which is what put a `position: absolute`
5033 /// in goingson's stylesheet in the first place. Container semantics instead: a
5034 /// group narrowed by a sidebar behaves the same as one narrowed by the window,
5035 /// and there is one code path rather than two.
5036 ///
5037 /// Ordered least room first, [`Priority`]'s convention, so a group nesting
5038 /// another takes the minimum of the two and relief still resolves inside-out.
5039 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
5040 #[non_exhaustive]
5041 pub enum Room {
5042 /// Not everything the group contains fits, and the group's [`Fallback`]
5043 /// decides what happens.
5044 Tight,
5045 /// Everything fits as described.
5046 Ample,
5047 }
5048
5049 /// What a group does when it is [`Room::Tight`].
5050 ///
5051 /// Authored, and required: the field carrying this has no `Default` and a group
5052 /// cannot be described without saying what it does when it runs out of room.
5053 /// Max ruled on that 2026-08-18 -- more intentionality from layout designers is
5054 /// acceptable so long as the constraints are solvable, because the goal is
5055 /// enabling good layouts rather than rescuing bad ones. A default here would be
5056 /// the crate guessing, and the guess would be silently wrong on the screens
5057 /// that matter.
5058 ///
5059 /// Relief resolves inside-out. A group asks its children to fall back before
5060 /// falling back itself, or an outer group collapses while an inner one still
5061 /// had slack.
5062 ///
5063 /// # No `Swap`
5064 ///
5065 /// An authored alternate group for the tight case is deliberately out of the
5066 /// first cut. It doubles the description for that group and the two halves can
5067 /// drift, which is the failure this vocabulary exists to end. Add it when a
5068 /// site proves it needs one.
5069 ///
5070 /// `#[non_exhaustive]`, [`Width`]'s reasoning. Unlike [`Priority`] there is no
5071 /// order to preserve, so a member can be appended.
5072 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
5073 #[non_exhaustive]
5074 pub enum Fallback {
5075 /// One row becomes two. Every member stays, in the order described.
5076 Wrap,
5077 /// A row becomes a column. Every member stays, full width.
5078 Stack,
5079 /// Members drop by [`Priority`], down to [`Priority::Essential`].
5080 ///
5081 /// What a narrow table already does with its columns, applied to a group.
5082 /// What drops is gone from the screen, so this is right when the dropped
5083 /// members are facts the reader can do without and wrong when they are the
5084 /// only way to act.
5085 Shed,
5086 /// The members [`Shed`](Self::Shed) would drop move into one overflow
5087 /// control instead.
5088 ///
5089 /// The answer when a group holds actions. A control is not a fact: dropping
5090 /// it does not cost the reader a detail, it costs them the only way to act,
5091 /// which is [`RowPart::priority`]'s argument one level up.
5092 Menu,
5093 }
5094
5095 /// One column of a table.
5096 ///
5097 /// Described once. The grid track, the cell order and the drop behaviour are
5098 /// all derived from this, rather than being three hand-written encodings that
5099 /// must agree and are never checked against each other.
5100 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
5101 pub struct Column<'a> {
5102 /// The heading, and the name the cell is addressed by.
5103 pub name: &'a str,
5104 /// How much room it asks for.
5105 pub width: Width,
5106 /// What it is worth when room runs out.
5107 pub priority: Priority,
5108 /// Whether the user can reorder the table by this column.
5109 ///
5110 /// `ce620871`. What reordering *calls* is not here — that is an address, and
5111 /// this crate names none — so a host pairs this with the route the way it
5112 /// pairs a row's parts with the row's activation. This says the affordance
5113 /// exists, which is what a renderer needs to draw a header a user can press
5114 /// rather than a heading they cannot.
5115 pub sortable: bool,
5116 /// Which way the table is ordered by this column, if it is.
5117 ///
5118 /// `None` on every column but the one in force. A renderer draws the caret
5119 /// from this and a webview sets `aria-sort`, which is why it is per column
5120 /// rather than a single fact on the table: the host idiom is a property of
5121 /// the header cell.
5122 ///
5123 /// Independent of [`sortable`](Self::sortable) rather than implied by it,
5124 /// because both combinations mean something. A column sorted and not
5125 /// sortable is a list ordered by a key the user cannot change, which is a
5126 /// real thing to describe and a caret worth drawing.
5127 pub sorted: Option<Sort>,
5128 }
5129
5130 /// Which way a column is ordered.
5131 ///
5132 /// Two, because there is no third. "Unsorted" is [`Column::sorted`] being
5133 /// `None`, and folding it in here would be the same absence said twice.
5134 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
5135 pub enum Sort {
5136 /// Smallest, earliest or first alphabetically at the top.
5137 Ascending,
5138 /// The other way.
5139 Descending,
5140 }
5141
5142 impl Sort {
5143 /// The other direction, for a header that flips when pressed.
5144 #[must_use]
5145 pub const fn reversed(self) -> Self {
5146 match self {
5147 Self::Ascending => Self::Descending,
5148 Self::Descending => Self::Ascending,
5149 }
5150 }
5151
5152 /// What a webview writes into `aria-sort`.
5153 ///
5154 /// Named here rather than in the webview renderer because a terminal and an
5155 /// immediate-mode painter both want the same two words for a caret's label,
5156 /// and three renderers picking their own is the drift this crate ends.
5157 #[must_use]
5158 pub const fn as_str(self) -> &'static str {
5159 match self {
5160 Self::Ascending => "ascending",
5161 Self::Descending => "descending",
5162 }
5163 }
5164
5165 /// The caret a renderer draws for this direction.
5166 ///
5167 /// Here for [`as_str`](Self::as_str)'s reason, said about a glyph rather
5168 /// than a word: three renderers picking their own is the drift this crate
5169 /// ends. They had picked their own — two on the solid triangles and
5170 /// `makeover-webview` on the arrows U+2191/U+2193 — and agreeing by
5171 /// coincidence in three files is not agreement.
5172 ///
5173 /// Settled 2026-08-16 (Max): the solid triangles, U+25B2 and U+25BC. The
5174 /// reason generalizes past this pair and is the house rule now — prefer the
5175 /// bolder, simpler glyph over the thinner or more complicated one. A third
5176 /// spelling is not open for re-argument.
5177 ///
5178 /// **Bare, with no spacing.** Where the gap goes is each renderer's
5179 /// business: `makeover-tui` and `makeover-immediate` carry a leading space
5180 /// inside their `TableStyle` string and a webview emits its own in
5181 /// `content`, so folding a space in here would make one of the two wrong.
5182 ///
5183 /// Neither face the web apps self-host carries these — IBM Plex Mono has one
5184 /// glyph in the whole geometric-shapes block and Lato has none — so a
5185 /// browser falls back per glyph until the in-house face ships with them
5186 /// drawn in (makeover `6d6d9146`, wiki `typography-standard`). Cosmetic
5187 /// drift in one renderer, not a reason to spell it three ways.
5188 #[must_use]
5189 pub const fn glyph(self) -> &'static str {
5190 match self {
5191 Self::Ascending => "\u{25B2}",
5192 Self::Descending => "\u{25BC}",
5193 }
5194 }
5195 }
5196
5197 impl<'a> Column<'a> {
5198 /// A column that absorbs slack and drops after the optional ones.
5199 #[must_use]
5200 pub const fn new(name: &'a str) -> Self {
5201 Self {
5202 name,
5203 width: Width::Fill,
5204 priority: Priority::Secondary,
5205 sortable: false,
5206 sorted: None,
5207 }
5208 }
5209
5210 /// Whether this column survives at the given cutoff.
5211 ///
5212 /// A renderer narrows by raising the cutoff, and never by counting
5213 /// positions.
5214 #[must_use]
5215 pub const fn kept_at(&self, cutoff: Priority) -> bool {
5216 (self.priority as u8) >= (cutoff as u8)
5217 }
5218 }
5219
5220 /// What a table cell holds.
5221 ///
5222 /// [`RowPart`] for tables, and it exists for the same reason: a part that
5223 /// carries a control is not text, and a renderer with one class for the whole
5224 /// cell paints it as though it were. `makeover-webview` emitted a single
5225 /// `.cell` until 0.25.0, so a button in a cell inherited the cell's content
5226 /// colour, which is the exact drift [`RowPart::intent`] prevents for rows and
5227 /// prevented for nothing here.
5228 ///
5229 /// Four members, and the count is what quasi's `Cell` was measured to carry:
5230 /// a value, tokens (33 cells across 22 server templates), actions (30 rows
5231 /// carrying a control, 5 beside a value) and a link (35 cells across 18
5232 /// templates). Nothing was added past what something holds.
5233 ///
5234 /// `#[non_exhaustive]` for [`RowPart`]'s reason: growth here must not be a
5235 /// lockstep event across three renderers.
5236 ///
5237 /// # No hover-reveal
5238 ///
5239 /// [`RowPart`] carried a `revealed_on_hover` until 0.13.0 retired it, and this
5240 /// enum never gets one. A cell's actions are shown at rest in every consumer
5241 /// measured, and a member nothing uses is one three renderers owe an answer
5242 /// for.
5243 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
5244 #[non_exhaustive]
5245 pub enum CellPart {
5246 /// The cell's own text.
5247 Value,
5248 /// Small labelled things in the cell: a status badge, a chip.
5249 Tokens,
5250 /// Controls that act on what the row is about.
5251 Actions,
5252 /// The cell's value, where the value is itself a link.
5253 Link,
5254 }
5255
5256 impl CellPart {
5257 /// The content intent the part takes.
5258 ///
5259 /// One part is text and three are not, so three answer with the intent
5260 /// inheriting already gives. That is [`RowPart::intent`]'s shape with the
5261 /// text side narrower: a cell's secondary and muted readings are the
5262 /// column's business, not the cell's.
5263 #[must_use]
5264 pub const fn intent(self) -> &'static str {
5265 match self {
5266 Self::Value => "content",
5267 // A token carries its own tone, and a part-level intent underneath
5268 // it would fight the token sitting on it.
5269 Self::Tokens => "content",
5270 // Actions carry controls rather than text.
5271 Self::Actions => "content",
5272 // A link takes the action colour from the control it is, rather
5273 // than the cell's text colour from the cell it sits in.
5274 Self::Link => "content",
5275 }
5276 }
5277 }
5278
5279 /// A named dimension a set can be narrowed by.
5280 ///
5281 /// One word for six things that were six mechanisms. MNW's discover page filters
5282 /// by free text, a flat any-of over item types, a tree of tags, a numeric range
5283 /// over price, a nested one-of over AI tier, and a browse position in the tag
5284 /// tree held separately from the tag selection — and the last two being separate
5285 /// is the whole reason a filter row there needs a tick box *and* a chevron. The
5286 /// panel is a mixed bag of hand-written controls because nothing named the thing
5287 /// they all are.
5288 ///
5289 /// Deliberately wider than that one page. audiofiles' library browser and
5290 /// goingson's filters are the same shape, and a word that only fitted discover
5291 /// would be discover's markup with a neutral name on it.
5292 ///
5293 /// # What it does not say
5294 ///
5295 /// **What picking a value calls.** This crate names no address, so a facet is
5296 /// paired with routes the way a column's [`sortable`](Column::sortable) flag is
5297 /// paired with what reordering calls.
5298 ///
5299 /// **How a tree is drawn.** Indented rows, a column of panes, a breadcrumb and a
5300 /// list: all four are honest renderings of the same described facet, and a
5301 /// terminal will not pick the same one a browser does. [`FacetValue::depth`] is
5302 /// what a renderer needs to draw any of them; the choice is not described.
5303 ///
5304 /// **Which values to show.** A tag tree has thousands of nodes and a panel shows
5305 /// a handful. Deciding which handful is the app's — it is the same question as
5306 /// which rows go in a table, and no table member answers it either.
5307 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
5308 #[non_exhaustive]
5309 pub struct Facet<'a> {
5310 /// What the dimension is called, as the user reads it.
5311 pub name: &'a str,
5312 /// How many of its values may be in force, and in what shape.
5313 pub mode: Selecting,
5314 /// The values on offer, in the order they are drawn.
5315 ///
5316 /// A [`Selecting::Text`] facet has none: the value is whatever was typed,
5317 /// and a description that listed the possible strings would be listing the
5318 /// corpus. A [`Selecting::Range`] facet has none either, for the reason
5319 /// [`FieldKind::Range`] takes bounds rather than options — the ends are the
5320 /// question and the values between them are not enumerable.
5321 pub values: &'a [FacetValue<'a>],
5322 }
5323
5324 impl<'a> Facet<'a> {
5325 /// A dimension with values to pick from.
5326 #[must_use]
5327 pub const fn new(name: &'a str, mode: Selecting, values: &'a [FacetValue<'a>]) -> Self {
5328 Self { name, mode, values }
5329 }
5330
5331 /// Whether the facet is narrowing the set right now.
5332 ///
5333 /// The question a renderer asks to decide whether to offer a way out of it,
5334 /// and the reason it is derived rather than carried: a facet with nothing
5335 /// standing is unengaged by construction, so a member saying so could
5336 /// disagree with the values beside it. [`Standing::Inherited`] does not
5337 /// count — something further up is what is doing the narrowing, and clearing
5338 /// a child that was never picked clears nothing.
5339 ///
5340 /// Always false for [`Selecting::Text`] and [`Selecting::Range`], which
5341 /// carry no values. A host that wants a clear affordance on those knows
5342 /// whether its own box is empty; the description does not hold the typed
5343 /// string.
5344 #[must_use]
5345 pub fn engaged(&self) -> bool {
5346 self.values.iter().any(|value| value.standing.is_picked())
5347 }
5348
5349 /// The deepest value in the facet, or zero when it is flat.
5350 ///
5351 /// What an indenting renderer needs to reserve a gutter before it draws the
5352 /// first row, which is "First paint is final paint" applied to a tree: a
5353 /// gutter widened as deeper values arrive is the reflow that rule forbids.
5354 #[must_use]
5355 pub fn reach(&self) -> u8 {
5356 self.values
5357 .iter()
5358 .map(|value| value.depth)
5359 .max()
5360 .unwrap_or(0)
5361 }
5362 }
5363
5364 /// How many of a [`Facet`]'s values may be in force, and in what shape.
5365 ///
5366 /// Five, and the fifth is what made this an enum rather than a bool. `one-of`,
5367 /// `any-of`, a range and free text are the four a form vocabulary already has in
5368 /// [`FieldKind`]; a tree's selection is none of them, and describing tags as
5369 /// any-of was what forced browsing to be a second mechanism beside filtering.
5370 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
5371 #[non_exhaustive]
5372 pub enum Selecting {
5373 /// Exactly one value, and picking another replaces it.
5374 ///
5375 /// MNW's AI tier, whose three options are nested ranges rather than
5376 /// independent values, so two of them at once means nothing.
5377 OneOf,
5378 /// Any number of values, each independent of the others.
5379 AnyOf,
5380 /// A low end, a high end, or both.
5381 ///
5382 /// Carries no values for [`FieldKind::Range`]'s reason: the ends are the
5383 /// question.
5384 Range,
5385 /// Whatever the user types.
5386 Text,
5387 /// A position in a tree, edited by taking branches in and pruning branches
5388 /// out.
5389 ///
5390 /// The one mode that is not reducible to the others, and the one gesture
5391 /// that replaced two. Picking a value narrows the set to it *and* reveals
5392 /// its children, so browsing a tree and filtering by it stop being separate
5393 /// mechanisms with separate state. What a selection then is: a set of
5394 /// branches taken and a set pruned, resolved nearest-ancestor-first, so
5395 /// `music` in and `music/synths` out is sayable and no flat mode can say it.
5396 ///
5397 /// Resolution happens in the app, and what reaches a renderer is the
5398 /// [`Standing`] each drawn value ended up with. A renderer walking ancestors
5399 /// itself would be a renderer that can disagree with the results beside it.
5400 Subtree,
5401 }
5402
5403 impl Selecting {
5404 /// Whether the mode picks from values the description lists.
5405 ///
5406 /// False for [`Text`](Self::Text) and [`Range`](Self::Range), which are the
5407 /// two whose answer is not one of a set. A renderer asks this before it
5408 /// looks at [`Facet::values`], the way it asks
5409 /// [`FieldKind::offers_options`] before it looks at [`Field::options`].
5410 #[must_use]
5411 pub const fn offers_values(self) -> bool {
5412 matches!(self, Self::OneOf | Self::AnyOf | Self::Subtree)
5413 }
5414
5415 /// Whether a value can be pruned as well as picked.
5416 ///
5417 /// [`Subtree`](Self::Subtree) alone. Excluding a value from a flat facet is
5418 /// the same fact as not picking it, so an exclude affordance there would be
5419 /// a second control for a state the first one already holds.
5420 #[must_use]
5421 pub const fn prunes(self) -> bool {
5422 matches!(self, Self::Subtree)
5423 }
5424
5425 /// Whether picking a second value keeps the first.
5426 #[must_use]
5427 pub const fn accumulates(self) -> bool {
5428 matches!(self, Self::AnyOf | Self::Subtree)
5429 }
5430 }
5431
5432 /// One value a [`Facet`] offers, as it currently stands.
5433 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
5434 #[non_exhaustive]
5435 pub struct FacetValue<'a> {
5436 /// What identifies it, and what a host keys its route on.
5437 ///
5438 /// [`Choice::value`]'s split, and a tree is why it is not optional: two
5439 /// leaves under different parents are legitimately both called "Ambient",
5440 /// and the path is the only thing telling them apart. It is also what
5441 /// nearest-ancestor-wins resolves over, so an app that carried only labels
5442 /// could not compute the [`standing`](Self::standing) it hands back here.
5443 pub value: &'a str,
5444 /// What it is called, as the user reads it.
5445 ///
5446 /// The leaf's own name rather than its path: a facet drawn as an indented
5447 /// tree repeats every ancestor on every line otherwise, and one drawn as a
5448 /// breadcrumb has the ancestors already.
5449 pub label: &'a str,
5450 /// How many members of the set carry it.
5451 ///
5452 /// Optional, and settled that way rather than made mandatory: a count is a
5453 /// measured fact the app may not have. Counting a tag subtree under an
5454 /// active text search is a second query, and an app that will not pay for it
5455 /// should be able to describe the facet anyway rather than write a zero that
5456 /// reads as "none of them". That is [`Awaiting::amount`]'s rule in a second
5457 /// place — state a number when it was measured, and nothing when it was not.
5458 pub count: Option<u64>,
5459 /// Whether it is narrowing the set, and how it came to be.
5460 pub standing: Standing,
5461 /// How far down the tree it sits, counting from zero at the root.
5462 ///
5463 /// Always zero for a flat facet, which is what makes an indenting renderer
5464 /// one code path rather than two. A renderer that draws no tree at all still
5465 /// reads this, since a value's depth is what distinguishes two same-named
5466 /// leaves under different parents.
5467 pub depth: u8,
5468 /// Whether taking it reveals values under it.
5469 ///
5470 /// Distinct from having a nonzero [`depth`](Self::depth): a leaf deep in the
5471 /// tree branches no further, and a root with children does. Both facts are
5472 /// needed and neither implies the other, which is why the pair is two
5473 /// members rather than one count.
5474 pub branching: bool,
5475 }
5476
5477 impl<'a> FacetValue<'a> {
5478 /// An unpicked value at the root of the facet.
5479 #[must_use]
5480 pub const fn new(value: &'a str, label: &'a str) -> Self {
5481 Self {
5482 value,
5483 label,
5484 count: None,
5485 standing: Standing::Open,
5486 depth: 0,
5487 branching: false,
5488 }
5489 }
5490
5491 /// A value whose identifier is also what the user reads.
5492 ///
5493 /// [`Choice::of`]'s convenience, and it is the flat case: a type or a tier
5494 /// is its own name, and only a tree needs a path that is not one.
5495 #[must_use]
5496 pub const fn of(value: &'a str) -> Self {
5497 Self::new(value, value)
5498 }
5499
5500 /// How many members carry it, when that was measured.
5501 #[must_use]
5502 pub const fn counted(mut self, count: u64) -> Self {
5503 self.count = Some(count);
5504 self
5505 }
5506
5507 /// How it stands in the current selection.
5508 #[must_use]
5509 pub const fn standing(mut self, standing: Standing) -> Self {
5510 self.standing = standing;
5511 self
5512 }
5513
5514 /// Where it sits in the tree, and whether anything hangs off it.
5515 #[must_use]
5516 pub const fn at(mut self, depth: u8, branching: bool) -> Self {
5517 self.depth = depth;
5518 self.branching = branching;
5519 self
5520 }
5521 }
5522
5523 /// Whether a [`FacetValue`] is narrowing the set, and how it came to be.
5524 ///
5525 /// Four rather than a bool, and the two extra members are what a tree costs. A
5526 /// pruned branch and an untaken one are not the same state — one was decided
5527 /// against and the other was never reached — and a child under a taken parent is
5528 /// in force without anybody having picked it. A renderer given a bool either
5529 /// marks every descendant of a taken branch, which reads as forty deliberate
5530 /// choices, or marks none of them, which reads as unfiltered.
5531 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
5532 #[non_exhaustive]
5533 pub enum Standing {
5534 /// Not picked, and nothing above it is either.
5535 #[default]
5536 Open,
5537 /// Picked here. The set is narrowed to it and whatever hangs off it.
5538 Taken,
5539 /// In force because something above it was taken.
5540 Inherited,
5541 /// Pruned out, though something above it was taken.
5542 ///
5543 /// The state that only [`Selecting::Subtree`] can reach, and the reason
5544 /// exclusion is drawn as a visible affordance beside each label rather than
5545 /// as a modifier on the ordinary one: a gesture a terminal cannot express is
5546 /// a gesture half the renderers would have to leave out, and an affordance
5547 /// nothing teaches is one users do not find.
5548 Pruned,
5549 }
5550
5551 impl Standing {
5552 /// Whether the user decided this value, either way.
5553 ///
5554 /// True for [`Taken`](Self::Taken) and [`Pruned`](Self::Pruned) — both are
5555 /// choices, and both are things a "clear this" affordance has to clear.
5556 /// [`Inherited`](Self::Inherited) is not: clearing it clears nothing,
5557 /// because the decision is further up.
5558 #[must_use]
5559 pub const fn is_picked(self) -> bool {
5560 matches!(self, Self::Taken | Self::Pruned)
5561 }
5562
5563 /// Whether the value narrows the set in.
5564 ///
5565 /// [`Taken`](Self::Taken) and [`Inherited`](Self::Inherited): one was picked
5566 /// and one came down from above, and to the set they mean the same thing.
5567 /// The pair is named here so a renderer colouring in-force values does not
5568 /// have to know which is which.
5569 #[must_use]
5570 pub const fn in_force(self) -> bool {
5571 matches!(self, Self::Taken | Self::Inherited)
5572 }
5573
5574 /// The content intent the value takes.
5575 ///
5576 /// [`Pruned`](Self::Pruned) reads back a step, which is the three-tone rule
5577 /// above rather than a new decision: a pruned branch is still a live control
5578 /// — pressing it takes the prune off — so it may not wear `content-muted`,
5579 /// and it is not the thing itself either.
5580 #[must_use]
5581 pub const fn intent(self) -> &'static str {
5582 match self {
5583 Self::Taken | Self::Inherited | Self::Open => "content",
5584 Self::Pruned => "content-secondary",
5585 }
5586 }
5587 }
5588
5589 #[cfg(test)]
5590 mod tests {
5591 use super::*;
5592
5593 #[test]
5594 fn a_markdown_field_is_multiline_and_offers_nothing() {
5595 // The editing counterpart of markdown prose is still text: every host
5596 // can draw it, which is the whole reason the kind was addable.
5597 assert!(FieldKind::Rich.multiline());
5598 assert!(FieldKind::Textarea.multiline());
5599 assert!(!FieldKind::Text.multiline());
5600 // It is not a chooser and not a moment.
5601 assert!(!FieldKind::Rich.offers_options());
5602 assert!(!FieldKind::Rich.temporal());
5603 assert!(FieldKind::Rich.visible());
5604 }
5605
5606 #[test]
5607 fn only_the_numeric_kinds_are_measurable() {
5608 assert!(FieldKind::Number.measurable());
5609 assert!(FieldKind::Range.measurable());
5610 // An axis is measured in something and both its ends are in it, so the
5611 // unit is read once for the pair rather than per end.
5612 assert!(FieldKind::Interval.measurable());
5613 // A date is ordered and is not a quantity with a unit to choose: its
5614 // unit is fixed by the kind, so saying one would restate `kind`.
5615 for kind in [
5616 FieldKind::Text,
5617 FieldKind::Date,
5618 FieldKind::DateTime,
5619 FieldKind::Select,
5620 FieldKind::Checkbox,
5621 FieldKind::File,
5622 ] {
5623 assert!(!kind.measurable(), "{kind:?}");
5624 }
5625 }
5626
5627 #[test]
5628 fn a_field_carries_no_unit_until_one_is_given() {
5629 // Additive: absent is what every field described before 0.33.0 meant.
5630 let plain = Field::new(FieldKind::Number, "attack", "Attack");
5631 assert_eq!(plain.unit, None);
5632 let measured = Field {
5633 unit: Some("s"),
5634 ..Field::range("attack", "Attack", "0.001", "5")
5635 };
5636 assert_eq!(measured.unit, Some("s"));
5637 assert!(measured.kind.measurable());
5638 }
5639
5640 #[test]
5641 fn an_interval_states_both_ends_names() {
5642 // Stated rather than derived: the two measured sites disagree about
5643 // affix order, so a rule here would rename one of them.
5644 let suffixed = Field::interval("bpm_min", "bpm_max", "BPM");
5645 assert_eq!(suffixed.name, "bpm_min");
5646 assert_eq!(suffixed.upper_name, Some("bpm_max"));
5647 let prefixed = Field::interval("min_price", "max_price", "Price");
5648 assert_eq!(prefixed.name, "min_price");
5649 assert_eq!(prefixed.upper_name, Some("max_price"));
5650 assert_eq!(suffixed.kind, FieldKind::Interval);
5651 }
5652
5653 #[test]
5654 fn every_other_kind_has_no_upper_end() {
5655 // Additive: absent is what every field described before 0.34.0 meant.
5656 for kind in [FieldKind::Text, FieldKind::Number, FieldKind::Range] {
5657 assert_eq!(Field::new(kind, "n", "N").upper_name, None, "{kind:?}");
5658 }
5659 assert_eq!(Field::range("t", "T", "0", "1").upper_name, None);
5660 }
5661
5662 #[test]
5663 fn an_interval_owes_no_bounds_and_takes_the_axis_facts_once() {
5664 // A range's bounds are the control's extent and are owed; an interval's
5665 // are a rule on each end, which is Number's arrangement.
5666 let plain = Field::interval("bpm_min", "bpm_max", "BPM");
5667 assert!(!plain.bounded());
5668 let axis = Field {
5669 min: Some("0"),
5670 max: Some("300"),
5671 step: Some("1"),
5672 unit: Some("BPM"),
5673 ..Field::interval("bpm_min", "bpm_max", "BPM")
5674 };
5675 assert!(axis.bounded());
5676 assert_eq!(axis.unit, Some("BPM"));
5677 // Nothing here checks the crossing rule, exactly as nothing checks
5678 // `min` for a number: the description carries constraints and whoever
5679 // validated decides a value is wrong.
5680 assert!(axis.error.is_none());
5681 }
5682
5683 #[test]
5684 fn only_a_subtree_prunes_and_only_the_listing_modes_offer_values() {
5685 // Excluding a value from a flat facet is the same fact as not picking
5686 // it, so the affordance exists in exactly one mode.
5687 assert!(Selecting::Subtree.prunes());
5688 for mode in [
5689 Selecting::OneOf,
5690 Selecting::AnyOf,
5691 Selecting::Range,
5692 Selecting::Text,
5693 ] {
5694 assert!(!mode.prunes(), "{mode:?}");
5695 }
5696 // Text and Range answer with something that is not one of a set.
5697 assert!(!Selecting::Text.offers_values());
5698 assert!(!Selecting::Range.offers_values());
5699 assert!(Selecting::OneOf.offers_values());
5700 assert!(Selecting::AnyOf.accumulates());
5701 assert!(!Selecting::OneOf.accumulates());
5702 }
5703
5704 #[test]
5705 fn an_inherited_value_is_in_force_without_having_been_picked() {
5706 // The distinction a bool cannot hold, and the reason Standing has four
5707 // members: a child under a taken parent narrows the set, and clearing
5708 // it clears nothing.
5709 assert!(Standing::Inherited.in_force());
5710 assert!(!Standing::Inherited.is_picked());
5711 assert!(Standing::Taken.in_force());
5712 assert!(Standing::Taken.is_picked());
5713 // A prune is a decision that takes the value out.
5714 assert!(Standing::Pruned.is_picked());
5715 assert!(!Standing::Pruned.in_force());
5716 assert!(!Standing::Open.is_picked());
5717 assert!(!Standing::Open.in_force());
5718 // A pruned branch still answers a press, so it may not read as inert.
5719 assert_ne!(Standing::Pruned.intent(), "content-muted");
5720 }
5721
5722 #[test]
5723 fn a_facet_is_engaged_by_a_decision_and_not_by_an_inherited_value() {
5724 let inherited = [
5725 FacetValue::of("music")
5726 .standing(Standing::Taken)
5727 .at(0, true),
5728 FacetValue::new("music/synths", "synths")
5729 .standing(Standing::Inherited)
5730 .at(1, false),
5731 ];
5732 let facet = Facet::new("Tag", Selecting::Subtree, &inherited);
5733 assert!(facet.engaged());
5734 // The gutter an indenting renderer reserves before its first paint.
5735 assert_eq!(facet.reach(), 1);
5736
5737 let untouched = [
5738 FacetValue::of("music").at(0, true),
5739 FacetValue::new("music/synths", "synths")
5740 .standing(Standing::Inherited)
5741 .at(1, false),
5742 ];
5743 // Inherited alone is something further up doing the narrowing, and
5744 // there is nothing further up here.
5745 assert!(!Facet::new("Tag", Selecting::Subtree, &untouched).engaged());
5746
5747 // A text facet lists nothing, so it is flat and never reads as engaged
5748 // from its values: the typed string is not held here.
5749 let typed = Facet::new("Search", Selecting::Text, &[]);
5750 assert!(!typed.engaged());
5751 assert_eq!(typed.reach(), 0);
5752 }
5753
5754 #[test]
5755 fn a_count_is_absent_rather_than_zero_when_it_was_not_measured() {
5756 // Awaiting::amount's rule in a second place: a written zero reads as
5757 // "none of them", which is a different claim from "not counted".
5758 assert_eq!(FacetValue::of("Ambient").count, None);
5759 assert_eq!(FacetValue::of("Ambient").counted(0).count, Some(0));
5760 }
5761
5762 #[test]
5763 fn one_kind_takes_files_and_the_two_file_members_are_its_alone() {
5764 assert!(FieldKind::File.takes_files());
5765 for kind in [
5766 FieldKind::Text,
5767 FieldKind::Textarea,
5768 FieldKind::Rich,
5769 FieldKind::Select,
5770 FieldKind::Checkbox,
5771 FieldKind::Hidden,
5772 ] {
5773 assert!(!kind.takes_files());
5774 }
5775 // The default is a field that takes any one file, which is what an
5776 // input with no accept and no multiple already is.
5777 let plain = Field::new(FieldKind::File, "cover", "Cover");
5778 assert!(plain.accept.is_empty());
5779 assert!(!plain.multiple);
5780 }
5781
5782 #[test]
5783 fn an_accept_list_says_which_disclosure_and_a_suffix_says_none() {
5784 // The three shapes are the MNW server's own three, and the family is
5785 // the question a renderer asks before it keeps room for a preview.
5786 assert_eq!(
5787 Accepted::Family(Family::Image).family(),
5788 Some(Family::Image)
5789 );
5790 assert_eq!(Accepted::Type("image/jpeg").family(), Some(Family::Image));
5791 assert_eq!(Accepted::Type("audio/flac").family(), Some(Family::Audio));
5792 assert_eq!(
5793 Accepted::Type("video/quicktime").family(),
5794 Some(Family::Video)
5795 );
5796 // A media type outside the three families names none, and neither does
5797 // a suffix. `.mp3` is audio in fact and this crate will not infer it:
5798 // the table that said so would rot.
5799 assert_eq!(Accepted::Type("text/csv").family(), None);
5800 assert_eq!(Accepted::Suffix(".mp3").family(), None);
5801 assert_eq!(Accepted::Suffix(".tar.gz").family(), None);
5802 // Media types are case-insensitive and half the tree writes them
5803 // lowercase by habit rather than by rule.
5804 assert_eq!(Accepted::Type("IMAGE/PNG").family(), Some(Family::Image));
5805 }
5806
5807 #[test]
5808 fn every_accepted_entry_has_one_spelling_a_host_can_write() {
5809 assert_eq!(Accepted::Family(Family::Image).as_str(), "image/*");
5810 assert_eq!(Accepted::Family(Family::Audio).as_str(), "audio/*");
5811 assert_eq!(Accepted::Family(Family::Video).as_str(), "video/*");
5812 assert_eq!(Accepted::Type("text/csv").as_str(), "text/csv");
5813 assert_eq!(Accepted::Suffix(".tar.gz").as_str(), ".tar.gz");
5814 }
5815
5816 #[test]
5817 fn a_list_accepting_two_families_still_has_a_disclosure_to_offer() {
5818 // The measured dropzone: `accept="image/*,video/*"`. There is no single
5819 // family to return and there is still a preview to keep room for, which
5820 // is why the question is asked of the list rather than of one entry.
5821 const MEDIA: &[Accepted<'_>] = &[
5822 Accepted::Family(Family::Image),
5823 Accepted::Family(Family::Video),
5824 ];
5825 assert!(Field::upload("media", "Media", MEDIA).accepts_media());
5826 // An installer's suffix list wants no disclosure, which is the measured
5827 // case rather than a hypothetical one.
5828 const BUILDS: &[Accepted<'_>] = &[Accepted::Suffix(".zip"), Accepted::Suffix(".dmg")];
5829 assert!(!Field::upload("build", "Build", BUILDS).accepts_media());
5830 // And a field that takes anything says so by listing nothing.
5831 assert!(!Field::upload("any", "File", &[]).accepts_media());
5832 }
5833
5834 #[test]
5835 fn an_upload_carries_its_list_and_takes_one_file_until_it_says_otherwise() {
5836 const IMAGES: &[Accepted<'_>] = &[
5837 Accepted::Type("image/jpeg"),
5838 Accepted::Type("image/png"),
5839 Accepted::Type("image/webp"),
5840 ];
5841 let avatar = Field::upload("avatar", "Avatar", IMAGES);
5842 assert_eq!(avatar.kind, FieldKind::File);
5843 assert_eq!(avatar.accept, IMAGES);
5844 assert!(!avatar.multiple);
5845 let several = Field {
5846 multiple: true,
5847 ..avatar
5848 };
5849 assert!(several.multiple);
5850 }
5851
5852 #[test]
5853 fn the_four_readiness_states_are_one_axis_and_only_one_shows_content() {
5854 // Mutually exclusive is the test for one enum against several fields: a
5855 // region shows its content, or that it is coming, or that there is none,
5856 // or that it broke. Never two.
5857 assert!(Readiness::Ready.shows_content());
5858 for state in [Readiness::Pending, Readiness::Empty, Readiness::Failed] {
5859 assert!(!state.shows_content());
5860 }
5861 }
5862
5863 #[test]
5864 fn a_region_shows_all_of_its_children_unless_it_says_otherwise() {
5865 // The default is the behaviour every region had before this member
5866 // existed, which is what keeps it additive: a description written
5867 // against 0.22.0 says the same thing under 0.23.0.
5868 assert_eq!(Showing::default(), Showing::All);
5869 assert!(!Showing::All.selective());
5870 }
5871
5872 #[test]
5873 fn only_a_disclosure_can_show_nothing() {
5874 // The two derived idioms differ in one respect and this is it. A
5875 // carousel's row moves between frames and never reaches empty; a
5876 // disclosure's summary line is the same control wearing its closed
5877 // state, so a renderer has to know which it is drawing.
5878 assert!(Showing::AtMostOne.dismissible());
5879 assert!(!Showing::One.dismissible());
5880 assert!(!Showing::All.dismissible());
5881
5882 // Both are selective, though. Deriving chrome is one question and
5883 // whether that chrome closes is another.
5884 assert!(Showing::One.selective());
5885 assert!(Showing::AtMostOne.selective());
5886 }
5887
5888 #[test]
5889 fn an_empty_region_is_not_a_broken_one() {
5890 // An empty list is the normal state of a new install. Drawing it in a
5891 // danger tone reports a fault where there is none, and this is the one
5892 // place the distinction is carried.
5893 assert_eq!(Readiness::Empty.tone(), Tone::Neutral);
5894 assert_eq!(Readiness::Failed.tone(), Tone::Danger);
5895 assert_eq!(Readiness::Pending.tone(), Tone::Neutral);
5896 }
5897
5898 #[test]
5899 fn a_column_can_be_sorted_without_being_sortable() {
5900 // Both combinations mean something, which is why the two fields are
5901 // independent rather than one implying the other. A list ordered by a
5902 // key the user cannot change is a real thing with a caret worth drawing.
5903 let fixed = Column {
5904 sorted: Some(Sort::Descending),
5905 ..Column::new("Created")
5906 };
5907
5908 assert!(!fixed.sortable);
5909 assert_eq!(fixed.sorted.map(Sort::as_str), Some("descending"));
5910
5911 let offered = Column {
5912 sortable: true,
5913 ..Column::new("Name")
5914 };
5915 assert_eq!(offered.sorted, None);
5916 }
5917
5918 #[test]
5919 fn a_direction_flips_and_says_what_it_is() {
5920 assert_eq!(Sort::Ascending.reversed(), Sort::Descending);
5921 assert_eq!(Sort::Descending.reversed().reversed(), Sort::Descending);
5922 assert_eq!(Sort::Ascending.as_str(), "ascending");
5923 }
5924
5925 #[test]
5926 fn a_direction_carries_its_caret_and_the_two_are_not_the_same_glyph() {
5927 // The spelling every renderer reads, so that agreeing is composition
5928 // rather than three files happening to hold the same literal.
5929 assert_eq!(Sort::Ascending.glyph(), "\u{25B2}");
5930 assert_eq!(Sort::Descending.glyph(), "\u{25BC}");
5931 assert_ne!(Sort::Ascending.glyph(), Sort::Descending.glyph());
5932 // Bare. The gap is the renderer's, and a space here would be a second
5933 // one wherever a renderer already carries its own.
5934 for d in [Sort::Ascending, Sort::Descending] {
5935 assert_eq!(d.glyph().trim(), d.glyph());
5936 }
5937 }
5938
5939 #[test]
5940 fn a_figure_carries_its_tone_because_no_renderer_can_derive_it() {
5941 // Three of goingson's five sites tone the figure by their own means, so
5942 // tone is carried at every site that needs it and derived at none. The
5943 // same reasoning `Meter` reached, from a different direction.
5944 let streak = Figure::new("0", "Current Streak").tone(Tone::Warning);
5945 assert_eq!(streak.tone, Tone::Warning);
5946 assert_eq!(Figure::new("17", "Total").tone, Tone::Neutral);
5947 }
5948
5949 #[test]
5950 fn a_figures_change_is_the_toned_part_and_is_absent_by_default() {
5951 // 0.13.0. The MNW server's stat card is a label, a value and a delta,
5952 // across four screens, and the delta is what reads as good or bad. Tone
5953 // had no consumer before this: the figure itself is an ordinary fact.
5954 let views = Figure::new("1,204", "Views")
5955 .change("+12.5%")
5956 .tone(Tone::Success);
5957 assert_eq!(views.change, Some("+12.5%"));
5958 assert_eq!(views.tone, Tone::Success);
5959
5960 // A figure with nothing to compare against says so by having no change,
5961 // rather than by carrying an empty string a renderer has to test for.
5962 assert_eq!(Figure::new("3.1%", "Conversion").change, None);
5963 }
5964
5965 #[test]
5966 fn a_figures_value_is_text_because_only_the_app_knows_what_it_is() {
5967 // "84%", "12/30", "3d". A figure is whatever the app computed, already
5968 // formatted, and that is the line between this and `Meter`: a meter is
5969 // a proportion a renderer draws, a figure is a fact it sets in type.
5970 for value in ["84%", "12/30", "3d"] {
5971 assert_eq!(Figure::new(value, "Rate").value, value);
5972 }
5973 }
5974
5975 #[test]
5976 fn a_proportion_is_a_row_part_and_takes_no_intent_of_its_own() {
5977 // The meter carries the tone, so a part-level intent underneath would
5978 // fight it. Same answer `Tokens` needed, for the same reason.
5979 assert_eq!(RowPart::Proportion.intent(), RowPart::Tokens.intent());
5980 }
5981
5982 #[test]
5983 fn a_file_field_is_drawn_and_offers_no_options() {
5984 // It is a control the user operates, unlike `Hidden`, and it does not
5985 // pick from a list the description carries, unlike `Select`.
5986 assert!(FieldKind::File.visible());
5987 assert!(!FieldKind::File.offers_options());
5988 assert!(!FieldKind::File.confidential());
5989 }
5990
5991 #[test]
5992 fn a_constraint_is_a_fact_about_the_question_and_not_a_verdict() {
5993 // The whole model: the description carries the rule, the renderer emits
5994 // its host's idiom, and `error` is what arrives back when someone
5995 // validated. Nothing here decides a value is wrong.
5996 let field = Field {
5997 max_length: Some(100),
5998 min: Some("1"),
5999 max: Some("240"),
6000 required: true,
6001 ..Field::new(FieldKind::Number, "minutes", "Minutes")
6002 };
6003 assert!(!field.invalid());
6004
6005 // A bound is text because it is only a number for some of the kinds
6006 // that take one. goingson has both shapes live.
6007 let when = Field {
6008 min: Some("2026-08-09T14:30"),
6009 ..Field::new(FieldKind::Text, "starts", "Starts")
6010 };
6011 assert_eq!(when.min, Some("2026-08-09T14:30"));
6012 }
6013
6014 #[test]
6015 fn a_meter_keeps_the_over_run_the_percentage_throws_away() {
6016 // The whole reason this is a pair. goingson's `Task::time_progress`
6017 // clamps to 100 and then carries `is_over_estimate` beside it to say
6018 // what the clamp dropped; a meter says both from one fact.
6019 let over = Meter::new(45, 30);
6020 assert_eq!(over.percent(), 100);
6021 assert!(over.overflowing());
6022
6023 let exact = Meter::new(30, 30);
6024 assert_eq!(exact.percent(), over.percent());
6025 assert!(!exact.overflowing());
6026 }
6027
6028 #[test]
6029 fn an_empty_set_does_not_divide_by_zero() {
6030 // Sayable on purpose, so it has to be answerable. A meter over an
6031 // unloaded count is what an app actually has for a frame.
6032 let none = Meter::new(0, 0);
6033 assert_eq!(none.percent(), 0);
6034 assert!(none.is_empty());
6035 assert!(!none.overflowing());
6036 }
6037
6038 #[test]
6039 fn the_ratio_survives_where_a_percentage_would_not() {
6040 // Given 43 nothing can recover "3 of 7", which is why the numbers are
6041 // carried and the label names only the noun.
6042 let m = Meter::new(3, 7).label("subtasks");
6043 assert_eq!(m.percent(), 42);
6044 assert_eq!((m.done, m.total), (3, 7));
6045 assert_eq!(m.label, Some("subtasks"));
6046 }
6047
6048 #[test]
6049 fn tone_is_carried_because_no_renderer_can_derive_it() {
6050 // The same fullness means opposite things on two of goingson's bars,
6051 // and only the app knows which.
6052 let subtasks = Meter::new(9, 10).tone(Tone::Success);
6053 let estimate = Meter::new(9, 10).tone(Tone::Danger);
6054 assert_eq!(subtasks.percent(), estimate.percent());
6055 assert_ne!(subtasks.tone, estimate.tone);
6056 // Untoned by default: a bar says nothing about status until something
6057 // says so, the same way a row is not selectable until told.
6058 assert_eq!(Meter::new(9, 10).tone, Tone::Neutral);
6059 }
6060
6061 #[test]
6062 fn an_act_is_reachable_until_it_is_disabled() {
6063 // The one member a renderer must branch on, and since 0.19.0 the only
6064 // member there is. A stated state is not by itself a reason to stop
6065 // answering, which is the distinction `State` makes and every
6066 // hand-rolled button in the tree had to remember.
6067 assert!(!Act::new("Save").disabled());
6068 assert!(Act::new("Save").state(State::Disabled).disabled());
6069 }
6070
6071 #[test]
6072 fn an_act_carries_its_key_because_a_terminal_has_nothing_else() {
6073 // No key is the ordinary case, and the webview hosts that ignore it
6074 // are why it stayed optional.
6075 assert_eq!(Act::new("Delete").key, None);
6076 let quit = Act::new("Quit").key("q").tone(Tone::Danger);
6077 assert_eq!(quit.key, Some("q"));
6078 assert_eq!(quit.tone, Tone::Danger);
6079 }
6080
6081 #[test]
6082 fn a_meter_does_not_overflow_on_large_counts() {
6083 // done * 100 in u32 would wrap somewhere past 42 million. Counts that
6084 // size are not tasks, but a description layer that silently reports 3%
6085 // for a full bar is worse than one that is slow.
6086 let big = Meter::new(u32::MAX, u32::MAX);
6087 assert_eq!(big.percent(), 100);
6088 assert!(!big.overflowing());
6089 }
6090
6091 #[test]
6092 fn inset_is_raised_with_the_light_moved() {
6093 let (rl, rd) = Bevel::Raised.edges();
6094 let (il, id) = Bevel::Inset.edges();
6095 assert_eq!((rl, rd), (Edge::Light, Edge::Dark));
6096 assert_eq!((il, id), (rd, rl));
6097 }
6098
6099 #[test]
6100 fn pressing_twice_is_a_no_op() {
6101 for b in [Bevel::Raised, Bevel::Inset] {
6102 assert_eq!(b.pressed().pressed(), b);
6103 }
6104 }
6105
6106 #[test]
6107 fn a_raised_region_is_never_filled_with_a_recessed_surface() {
6108 // The bug this vocabulary exists to make unrepresentable.
6109 assert_eq!(Depth::Raised.fill(), Some(Fill::Raised));
6110 assert_eq!(Depth::Raised.bevel(), Some(Bevel::Raised));
6111 assert_eq!(Depth::Well.bevel(), Some(Bevel::Inset));
6112 assert_ne!(Depth::Well.fill(), Depth::Raised.fill());
6113 }
6114
6115 #[test]
6116 fn state_is_orthogonal_to_depth() {
6117 // The reason State is its own axis and not a Depth member: a disabled
6118 // button and a disabled field are both disabled and are not the same
6119 // shape, which one shared variant could not have said.
6120 assert_eq!(Depth::Raised.fill(), Some(Fill::Raised));
6121 assert_eq!(Depth::Well.fill(), Some(Fill::Well));
6122 assert!(State::Disabled.suppresses_interaction());
6123 }
6124
6125 #[test]
6126 fn only_disabled_stops_answering() {
6127 // Kept in spirit from the version where `Focus` was the counter-example:
6128 // suppressing interaction is `Disabled`'s alone, so a member added here
6129 // later does not get to inherit it by being a state.
6130 assert!(State::Disabled.suppresses_interaction());
6131 }
6132
6133 #[test]
6134 fn disabled_resolves_against_an_intent_makeover_already_derives() {
6135 // No new token, so this costs no `makeover` release.
6136 assert_eq!(State::Disabled.token(), "content-muted");
6137 }
6138
6139 #[test]
6140 fn flat_has_neither_edge_nor_fill() {
6141 assert_eq!(Depth::Flat.bevel(), None);
6142 assert_eq!(Depth::Flat.fill(), None);
6143 }
6144
6145 #[test]
6146 fn sunken_is_recessed_by_colour_with_no_edge() {
6147 // The one member carrying a fill without a bevel. A renderer that
6148 // assumes the two arrive together drops the fill silently, which is
6149 // exactly what makeover-webview did before 0.3.0.
6150 assert_eq!(Depth::Sunken.fill(), Some(Fill::Sunken));
6151 assert_eq!(Depth::Sunken.bevel(), None);
6152 }
6153
6154 #[test]
6155 fn sunken_and_flat_are_different_claims() {
6156 // Both edgeless, and only one of them needs a colour. Collapsing them
6157 // is what left an unchosen tab unsayable.
6158 assert_eq!(Depth::Flat.bevel(), Depth::Sunken.bevel());
6159 assert_ne!(Depth::Flat.fill(), Depth::Sunken.fill());
6160 }
6161
6162 #[test]
6163 fn a_sunken_surface_is_not_a_well() {
6164 // Authored in opposite directions: makeover derives surface-well by
6165 // inverting against the theme's content colour, while surface-sunken is
6166 // authored and may sit darker than raised.
6167 assert_ne!(Fill::Sunken, Fill::Well);
6168 assert_eq!(Fill::Sunken.token(), "surface-sunken");
6169 assert_eq!(Fill::Well.token(), "surface-well");
6170 }
6171
6172 #[test]
6173 fn every_selector_describes_both_of_its_states() {
6174 // The gap 0.3.0 closed. Before it, only `chosen` existed and the
6175 // unchosen option fell through to Flat at every renderer.
6176 for s in [Selector::Tabs, Selector::Segmented, Selector::Toggle] {
6177 assert_ne!(
6178 s.chosen(),
6179 s.unchosen(),
6180 "{s:?} cannot tell picked from unpicked"
6181 );
6182 }
6183 }
6184
6185 #[test]
6186 fn only_a_tab_inverts_the_other_way() {
6187 // Tabs recede so the chosen one comes forward; a segment and a toggle
6188 // stand up so the chosen one is held in. That inversion is the whole
6189 // content of "picked" once colour is deferred, and it is why the three
6190 // are not one member with a flag.
6191 assert_eq!(Selector::Tabs.unchosen(), Depth::Sunken);
6192 assert_eq!(Selector::Tabs.chosen(), Depth::Raised);
6193
6194 for s in [Selector::Segmented, Selector::Toggle] {
6195 assert_eq!(s.unchosen(), Depth::Raised);
6196 assert_eq!(s.chosen(), Depth::Well);
6197 // Held in is what pressing produces: one appearance, two reasons.
6198 assert_eq!(s.unchosen().pressed(), s.chosen());
6199 }
6200 }
6201
6202 #[test]
6203 fn pressing_a_card_makes_a_well() {
6204 assert_eq!(Depth::Raised.pressed(), Depth::Well);
6205 assert_eq!(
6206 Depth::Raised.pressed().bevel(),
6207 Depth::Raised.bevel().map(Bevel::pressed)
6208 );
6209 // Only raised regions respond to being pressed.
6210 assert_eq!(Depth::Flat.pressed(), Depth::Flat);
6211 assert_eq!(Depth::Well.pressed(), Depth::Well);
6212 // An overlay is a surface, not a control.
6213 assert_eq!(Depth::Overlay.pressed(), Depth::Overlay);
6214 }
6215
6216 #[test]
6217 fn an_overlay_is_lifted_rather_than_edged() {
6218 // The wave-2 rule: a surface over the page takes elevation, a surface
6219 // in the page takes a bevel. Both halves come off the one Depth, so
6220 // they cannot disagree.
6221 assert_eq!(Depth::Overlay.fill(), Some(Fill::Overlay));
6222 assert_eq!(Depth::Overlay.bevel(), None);
6223
6224 // Three depths have no bevel and they are not the same claim. Flat has
6225 // nothing to separate from, Sunken's colour is doing the separating,
6226 // and an overlay is separated by the lift.
6227 assert_ne!(Depth::Overlay.fill(), Depth::Sunken.fill());
6228 assert_ne!(Depth::Overlay.fill(), Depth::Flat.fill());
6229 }
6230
6231 #[test]
6232 fn a_note_is_neither_a_hint_nor_an_error() {
6233 // audiofiles' export Format field: choosing WAV over Original
6234 // re-encodes and drops the embedded metadata. Perfectly valid, and it
6235 // costs something.
6236 let format = Field {
6237 note: Some((Tone::Warning, "Re-encoding drops embedded BWF and iXML")),
6238 ..Field::select("format", "Format", &[])
6239 };
6240 assert!(!format.invalid(), "a note is not a validation failure");
6241 assert!(format.hint.is_none());
6242 assert!(format.error.is_none());
6243 assert_eq!(format.note.unwrap().0, Tone::Warning);
6244
6245 // The default is no note, so the 15 in-tree `..Field::new(..)`
6246 // literals absorb the member with no call-site edit.
6247 assert!(Field::new(FieldKind::Text, "title", "Title").note.is_none());
6248 }
6249
6250 #[test]
6251 fn neutral_is_content_not_muted_content() {
6252 // Neutral means "no status", and that is all it means. It answered
6253 // `content-muted` until 2026-08-27, which muted a figure's headline
6254 // number to the colour of its own caption. What makes a badge quiet
6255 // is `Token::Badge` answering no click, which lives on the renderer.
6256 assert_eq!(Tone::Neutral.token(), "content");
6257 assert!(!Token::Badge.interactive());
6258 assert_eq!(State::Disabled.token(), "content-muted");
6259 }
6260
6261 #[test]
6262 fn intents_name_makeover_tokens_and_nothing_else() {
6263 assert_eq!(Edge::Light.token(), "bevel-light");
6264 assert_eq!(Edge::Dark.token(), "bevel-dark");
6265 assert_eq!(Fill::Raised.token(), "surface-raised");
6266 assert_eq!(Fill::Well.token(), "surface-well");
6267 // No value ever leaves this crate.
6268 for t in [
6269 Edge::Light.token(),
6270 Edge::Dark.token(),
6271 Tone::Danger.token(),
6272 Tone::Neutral.token(),
6273 State::Disabled.token(),
6274 ] {
6275 assert!(!t.starts_with('#'), "{t} looks like a value");
6276 assert!(
6277 !t.chars().next().unwrap().is_ascii_digit(),
6278 "{t} is a value"
6279 );
6280 }
6281 }
6282
6283 #[test]
6284 fn a_badge_cannot_be_pressed_and_a_chip_latches() {
6285 // The one line that runs through all three apps' taxonomies.
6286 assert!(!Token::Badge.interactive());
6287 assert!(Token::Chip { removable: false }.interactive());
6288 assert!(Token::Chip { removable: true }.interactive());
6289
6290 // A badge is a label, so giving it an edge would lie about it.
6291 assert_eq!(Token::Badge.depth(false), Depth::Flat);
6292 assert_eq!(Token::Badge.depth(true), Depth::Flat);
6293
6294 // A latched chip wears the same shape a pressed one does.
6295 let chip = Token::Chip { removable: false };
6296 assert_eq!(chip.depth(false), Depth::Raised);
6297 assert_eq!(chip.depth(true), Depth::Raised.pressed());
6298 }
6299
6300 #[test]
6301 fn a_toast_and_a_banner_differ_in_more_than_placement() {
6302 assert!(Notice::Toast.transient());
6303 assert!(!Notice::Banner.transient());
6304 // A toast floats above the page; a banner rests in the flow.
6305 assert_eq!(Notice::Toast.fill(), Fill::Overlay);
6306 assert_eq!(Notice::Banner.fill(), Fill::Raised);
6307 }
6308
6309 #[test]
6310 fn emphasis_falls_off_down_the_row() {
6311 // `revealed_on_hover` was asserted here until 0.13.0 retired it. It said
6312 // a row's actions stay hidden until hover, which stopped being true when
6313 // makeover-webview 0.23.0 showed them at rest, and nothing had consumed
6314 // it for a release either way.
6315 assert_eq!(RowPart::Primary.intent(), "content");
6316 assert_eq!(RowPart::Secondary.intent(), "content-secondary");
6317 assert_eq!(RowPart::Meta.intent(), "content-muted");
6318 }
6319
6320 #[test]
6321 fn a_token_part_carries_no_intent_of_its_own() {
6322 // Each token carries its own tone, so a part-level intent underneath
6323 // would fight the thing sitting on it. Same reasoning as actions, which
6324 // is why they answer alike.
6325 assert_eq!(RowPart::Tokens.intent(), RowPart::Actions.intent());
6326 assert_eq!(RowPart::Tokens.intent(), "content");
6327 }
6328
6329 #[test]
6330 fn the_two_temporal_kinds_are_the_two_that_name_a_moment() {
6331 // The pair is named once so a host with parsing to do asks here rather
6332 // than spelling it out, which is `offers_options`' reason.
6333 assert!(FieldKind::Date.temporal());
6334 assert!(FieldKind::DateTime.temporal());
6335
6336 for kind in [
6337 FieldKind::Text,
6338 FieldKind::Secret,
6339 FieldKind::Number,
6340 FieldKind::Email,
6341 FieldKind::Url,
6342 FieldKind::Tel,
6343 FieldKind::Range,
6344 FieldKind::Textarea,
6345 FieldKind::Rich,
6346 FieldKind::Select,
6347 FieldKind::Radio,
6348 FieldKind::Checkbox,
6349 FieldKind::File,
6350 FieldKind::Hidden,
6351 ] {
6352 assert!(!kind.temporal(), "{kind:?}");
6353 }
6354 }
6355
6356 #[test]
6357 fn a_date_carries_no_time_and_a_datetime_carries_no_zone() {
6358 // The formats are the whole reason the members are worth naming apart
6359 // from text, so the doc comments and the constants have to agree. A
6360 // host reading one and meeting the other is the silent failure.
6361 assert_eq!(DATE_FORMAT, "%Y-%m-%d");
6362 assert!(!DATE_FORMAT.contains("%H"), "a day carries no hour");
6363
6364 assert_eq!(DATETIME_FORMAT, "%Y-%m-%dT%H:%M");
6365 assert!(
6366 DATETIME_FORMAT.starts_with(DATE_FORMAT),
6367 "a moment starts with the day it is on"
6368 );
6369 // Local, and that is a property of the value rather than an omission.
6370 assert!(!DATETIME_FORMAT.contains("%Z"), "no zone name");
6371 assert!(!DATETIME_FORMAT.ends_with('Z'), "not UTC-stamped");
6372 assert!(!DATETIME_FORMAT.contains("%S"), "no seconds by default");
6373 }
6374
6375 #[test]
6376 fn a_temporal_kind_takes_a_label_above_it_and_offers_no_options() {
6377 // Neither is a checkbox and neither is a fixed set, so both fall where
6378 // text does. Asserted because a new kind lands in three predicates and
6379 // only one of them is the interesting one.
6380 for kind in [FieldKind::Date, FieldKind::DateTime] {
6381 assert!(kind.visible(), "{kind:?}");
6382 assert!(!kind.confidential(), "{kind:?}");
6383 assert!(!kind.labels_itself(), "{kind:?}");
6384 assert!(!kind.offers_options(), "{kind:?}");
6385 }
6386 }
6387
6388 #[test]
6389 fn a_cell_part_names_an_intent_and_only_the_value_is_text() {
6390 // The table half of what RowPart::intent does for rows. A cell holding
6391 // a control and a cell holding text answered alike until 0.14.0, and a
6392 // control in a cell took the cell's text colour.
6393 assert_eq!(CellPart::Value.intent(), "content");
6394
6395 for part in [CellPart::Tokens, CellPart::Actions, CellPart::Link] {
6396 // Each for its own reason -- a token carries its tone, an action is
6397 // a control, a link takes the action colour -- and all three reach
6398 // the intent inheriting already gives.
6399 assert_eq!(part.intent(), CellPart::Value.intent(), "{part:?}");
6400 }
6401 }
6402
6403 #[test]
6404 fn every_cell_part_answers_with_a_token_and_never_a_value() {
6405 for part in [
6406 CellPart::Value,
6407 CellPart::Tokens,
6408 CellPart::Actions,
6409 CellPart::Link,
6410 ] {
6411 let intent = part.intent();
6412 assert!(!intent.is_empty(), "{part:?} names nothing");
6413 assert!(!intent.starts_with('#'), "{part:?} looks like a value");
6414 }
6415 }
6416
6417 #[test]
6418 fn a_separator_is_what_tells_a_section_from_a_subsection() {
6419 assert!(Heading::Section.separated());
6420 assert!(!Heading::Subsection.separated());
6421 assert!(!Heading::Page.separated());
6422 }
6423
6424 #[test]
6425 fn a_chosen_segment_is_held_in_and_a_chosen_tab_comes_forward() {
6426 assert_eq!(Selector::Segmented.chosen(), Depth::Well);
6427 assert_eq!(Selector::Toggle.chosen(), Depth::Well);
6428 // The exception, and the whole folder semantic: the open tab joins its
6429 // pane rather than sinking away from it.
6430 assert_eq!(Selector::Tabs.chosen(), Depth::Raised);
6431
6432 // A held-in segment is indistinguishable from a pressed raised one,
6433 // which is the economy the light model buys over a colour swap.
6434 assert_eq!(Selector::Segmented.chosen(), Depth::Raised.pressed());
6435
6436 // A toggle stands alone; the other two are built out of parts that
6437 // touch.
6438 assert!(Selector::Segmented.abutting());
6439 assert!(Selector::Tabs.abutting());
6440 assert!(!Selector::Toggle.abutting());
6441 }
6442
6443 #[test]
6444 fn columns_are_peers_and_a_split_is_not() {
6445 // The distinction the member exists for. A split's two panes stand in a
6446 // master-detail relationship; columns choose nothing about each other.
6447 // Both are flat, so depth cannot tell them apart and the doc has to.
6448 assert_eq!(Region::Columns.depth(), Depth::Flat);
6449 assert_eq!(Region::Split.depth(), Depth::Flat);
6450 assert_ne!(Region::Columns, Region::Split);
6451 }
6452
6453 #[test]
6454 fn columns_carry_no_count_and_no_share() {
6455 // The two things a board is always asked to carry and must not. How
6456 // many is what the children say; how wide is settled by "peers are
6457 // equal".
6458 //
6459 // The guard is the binding itself and it is a compile-time one: adding
6460 // a field to `Columns` stops this line compiling, which is a better
6461 // failure than any assertion about it. Written out rather than inlined
6462 // for exactly that reason.
6463 let columns: Region<'_> = Region::Columns;
6464 assert_eq!(columns.name(), None);
6465 }
6466
6467 #[test]
6468 fn columns_are_described_and_the_escape_hatch_is_still_one_member() {
6469 // A board's contents are ordinary description all the way down, so a
6470 // renderer that does not lay them across still draws every column.
6471 // Stacking them vertically is honouring this member, not degrading it.
6472 assert!(Region::Columns.described());
6473 assert!(!Region::Bespoke { name: "timeline" }.described());
6474 }
6475
6476 #[test]
6477 fn a_span_never_has_zero_minutes_however_it_is_asked_for() {
6478 // Every renderer divides by this. A caller passing a backwards or empty
6479 // span is a bug, but it is not a bug worth a panic three renderers deep.
6480 assert_eq!(Span::new(600, 600).length(), 1);
6481 assert_eq!(Span::new(600, 300).length(), 1);
6482 assert_eq!(Span::DAY.length(), 1440);
6483 }
6484
6485 #[test]
6486 fn a_span_can_run_past_midnight_without_a_second_date() {
6487 // 22:00 to 02:00. The alternative was carrying a date, which drags a
6488 // timezone into the vocabulary for the sake of one night shift.
6489 let overnight = Span::new(1320, 1560);
6490 assert_eq!(overnight.length(), 240);
6491 assert!(overnight.holds(1500));
6492 assert!(!overnight.holds(1200));
6493 }
6494
6495 #[test]
6496 fn overlap_is_computed_rather_than_declared() {
6497 // The reason Placement carries no `conflicts` flag: the times already
6498 // say it, and a second source for one fact is how a stale conflict
6499 // badge outlives the conflict.
6500 let morning = Placement::new(540, 60); // 09:00-10:00
6501 let overlapping = Placement::new(570, 60); // 09:30-10:30
6502 let after = Placement::new(600, 60); // 10:00-11:00
6503
6504 assert!(morning.overlaps(overlapping));
6505 assert!(overlapping.overlaps(morning), "overlap is symmetric");
6506 // Touching end to end is not overlapping: `to` is exclusive, so a
6507 // 10:00 start does not collide with a 10:00 end.
6508 assert!(!morning.overlaps(after));
6509 assert!(!after.overlaps(morning));
6510 }
6511
6512 #[test]
6513 fn a_placement_is_always_drawable() {
6514 assert_eq!(Placement::new(540, 0).length(), 1);
6515 assert_eq!(Placement::new(540, 30).end(), 570);
6516 }
6517
6518 #[test]
6519 fn a_track_places_the_fraction_every_renderer_would_otherwise_compute() {
6520 let day = Track::DAY;
6521 assert!((day.fraction(0) - 0.0).abs() < f32::EPSILON);
6522 assert!((day.fraction(720) - 0.5).abs() < f32::EPSILON);
6523 // Clamped rather than off the end: an event running past the span's
6524 // close draws at the edge, which beats panicking or drawing nowhere.
6525 assert!((day.fraction(2000) - 1.0).abs() < f32::EPSILON);
6526 }
6527
6528 #[test]
6529 fn a_track_counts_its_slots_and_never_divides_by_zero() {
6530 assert_eq!(Track::DAY.slots(), 96);
6531 assert_eq!(Track::over(Span::new(540, 1020)).slots(), 32);
6532 // A span that does not divide evenly keeps a slot for its tail.
6533 assert_eq!(Track::over(Span::new(0, 50)).slots(), 4);
6534 // slot: 0 is a caller bug that reads as one slot, not a panic.
6535 let degenerate = Track {
6536 span: Span::DAY,
6537 slot: 0,
6538 tick: 60,
6539 unit: Unit::Minutes,
6540 };
6541 assert_eq!(degenerate.slots(), 1);
6542 }
6543
6544 #[test]
6545 fn a_track_carries_facts_and_no_presentation() {
6546 // The guard on the thing the withdrawn refusal was right about. If a
6547 // pixel measure, a scroll offset or a colour ever lands on Track, the
6548 // member has stopped being a fact about the data and the timeline
6549 // really has become a component library wearing a description's name.
6550 let day = Track::DAY;
6551 assert_eq!(day.span, Span::DAY);
6552 assert_eq!(day.slot, 15);
6553 assert_eq!(day.tick, 60);
6554 assert_eq!(day.unit, Unit::Minutes);
6555
6556 // Three fields when this was written, and the fourth came here to say
6557 // why, which is the whole point of the assertion. `unit` is what the
6558 // integers COUNT -- a fact about the data, unavailable from the numbers
6559 // themselves, and the absence of it is what let a month strip render
6560 // under a wall clock. A fifth field still has to argue, and "the
6561 // renderer would find it handy" is still not the argument.
6562 // Destructured rather than rebuilt: this is the form that names every
6563 // field and stops compiling when a fifth arrives, without binding
6564 // anything a lint has to forgive.
6565 let Track {
6566 span: _,
6567 slot: _,
6568 tick: _,
6569 unit: _,
6570 } = day;
6571 }
6572
6573 #[test]
6574 fn a_day_strip_is_the_same_arithmetic_under_a_different_unit() {
6575 // The probe that found the defect, kept as a test. Fifteen days from
6576 // day three, on a thirty-one day month: the geometry was always right
6577 // and only the label was wrong, which is why `unit` is a fact and not
6578 // presentation.
6579 let march = Track::days(Span::new(0, 31));
6580 assert_eq!(march.slots(), 31);
6581 assert_eq!(march.unit, Unit::Days);
6582
6583 let leave = Placement::new(2, 15);
6584 assert!((march.fraction(leave.at()) - 2.0 / 31.0).abs() < 0.0001);
6585 assert!((march.fraction(leave.end()) - 17.0 / 31.0).abs() < 0.0001);
6586 }
6587
6588 #[test]
6589 fn a_pane_is_looked_into_and_a_band_is_not() {
6590 assert_eq!(Region::Pane.depth(), Depth::Well);
6591 assert_eq!(Region::Modal.depth(), Depth::Raised);
6592 for r in [
6593 Region::Band,
6594 Region::Sidebar,
6595 Region::Group,
6596 Region::Split,
6597 Region::TabGroup,
6598 ] {
6599 assert_eq!(r.depth(), Depth::Flat, "{r:?} should carry no edge");
6600 }
6601 }
6602
6603 #[test]
6604 fn exactly_one_region_is_opaque() {
6605 // The escape hatch is one member and stays one member. If a second
6606 // undescribed region ever appears, the description has started
6607 // conceding rather than deferring.
6608 for r in [
6609 Region::Band,
6610 Region::Sidebar,
6611 Region::Pane,
6612 Region::Group,
6613 Region::Split,
6614 Region::TabGroup,
6615 Region::Modal,
6616 // A widget is described, and that is the whole of what separates it
6617 // from a bespoke here. Both carry a name this crate never reads;
6618 // only one of them has contents under it that a renderer which does
6619 // not know the name can still walk.
6620 Region::Widget { name: "carousel" },
6621 ] {
6622 assert!(r.described(), "{r:?} should be describable");
6623 }
6624 assert!(!Region::Bespoke { name: "day-plan" }.described());
6625 }
6626
6627 #[test]
6628 fn a_picture_that_says_nothing_is_a_claim_and_not_an_oversight() {
6629 // The distinction a renderer with no graphics protocol runs on: draw
6630 // the words, or draw nothing. Standing in for a decorative rule with
6631 // the word "decoration" is worse than leaving the space empty.
6632 assert!(Image::new("The library view, mid-import").speaks());
6633 assert!(!Image::new("").speaks());
6634 }
6635
6636 #[test]
6637 fn a_caption_and_alt_text_are_not_the_same_line() {
6638 // A caption is content everybody reads; alt text stands in for the
6639 // picture. A screenshot with a caption still needs alt text.
6640 let shot = Image::new("A file list with three rows selected").caption("The library view");
6641 assert_eq!(shot.caption, Some("The library view"));
6642 assert!(shot.speaks());
6643 assert_ne!(shot.alt, shot.caption.unwrap());
6644 }
6645
6646 #[test]
6647 fn a_picture_can_say_how_much_room_to_hold() {
6648 // The whole point: a renderer reserves from the ratio, so the space is
6649 // right at any width. A fixed height would only be right at one.
6650 let shot = Image::new("a screenshot").intrinsic(5120, 3412);
6651 let e = shot.intrinsic.expect("carried");
6652 assert_eq!((e.width, e.height), (5120, 3412));
6653 assert!((e.ratio().unwrap() - 1.5006).abs() < 0.001);
6654 }
6655
6656 #[test]
6657 fn a_picture_with_no_dimensions_reserves_nothing_rather_than_guessing() {
6658 // `None` is honest: a creator upload whose size was never recorded does
6659 // not know it. A renderer must not invent one.
6660 assert_eq!(Image::new("unknown upload").intrinsic, None);
6661 assert_eq!(Extent::new(0, 10).ratio(), None);
6662 assert_eq!(Extent::new(10, 0).ratio(), None);
6663 }
6664
6665 #[test]
6666 fn a_picture_is_wanted_now_unless_the_app_says_otherwise() {
6667 // Eager is the safe default and lazy is the opt-in, because deferring
6668 // something already on screen saves nothing and moves its shift later.
6669 assert_eq!(Image::new("hero").loading, Loading::Eager);
6670 assert_eq!(Loading::default(), Loading::Eager);
6671 assert_eq!(Image::new("frame 2").lazy().loading, Loading::Lazy);
6672 }
6673
6674 #[test]
6675 fn a_picture_keeps_its_own_proportions_unless_told_otherwise() {
6676 // The default is the one that shows the whole picture at its own shape,
6677 // so a renderer ignoring Fit entirely is still right about the common
6678 // case. The shipped MNW carousel sets no object-fit at all, which is
6679 // this.
6680 assert_eq!(Image::new("a").fit, Fit::Natural);
6681 assert_eq!(Fit::default(), Fit::Natural);
6682 assert_eq!(Image::new("a").fit(Fit::Cover).fit, Fit::Cover);
6683 }
6684
6685 #[test]
6686 fn a_group_contains_a_section_without_claiming_to_be_a_pane() {
6687 // The whole of why this is a member rather than a `Pane`. A pane is
6688 // looked into and scrolls; a group is neither, and four groups inside a
6689 // settings pane described as panes are four wells inside a well.
6690 assert_eq!(Region::Pane.depth(), Depth::Well);
6691 assert_eq!(Region::Group.depth(), Depth::Flat);
6692 assert_ne!(Region::Group, Region::Pane);
6693
6694 // Described, and it carries no name: a group is a primitive every
6695 // renderer draws from scratch, which is what separates it from the two
6696 // members that do carry one.
6697 assert!(Region::Group.described());
6698 assert_eq!(Region::Group.name(), None);
6699 }
6700
6701 #[test]
6702 fn a_section_heading_names_a_block_that_now_exists() {
6703 // `Heading::Section` has said "names a block within the screen" since
6704 // 0.2.0 and there was no block. The pairing is the point, and it is the
6705 // reason a group carries no heading of its own: the heading is an
6706 // ordinary node in the body, and a group without one is legal.
6707 assert!(Heading::Section.separated());
6708 assert_eq!(Region::Group.depth(), Depth::Flat);
6709 }
6710
6711 #[test]
6712 fn a_widget_inherits_its_depth_the_way_a_bespoke_does() {
6713 // Stronger than the bespoke case: a widget is drawn by whichever
6714 // renderer recognises the name, so a depth chosen here would be this
6715 // crate deciding a carousel is raised on every host.
6716 assert_eq!(Region::Widget { name: "carousel" }.depth(), Depth::Flat);
6717 assert_eq!(Region::Widget { name: "pager" }.depth(), Depth::Flat);
6718 }
6719
6720 #[test]
6721 fn a_name_is_readable_without_asking_which_member_carried_it() {
6722 // A renderer dispatching on a name wants the string, not the member.
6723 // Writing that `matches!` at each renderer is how the two drift apart.
6724 assert_eq!(Region::Widget { name: "carousel" }.name(), Some("carousel"));
6725 assert_eq!(
6726 Region::Bespoke { name: "day-plan" }.name(),
6727 Some("day-plan")
6728 );
6729
6730 for r in [
6731 Region::Band,
6732 Region::Sidebar,
6733 Region::Pane,
6734 Region::Group,
6735 Region::Split,
6736 Region::TabGroup,
6737 Region::Modal,
6738 ] {
6739 assert_eq!(r.name(), None, "{r:?} names nothing an app chose");
6740 }
6741 }
6742
6743 #[test]
6744 fn a_bespoke_region_inherits_its_depth_rather_than_choosing_one() {
6745 // The app owns the contents, not the placement. An app that wants its
6746 // timeline in a well frames it in a Pane.
6747 assert_eq!(Region::Bespoke { name: "day-plan" }.depth(), Depth::Flat);
6748 assert_eq!(Region::Bespoke { name: "kanban" }.depth(), Depth::Flat);
6749 }
6750
6751 #[test]
6752 fn a_screen_with_a_bespoke_region_is_still_a_whole_screen() {
6753 // The argument the member exists for: goingson's day-plan has to be
6754 // routable, or the description covers only the boring screens and the
6755 // interesting four need a second path beside the router.
6756 let day_plan = [
6757 Region::Band,
6758 Region::Bespoke { name: "day-plan" },
6759 Region::Sidebar,
6760 ];
6761 assert_eq!(day_plan.iter().filter(|r| r.described()).count(), 2);
6762 assert_eq!(day_plan.iter().filter(|r| !r.described()).count(), 1);
6763 }
6764
6765 #[test]
6766 fn a_secret_field_is_marked_as_one_and_a_hidden_field_is_not_drawn() {
6767 let secret = Field::new(FieldKind::Secret, "password", "Password");
6768 assert!(secret.kind.confidential());
6769 assert!(secret.kind.visible());
6770
6771 assert!(!FieldKind::Hidden.visible());
6772 // Nothing else is confidential, or the marker means nothing.
6773 for k in [
6774 FieldKind::Text,
6775 FieldKind::Number,
6776 FieldKind::Textarea,
6777 FieldKind::Rich,
6778 FieldKind::Select,
6779 FieldKind::Checkbox,
6780 FieldKind::Hidden,
6781 ] {
6782 assert!(!k.confidential(), "{k:?} should not be confidential");
6783 }
6784
6785 // Only a checkbox carries its own label.
6786 assert!(FieldKind::Checkbox.labels_itself());
6787 assert!(!FieldKind::Text.labels_itself());
6788 }
6789
6790 #[test]
6791 fn a_plain_field_offers_nothing_and_a_select_offers_its_options() {
6792 let text = Field::new(FieldKind::Text, "title", "Title");
6793 assert!(text.options.is_empty());
6794 assert_eq!(text.placeholder, None);
6795
6796 let sizes = [Choice::plain("small"), Choice::plain("large")];
6797 let select = Field::select("size", "Size", &sizes);
6798 assert_eq!(select.kind, FieldKind::Select);
6799 assert_eq!(select.options.len(), 2);
6800 }
6801
6802 #[test]
6803 fn a_choice_says_what_submits_and_what_is_read_apart() {
6804 // The whole reason it is two strings. `plain` is the case where they
6805 // coincide, and it is a shorthand rather than the general shape.
6806 let plain = Choice::plain("7");
6807 assert_eq!((plain.value, plain.label), ("7", "7"));
6808
6809 let spelled = Choice::new("7", "One week");
6810 assert_ne!(spelled.value, spelled.label);
6811 assert!(
6812 spelled.available(),
6813 "an option is pickable until it says not"
6814 );
6815 }
6816
6817 #[test]
6818 fn a_candidate_carries_the_line_that_tells_it_from_its_neighbours() {
6819 // The gap this type was born for: two candidates whose labels read
6820 // alike, told apart by the second string and by nothing else. The
6821 // measured site is the MNW tag box, where "Format" is a leaf under
6822 // audio, software, writing and video.
6823 let audio = Candidate::new("audio/format", "Format").detailed("Audio");
6824 let writing = Candidate::new("writing/format", "Format").detailed("Writing");
6825
6826 assert_eq!(audio.label, writing.label);
6827 assert_ne!(audio.detail, writing.detail);
6828 assert_ne!(
6829 audio, writing,
6830 "two rows a user cannot tell apart are two rows the type can"
6831 );
6832 }
6833
6834 #[test]
6835 fn a_candidate_is_read_differently_from_an_option_and_written_the_same() {
6836 // The ruling's own distinction, held as a test so the two types do not
6837 // drift back together. Submitting is identical; the second line is the
6838 // whole of what differs, and it is absent by default because a list of
6839 // distinct labels wants nothing there.
6840 let candidate = Candidate::plain("rust");
6841 assert_eq!((candidate.value, candidate.label), ("rust", "rust"));
6842 assert_eq!(
6843 candidate.detail, None,
6844 "one line unless the route says otherwise"
6845 );
6846
6847 let option = Choice::plain("rust");
6848 assert_eq!(
6849 (candidate.value, candidate.label),
6850 (option.value, option.label)
6851 );
6852 }
6853
6854 #[test]
6855 fn a_radio_asks_the_same_question_as_a_select_and_is_not_the_same_kind() {
6856 // Both offer a fixed set and both read `options`, so the two
6857 // constructors differ in exactly one thing. That one thing is the
6858 // point: a renderer decides whether the alternatives are readable
6859 // without opening anything, and it can only decide that if the
6860 // description said which question was asked.
6861 let styles = [
6862 Choice::new("copy", "Copy samples in"),
6863 Choice::new("reference", "Reference in place"),
6864 ];
6865 let radio = Field::radio("storage", "Storage style", &styles);
6866 let select = Field::select("storage", "Storage style", &styles);
6867
6868 assert_eq!(radio.kind, FieldKind::Radio);
6869 assert_ne!(radio.kind, select.kind);
6870 assert_eq!(radio.options, select.options);
6871 assert_eq!(
6872 Field {
6873 kind: select.kind,
6874 ..radio
6875 },
6876 select
6877 );
6878 }
6879
6880 #[test]
6881 fn an_unavailable_option_cannot_be_silent_about_it() {
6882 // The whole content of the one-member shape: saying an option is not
6883 // pickable and saying why are the same act, so the greyed-out-with-no-
6884 // reason state is unsayable rather than merely discouraged.
6885 let multi =
6886 Choice::new("multi", "Multi-sample").unless("Drop a second sample onto the keyboard.");
6887 assert!(!multi.available());
6888 assert_eq!(
6889 multi.unavailable,
6890 Some("Drop a second sample onto the keyboard.")
6891 );
6892
6893 // And the option is still in the list, carrying what it submits, so a
6894 // renderer draws it rather than the app dropping it.
6895 assert_eq!(multi.value, "multi");
6896 assert_eq!(multi.label, "Multi-sample");
6897 }
6898
6899 #[test]
6900 fn a_range_carries_both_ends_and_a_validated_number_need_not() {
6901 // The distinction the kind exists for, asserted rather than only
6902 // written down: bounds are a rule for one and the control itself for
6903 // the other.
6904 let threshold = Field::range("review", "Review above", "0", "1");
6905 assert_eq!(threshold.kind, FieldKind::Range);
6906 assert!(threshold.bounded());
6907 assert_eq!(threshold.min, Some("0"));
6908 assert_eq!(threshold.max, Some("1"));
6909 // Granularity is the host's until an app says otherwise.
6910 assert_eq!(threshold.step, None);
6911
6912 // goingson's duration: a typed number with a floor, and it must not
6913 // read as a slider.
6914 let minutes = Field {
6915 min: Some("1"),
6916 ..Field::new(FieldKind::Number, "minutes", "Minutes")
6917 };
6918 assert_ne!(minutes.kind, FieldKind::Range);
6919 assert!(!minutes.bounded(), "one end is a rule, not an extent");
6920 }
6921
6922 #[test]
6923 fn a_range_described_with_one_end_says_so_rather_than_being_refused() {
6924 // Nothing here enforces the pair, for the reason nothing here enforces
6925 // `required`: the description states the constraint and the renderer
6926 // asks. What it must not do is look bounded.
6927 let half = Field {
6928 max: Some("1"),
6929 ..Field::new(FieldKind::Range, "review", "Review above")
6930 };
6931 assert!(!half.bounded());
6932 }
6933
6934 #[test]
6935 fn exactly_the_option_taking_kinds_say_so() {
6936 // The renderers branch on this rather than on a list of their own, so
6937 // a kind added without a decision here renders its options nowhere.
6938 assert!(FieldKind::Select.offers_options());
6939 assert!(FieldKind::Radio.offers_options());
6940 for kind in [
6941 FieldKind::Text,
6942 FieldKind::Secret,
6943 FieldKind::Number,
6944 FieldKind::Email,
6945 FieldKind::Url,
6946 FieldKind::Tel,
6947 FieldKind::Range,
6948 FieldKind::Textarea,
6949 FieldKind::Rich,
6950 FieldKind::Checkbox,
6951 FieldKind::Hidden,
6952 ] {
6953 assert!(!kind.offers_options(), "{kind:?} does not offer options");
6954 }
6955 }
6956
6957 #[test]
6958 fn a_radio_group_takes_a_label_even_though_its_options_carry_their_own() {
6959 // The near-miss: each option is labelled beside its own button, so a
6960 // renderer could plausibly read the group as self-labelling and drop
6961 // the question. Checkbox is the only kind that does that.
6962 assert!(!FieldKind::Radio.labels_itself());
6963 assert!(FieldKind::Checkbox.labels_itself());
6964 }
6965
6966 #[test]
6967 fn a_select_with_no_options_is_sayable() {
6968 // An app whose option list has not loaded has exactly this. Making it
6969 // unrepresentable would push the state somewhere less visible, and a
6970 // renderer drawing an empty select reports it on screen.
6971 let loading = Field::select("project", "Project", &[]);
6972 assert!(loading.options.is_empty());
6973 }
6974
6975 #[test]
6976 fn the_description_carries_the_question_and_never_the_answer() {
6977 // The line 0.8.0 drew. Placeholder and options are properties of what
6978 // is being asked; the current value is what came back, and no field
6979 // here holds one.
6980 let f = Field {
6981 placeholder: Some("yyyy-mm-dd"),
6982 ..Field::new(FieldKind::Text, "due", "Due")
6983 };
6984 assert_eq!(f.placeholder, Some("yyyy-mm-dd"));
6985 // A placeholder is not a label, and having one does not excuse the
6986 // field from carrying the other.
6987 assert_eq!(f.label, "Due");
6988 }
6989
6990 #[test]
6991 fn a_field_reports_its_own_error_state() {
6992 let mut f = Field::new(FieldKind::Text, "title", "Title");
6993 assert!(!f.invalid());
6994 f.error = Some("Required");
6995 assert!(f.invalid());
6996 }
6997
6998 #[test]
6999 fn columns_drop_by_priority_and_never_by_position() {
7000 let cols = [
7001 Column {
7002 width: Width::Fill,
7003 priority: Priority::Essential,
7004 ..Column::new("Title")
7005 },
7006 Column {
7007 width: Width::Fixed,
7008 priority: Priority::Secondary,
7009 ..Column::new("Due")
7010 },
7011 Column {
7012 width: Width::Fixed,
7013 priority: Priority::Optional,
7014 ..Column::new("Estimate")
7015 },
7016 ];
7017
7018 // Widest: everything survives.
7019 assert_eq!(
7020 cols.iter()
7021 .filter(|c| c.kept_at(Priority::Optional))
7022 .count(),
7023 3
7024 );
7025 // Narrower: the optional column goes first.
7026 let kept: Vec<_> = cols
7027 .iter()
7028 .filter(|c| c.kept_at(Priority::Secondary))
7029 .map(|c| c.name)
7030 .collect();
7031 assert_eq!(kept, ["Title", "Due"]);
7032 // Narrowest: only what identifies the row.
7033 let kept: Vec<_> = cols
7034 .iter()
7035 .filter(|c| c.kept_at(Priority::Essential))
7036 .map(|c| c.name)
7037 .collect();
7038 assert_eq!(kept, ["Title"]);
7039 }
7040
7041 #[test]
7042 fn inserting_a_column_does_not_move_what_gets_dropped() {
7043 // The bug the ordinal form has and this form cannot: goingson hides
7044 // `nth-child(n+5)` against a seven-column table, so a column inserted
7045 // anywhere to the left silently hides a different one.
7046 let before = [
7047 Column::new("Title"),
7048 Column {
7049 width: Width::Fixed,
7050 priority: Priority::Optional,
7051 ..Column::new("Estimate")
7052 },
7053 ];
7054 let after = [
7055 Column::new("Title"),
7056 Column::new("Project"), // inserted
7057 Column {
7058 width: Width::Fixed,
7059 priority: Priority::Optional,
7060 ..Column::new("Estimate")
7061 },
7062 ];
7063
7064 fn dropped<'a>(cols: &[Column<'a>]) -> Vec<&'a str> {
7065 cols.iter()
7066 .filter(|c| !c.kept_at(Priority::Secondary))
7067 .map(|c| c.name)
7068 .collect()
7069 }
7070 assert_eq!(dropped(&before), ["Estimate"]);
7071 assert_eq!(dropped(&after), ["Estimate"]);
7072 }
7073
7074 #[test]
7075 fn an_arrangement_carries_the_tab_group_as_a_modifier() {
7076 // goingson uses the tab group inside the content region rather than
7077 // instead of one, so it is not a third arrangement.
7078 let go = Arrangement::list_detail(true);
7079 let plain = Arrangement::list_detail(false);
7080 assert_ne!(go, plain);
7081 assert_ne!(go, Arrangement::sidebar_content());
7082 }
7083
7084 #[test]
7085 fn a_share_is_a_proportion_and_resolves_the_same_way_everywhere() {
7086 // The point of the member: a terminal reading columns and a webview
7087 // reading a grid honour one fact, so two hosts showing one screen agree
7088 // about its proportions.
7089 assert_eq!(Share::LIST.as_percent(), 40);
7090 assert_eq!(Share::LIST.of(100), 40);
7091 assert_eq!(
7092 Share::SIDEBAR.of(96),
7093 24,
7094 "quasi-tui's 24 columns, said as a quarter"
7095 );
7096 }
7097
7098 #[test]
7099 fn a_region_never_resolves_to_nothing() {
7100 // A region the description named should be visible. A zero-width one
7101 // reads on screen as a region that vanished, which is the hardest kind
7102 // of bug to find from what is drawn.
7103 assert_eq!(Share::percent(5).of(1), 1);
7104 assert_eq!(Share::percent(5).of(0), 1);
7105 }
7106
7107 #[test]
7108 fn a_share_outside_the_range_is_clamped_rather_than_refused() {
7109 assert_eq!(Share::percent(0), Share::percent(5));
7110 assert_eq!(Share::percent(200), Share::percent(95));
7111 }
7112
7113 #[test]
7114 fn the_share_rides_on_the_arrangement_that_knows_which_question_it_is() {
7115 // How much a sidebar takes and how much a list side takes are different
7116 // questions, and this enum is the only thing that knows which is being
7117 // asked.
7118 assert_eq!(Arrangement::sidebar_content().share(), Share::SIDEBAR);
7119 assert_eq!(Arrangement::list_detail(false).share(), Share::LIST);
7120
7121 let narrow = Arrangement::sidebar_content().with_share(Share::percent(20));
7122 assert_eq!(narrow.share(), Share::percent(20));
7123 assert!(matches!(narrow, Arrangement::SidebarContent { .. }));
7124 }
7125
7126 #[test]
7127 fn a_measure_defaults_to_the_one_53_of_69_templates_asked_for() {
7128 // The default is meaningful: a screen nobody said anything about uses
7129 // the window it was given.
7130 assert_eq!(Measure::default(), Measure::Wide);
7131 assert_eq!(Measure::Reading.as_str(), "reading");
7132 }
7133
7134 #[test]
7135 fn readiness_names_the_state_and_not_the_shimmer() {
7136 // Two members and no third. If a skeleton ever appears in this enum,
7137 // the deferral rule has been broken.
7138 assert_ne!(Readiness::Ready, Readiness::Pending);
7139 }
7140
7141 #[test]
7142 fn a_window_with_no_length_still_answers_what_it_can() {
7143 // The uncounted case is the common one, not the degenerate one: a query
7144 // that asked for 51 to learn there were more than 50 knows there are,
7145 // and not how many.
7146 let uncounted = Window::new(100, 50);
7147 assert_eq!(uncounted.index(), Some(2));
7148 assert_eq!(uncounted.windows(), None);
7149 assert!(uncounted.has_before());
7150 // Unknown length cannot rule out more, and offering a way forward that
7151 // turns out empty is the cheaper mistake.
7152 assert!(uncounted.has_after());
7153 }
7154
7155 #[test]
7156 fn a_counted_window_knows_where_it_ends() {
7157 let last = Window::new(350, 50).of(400);
7158 assert_eq!(last.index(), Some(7));
7159 assert_eq!(last.windows(), Some(8));
7160 assert!(last.has_before());
7161 assert!(!last.has_after());
7162
7163 let first = Window::new(0, 50).of(400);
7164 assert!(!first.has_before());
7165 assert!(first.has_after());
7166 }
7167
7168 #[test]
7169 fn a_window_that_does_not_divide_evenly_rounds_up() {
7170 // 401 rows in pages of 50 is eight pages and a straggler, which is nine
7171 // pages. Rounding down would make the last one unreachable.
7172 assert_eq!(Window::new(0, 50).of(401).windows(), Some(9));
7173 }
7174
7175 #[test]
7176 fn a_zero_count_answers_none_rather_than_dividing() {
7177 let empty = Window::new(0, 0).of(400);
7178 assert_eq!(empty.index(), None);
7179 assert_eq!(empty.windows(), None);
7180 // And it still clamps rather than panicking.
7181 assert_eq!(Window::new(900, 0).of(400).clamped().from, 399);
7182 }
7183
7184 #[test]
7185 fn a_window_past_the_end_clamps_inside_rather_than_vanishing() {
7186 // `Slot::current`'s reasoning, one layer down: a description pointing
7187 // past the end is a host bug, and answering it by drawing nothing
7188 // reports a region that vanished.
7189 assert_eq!(Window::new(900, 50).of(400).clamped().from, 350);
7190 // Nothing to clamp against when the length is unknown.
7191 assert_eq!(Window::new(900, 50).clamped().from, 900);
7192 }
7193
7194 #[test]
7195 fn a_carousel_frame_is_a_window_of_one() {
7196 // The shape a carousel instantiates. Same code as a paged list, which is
7197 // the whole reason `Window` exists rather than two copies of it.
7198 let third = Window::frame(2, 5);
7199 assert_eq!(third.index(), Some(2));
7200 assert_eq!(third.windows(), Some(5));
7201 assert!(third.has_before());
7202 assert!(third.has_after());
7203
7204 let last = Window::frame(4, 5);
7205 assert!(!last.has_after());
7206 }
7207
7208 #[test]
7209 fn numbered_pages_read_from_one_and_load_more_has_no_page() {
7210 // The page number is read aloud, so it is one-based; `Window::index` is
7211 // the zero-based form for indexing.
7212 let third = Paging::pages(100, 50).of(400);
7213 assert_eq!(third.page(), Some(3));
7214 assert_eq!(third.pages_total(), Some(8));
7215 assert_eq!(third.total(), Some(400));
7216 assert!(third.has_previous());
7217 assert!(third.has_more());
7218
7219 // Load-more grew a window from the start, so "page 2" would name
7220 // nothing and the type says so rather than inventing one.
7221 let grown = Paging::more(150).of(400);
7222 assert_eq!(grown.page(), None);
7223 assert_eq!(grown.pages_total(), None);
7224 assert_eq!(grown.shown(), 150);
7225 assert!(!grown.has_previous());
7226 assert!(grown.has_more());
7227 }
7228
7229 #[test]
7230 fn an_uncounted_paging_offers_forward_and_admits_no_total() {
7231 // What a host that will not pay for a COUNT describes. `None` here is
7232 // permanent: a total arriving later would widen the text that prints it,
7233 // which is the reflow "first paint is final paint" forbids.
7234 let feed = Paging::more(50);
7235 assert_eq!(feed.total(), None);
7236 assert_eq!(feed.pages_total(), None);
7237 assert_eq!(feed.remaining(), None);
7238 assert!(feed.has_more());
7239 }
7240
7241 #[test]
7242 fn what_is_left_is_derived_and_never_underflows() {
7243 assert_eq!(Paging::more(150).of(400).remaining(), Some(250));
7244 assert_eq!(Paging::pages(350, 50).of(400).remaining(), Some(0));
7245 // A host that overshot its own total gets zero rather than a wrapped
7246 // usize, which would print as "18446744073709551516 remaining".
7247 assert_eq!(Paging::more(500).of(400).remaining(), Some(0));
7248 }
7249
7250 #[test]
7251 fn a_group_out_of_room_is_not_the_same_fact_as_a_narrow_window() {
7252 // The case the type exists for: 913px is a roomy window holding a group
7253 // that has run out of room, so room is measured against the group's own
7254 // allocation and never against the viewport.
7255 assert!(Room::Tight < Room::Ample);
7256 // A group nesting another has whichever room is scarcer, which is what
7257 // makes relief resolve inside-out rather than by declaration order.
7258 assert_eq!(Room::Ample.min(Room::Tight), Room::Tight);
7259 }
7260
7261 #[test]
7262 fn a_fallback_is_authored_and_a_group_cannot_omit_it() {
7263 // No `Default`. The compiler is what enforces rule 2, so the assertion
7264 // that matters is one this file cannot write; what it can say is that
7265 // the four authored answers are distinct and none is privileged.
7266 let all = [
7267 Fallback::Wrap,
7268 Fallback::Stack,
7269 Fallback::Shed,
7270 Fallback::Menu,
7271 ];
7272 for (i, a) in all.iter().enumerate() {
7273 for b in &all[i + 1..] {
7274 assert_ne!(a, b);
7275 }
7276 }
7277 }
7278
7279 #[test]
7280 fn shedding_stops_at_essential_whatever_the_group_holds() {
7281 // Priority is read the same way for a group member as for a column,
7282 // which is the whole claim of generalising it off `Column`.
7283 let members = [
7284 ("tabs", Priority::Essential),
7285 ("search", Priority::Secondary),
7286 ("count", Priority::Optional),
7287 ];
7288 let kept: Vec<_> = members
7289 .iter()
7290 .filter(|(_, p)| *p >= Priority::Essential)
7291 .map(|(n, _)| *n)
7292 .collect();
7293 assert_eq!(kept, ["tabs"]);
7294 }
7295
7296 #[test]
7297 fn a_role_says_what_a_part_is_worth_when_the_run_does_not_fit() {
7298 // The row still identifies itself after everything droppable has gone,
7299 // which is the property the ladder exists for.
7300 assert_eq!(RowPart::Primary.priority(), Priority::Essential);
7301 // A control is not a fact. Room comes out of what the row says, never
7302 // out of what it offers.
7303 assert_eq!(RowPart::Actions.priority(), Priority::Essential);
7304 assert_eq!(RowPart::Meta.priority(), Priority::Optional);
7305 assert_eq!(RowPart::Proportion.priority(), Priority::Optional);
7306 assert_eq!(RowPart::Secondary.priority(), Priority::Secondary);
7307 // Tokens sit in the middle deliberately: a toned badge is often the
7308 // most scannable thing in a row, so it does not go first.
7309 assert_eq!(RowPart::Tokens.priority(), Priority::Secondary);
7310 }
7311
7312 #[test]
7313 fn a_run_is_one_line_unless_the_description_says_two() {
7314 // The default is what every part did before flows existed, so a
7315 // description written against the old vocabulary keeps its rendering.
7316 assert_eq!(Flow::default(), Flow::Tight);
7317 assert_eq!(Flow::Tight.lines(), 1);
7318 assert_eq!(Flow::Relaxed.lines(), 2);
7319 }
7320
7321 #[test]
7322 fn an_unknown_flow_reads_as_one_line() {
7323 // `#[non_exhaustive]`'s cost, taken deliberately. A tier added upstream
7324 // reaches an old renderer as one line rather than as a build break, and
7325 // one line is the reading that cannot break a neighbour's layout. The
7326 // match in `lines` is what this holds; it fails if a new tier is given
7327 // an arm that returns something unbounded.
7328 for flow in [Flow::Tight, Flow::Relaxed] {
7329 assert!((1..=2).contains(&flow.lines()));
7330 }
7331 }
7332
7333 #[test]
7334 fn an_awaiting_mark_is_indeterminate_until_something_is_measured() {
7335 // The default is the common case: a call waits, and nothing about it is
7336 // countable. A determinate bar is the exception and says so.
7337 assert_eq!(Awaiting::default(), Awaiting::unmeasured());
7338 assert!(!Awaiting::unmeasured().is_determinate());
7339 assert!(Awaiting::of(40 * 1024 * 1024).is_determinate());
7340 assert_eq!(Awaiting::of(7).amount, Some(7));
7341 }
7342
7343 // A slider is a fraction and a mapping
7344 //
7345 // `Curve` is the one thing in this crate that computes rather than
7346 // describes, and it does so because four renderers would otherwise each
7347 // write these two formulas and drift. So the formulas are pinned here.
7348
7349 /// The bounds of audiofiles' envelope attack, the curve's first consumer.
7350 const ATTACK: (f64, f64) = (0.001, 5.0);
7351
7352 #[test]
7353 fn a_curve_is_linear_with_no_step_until_a_field_says_otherwise() {
7354 assert_eq!(Curve::default(), Curve::Linear { step: None });
7355 let plain = Field::range("t", "T", "0", "1");
7356 assert_eq!(plain.curve, Curve::Linear { step: None });
7357 assert_eq!(plain.curve.step(), None);
7358 }
7359
7360 #[test]
7361 fn every_curve_carries_its_own_granularity() {
7362 assert_eq!(Curve::Linear { step: Some("0.01") }.step(), Some("0.01"));
7363 assert_eq!(
7364 Curve::Logarithmic {
7365 step: Some("0.001")
7366 }
7367 .step(),
7368 Some("0.001")
7369 );
7370 }
7371
7372 #[test]
7373 fn both_ends_of_the_track_are_the_bounds_under_either_curve() {
7374 // `min` and `max` are `f(0)` and `f(1)`. That is the whole reframe, and
7375 // it has to hold for a mapping that is not the identity or the bounds
7376 // have stopped meaning what the field says they mean.
7377 let (min, max) = ATTACK;
7378 for curve in [
7379 Curve::Linear { step: None },
7380 Curve::Logarithmic { step: None },
7381 ] {
7382 assert!((curve.value_at(0.0, min, max) - min).abs() < 1e-12);
7383 assert!((curve.value_at(1.0, min, max) - max).abs() < 1e-12);
7384 }
7385 }
7386
7387 #[test]
7388 fn a_linear_midpoint_is_the_average_and_a_ratio_midpoint_is_the_geometric_mean() {
7389 let (min, max) = ATTACK;
7390 let linear = Curve::Linear { step: None }.value_at(0.5, min, max);
7391 assert!((linear - 2.5005).abs() < 1e-9);
7392
7393 // The reason the envelope is not linear: half way along a log track is
7394 // 70 ms, and half way along a linear one is 2.5 seconds. Every attack a
7395 // sampler is actually played with lives below the first.
7396 let ratio = Curve::Logarithmic { step: None }.value_at(0.5, min, max);
7397 assert!((ratio - (min * max).sqrt()).abs() < 1e-12);
7398 assert!(ratio < 0.08);
7399 }
7400
7401 #[test]
7402 fn a_position_and_a_value_round_trip_under_either_curve() {
7403 let (min, max) = ATTACK;
7404 for curve in [
7405 Curve::Linear { step: None },
7406 Curve::Logarithmic { step: None },
7407 ] {
7408 for position in [0.0, 0.1, 0.25, 0.5, 0.75, 0.99, 1.0] {
7409 let back = curve.position_of(curve.value_at(position, min, max), min, max);
7410 assert!(
7411 (back - position).abs() < 1e-9,
7412 "{curve:?} lost {position} (got {back})"
7413 );
7414 }
7415 }
7416 }
7417
7418 #[test]
7419 fn a_ratio_curve_across_zero_is_drawn_linearly_rather_than_refused() {
7420 // An envelope's sustain is a 0-to-1 level. A constant ratio is
7421 // undefined there, and the answer is the linear mapping rather than a
7422 // NaN reaching a renderer that would paint it.
7423 let curve = Curve::Logarithmic { step: None };
7424 assert!(!curve.is_ratio(0.0, 1.0));
7425 assert!((curve.value_at(0.5, 0.0, 1.0) - 0.5).abs() < 1e-12);
7426 assert!(curve.value_at(0.5, -96.0, -20.0).is_finite());
7427 assert!(curve.is_ratio(ATTACK.0, ATTACK.1));
7428 }
7429
7430 #[test]
7431 fn a_track_with_no_extent_has_one_value_on_it() {
7432 for curve in [
7433 Curve::Linear { step: None },
7434 Curve::Logarithmic { step: None },
7435 ] {
7436 assert!((curve.value_at(0.7, 4.0, 4.0) - 4.0).abs() < f64::EPSILON);
7437 assert!(curve.position_of(4.0, 4.0, 4.0).abs() < f64::EPSILON);
7438 // Inverted bounds are the same degenerate answer, not a negative
7439 // extent a renderer would draw backwards.
7440 assert!((curve.value_at(0.7, 9.0, 2.0) - 9.0).abs() < f64::EPSILON);
7441 }
7442 }
7443
7444 #[test]
7445 fn a_position_or_a_value_outside_the_track_is_clamped_to_it() {
7446 let (min, max) = ATTACK;
7447 let curve = Curve::Logarithmic { step: None };
7448 assert!((curve.value_at(-3.0, min, max) - min).abs() < 1e-12);
7449 assert!((curve.value_at(4.0, min, max) - max).abs() < 1e-12);
7450 assert!(curve.position_of(0.0, min, max).abs() < 1e-12);
7451 assert!((curve.position_of(500.0, min, max) - 1.0).abs() < 1e-12);
7452 }
7453
7454 #[test]
7455 fn a_typed_number_keeps_its_own_step_and_a_range_reads_its_curve() {
7456 // The split the 0.32.0 narrowing is: two granularities that were one
7457 // member, and the kinds that take them do not overlap.
7458 let typed = Field {
7459 step: Some("5"),
7460 ..Field::new(FieldKind::Number, "port", "Port")
7461 };
7462 assert_eq!(typed.step, Some("5"));
7463
7464 let slid = Field {
7465 curve: Curve::Logarithmic {
7466 step: Some("0.001"),
7467 },
7468 ..Field::range("attack", "Attack", "0.001", "5")
7469 };
7470 assert_eq!(slid.step, None);
7471 assert_eq!(slid.curve.step(), Some("0.001"));
7472 }
7473
7474 #[test]
7475 fn a_theme_picker_offers_themes_and_no_options() {
7476 // The substitution hazard the constructor exists against: `options` is
7477 // right there and reads as if it would work, and a renderer walking it
7478 // for a theme picker draws an empty control.
7479 let themes = [
7480 ThemeChoice::new("goingson", "GoingsOn", ThemeVariant::Light, Contrast::High),
7481 ThemeChoice::new("dracula", "Dracula", ThemeVariant::Dark, Contrast::Standard),
7482 ];
7483 let field = Field::theme("theme", "Theme", &themes);
7484
7485 assert_eq!(field.kind, FieldKind::Theme);
7486 assert!(field.kind.offers_themes());
7487 assert!(!field.kind.offers_options());
7488 assert_eq!(field.themes.len(), 2);
7489 assert!(field.options.is_empty());
7490 assert_eq!(field.follows, None);
7491 }
7492
7493 #[test]
7494 fn following_carries_the_store_s_own_spelling() {
7495 // Not hardcoded here: the value belongs to the app's config table, and
7496 // this crate holds no facts about somebody else's store.
7497 let field =
7498 Field::theme("theme", "Theme", &[]).following(Choice::new("system", "Follow System"));
7499 let follow = field.follows.expect("the row was offered");
7500 assert_eq!(follow.value, "system");
7501 assert_eq!(follow.label, "Follow System");
7502 }
7503
7504 #[test]
7505 fn a_picker_with_nothing_resolved_is_sayable() {
7506 // A machine whose theme directories hold nothing. The description is
7507 // true and a renderer says so on screen rather than in a log, which is
7508 // `Field::options`' own arrangement.
7509 let field = Field::theme("theme", "Theme", &[]);
7510 assert!(field.themes.is_empty());
7511 }
7512
7513 #[test]
7514 fn every_kind_but_theme_offers_no_themes() {
7515 for kind in [
7516 FieldKind::Text,
7517 FieldKind::Select,
7518 FieldKind::Radio,
7519 FieldKind::Checkbox,
7520 FieldKind::File,
7521 FieldKind::Hidden,
7522 ] {
7523 assert!(
7524 !kind.offers_themes(),
7525 "{kind:?} does not read Field::themes"
7526 );
7527 }
7528 }
7529
7530 #[test]
7531 fn a_contrast_tier_reads_worst_first() {
7532 // Matches `makeover::ContrastTier`, so an adopter's conversion cannot
7533 // invert an ordering by accident and a sort agrees across the seam.
7534 assert!(Contrast::Low < Contrast::Standard);
7535 assert!(Contrast::Standard < Contrast::High);
7536 }
7537
7538 #[test]
7539 fn the_groups_and_badges_have_one_spelling_each() {
7540 // The whole argument for these living here: three renderers picking
7541 // their own is one picker reading three ways.
7542 assert_eq!(ThemeVariant::Light.heading(), "Light");
7543 assert_eq!(ThemeVariant::Dark.heading(), "Dark");
7544 assert_eq!(ThemeVariant::HighContrast.heading(), "High Contrast");
7545
7546 assert_eq!(ThemeVariant::HighContrast.as_str(), "high-contrast");
7547
7548 assert_eq!(Contrast::High.badge(), "AA");
7549 assert_eq!(Contrast::Standard.badge(), "OK");
7550 assert_eq!(Contrast::Low.badge(), "low");
7551 }
7552
7553 #[test]
7554 fn the_variant_spelling_matches_the_theme_file_s_own() {
7555 // The seam this enum is duplicated across. `makeover::parse_meta` reads
7556 // `meta.variant` as one of these three strings; a rename on either side
7557 // that does not move together silently regroups every picker.
7558 for (variant, spelling) in [
7559 (ThemeVariant::Light, "light"),
7560 (ThemeVariant::Dark, "dark"),
7561 (ThemeVariant::HighContrast, "high-contrast"),
7562 ] {
7563 assert_eq!(variant.as_str(), spelling);
7564 assert_eq!(variant.to_string(), spelling);
7565 }
7566 }
7567 }
7568