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1 //! The webview renderer for [`makeover_layout`].
2 //!
3 //! <!-- wiki: makeover-webview -->
4 //!
5 //! # The renderer that needs no palette
6 //!
7 //! `makeover-immediate` and `makeover-tui` both take a `Palette`, because egui
8 //! and a terminal need an actual colour before they can put anything on
9 //! screen. A webview does not: `var(--surface-raised)` *is* the late binding,
10 //! and the browser resolves it against whatever `themes.js` last wrote onto
11 //! `:root`.
12 //!
13 //! So this crate emits text naming intents, and never learns a colour. It is
14 //! the deferral rule with no adapter in the way, and it is why the webview was
15 //! always the wrong renderer to derive a vocabulary from: it can express
16 //! anything, so it never pushes back.
17 //!
18 //! # Phase A: the stylesheet
19 //!
20 //! This module emits component CSS and no markup, deliberately. GoingsOn has
21 //! 145 `innerHTML` sites and Balanced Breakfast 175 `createElement` sites, so
22 //! moving markup is a migration where adopting a generated stylesheet is not.
23 //! The apps keep every line of their markup and gain the classes.
24 //!
25 //! It is not a deletion either, which this header claimed until the measurement
26 //! came in. Adoption across goingson removed 49 declarations net and *added* 25
27 //! lines: a rule loses its depth declarations and gains a variant selector next
28 //! to it, so the file stays the same size. What phase A moves is where depth is
29 //! defined, not how much CSS exists. Numbers and method in the wiki note under
30 //! "The deletion test, run".
31 //!
32 //! The bevel properties are byte-identical to what both apps already
33 //! hand-write, which is asserted below.
34 //!
35 //! Some of what phase A emits is not a look but the withdrawal of one. A
36 //! renderer that picks its element from the description inherits that element's
37 //! user-agent chrome, and [`reset`] is where a primitive says which parts of it
38 //! were never asked for.
39 //!
40 //! # Phase B: the markup, one description at a time
41 //!
42 //! [`form`] renders [`makeover_layout::Field`], which is the half of phase B
43 //! whose description is settled. It emits strings, because both apps
44 //! interpolate their fields into larger string-built forms and returning nodes
45 //! would rewrite those too. It owns its own escaping, on the reasoning in that
46 //! module: a Rust encoder can cover element text and attribute values with one
47 //! function, where the apps need four and have to choose correctly at every
48 //! call site.
49 //!
50 //! [`facet`] renders `makeover_layout::Facet`: a dimension a set is narrowed by,
51 //! and the one phase-B emitter whose markup an app is not keeping, because the
52 //! markup it replaces was two mechanisms rather than one. A tag's selection and
53 //! a tag's browse position were separate state on MNW's discover page, which is
54 //! why every filter row there carries a tick box *and* a chevron; one gesture
55 //! doing both is what lets the second one go.
56 //!
57 //! [`list`] is the other half: column tracks, the narrowing rules, and the cell
58 //! containers a row is made of. It stops at the cell boundary and does not
59 //! render what goes inside one, on the reasoning in that module. So phase B is
60 //! now the frame around content in both directions, and what an app still owns
61 //! is the content itself.
62 //!
63 //! # What phase A settled, and what it costs
64 //!
65 //! Measured against goingson's `styles.css` rather than against a component
66 //! list: `.btn`, `.card` and `.tag, .badge` each hand-write the same
67 //! composition, so three quarters of phase A is one rule with several names.
68 //!
69 //! Two of the four decisions change how goingson looks, and adoption should
70 //! not be described as a pure deletion:
71 //!
72 //! - **Pressed carries its fill.** [`interactive_rules`] emits
73 //! [`Depth::pressed`] whole. goingson presses to `--surface-sunken` today and
74 //! will press to `--surface-well`, and hovers to `--surface-overlay` today
75 //! and will hover to `--hover-surface`. Since `surface-well` inverts by theme
76 //! where `surface-sunken` does not, a dark theme presses *lighter* than it
77 //! hovers. That falls out of `makeover`'s own derivation, which says outright
78 //! that `surface-sunken` cannot serve as a well, so if it reads wrong the
79 //! answer is there and not here.
80 //! - **Badges go flat.** See [`token_rules`].
81 //!
82 //! The other two: the progress trough is renderer-local and the scrollbar
83 //! track was dropped ([`component_rules`]), and no class prefix ships by
84 //! default, so adoption means deleting the app's hand-written rule in the same
85 //! commit that adds the generated one. `.card`, `.badge` and the tab classes
86 //! all already exist in goingson, and while both rules exist the cascade order
87 //! decides which wins. That is the one real risk in adopting this, and it is
88 //! why the migration lands per component rather than in one commit.
89 //!
90 //! # Interaction states
91 //!
92 //! [`interactive_rules`] emits four states, in emission order, and the order is
93 //! load-bearing: they are all specificity (0,2,0), so disabled beats hover by
94 //! coming last and by nothing else. Nothing here reaches for `:not(:disabled)`,
95 //! which would raise a selector this crate wraps in its own layer.
96 //!
97 //! Emitting the states here is what keeps an app from completing the primitive
98 //! from outside, by out-specifying a rule it does not own. Those overrides are
99 //! also what breaks under cascade layers: an app that declares `@layer` puts
100 //! its own rules in a named layer, and unlayered declarations outrank every
101 //! named layer regardless of specificity.
102 //!
103 //! Hover sits inside a capability query. `makeover-touch` answers whether a
104 //! fingertip has hover and `makeover-geometry` spells the condition; this crate
105 //! asks and does not decide, so no app has to take the hover state back on
106 //! touch.
107 //!
108 //! # The layer contract
109 //!
110 //! [`stylesheet`] emits into the `makeover` cascade layer ([`CSS_LAYER`], which
111 //! lives in `makeover-geometry` because that is the one crate every CSS emitter
112 //! in the family already depends on). `makeover-geometry` does the same for
113 //! `geometry.css`.
114 //!
115 //! The cascade resolves origin and importance, then layer, then specificity,
116 //! then source order, and **unlayered normal declarations outrank every named
117 //! layer**. An unlayered generated file therefore beats every rule an app owns,
118 //! regardless of specificity and regardless of loading last. Nothing errors when
119 //! that happens: the CSS is valid, the minifier is happy, and buttons and badges
120 //! look subtly wrong. The layer belongs here rather than in each app, because an
121 //! app cannot fix it from its own stylesheet: the fix is to layer the file it
122 //! does not own.
123 //!
124 //! An app should declare the order once, or the layer's position is decided by
125 //! whichever generated file the browser happens to see first:
126 //!
127 //! ```css
128 //! @layer makeover, base, components, responsive;
129 //! ```
130 //!
131 //! [`in_css_layer`] is re-exported for an app that assembles its own stylesheet
132 //! from this crate's pieces. Rules an app generates from
133 //! [`list::narrowing_css`] and [`list::grid_template_columns`] are as generated
134 //! as the ones here, so they belong in the same layer and this crate cannot put
135 //! them there on the app's behalf.
136 //!
137 //! # Suggestions
138 //!
139 //! `Outcome::Suggestions` carries `Candidate` rather than `Choice`, and a
140 //! candidate has no `unavailable`: a suggestion that cannot be picked is a row
141 //! a route should not have offered. What it has instead is a `detail`, the line
142 //! that tells it from a row reading the same, and it is drawn in
143 //! `--content-muted` rather than in the disabled token. A detail orients rather
144 //! than refuses, and every other secondary line in this crate reads the same
145 //! way. The class is `.form-suggestion-detail`.
146 //!
147 //! # An interval is one question with two ends
148 //!
149 //! [`makeover_layout::FieldKind::Interval`] emits a `role="group"` named by the
150 //! field's label, holding one `<input type="number">` per end.
151 //!
152 //! - **The group carries the error and the descriptions**, on the split
153 //! [`makeover_layout::FieldKind::Radio`] already uses here: what is wrong is
154 //! the answer, and a crossed interval is not the fault of either end.
155 //! - **Both boxes take the whole extent.** `min`, `max` and `step` describe the
156 //! axis, so they are written twice. The crossing rule is not emitted, because
157 //! HTML has no attribute for it and the description does not carry it: it
158 //! comes back as an error on the group, like every other refusal.
159 //! - **Which end is which is `aria-label` and nothing more.** The description
160 //! states direction structurally, by which member holds which name, and never
161 //! in words. Visible Min and Max captions are a page's own and reach the
162 //! group through [`form::Filling::trailing`].
163 //!
164 //! [`form::Value::Between`] is the second value. A separator inside one string
165 //! would make this crate the owner of a delimiter that either end could contain.
166 //!
167 //! # A number's unit is adjacent text
168 //!
169 //! HTML has no unit attribute and inventing one would be markup nothing reads,
170 //! so `Field::unit` is a `<span>` after the control. It is named in
171 //! `aria-describedby` rather than left as decoration, because a number and what
172 //! it is measured in are one fact and reading the first without the second is
173 //! reading it wrong. What that buys is a unit a consumer can read back rather
174 //! than a suffix on a label it would have to parse.
175 //!
176 //! # A curve this renderer can carry, and one it declines
177 //!
178 //! A range takes its granularity from the curve (`Field::curve.step()`), every
179 //! other kind keeps `Field::step`, and `Curve::Linear` emits a plain range.
180 //!
181 //! **A constant-ratio curve emits a linear track, and that is the answer, not a
182 //! debt.** HTML has no logarithmic range input, so a described screen asking
183 //! for one is asking the browser for something it does not have, the same class
184 //! of request as [`makeover_layout::FieldKind::Date`] on a host with no
185 //! calendar. The renderer answers with the nearest control the host really
186 //! offers and keeps every fact that survives the translation: the extent, the
187 //! granularity, and the value's own units. What does not survive is resolution
188 //! at the small end. The value submitted is still a value in the field's own
189 //! units, which is what every handler on this path reads.
190 //!
191 //! The alternatives are worse in the specific way this stack exists to avoid.
192 //! Shipping JS that maps thumb position to value puts app code back in the
193 //! renderer. Changing what the control submits from a value to a fraction moves
194 //! the mapping to whoever reads the form, and a server reading these forms with
195 //! its own handlers would take a fraction where a value is expected, silently.
196 //!
197 //! When this reopens: the day a described screen on the webview path asks for a
198 //! non-linear range. The answer then is mapping in `quasi-router`, where one
199 //! implementation serves every host, not JS here.
200 //!
201 //! # A markdown field gets a preview
202 //!
203 //! A [`makeover_layout::FieldKind::Rich`] field is marked
204 //! `data-format="markdown"`, and [`form::editor_rules`] is what spends that
205 //! mark. The Write/Preview pair is a segmented control, so it takes the depth,
206 //! the focus ring and the chosen state from rules that already exist; the
207 //! preview pane is a well, because it stands where the control stood. Both are
208 //! gated on the attribute rather than on a class, which is what the attribute is
209 //! for. A permission taken and not spent turns every conversion into a
210 //! regression.
211 //!
212 //! **This crate renders no markdown.** The pane arrives empty and is filled by
213 //! whatever binds the editor, which is where the host's sanitiser already is. A
214 //! converter here would move that guarantee into a crate with no view of the
215 //! host's content-security posture.
216 //!
217 //! # Ranges, ghost text, and an option that cannot be picked
218 //!
219 //! - `FieldKind::Range` emits `<input type="range">`, and `Field::step` emits
220 //! `step`. The step is emitted only when the description carries one: the
221 //! browser's own default is `step="1"`, which is what a description means by
222 //! saying nothing, and is also what turns a 0-to-1 threshold into a
223 //! two-position control.
224 //! - A select with nothing chosen emits a disabled, selected, valueless first
225 //! option carrying `Field::placeholder`. HTML has no placeholder attribute on
226 //! `<select>`; this is the idiom, and `required` keeps working through it
227 //! because the option's value is empty.
228 //! - `Choice::unavailable` emits `disabled` plus the reason. Where it goes
229 //! differs by control and the difference is forced: a radio group gets a
230 //! `.form-option-reason` span beside the label, and a `<select>` option has
231 //! room for no element at all, so the reason runs into its text.
232 //! - `Choice::detail` takes the same split for the same reason: a
233 //! `.form-option-detail` span in a radio group, run into the text of a
234 //! `<select>`'s option. An option carrying both reads what it is before why it
235 //! cannot be picked.
236 //!
237 //! # A cell says what it holds
238 //!
239 //! [`CellPart`](makeover_layout::CellPart) names the four things a cell holds,
240 //! and [`table_rules`] turns them into `.cell-value`, `.cell-tokens`,
241 //! `.cell-actions` and `.cell-link`. Only the first takes a colour: a token
242 //! carries its own tone, an action is a control rather than text, and a link
243 //! takes the action colour from the anchor it is.
244 //!
245 //! The colour goes on `.cell-value` rather than on `.cell`. On the container it
246 //! cascades into the parts that are not text, and a control in a cell is painted
247 //! as text, which is the drift
248 //! [`RowPart::intent`](makeover_layout::RowPart) prevents for list rows.
249 //!
250 //! [`list::Cell::part`] is `Option<CellPart>` and never `Option<RowPart>`: the
251 //! two answer different questions, and only one of them is about a cell.
252 //!
253 //! # A table lays itself out
254 //!
255 //! [`list::narrowing_css`] emits the track list and has to be called with the
256 //! columns, so it works where the columns are known at build time. A table a
257 //! description produced knows its columns at render time, and the rules would
258 //! have to travel with the markup: a `<style>` element per table, which needs
259 //! `style-src 'unsafe-inline'`, or the head, which an htmx fragment swap does
260 //! not carry. [`table_rules`] lays a table out with `display: table` instead,
261 //! which aligns columns across rows knowing nothing about how many there are.
262 //! [`Priority`](makeover_layout::Priority) hiding is one rule per drop class,
263 //! and [`list::column_classes`] is what puts those classes on a cell. **A header
264 //! row emitted by a renderer's own code has to call it too**, or the header and
265 //! the body disagree about which column just dropped.
266 //!
267 //! `.button` takes the four tones as colour, off `data-tone`, the way the badge
268 //! does, so a destructive button has somewhere for its tone to land. A list is
269 //! reset rather than left as a bulleted list.
270 //!
271 //! `RowPart::revealed_on_hover` is not honoured. Hiding a row's actions until
272 //! hover hides them from pointer users alone, who are the ones scanning a list
273 //! to learn what can be done to a row, and every escape the rule grows
274 //! (`focus-within` for the keyboard, a capability gate for a fingertip) is a
275 //! report that hiding was wrong for somebody.
276 //!
277 //! # The depth classes are not controls
278 //!
279 //! `.raised` is a statement about shape and carries no interactive set, so the
280 //! vocabulary has a raised surface that is merely an object. An app that wants
281 //! one does not have to take a control class and cancel the control half.
282 //!
283 //! `.card` and `.button` are the same depth *and* controls, and they take their
284 //! states from [`surface_rules`], which is where a state belongs: on the thing
285 //! that claims to answer a pointer.
286 //!
287 //! # Substitution, three ways
288 //!
289 //! A theme with no `surface-well` is answered differently by each renderer,
290 //! which is why substitution belongs to a renderer and not to the description:
291 //!
292 //! - `makeover-immediate` substitutes the page in Rust.
293 //! - `makeover-tui` refuses to substitute and draws an edge instead, because a
294 //! terminal would quantise the two together.
295 //! - here, CSS already has the mechanism: `var(--surface-well,
296 //! var(--surface-page))` falls back in the browser, and nothing in Rust
297 //! decides anything.
298
299 #![forbid(unsafe_code)]
300
301 pub mod facet;
302 pub mod figure;
303 pub mod form;
304 pub mod list;
305 pub mod meter;
306 pub mod placeholder;
307 pub mod reset;
308 pub mod vocabulary;
309
310 /// A render of every emitter, scraped for the classes it wrote.
311 ///
312 /// Test-only, and the guard behind [`vocabulary::names`]. See the module's own
313 /// header for why the check renders rather than reads the source.
314 #[cfg(test)]
315 mod corpus;
316
317 use crate::list::{cell_part_class, part_class};
318 use crate::reset::{Chrome, Reset};
319 use makeover_geometry::{Density, SizeClass};
320 // Re-exported rather than redefined. An app assembling its own stylesheet out
321 // of this crate's pieces needs the same layer name, and most such apps depend
322 // on this crate and not on `makeover-geometry` directly: goingson builds
323 // `tables.css` in its own build.rs from [`list::narrowing_css`], and those
324 // rules are as generated as the ones here.
325 pub use makeover_geometry::{CSS_LAYER, in_css_layer};
326
327 /// This crate's version, as the generated stylesheet reports it.
328 ///
329 /// A consumer whose lockfile still pins an old `makeover-webview` gets a
330 /// well-formed sheet with components missing and no error anywhere, so the
331 /// emitter has to name itself in what it writes. Read by
332 /// `makeover_build::layout_css` through [`stylesheet`].
333 pub const VERSION: &str = env!("CARGO_PKG_VERSION");
334 use makeover_layout::{
335 Bevel, CellPart, Depth, Fallback, Fill, Flow, Intent, RowPart, Selector, Sort, State, Token,
336 Tone,
337 };
338 use makeover_touch::Affordance;
339 use std::fmt::Write as _;
340
341 /// How the emitted CSS is shaped.
342 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
343 pub struct Emit {
344 /// Bevel thickness, as a CSS length.
345 ///
346 /// A value, so it arrives from the caller: border widths belong to
347 /// `makeover-geometry` and will come from there once it carries them.
348 pub border_width: &'static str,
349 /// Focus ring thickness, as a CSS length.
350 ///
351 /// Separate from [`border_width`](Self::border_width), and never derived
352 /// from it: a bevel and a focus indicator answer different questions, and
353 /// only one of them has to be noticed from across a desk.
354 ///
355 /// The default is the measured consensus rather than a new opinion. Every
356 /// consumer had already written its own ring and all three chose at least
357 /// 2px: the MNW server 2px across 10 rules, Balanced Breakfast 2px,
358 /// goingson 2px on three rules and 3px on the one covering twelve
359 /// selectors. The design system was the only thing in the tree saying 1px.
360 pub focus_width: &'static str,
361 /// Prefix for emitted class names, without the leading dot.
362 pub class_prefix: &'static str,
363 }
364
365 impl Default for Emit {
366 fn default() -> Self {
367 Self {
368 border_width: "1px",
369 focus_width: "2px",
370 class_prefix: "",
371 }
372 }
373 }
374
375 /// A string as CSS escapes, for a `content` value.
376 ///
377 /// `\u{25B2}` becomes `\25B2`. Emitted escaped rather than literally so the
378 /// stylesheet is ASCII whatever the description spells: a `content` string is
379 /// read by whatever encoding the consumer serves the file as, and a caret that
380 /// depends on that is a caret that works on one machine.
381 ///
382 /// Terminated by the closing quote at every site here. A CSS hex escape takes
383 /// up to six digits and ends at the first character that cannot be one, so an
384 /// escape followed by more text would need a space that these do not.
385 fn css_escape(text: &str) -> String {
386 text.chars().fold(String::new(), |mut out, c| {
387 let _ = write!(out, "\\{:X}", c as u32);
388 out
389 })
390 }
391
392 /// The CSS custom property holding a bevel's composition.
393 #[must_use]
394 pub fn bevel_var(bevel: Bevel) -> &'static str {
395 match bevel {
396 Bevel::Raised => "--bevel-raised",
397 Bevel::Inset => "--bevel-inset",
398 }
399 }
400
401 /// A `var()` reference to a fill intent, with the browser's own fallback where
402 /// the intent may be absent.
403 ///
404 /// The fallback is CSS syntax, not a decision made here. That is the whole
405 /// difference between this renderer and the other two.
406 #[must_use]
407 pub fn fill_var(fill: Fill) -> String {
408 match fill {
409 Fill::Well => format!("var(--{}, var(--{}))", fill.token(), Fill::Page.token()),
410 other => format!("var(--{})", other.token()),
411 }
412 }
413
414 /// The two-tone edge as a `box-shadow` value.
415 ///
416 /// Two inset shadows, one per corner pair: the light one offset down and
417 /// right so it lands on the top and left edges, the dark one the other way.
418 /// The same assignment `makeover-immediate` draws with polylines and
419 /// `makeover-tui` draws with box-drawing characters.
420 #[must_use]
421 pub fn bevel_shadow(bevel: Bevel, opts: &Emit) -> String {
422 let (top_left, bottom_right) = bevel.edges();
423 let w = opts.border_width;
424 format!(
425 "inset {w} {w} 0 var(--{}), inset -{w} -{w} 0 var(--{})",
426 top_left.token(),
427 bottom_right.token()
428 )
429 }
430
431 /// The custom properties both bevels resolve through.
432 ///
433 /// Emitted as properties rather than inlined into every rule because that is
434 /// what the apps already do, and because a consumer that wants the edge
435 /// without the fill reads the property directly.
436 #[must_use]
437 pub fn bevel_properties(opts: &Emit) -> String {
438 let mut css = String::new();
439 for bevel in [Bevel::Raised, Bevel::Inset] {
440 let _ = writeln!(
441 css,
442 " {}: {};",
443 bevel_var(bevel),
444 bevel_shadow(bevel, opts)
445 );
446 }
447 css.push_str(ELEVATION_PROPERTY);
448 css
449 }
450
451 /// The cast shadow of a surface that floats over the page.
452 ///
453 /// Composed here for the reason the bevel pair is: `makeover` derives the tone,
454 /// this crate owns the geometry, and neither has to know the other's numbers.
455 ///
456 /// **Only for a surface that overlays the page.** A menu, a toast, a popover, a
457 /// dropdown. A surface *in* the page takes `.raised` and its bevel, and a rule
458 /// that reaches for this on a card or a plate has renamed a literal rather than
459 /// replaced it.
460 ///
461 /// Two lengths rather than one, because a single blur reads as a smudge at
462 /// plate size and as a halo at menu size. The offset is small and downward: a
463 /// Platinum-era menu sits just off the page rather than hovering above it.
464 const ELEVATION_PROPERTY: &str =
465 " --elevation-overlay: 0 2px 4px var(--elevation), 0 8px 24px var(--elevation);\n";
466
467 /// The class name for a depth.
468 #[must_use]
469 pub fn depth_class(depth: Depth, opts: &Emit) -> Option<String> {
470 let name = match depth {
471 Depth::Flat => return None,
472 Depth::Raised => "raised",
473 Depth::Well => "well",
474 Depth::Sunken => "sunken",
475 // A depth added to the description since this renderer was last
476 // built. No class, on the same footing as Flat: emitting a name
477 // whose rule body we cannot write would put a class in the markup
478 // that the stylesheet never defines.
479 _ => return None,
480 };
481 Some(format!("{}{name}", opts.class_prefix))
482 }
483
484 /// A prefixed class name.
485 ///
486 /// Public, for the renderers that emit markup this crate does not. A screen
487 /// renderer writing `class="row"` has to prefix it the way the stylesheet half
488 /// does, or a prefixed app gets rules matching everything except the elements
489 /// that renderer wrote, and the failure is invisible: the CSS stays valid and
490 /// one element is unstyled. Call this rather than copying it.
491 #[must_use]
492 pub fn class(name: &str, opts: &Emit) -> String {
493 let mut out = String::with_capacity(opts.class_prefix.len() + name.len());
494 push_class(&mut out, name, opts);
495 out
496 }
497
498 /// A prefixed class name, written into a buffer the caller already has.
499 ///
500 /// The form the emitters use, and the reason it exists is [`escape_into`]'s:
501 /// putting every class on every element through a `format!` allocates even in
502 /// the default case, where the prefix is empty and the answer is the argument.
503 /// A described table row carries roughly eighty transient allocations that way,
504 /// and this and the escaper are most of them.
505 ///
506 /// [`class`] stays for callers holding a name rather than a buffer.
507 ///
508 /// [`escape_into`]: crate::form::escape_into
509 pub fn push_class(out: &mut String, name: &str, opts: &Emit) {
510 out.push_str(opts.class_prefix);
511 out.push_str(name);
512 }
513
514 /// The class an option of a selector carries, which is what the rules key off.
515 ///
516 /// Named for the option and not for the group: [`selector_rules`] styles the
517 /// thing that gets picked, so `Selector::Tabs` is `tab` and not `tabs`. The
518 /// distinction is not pedantry. quasi-webview spelled these `tabs`, `segmented`
519 /// and `option`, put `toggle` on the wrapping element rather than on the
520 /// buttons inside it, and every described selector in that renderer came out
521 /// with no depth, no focus ring and no chosen state, while the toggle group got
522 /// a bevel meant for its buttons.
523 ///
524 /// The chosen option additionally carries `chosen`, the same way a latched chip
525 /// carries `latched`. That name is this crate's too; there is no reason for a
526 /// caller to spell it, and [`selector_rules`] is where it is written down.
527 #[must_use]
528 pub fn option_class(selector: Selector) -> &'static str {
529 match selector {
530 Selector::Tabs => "tab",
531 Selector::Segmented => "segment",
532 Selector::Toggle => "toggle",
533 }
534 }
535
536 /// The fill and edge declarations for a depth, as a rule body.
537 ///
538 /// Empty for [`Depth::Flat`], which has neither and inherits what it sits on.
539 /// Callers lean on the emptiness to skip the rule rather than emit a class that
540 /// sets nothing: a class that sets no properties is a class that means "I
541 /// thought about this", which is what comments are for.
542 ///
543 /// The two halves are emitted independently because [`Depth::Sunken`] has a
544 /// fill and no bevel. Requiring both would silently drop the fill for exactly
545 /// that case. Independent does not
546 /// mean unpaired: both halves still come off one `Depth`, so they cannot
547 /// disagree about what the region is.
548 #[must_use]
549 pub fn depth_declarations(depth: Depth) -> String {
550 let mut css = String::new();
551 if let Some(fill) = depth.fill() {
552 let _ = writeln!(css, " background: {};", fill_var(fill));
553 }
554 if let Some(bevel) = depth.bevel() {
555 let _ = writeln!(css, " box-shadow: var({});", bevel_var(bevel));
556 }
557 css
558 }
559
560 /// One rule giving a selector a depth, or nothing when the depth declares
561 /// nothing.
562 #[must_use]
563 pub fn depth_rule(selector: &str, depth: Depth) -> String {
564 let body = depth_declarations(depth);
565 if body.is_empty() {
566 return String::new();
567 }
568 format!(".{selector} {{\n{body}}}\n")
569 }
570
571 /// The media condition a hover rule has to sit inside, or `None` if hover is
572 /// unconditional.
573 ///
574 /// Two crates answer this and neither answer is made here. `makeover-touch`
575 /// owns *whether* hover exists at a density, and `makeover-geometry` owns how
576 /// that capability is spelled as a media condition. Asking both is what stops
577 /// this renderer minting a third opinion, which is what all three apps did:
578 /// goingson sniffed the user agent, Balanced Breakfast used `(hover: none)`
579 /// alone, and the MNW server had no gate at all.
580 ///
581 /// [`SizeClass`] is required by [`Affordance::available`] and ignored by this
582 /// member, which reports as much through `reads_size`. Passing Compact is not
583 /// a claim about width; the test below pins that every class agrees.
584 fn hover_condition() -> Option<&'static str> {
585 if Affordance::Hover.available(Density::Touch, SizeClass::Compact) {
586 // A fingertip grew a hover state. Nothing to gate, and this renderer
587 // should not invent a reason to gate anyway.
588 None
589 } else {
590 Some(Density::Pointer.media_condition())
591 }
592 }
593
594 /// Put a rule inside a media query, or leave it alone.
595 fn gated(condition: Option<&str>, rule: &str) -> String {
596 let Some(condition) = condition else {
597 return rule.to_string();
598 };
599 let mut css = format!("@media {condition} {{\n");
600 for line in rule.lines() {
601 // Blank lines stay blank. Indenting one leaves trailing whitespace,
602 // which is the sort of thing a formatter later reverts and calls a diff.
603 if line.is_empty() {
604 css.push('\n');
605 } else {
606 let _ = writeln!(css, " {line}");
607 }
608 }
609 css.push_str("}\n");
610 css
611 }
612
613 /// The keyboard focus ring, placed by the depth it lands on.
614 ///
615 /// This is the webview's **focus ring** and nothing more. **Reach** and
616 /// **focus** are both the browser's — the document decides what is reachable
617 /// and `:focus-visible` decides which reached thing wears the ring — and no
618 /// description states either. The three terms are defined once in
619 /// `makeover_layout`'s crate header, "Reach, focus and the focus ring".
620 ///
621 /// One ring for the whole system, because a focus ring's job is to be
622 /// recognised and three apps having three of them is the failure. What varies
623 /// is where it sits, and that comes off [`Depth`] rather than off a per-
624 /// component choice: a well takes the ring inside its own edge, and anything
625 /// standing proud of the page takes it outside.
626 ///
627 /// `outline` rather than the composed `box-shadow` the invalid-field ring at
628 /// [`field_rules`] uses, and deliberately the one place the two rings are built
629 /// differently. A `box-shadow` ring has to restate the bevel beside it, because
630 /// `box-shadow` is not additive and a lone ring silently drops the well out
631 /// from under the element. That restatement is a second copy of the depth,
632 /// living in a different function from the first, and it is exactly the
633 /// duplication `Depth` exists to prevent. `outline` occupies its own property,
634 /// so the bevel survives untouched and there is nothing to keep in agreement.
635 /// They render the same: both are a flush ring one border-width wide.
636 #[must_use]
637 pub fn focus_rule(selector: &str, depth: Depth, opts: &Emit) -> String {
638 let w = opts.focus_width;
639 // Same magnitude either way, and only the sign comes off the depth. Both
640 // values are what the consumers had already converged on independently:
641 // 2px out is what all three wrote, and 2px in is the MNW server's own
642 // answer for the one inset ring it had.
643 let offset = match depth.bevel() {
644 // Inside the well, clear of its edge rather than painted over it.
645 Some(Bevel::Inset) => format!("calc(-1 * {w})"),
646 // Raised, or no edge at all. Outside, standing off by its own width.
647 _ => w.to_string(),
648 };
649 // The token by name. It is `makeover`'s, derived from the action colour,
650 // and reaching it through a description member was a second path to the
651 // same variable for as long as one existed.
652 format!(
653 ".{selector}:focus-visible {{\n outline: {w} solid var(--focus-ring);\n outline-offset: {offset};\n}}\n"
654 )
655 }
656
657 /// A rest depth said out loud on both axes, for a rule that has to beat the
658 /// states above it.
659 ///
660 /// [`depth_declarations`] states an axis only when the depth has something to
661 /// say about it, which is right for a rest rule: a [`Depth::Flat`] region
662 /// inherits what it sits on, and asserting `background: none` there would be
663 /// the difference between level-with and painted-transparent. It is wrong for
664 /// a rule whose whole job is to take a state back. An axis left unstated is an
665 /// axis the state above keeps, so `Flat` re-asserted nothing at all and a
666 /// disabled control kept whatever hover had given it.
667 ///
668 /// So the axes the depth is silent on are withdrawn rather than skipped, and
669 /// the withdrawal is spelled by [`reset`] rather than here, so a disabled
670 /// control and a flat one say the same words. Reaches further than the fill:
671 /// [`Depth::Sunken`] and [`Depth::Overlay`] have no bevel either, and the
672 /// pressed rule above hands out an inset one.
673 fn rest_declarations(depth: Depth) -> String {
674 let mut css = String::new();
675 match depth.fill() {
676 Some(fill) => {
677 let _ = writeln!(css, " background: {};", fill_var(fill));
678 }
679 None => css.push_str(&Reset::NOTHING.and(Chrome::Fill).declarations()),
680 }
681 match depth.bevel() {
682 Some(bevel) => {
683 let _ = writeln!(css, " box-shadow: var({});", bevel_var(bevel));
684 }
685 None => css.push_str(&Reset::NOTHING.and(Chrome::Shadow).declarations()),
686 }
687 css
688 }
689
690 /// Present, visible, and not answering.
691 ///
692 /// Matches the ARIA attribute as well as the pseudo-class, because `:disabled`
693 /// only matches form elements and half the things this crate emits are not
694 /// one: a `div` carrying `.chip` or `.tab` can never be `:disabled`. Keying on
695 /// the accessible state is the pattern [`field_rules`] already establishes for
696 /// `aria-invalid`, on the reasoning that one fact read by both the styling and
697 /// the accessibility tree cannot drift from itself.
698 ///
699 /// The rest depth is re-asserted rather than assumed, because this rule has to
700 /// beat the hover and pressed rules above it. It does that on source order at
701 /// equal specificity, not by out-specifying them: every rule this function's
702 /// caller emits is (0,2,0), and adding a `:not(:disabled)` anywhere would raise
703 /// one of them and have to be unpicked when this output moves inside its own
704 /// cascade layer.
705 ///
706 /// Re-asserted on **both** axes, through [`rest_declarations`].
707 /// `depth_declarations` alone is empty for [`Depth::Flat`], so a flat control
708 /// would win the contest with nothing to say and keep the hover surface
709 /// underneath a control that had stopped answering.
710 #[must_use]
711 pub fn disabled_rule(selector: &str, depth: Depth) -> String {
712 format!(
713 ".{selector}:disabled,\n.{selector}[aria-disabled=\"true\"] {{\n{} color: var(--{});\n cursor: not-allowed;\n}}\n",
714 rest_declarations(depth),
715 State::Disabled.token()
716 )
717 }
718
719 /// Every state a selector that answers a click implies: hover, pressed, focus
720 /// and disabled, in that order.
721 ///
722 /// Order is the whole cascade mechanism here. All four selectors are
723 /// specificity (0,2,0), so disabled wins over hover and pressed by coming last
724 /// and by nothing else.
725 ///
726 /// Pressed emits [`Depth::pressed`] in full, fill and edge together. Emitting
727 /// only the edge is what left goingson hand-writing `background:
728 /// var(--surface-sunken)` on three separate rules, and a fill that does not
729 /// travel with its edge is precisely the disagreement `Depth` exists to make
730 /// unrepresentable. So the pressed fill comes from the description
731 /// (`--surface-well`) rather than from whatever each app reached for.
732 ///
733 /// Hover has no member in the description and is renderer policy: a terminal
734 /// and an immediate-mode painter have no hover to express. It resolves against
735 /// `--hover-surface`, which `makeover` already derives and which nothing
736 /// consumed until now. What it *is* gated on is capability, via
737 /// [`hover_condition`]. Before that gate existed the apps each wrote their own:
738 /// goingson's section 60 exists solely to take back the hover state this
739 /// function had just handed it, by out-specifying a rule it does not own.
740 ///
741 /// `depth` is the selector's **rest** depth, used to place the focus ring and
742 /// to restore the surface under a disabled control. The pressed rule keeps
743 /// inverting from [`Depth::Raised`] regardless: a tab's unchosen depth is
744 /// [`Depth::Sunken`], and `Sunken.pressed()` is `Sunken`, so deriving the press
745 /// from the rest depth would leave a tab with no press at all.
746 #[must_use]
747 pub fn interactive_rules(selector: &str, depth: Depth, opts: &Emit) -> String {
748 let mut css = gated(
749 hover_condition(),
750 &format!(".{selector}:hover {{\n background: var(--hover-surface);\n}}\n"),
751 );
752 css.push_str(&depth_rule(
753 &format!("{selector}:active"),
754 Depth::Raised.pressed(),
755 ));
756 css.push_str(&focus_rule(selector, depth, opts));
757 css.push_str(&disabled_rule(selector, depth));
758 css
759 }
760
761 /// One rule per depth: its fill and its edge, together.
762 ///
763 /// A depth and nothing else. `.raised` says a surface sits on what is behind
764 /// it, which is a statement about the shape and not about what happens when a
765 /// pointer arrives, so it emits no hover, press, focus or disabled rule. The
766 /// named surfaces are where interaction lives: `.card` and `.button` are the
767 /// same depth *and* controls, and they get their states from
768 /// [`surface_rules`].
769 ///
770 /// Giving this class the interactive set leaves the vocabulary with no raised
771 /// surface that is merely an object, so a consumer that needs one has to take a
772 /// control class and cancel half of it.
773 #[must_use]
774 pub fn depth_rules(opts: &Emit) -> String {
775 let mut css = String::new();
776 for depth in [Depth::Raised, Depth::Well] {
777 let Some(class) = depth_class(depth, opts) else {
778 continue;
779 };
780 css.push_str(&depth_rule(&class, depth));
781 }
782 css
783 }
784
785 /// The three surfaces that are a depth with a name.
786 ///
787 /// `button` and `card` are both [`Depth::Raised`], and `field` is a
788 /// [`Depth::Well`] because that is the reading `Depth`'s own documentation
789 /// gives a text field. Their bodies come out identical by construction rather
790 /// than by hand: three hand-written copies in goingson's stylesheet is what
791 /// phase A deletes, and generating them from one call is what stops them
792 /// drifting apart again.
793 fn surface_rules(opts: &Emit) -> String {
794 let mut css = String::new();
795 for name in ["button", "card"] {
796 let c = class(name, opts);
797 css.push_str(&depth_rule(&c, Depth::Raised));
798 css.push_str(&interactive_rules(&c, Depth::Raised, opts));
799 }
800
801 let field = class("field", opts);
802 css.push_str(&depth_rule(&field, Depth::Well));
803
804 // A field takes focus and refuses input like everything else here, and got
805 // neither until now, which is why all three apps hand-write a focus ring
806 // for it and no two of them match. No hover or pressed: a text field does
807 // not light up under the pointer and does not invert when clicked, so the
808 // two states `interactive_rules` would add are the two it does not have.
809 css.push_str(&focus_rule(&field, Depth::Well, opts));
810 css.push_str(&disabled_rule(&field, Depth::Well));
811
812 // Keyed on the ARIA attribute rather than on a class, so the visual state
813 // and the accessible state cannot drift apart: there is one fact and both
814 // read it. goingson already drove its invalid styling this way and was
815 // right to; the `.invalid` class this emitted before 0.5.0 was a second
816 // place to forget.
817 //
818 // The ring composes *after* the bevel rather than replacing it. box-shadow
819 // is not additive, so a lone ring silently dropped the well out from under
820 // an invalid field. Flat and unlit: this edge is saying "wrong", and
821 // lighting one side would have it say "raised" at the same time.
822 let _ = writeln!(
823 css,
824 ".{field}[aria-invalid=\"true\"] {{\n box-shadow: var({}), 0 0 0 {} var(--danger);\n}}",
825 bevel_var(Bevel::Inset),
826 opts.border_width
827 );
828 css
829 }
830
831 /// Badges and chips.
832 ///
833 /// The one place phase A changes how goingson looks rather than only where its
834 /// rules live. [`Token::Badge`] is [`Depth::Flat`], so a badge emits no fill
835 /// and no edge at all, where goingson ships `.tag, .badge` as a single rule
836 /// carrying the raised bevel. Splitting that means reading every call site to
837 /// decide which of the two it always was.
838 ///
839 /// What a badge does carry is a [`Tone`], the intent family it shares with
840 /// notices and nothing else. Neutral is the bare class rather than a variant,
841 /// because it is the absence of a status and not a status called "none".
842 /// Text that goes somewhere.
843 ///
844 /// The one inline control. A table cell carries `cell-link`, deliberately
845 /// unruled because the cell's own rule covers it; this is the same thing
846 /// outside a table, which is what a described run holds when a sentence
847 /// contains a link.
848 ///
849 /// Colour and underline only. Whether a link is inline in a sentence or sitting
850 /// on its own line is the app's layout, and how much room it takes is
851 /// `makeover-geometry`'s. What is here is the pair of signals that say "this
852 /// goes somewhere" and nothing that says where it sits.
853 ///
854 /// The visited arm is deliberately absent. A link inside an app points at the
855 /// app's own screens, which the user is expected to have been to, so painting
856 /// them differently marks almost everything and distinguishes nothing.
857 fn link_rules(opts: &Emit) -> String {
858 let mut css = String::new();
859 let link = class("link", opts);
860
861 let _ = writeln!(
862 css,
863 ".{link} {{\n color: var(--action);\n \
864 text-decoration: underline;\n}}"
865 );
866 // The hover step is the same one every other control takes, and it is a
867 // colour rather than a surface: a link has no box to raise.
868 let _ = writeln!(
869 css,
870 "@media (hover: hover) and (pointer: fine) {{\n .{link}:hover \
871 {{\n color: var(--action-hover);\n }}\n}}"
872 );
873 let _ = writeln!(
874 css,
875 ".{link}:focus-visible {{\n outline: {} solid var(--focus-ring);\n \
876 outline-offset: 2px;\n}}",
877 opts.focus_width
878 );
879 // A link is often a `<button>` rather than an `<a>`: a renderer picks the
880 // element from the method, so a link that writes is a button that has to
881 // stop looking like one. What that costs is named in [`reset`].
882 css.push_str(&Reset::TEXT_BUTTON.rule(&format!("button.{link}")));
883 css
884 }
885
886 fn token_rules(opts: &Emit) -> String {
887 let mut css = String::new();
888
889 // No `depth_rule` call here, deliberately: `Token::Badge.depth(_)` is Flat,
890 // and a label with an edge says it can be pressed.
891 let badge = class("badge", opts);
892 // `content-muted` literally, not `Tone::Neutral.token()`. What makes a
893 // badge quiet is `Token::Badge` answering no click, which this crate holds
894 // and `Tone` genuinely does not know. Routing it through Neutral put the
895 // claim where the evidence was not, and the bill arrived on the figure
896 // value: it took the same muting from the same call and read as its own
897 // caption. Neutral answers `content` from makeover-layout 0.36.0.
898 let _ = writeln!(css, ".{badge} {{\n color: var(--content-muted);\n}}");
899 for tone in [Tone::Info, Tone::Success, Tone::Warning, Tone::Danger] {
900 let _ = writeln!(
901 css,
902 ".{badge}[data-tone=\"{0}\"] {{\n color: var(--{0});\n}}",
903 tone.token()
904 );
905 }
906
907 // A button carries the four tones a badge does. It had none, on the reading
908 // that a control's colour is its surface rather than its text, and that
909 // reading has one hole big enough to matter: the button that destroys
910 // something. Every consumer had written that rule itself, and a description
911 // that says `Tone::Danger` on an act had nowhere for it to land.
912 //
913 // Colour and not a fill, matching the badge. A red surface is a decision
914 // about emphasis that belongs to an app's own layer, and two of them
915 // fighting is worse than neither.
916 let button = class("button", opts);
917 for tone in [Tone::Info, Tone::Success, Tone::Warning, Tone::Danger] {
918 let _ = writeln!(
919 css,
920 ".{button}[data-tone=\"{0}\"] {{\n color: var(--{0});\n}}",
921 tone.token()
922 );
923 }
924
925 // A chip holds itself down, which is `Depth::pressed` arrived at
926 // independently by two apps. `removable` is a remove affordance, so it is
927 // markup and waits for phase B.
928 let chip = class("chip", opts);
929 let unlatched = Token::Chip { removable: false };
930 css.push_str(&depth_rule(&chip, unlatched.depth(false)));
931 css.push_str(&interactive_rules(&chip, unlatched.depth(false), opts));
932 css.push_str(&depth_rule(
933 &format!("{chip}.latched"),
934 unlatched.depth(true),
935 ));
936 css
937 }
938
939 /// The three selectors, each named by what it picks.
940 ///
941 /// A tab comes *forward* to join the pane it opens, which is why
942 /// [`Selector::Tabs`] chooses [`Depth::Raised`] where a segment and a toggle
943 /// are held in. That is the folder semantic, and it is the whole reason the
944 /// three are not one member with a flag.
945 ///
946 /// [`Selector::abutting`] is not emitted: whether the options touch is
947 /// spacing, and spacing is `makeover-geometry`'s question to answer.
948 ///
949 /// Both states emit. Naming only the chosen option leaves an unchosen one
950 /// falling through to [`Depth::Flat`] with nothing drawn for it, so an app has
951 /// to hand-write the recess that makes its chosen tab read as forward.
952 fn selector_rules(opts: &Emit) -> String {
953 let mut css = String::new();
954 for selector in [Selector::Tabs, Selector::Segmented, Selector::Toggle] {
955 let c = class(option_class(selector), opts);
956 css.push_str(&depth_rule(&c, selector.unchosen()));
957 css.push_str(&interactive_rules(&c, selector.unchosen(), opts));
958 css.push_str(&depth_rule(&format!("{c}.chosen"), selector.chosen()));
959 }
960 css
961 }
962
963 /// The parts of a list row.
964 ///
965 /// The list is written out rather than derived because `RowPart` is
966 /// `#[non_exhaustive]`, so there is nothing to iterate. A member added upstream emits no rule until it is named here, which
967 /// is the trade `non_exhaustive` makes: a silent gap instead of a build break.
968 /// [`part_class`] carries the same list and the same obligation.
969 fn row_rules(opts: &Emit) -> String {
970 let mut css = String::new();
971
972 // The container the rows sit in, giving back what a `<ul>` brought. Not a
973 // size: there is no magnitude in it, which is the line this crate holds.
974 css.push_str(&Reset::BULLETS.rule(&format!(".{}", class("list", opts))));
975
976 for part in [
977 RowPart::Primary,
978 RowPart::Secondary,
979 RowPart::Meta,
980 RowPart::Actions,
981 RowPart::Tokens,
982 RowPart::Proportion,
983 ] {
984 let c = class(part_class(part), opts);
985
986 // Actions carry controls rather than text, and `RowPart::intent` says
987 // so by returning the same intent inheriting already gives. Pinning it
988 // would be louder than saying nothing. Tokens answer alike, for their
989 // own reason: each token carries its own tone, and a colour on the
990 // strip would fight the things sitting in it. A proportion is the same
991 // case again: the meter inside carries the tone.
992 if !matches!(
993 part,
994 RowPart::Actions | RowPart::Tokens | RowPart::Proportion
995 ) {
996 let _ = writeln!(css, ".{c} {{\n color: var(--{});\n}}", part.intent());
997 }
998
999 // A row's actions are shown at rest. `RowPart::revealed_on_hover` said
1000 // otherwise and was not honoured here from 0.23.0; makeover-layout
1001 // 0.13.0 retired the method, so there is no longer a description saying
1002 // one thing and a renderer doing another.
1003 //
1004 // The rule was `opacity: 0` gated to pointer devices, revealed on
1005 // `:hover` and on `:focus-within`. Each escape it needed was a report
1006 // that hiding was wrong for somebody: `focus-within` because tabbing
1007 // could never reach an action; the gate because a fingertip had no way
1008 // to unhide, which both webview apps had already hand-written
1009 // `opacity: 1` to undo. What was left was a control hidden from
1010 // exactly one group: people using a pointer, who are also the group
1011 // scanning a list to find out what can be done to a row.
1012 //
1013 // A settings screen is where that reads worst: the whole reason to be
1014 // on it is to remove a key, and the button doing so was invisible
1015 // until pointed at. A table cell's actions were never hidden, so the
1016 // two arrangements now agree.
1017 }
1018
1019 // A part that may take two lines. `Flow::Tight` gets no rule: one line is
1020 // what a run already does, and restating it here would put a declaration on
1021 // every part in every row to say nothing.
1022 //
1023 // This is the shape both webview apps had already written by hand and
1024 // commented -- Balanced Breakfast on a feed row's title, goingson on a
1025 // problem's body -- which is the whole argument for the description
1026 // carrying it. `-webkit-` prefixed and unprefixed together: the prefixed
1027 // trio is what every engine actually implements, and `line-clamp` is the
1028 // standard property landing behind it.
1029 let _ = writeln!(
1030 css,
1031 ".{} {{\n display: -webkit-box;\n -webkit-box-orient: vertical;\n -webkit-line-clamp: {lines};\n line-clamp: {lines};\n overflow: hidden;\n}}",
1032 class("row-relaxed", opts),
1033 lines = Flow::Relaxed.lines()
1034 );
1035
1036 // A row inside a hierarchy: a tree, an outline, a threaded list.
1037 // `edf33114`, decided 2026-08-30 (Max). makeover-layout names the concept
1038 // as `Nesting` -- deliberately not `Depth`, which is surface bevel in that
1039 // crate -- and this is the rule.
1040 //
1041 // Measured 2026-08-30: quasi-webview has been emitting `row-nested` with
1042 // `style="--row-depth:N"` on every described hierarchy, and **no stylesheet
1043 // anywhere in the tree read any of it**. So a described outline in a
1044 // browser was a flat list with chevrons in it -- the folding worked and the
1045 // indent did not exist.
1046 //
1047 // The magnitude is a custom property with a fallback, which is this crate's
1048 // own shape: `--awaiting-gap` above is the precedent, and an app overriding
1049 // `--row-indent` is how a level becomes worth more or less. What a level IS
1050 // stays the description's; what it is WORTH is a renderer's, and a terminal
1051 // spending columns for the same fact is not disagreeing.
1052 //
1053 // Here rather than in each app, and that was a live option rather than an
1054 // oversight. `row-select`, `row-current` and `row-chosen` are app-styled by
1055 // design; the indent is not decoration, it is what the description MEANS,
1056 // and three apps agreeing about it by accident is not agreement.
1057 //
1058 // `padding` and not `margin`: a row is a box that can be selected and
1059 // hovered, and indenting with margin would take the indent out of the
1060 // highlight, so the shading under a nested row would start where its text
1061 // does rather than where its row does.
1062 let _ = writeln!(
1063 css,
1064 ".{} {{\n padding-inline-start: calc(var(--row-depth, 0) * var(--row-indent, 1.5ch));\n}}",
1065 class("row-nested", opts)
1066 );
1067
1068 // The two halves of a branch, emitted by quasi-webview and unstyled until
1069 // now for the same reason.
1070 //
1071 // A branch row is the one a reader can fold, and the chevron is its hit
1072 // target. The chevron is drawn by the app or the description -- this says
1073 // where it sits and how big the target is, which is the accessibility fact
1074 // rather than the decorative one: a control smaller than this is one a
1075 // finger misses.
1076 let _ = writeln!(
1077 css,
1078 ".{} {{\n display: flex;\n align-items: baseline;\n gap: var(--row-disclose-gap, 0.5ch);\n}}",
1079 class("row-branch", opts)
1080 );
1081 let _ = writeln!(
1082 css,
1083 ".{} {{\n flex: none;\n min-inline-size: var(--tap-target, 2rem);\n min-block-size: var(--tap-target, 2rem);\n background: none;\n border: 0;\n color: inherit;\n cursor: pointer;\n}}",
1084 class("row-disclose", opts)
1085 );
1086
1087 css
1088 }
1089
1090 /// A row of things that share their space, and what each fallback gets here.
1091 ///
1092 /// Ruling: wiki `layout-room-and-fallback`, Max. Rule 1 is that every described
1093 /// member is in flow, and these rules are how that is kept rather than asked
1094 /// for. A member taken out of flow with `position: absolute` contributes zero
1095 /// width to the row it shares, so nothing can collide with it and nothing
1096 /// prevents the collision.
1097 ///
1098 /// # The floor, which is most of the fix
1099 ///
1100 /// `.run > *` gets `min-width: min-content`. That is the derived minimum the
1101 /// ruling asks for, in this renderer's own unit and stated by the browser
1102 /// rather than by anybody: a member cannot be squeezed narrower than what is
1103 /// in it, so members in one flow push each other instead of overlapping. It
1104 /// costs no query and no number, and it is what fixes all four measured widths
1105 /// whichever fallback the group declared.
1106 ///
1107 /// # A member that asks to fill
1108 ///
1109 /// `.run > [data-width="fill"]` gets `flex: 1 1 0`, which is the second half of
1110 /// what a column has always been able to say, reaching a row of regions.
1111 /// `flex-basis: 0` and not `auto` is what makes several fills divide the room
1112 /// equally rather than dividing the leftovers in proportion to their contents;
1113 /// equal division is [`makeover_layout::Width::Fill`]'s own stated rule. The
1114 /// floor above still applies, so a fill cannot shrink under what is in it.
1115 ///
1116 /// A member that says nothing gets nothing, because a flex item with the floor
1117 /// and no grow is already content-sized. That is why the omitted value here is
1118 /// `Content` while a control omits `Fill`: each position leaves out what it
1119 /// already did.
1120 ///
1121 /// # What each fallback gets, exactly
1122 ///
1123 /// [`Fallback::Wrap`] is `flex-wrap: wrap`, which is exact. The browser wraps
1124 /// the run when the members no longer fit, deciding that from their own
1125 /// intrinsic widths, which is the derived minimum doing the whole job.
1126 ///
1127 /// [`Fallback::Stack`] is wrap plus `flex: 1 1 max-content` on the members, so
1128 /// a member that cannot sit beside its sibling takes a line of its own and
1129 /// fills it. For the two-member run this was ruled on -- a tab strip and a
1130 /// band -- that is precisely "a row becomes a column".
1131 ///
1132 /// [`Fallback::Shed`] and [`Fallback::Menu`] get wrap, and this renderer is
1133 /// honouring less than the description says. **CSS cannot express either one
1134 /// without breaking the ruling's own first constraint.** Both need to know that
1135 /// the run is out of room in order to take a member out of it, a container
1136 /// query is the only construct that can ask, and `@container` compares against
1137 /// a `<length>` -- there is no `@container (inline-size < min-content)`. So
1138 /// every honest spelling of Shed here needs an authored breakpoint, which is
1139 /// the thing the ruling exists to forbid, and the dishonest ones are worse: a
1140 /// clamped height clips by document order rather than by [`Priority`], and
1141 /// `display: none` under a viewport `@media` is the `nth-child(n+5)` bug the
1142 /// vocabulary replaced.
1143 ///
1144 /// Wrapping is the right thing to do instead. It keeps every member reachable,
1145 /// which is the property that was actually broken -- goingson's new-contact
1146 /// button left the viewport entirely at 560 -- and it keeps rule 1. A renderer
1147 /// answering with less than was described is precedented and deliberate here:
1148 /// [`makeover_layout::Region::Columns`] says a terminal stacking a board's
1149 /// columns is honouring the description rather than degrading it.
1150 ///
1151 /// The real mechanism needs the shed members to have somewhere to go, which is
1152 /// markup and belongs to quasi-webview: an overflow control is a member of the
1153 /// run, and the description does not yet say that a member *is* one.
1154 ///
1155 /// # Menu, once a script is measuring
1156 ///
1157 /// That is now built, in `quasi-webview`'s `menu.js`, and this crate's half of
1158 /// it is two classes and one override. A script that has taken a menu run over
1159 /// marks it `data-menu`, and a marked run goes back to `nowrap`: wrapping is
1160 /// what hides the overflow condition the script is trying to measure. The
1161 /// unmarked rule above is untouched, so a page that ships no script still
1162 /// wraps, which is rule 1 — every member reachable — rather than a strip with
1163 /// tabs squeezed off the end.
1164 ///
1165 /// `.run-overflow` is the control the shed members move into and
1166 /// `.run-overflow-items` is where they land. The geometry is this crate's the
1167 /// way every other surface's is; what is *in* it is the script's, because which
1168 /// members no longer fit is a measurement and not a description.
1169 fn run_rules(opts: &Emit) -> String {
1170 let run = class("run", opts);
1171 let mut css = String::new();
1172
1173 // `flex-wrap: nowrap` is stated rather than left to the default, because
1174 // the fallbacks below are read as overrides of this line and a reader
1175 // should not have to know which way flexbox leans to see that.
1176 //
1177 // No gap. Spacing between members is the app's, the same way this crate
1178 // states no margins anywhere else; a gap here would be a size, and the one
1179 // hardcoded size in the mechanism is makeover-geometry's contact patch.
1180 let _ = writeln!(
1181 css,
1182 ".{run} {{\n display: flex;\n flex-wrap: nowrap;\n align-items: center;\n}}"
1183 );
1184
1185 // The derived minimum, and the whole reason a member can no longer be
1186 // overlapped. `min-width: auto` is flexbox's default for a flex item and is
1187 // *not* the same thing: auto lets an item be compressed below its content
1188 // in a nowrap run, which is how a toolbar ends up drawn over a tab strip
1189 // even without anything leaving the flow.
1190 let _ = writeln!(css, ".{run} > * {{\n min-width: min-content;\n}}");
1191
1192 // A member that absorbs what is left. `flex-basis: 0` rather than `auto` is
1193 // what makes several fills divide the room equally instead of dividing the
1194 // leftovers in proportion to what is already in them, which is
1195 // `Width::Fill`'s own rule and the one thing that type states about more
1196 // than one of them.
1197 //
1198 // The `min-width: min-content` floor above is deliberately not overridden.
1199 // A fill that could shrink below its contents would overlap its neighbour,
1200 // which is rule 1, and equal division under a floor is still equal division
1201 // everywhere the floor is not reached.
1202 //
1203 // Attribute rather than class, because the width is a fact the description
1204 // carried rather than a hook this crate invented: the same division
1205 // `data-tone` and `data-selector` are on the right side of. It beats the
1206 // `Stack` rule below on specificity whichever order they are written in,
1207 // which is what a member asking to fill should do to a blanket.
1208 let _ = writeln!(
1209 css,
1210 ".{run} > [data-width=\"fill\"] {{\n flex: 1 1 0;\n}}"
1211 );
1212
1213 for fallback in [
1214 Fallback::Wrap,
1215 Fallback::Stack,
1216 Fallback::Shed,
1217 Fallback::Menu,
1218 ] {
1219 let name = fallback_class(fallback);
1220 let c = class(name, opts);
1221 let _ = writeln!(css, ".{c} {{\n flex-wrap: wrap;\n}}");
1222 if matches!(fallback, Fallback::Stack) {
1223 let _ = writeln!(css, ".{c} > * {{\n flex: 1 1 max-content;\n}}");
1224 }
1225 }
1226
1227 // A menu run a script has taken over. The mark is the script's and this is
1228 // the only rule that reads it: wrapping is what a run does when nothing is
1229 // measuring, and it is also what makes the overflow unmeasurable, since a
1230 // wrapped run always fits. The two cannot both be on.
1231 let menu = class(fallback_class(Fallback::Menu), opts);
1232 let _ = writeln!(css, ".{menu}[data-menu] {{\n flex-wrap: nowrap;\n}}");
1233
1234 // The overflow control, and it is a member of the run like any other: in
1235 // flow, at the end, taking the width of what is in it. `relative` is what
1236 // the items hang off.
1237 let overflow = class("run-overflow", opts);
1238 let items = class("run-overflow-items", opts);
1239 let _ = writeln!(css, ".{overflow} {{\n position: relative;\n}}");
1240
1241 // Overlaid rather than in flow, for the reason every menu is: a control
1242 // that pushed the page down when it opened would change the layout it was
1243 // opened to escape. `inset-inline-end: 0` rather than a left, so the panel
1244 // stays on the page in both writing directions.
1245 //
1246 // No width, no padding and no border. All three are sizes and sizes are
1247 // makeover-geometry's; what is stated here is placement, the surface and
1248 // the shadow that separates it from the page, which is the same division
1249 // `figure_rules` and the timeline entry make. The elevation shadow is what
1250 // an overlaid surface takes instead of an edge -- see `ELEVATION_PROPERTY`.
1251 let _ = writeln!(
1252 css,
1253 ".{items} {{\n \
1254 position: absolute;\n \
1255 inset-block-start: 100%;\n \
1256 inset-inline-end: 0;\n \
1257 z-index: 1;\n \
1258 display: flex;\n \
1259 flex-direction: column;\n \
1260 align-items: stretch;\n \
1261 background: var(--surface-raised);\n \
1262 box-shadow: var(--elevation-overlay);\n\
1263 }}"
1264 );
1265
1266 // `hidden` is how the script closes it, and a flex display would otherwise
1267 // beat the attribute's own `display: none`.
1268 let _ = writeln!(css, ".{items}[hidden] {{\n display: none;\n}}");
1269
1270 css
1271 }
1272
1273 /// Every class [`fallback_class`] can return, plus the run itself.
1274 ///
1275 /// [`ROW_PART_CLASSES`](crate::list::ROW_PART_CLASSES)'s reasoning and the same
1276 /// obligation: a `match` over a `#[non_exhaustive]` enum cannot be enumerated
1277 /// from outside, so the list sits beside it and a test holds the two together.
1278 /// `run` is in it because it is emitted in its own right rather than only as a
1279 /// fallback's fallback.
1280 pub const RUN_CLASSES: &[&str] = &[
1281 "run",
1282 "run-wrap",
1283 "run-stack",
1284 "run-shed",
1285 "run-menu",
1286 // Not returned by `fallback_class`: these two are the overflow control a
1287 // measuring renderer builds, and they are in the list because the list is
1288 // what a host seals its vocabulary against. A class emitted by a script and
1289 // missing from here is a control with no surface and no edge.
1290 "run-overflow",
1291 "run-overflow-items",
1292 ];
1293
1294 /// The class a run carries for what it does when it is tight.
1295 ///
1296 /// A run always carries `.run` as well, so an unrecognised fallback -- the enum
1297 /// is `#[non_exhaustive]` -- lands as a plain nowrap row with the min-content
1298 /// floor still under it. That is the safe failure: every member in flow and
1299 /// none overlapped, which is the property, with only the rearrangement missing.
1300 #[must_use]
1301 pub fn fallback_class(fallback: Fallback) -> &'static str {
1302 match fallback {
1303 Fallback::Wrap => "run-wrap",
1304 Fallback::Stack => "run-stack",
1305 Fallback::Shed => "run-shed",
1306 Fallback::Menu => "run-menu",
1307 _ => "run",
1308 }
1309 }
1310
1311 /// The progress trough these rules fill.
1312 ///
1313 /// [`meter::meter_html`](crate::meter::meter_html) is what fills these.
1314 ///
1315 /// The rules stay a superset of what a description can ask for. An app drawing
1316 /// its own bar keeps these classes, which is what the four goingson grew
1317 /// independently were adopted onto.
1318 ///
1319 /// The trough is a [`Depth::Well`], the same reading a text field gets:
1320 /// something with its content down inside it.
1321 fn progress_rules(opts: &Emit) -> String {
1322 let progress = class("progress", opts);
1323 // `progress-fill` rather than a bare `fill`: an unprefixed build claims
1324 // these names in the app's own stylesheet, and `.fill` is grabby enough to
1325 // catch things that have nothing to do with progress. goingson already
1326 // calls it `.progress-fill`, so this is also the name that deletes.
1327 let fill = class("progress-fill", opts);
1328 let mut css = depth_rule(&progress, Depth::Well);
1329
1330 // The untoned bar is `--action`, not [`Tone::Neutral`]. That is the one
1331 // place this differs from the badge rules, and deliberately: a badge with
1332 // no status is a muted label, while a bar with no status is still
1333 // reporting progress, and `content-muted` would read as disabled.
1334 let _ = writeln!(
1335 css,
1336 ".{progress} > .{fill} {{\n background: var(--action);\n}}"
1337 );
1338
1339 // A bar can be saying something, same as a badge: goingson colours subtask
1340 // progress as success and an over-estimate as danger, which is real
1341 // information rather than decoration. Emitting the tones is what lets that
1342 // survive adoption instead of staying hand-written.
1343 for tone in [Tone::Info, Tone::Success, Tone::Warning, Tone::Danger] {
1344 let _ = writeln!(
1345 css,
1346 ".{progress} > .{fill}[data-tone=\"{0}\"] {{\n background: var(--{0});\n}}",
1347 tone.token()
1348 );
1349 }
1350 css
1351 }
1352
1353 /// What a wait looks like, for the attribute that has been describing one to
1354 /// nobody.
1355 ///
1356 /// Wiki `loading-and-progress-standard`, phase 2. `data-awaiting` is emitted
1357 /// as `data-awaiting="determinate"` with a `data-awaiting-amount` beside it, or
1358 /// `data-awaiting="indeterminate"` alone. This is the half that styles them,
1359 /// without which the two render identically.
1360 ///
1361 /// # Why it is keyed on `aria-busy` and not on the attribute alone
1362 ///
1363 /// `data-awaiting` is a fact about the control: pressing this waits. It is true
1364 /// when the page is painted and it stays true. Whether a wait is *running* is
1365 /// true only between two events, so it is the binder's to set, and `aria-busy`
1366 /// is the standard spelling of it — announced as well as drawn, which a class
1367 /// of our own would not be.
1368 ///
1369 /// That also keeps this crate out of any one client library's vocabulary.
1370 /// `quasi-webview` sets `aria-busy` from htmx's request events; a host driving
1371 /// the same markup another way sets it the same way and gets the same drawing.
1372 ///
1373 /// # The two drawings
1374 ///
1375 /// One pseudo-element either way, so no renderer has to emit an extra node.
1376 ///
1377 /// Indeterminate is the activity mark of rule 2: a small square that blinks.
1378 /// Determinate is a trough with a fill, drawn as a single gradient whose stop is
1379 /// `--awaiting-share`, a plain number from 0 to 1 that the binder sets from
1380 /// bytes it has actually watched land. A determinate control with nothing
1381 /// setting the share draws an empty trough rather than a full one, which is the
1382 /// honest reading: the size is known and the delivery is not.
1383 ///
1384 /// **What the bar may not do**, from rule 1 and from `Awaiting`'s own docs:
1385 /// what is done over what there is, and never a remaining time, an arrival time
1386 /// or a rate extrapolated forward. Nothing here can express one, which is
1387 /// deliberate — the only input is a share of a measured payload.
1388 ///
1389 /// # Sizes, and the deferral rule
1390 ///
1391 /// `progress_rules` emits the tones and never the width, because the width is
1392 /// not this crate's to know. A pseudo-element has no intrinsic size at all, so
1393 /// the same treatment would render nothing anywhere. Both sizes are therefore
1394 /// custom properties with defaults: an app that wants a different mark sets
1395 /// `--awaiting-mark` and `--awaiting-bar` once, and one that says nothing gets a
1396 /// mark that is visible.
1397 ///
1398 /// # The cadence, and what happens without it
1399 ///
1400 /// `--cadence-activity` comes from `makeover-timing` through `makeover-build`,
1401 /// and is a half-period, so a full cycle is twice it. It is used bare rather
1402 /// than with a fallback: a number written here would be a second heartbeat for
1403 /// a mark three renderers draw.
1404 ///
1405 /// A sheet assembled without the time axis leaves `animation-duration` invalid,
1406 /// which resolves to `0s`, which runs no animation and leaves the base style —
1407 /// a lit, still mark. That is also exactly what the reduced-motion block does,
1408 /// since it sets the cadence to `0ms`. Both fall out of one rule because the
1409 /// base style is lit and the keyframes do the dimming, which is the ordering
1410 /// `makeover_timing::reduced_motion_css` asks its consumers for by name.
1411 fn awaiting_rules(opts: &Emit) -> String {
1412 let mut css = String::new();
1413
1414 // Dimming rather than lighting, so a zero-length animation leaves a lit
1415 // mark rather than a blank one. See `makeover_timing::reduced_motion_css`.
1416 css.push_str(
1417 "@keyframes makeover-activity {\n \
1418 0%, 49.99% {\n background: var(--action);\n }\n \
1419 50%, 100% {\n background: var(--surface-sunken);\n }\n\
1420 }\n",
1421 );
1422
1423 // Nothing is drawn until something is waiting. `content` on the base rule
1424 // rather than on the busy one keeps the box the same box across the
1425 // transition, so a mark appearing does not reflow the line it is in.
1426 let _ = writeln!(
1427 css,
1428 "[data-awaiting]::after {{\n \
1429 content: \"\";\n \
1430 display: none;\n \
1431 margin-inline-start: var(--awaiting-gap, 0.5ch);\n \
1432 vertical-align: baseline;\n\
1433 }}"
1434 );
1435
1436 let _ = writeln!(
1437 css,
1438 "[data-awaiting][aria-busy=\"true\"]::after {{\n \
1439 display: inline-block;\n \
1440 inline-size: var(--awaiting-mark, 0.5em);\n \
1441 block-size: var(--awaiting-mark, 0.5em);\n \
1442 background: var(--action);\n \
1443 opacity: 1;\n \
1444 animation: makeover-activity calc(var(--cadence-activity) * 2) \
1445 step-end infinite;\n\
1446 }}"
1447 );
1448
1449 // The measured half. A wider box, no blink, and a gradient whose stop is
1450 // the share: the fill and the trough in one paint, so the markup stays one
1451 // pseudo-element on both branches.
1452 //
1453 // `--awaiting-share` unset is an empty trough, not a full one. A bar that
1454 // read full because nobody was counting would be the confidently-wrong
1455 // drawing rule 1 exists to forbid.
1456 //
1457 // The trough takes an edge for the reason a well does: a bar at zero share
1458 // is otherwise a rectangle of the surface it sits on, which is nothing at
1459 // all. `border_width` rather than a literal, the way `depth_rule` and
1460 // `track_rules` write theirs.
1461 let _ = writeln!(
1462 css,
1463 "[data-awaiting=\"determinate\"][aria-busy=\"true\"]::after {{\n \
1464 inline-size: var(--awaiting-bar, 6em);\n \
1465 animation: none;\n \
1466 outline: {} solid var(--border);\n \
1467 outline-offset: -{};\n \
1468 background: linear-gradient(\n \
1469 to inline-end,\n \
1470 var(--action) 0 calc(var(--awaiting-share, 0) * 100%),\n \
1471 var(--surface-sunken) 0\n \
1472 );\n\
1473 }}",
1474 opts.border_width, opts.border_width
1475 );
1476
1477 css
1478 }
1479
1480 /// A strip of figures, and the two spans inside each one.
1481 ///
1482 /// Colour only, which is the deferral rule applied to a component that badly
1483 /// wants to break it. A figure reads as a figure because the value is set large
1484 /// over a small caption, and that is a size: `makeover-geometry` answers how
1485 /// much space and this crate answers what the thing is. Emitting `font-size`
1486 /// here would be this crate naming a value, which is the one thing it is defined
1487 /// by not doing, and `progress_rules` is the precedent — it emits the tones and
1488 /// never the width, because the width is not its to know.
1489 ///
1490 /// So the arrangement and the type scale are the app's, and what is generated is
1491 /// the part an app cannot get right by itself: which of the two spans carries
1492 /// the tone.
1493 fn figure_rules(opts: &Emit) -> String {
1494 let figure = class("figure", opts);
1495 let value = class("figure-value", opts);
1496 let caption = class("figure-caption", opts);
1497 let change = class("figure-change", opts);
1498 let mut css = String::new();
1499
1500 // `content` literally. A figure's value is the thing itself, at full
1501 // weight -- wiki `three-tone-convention` classes it "active, emphasised",
1502 // and both other renderers already draw it that way (makeover-tui
1503 // `piece.rs:391` bold, makeover-immediate `widget.rs:244`). It reached
1504 // here through `Tone::Neutral.token()` and came out `content-muted`, so
1505 // the headline number sat at the colour of its own caption.
1506 let _ = writeln!(
1507 css,
1508 ".{figure} > .{value} {{\n color: var(--content);\n}}"
1509 );
1510 let _ = writeln!(
1511 css,
1512 ".{figure} > .{caption} {{\n color: var(--content-muted);\n}}"
1513 );
1514 let _ = writeln!(
1515 css,
1516 ".{figure} > .{change} {{\n color: var(--content-muted);\n}}"
1517 );
1518
1519 // A toned figure tones one part and never the caption. The caption is the
1520 // noun and stays muted.
1521 //
1522 // Which part depends on whether there is a change, and that is the whole of
1523 // what 0.13.0 changed here. A figure with a delta is an ordinary number that
1524 // has moved in a direction worth reading, so the delta takes the colour and
1525 // the number stays plain; a figure without one has nowhere else to put it.
1526 // `:has` is what lets one attribute mean both, and the alternative was the
1527 // emitter deciding by writing the attribute onto a different element, which
1528 // leaves two elements able to disagree about a figure's one meaning.
1529 for tone in [Tone::Info, Tone::Success, Tone::Warning, Tone::Danger] {
1530 let _ = writeln!(
1531 css,
1532 ".{figure}[data-tone=\"{0}\"] > .{change} {{\n color: var(--{0});\n}}",
1533 tone.token()
1534 );
1535 let _ = writeln!(
1536 css,
1537 ".{figure}[data-tone=\"{0}\"]:not(:has(> .{change})) > .{value} \
1538 {{\n color: var(--{0});\n}}",
1539 tone.token()
1540 );
1541 }
1542 css
1543 }
1544
1545 /// A picture, its frame and its caption.
1546 ///
1547 /// # The frame is a border, and this is the one place a bevel is wrong
1548 ///
1549 /// Emitting [`Depth::Raised`] here through [`depth_rule`], the same call
1550 /// `button` and `card` make, is wrong, and MNW's landing page is where it
1551 /// showed: **the frames had no visible edge at all.**
1552 ///
1553 /// `Depth::Raised`'s edge is `--bevel-raised`, which is an *inset* shadow — a
1554 /// 1px light run at the top-left and a dark one at the bottom-right, drawn
1555 /// **inside** the element's box. On a button or a card that box is a surface
1556 /// this crate owns, so an inset edge reads as the surface catching the light.
1557 /// On a picture it is drawn on top of the picture, over whatever pixels the
1558 /// image happens to have at its border. MNW's screenshots are light-on-light
1559 /// parchment, so the light half landed on a light image and the frame
1560 /// disappeared.
1561 ///
1562 /// **You cannot bevel a surface you do not own.** A picture's content is the
1563 /// app's, arrives at request time, and can be any colour, so its edge has to
1564 /// sit *outside* the content rather than on it. That is a border.
1565 ///
1566 /// The fill stays, and it is not decoration: it is what shows through a
1567 /// transparent PNG and what stands in the frame's place while the image is
1568 /// still loading.
1569 ///
1570 /// This is a real limit on [`Depth`] rather than a special case. Every other
1571 /// consumer of a depth draws its own surface; a picture is the first member
1572 /// whose surface belongs to someone else.
1573 ///
1574 /// # No size
1575 ///
1576 /// `width: 100%` and nothing else. How large a picture is depends on the box it
1577 /// was put in, which is the app's arrangement and `makeover-geometry`'s scales,
1578 /// and a renderer that picked one would be answering for every consumer at
1579 /// once. This is where `figure_rules` landed for the same reason.
1580 fn picture_rules(opts: &Emit) -> String {
1581 let picture = class("picture", opts);
1582 let img = class("picture-img", opts);
1583 let caption = class("picture-caption", opts);
1584 let mut css = String::new();
1585
1586 // Block, or an inline image sits on the text baseline and carries a
1587 // descender's worth of space under it that no app ever wants and every app
1588 // deletes by hand. The border is the frame; see the type docs for why it is
1589 // not the bevel every other surface here gets.
1590 let _ = writeln!(
1591 css,
1592 ".{img} {{\n display: block;\n width: 100%;\n height: auto;\n \
1593 background: var(--{});\n border: {} solid var(--border);\n}}",
1594 Fill::Raised.token(),
1595 opts.border_width
1596 );
1597
1598 // The two fits that need a rule. `Fit::Natural` emits no attribute at all,
1599 // so it is the bare rule above and needs nothing here.
1600 let _ = writeln!(
1601 css,
1602 ".{img}[data-fit=\"cover\"] {{\n height: 100%;\n object-fit: cover;\n}}"
1603 );
1604 let _ = writeln!(
1605 css,
1606 ".{img}[data-fit=\"contain\"] {{\n height: 100%;\n object-fit: contain;\n}}"
1607 );
1608
1609 // A caption reads back one step, which is `figure-caption`'s answer and the
1610 // same claim: it says what the thing above it is, and it is not the thing.
1611 let _ = writeln!(
1612 css,
1613 ".{picture} > .{caption} {{\n color: var(--content-muted);\n}}"
1614 );
1615
1616 css
1617 }
1618
1619 /// A region showing one child at a time, and the chrome that moves between them.
1620 ///
1621 /// [`makeover_layout::Showing`] lets a description say that a region holds
1622 /// several children and shows some of them. A renderer derives its own chrome
1623 /// from that, which is what stops every renderer growing a `match` on a widget
1624 /// name; these are the rules the derived chrome needs.
1625 ///
1626 /// # Why the default is every child, and the enhancement takes them away
1627 ///
1628 /// The controls are a lie until something binds them. A prev button rendered
1629 /// into a document with no script is a control that looks live and answers
1630 /// nothing, and the reader it lies to is exactly the one who cannot see the
1631 /// other children either — the collapsing and the moving are the same half.
1632 ///
1633 /// So the rules run in the direction the enhancement does. Nothing here hides a
1634 /// child and nothing here shows a control. Whatever binds the region sets
1635 /// `data-ready` on it, and that is what collapses the stack to one and reveals
1636 /// the row that moves it. A reader with no script gets every child in order and
1637 /// no controls, which is more content rather than less, and a reader with
1638 /// script gets a settled page rather than a stack that jumps to one frame after
1639 /// load.
1640 ///
1641 /// MNW proved this shape by hand — a `<noscript>` stylesheet opening its
1642 /// carousel back out — and it is here rather than there because the property is
1643 /// the description's, not one app's.
1644 ///
1645 /// # Not spacing
1646 ///
1647 /// The row's gaps are `makeover-geometry`'s question and are absent for
1648 /// [`row_rules`]'s reason. What is here is `display`, which carries no
1649 /// magnitude, and the muted readout, which is the same claim `picture-caption`
1650 /// makes: it says where you are among the children and it is not one of them.
1651 fn showing_rules(opts: &Emit) -> String {
1652 let controls = class("showing", opts);
1653 let position = class("showing-position", opts);
1654 let frame = class("showing-frame", opts);
1655 let mut css = String::new();
1656
1657 // Hidden until something binds it, which is the whole argument above.
1658 let _ = writeln!(css, ".{controls} {{\n display: none;\n}}");
1659 // Block, and nothing about how the three sit in it. A button and a span are
1660 // inline already, so they make a row without this crate saying so, and
1661 // saying so is where `align-items` and a gap would follow -- both spacing,
1662 // both `makeover-geometry`'s, and `row_rules` refuses them for the same
1663 // reason.
1664 let _ = writeln!(
1665 css,
1666 "[data-ready] > .{controls} {{\n display: block;\n}}"
1667 );
1668
1669 // A child is in flow until the region is bound, and then only the current
1670 // one is. `.current` is a modifier for the reason `.chosen` and `.latched`
1671 // are: one name for the state, set by whoever knows it.
1672 let _ = writeln!(
1673 css,
1674 "[data-ready] > .{frame}:not(.current) {{\n display: none;\n}}"
1675 );
1676
1677 // Reads back one step. `picture-caption`'s rule and its reason.
1678 let _ = writeln!(css, ".{position} {{\n color: var(--content-muted);\n}}");
1679
1680 css
1681 }
1682
1683 /// A time axis: the container, its gridlines and ruler, and the placed things.
1684 ///
1685 /// [`Track`](makeover_layout::Track), the one member here whose whole point is
1686 /// *position*. That makes the magnitude line this crate keeps worth restating
1687 /// rather than assuming.
1688 ///
1689 /// # Where the numbers come from
1690 ///
1691 /// Every value that varies per item is a custom property the caller sets
1692 /// inline, and every rule here reads one. `--track-at` and `--track-for` are
1693 /// percentages of the span, which
1694 /// [`Track::fraction`](makeover_layout::Track::fraction) computes once so three
1695 /// renderers cannot disagree about it. Nothing here knows a pixel.
1696 ///
1697 /// That is what lets the stylesheet stay static while the items move: an entry
1698 /// carries `style="--track-at: 37.5%; --track-for: 4.166%"` and the rule below
1699 /// turns it into a box. The alternative was emitting a rule per item, which is
1700 /// a stylesheet that grows with the data.
1701 ///
1702 /// **The height of the track is the app's**, not this crate's. 96 quarter-hour
1703 /// slots at some slot height is a size, and a size is `makeover-geometry`'s
1704 /// question -- the same refusal `figure_rules` and `placeholder_rules` make.
1705 /// Percentages need a resolved height above them, so `.track` gets
1706 /// `position: relative` and nothing else; the app says how tall a day is.
1707 ///
1708 /// # Overlap
1709 ///
1710 /// Two things at the same time is intrinsic to an axis and has no analogue in a
1711 /// list. The description does not declare it -- `Placement::overlaps` derives it
1712 /// from the times -- so what arrives here is a lane index and a lane count, and
1713 /// the rule divides the width. A renderer that would rather stack them ignores
1714 /// both properties and the defaults give it one full-width lane.
1715 fn track_rules(opts: &Emit) -> String {
1716 let track = class("track", opts);
1717 let slot = class("track-slot", opts);
1718 let tick = class("track-tick", opts);
1719 let entry = class("track-entry", opts);
1720 let mut css = String::new();
1721
1722 // The positioning context every entry resolves against, and the whole of
1723 // what this crate says about the container. No height: see the doc above.
1724 let _ = writeln!(css, ".{track} {{\n position: relative;\n}}");
1725
1726 // Gridlines and the ruler are the axis reading itself back, which is
1727 // `picture-caption` and `showing-position`'s claim: about the thing rather
1728 // than one of the things.
1729 //
1730 // `border_width` rather than a literal, the way `depth_rule` writes its
1731 // edge. A gridline is the one place a timeline would most naturally reach
1732 // for a hardcoded 1px, and a hardcoded 1px is this crate naming a size.
1733 let _ = writeln!(
1734 css,
1735 ".{slot} {{\n border-top: {} solid var(--border);\n}}",
1736 opts.border_width
1737 );
1738 let _ = writeln!(css, ".{tick} {{\n color: var(--content-muted);\n}}");
1739
1740 // The one rule that does real work. Top and height are the placement;
1741 // left and width are the lane. Both lane properties default so an entry
1742 // that names neither is full width, which is the common case and the one a
1743 // renderer gets for free.
1744 let _ = writeln!(
1745 css,
1746 ".{entry} {{\n \
1747 position: absolute;\n \
1748 top: var(--track-at, 0%);\n \
1749 height: var(--track-for, 100%);\n \
1750 left: calc(var(--track-lane, 0) / var(--track-lanes, 1) * 100%);\n \
1751 width: calc(100% / var(--track-lanes, 1));\n\
1752 }}"
1753 );
1754
1755 css
1756 }
1757
1758 /// A region's stand-in, and the header of a table that can be reordered.
1759 ///
1760 /// Both are colour and affordance only, the same place `figure_rules` lands:
1761 /// emitting a type scale is not this crate's. How much room
1762 /// a stand-in gets is a size — goingson has the same one at three, as
1763 /// `--compact`, `--dashboard` and `--padded` — and a size is
1764 /// `makeover-geometry`'s question.
1765 ///
1766 /// The caret is the one thing here that is neither colour nor affordance, and it
1767 /// is a renderer's own expression rather than a value the description named:
1768 /// `aria-sort` is what the table actually says, and this turns it into something
1769 /// visible for everyone not using a screen reader. A terminal draws its own; an
1770 /// immediate-mode painter draws its own.
1771 fn state_rules(opts: &Emit) -> String {
1772 let placeholder = class("placeholder", opts);
1773 let text = class("placeholder-text", opts);
1774 let heading = class("table-heading", opts);
1775 let mut css = String::new();
1776
1777 let _ = writeln!(
1778 css,
1779 ".{placeholder} > .{text} {{\n color: var(--content-muted);\n}}"
1780 );
1781 // Only the failure is toned. An empty list is the normal state of a new
1782 // install, and `Readiness::tone` is what says so.
1783 let _ = writeln!(
1784 css,
1785 ".{placeholder}[data-tone=\"{0}\"] > .{text} {{\n color: var(--{0});\n}}",
1786 Tone::Danger.token()
1787 );
1788
1789 // A header that reorders the table is a control, and the pointer is the
1790 // only part of saying so that is not the app's own type and spacing.
1791 let _ = writeln!(
1792 css,
1793 ".{heading}[data-sortable] {{\n cursor: pointer;\n}}"
1794 );
1795 // The caret carries its own leading space, the way `makeover-tui` and
1796 // `makeover-immediate` both write `" \u{25B2}"`. It used to be emitted bare,
1797 // and both apps that adopted the vocabulary had to put the gap back in their
1798 // own stylesheets on the same afternoon -- each having to work out first that
1799 // app CSS outranks this crate's cascade layer, so adding the space the
1800 // obvious way, as `content`, silently wins over the glyph and leaves the
1801 // heading with no caret at all. A consumer should not have to know that, and
1802 // with the space emitted here there is nothing left for one to add.
1803 //
1804 // Three states, three tones, on the convention in wiki
1805 // `three-tone-convention`. A column in force is `content`; a column offering
1806 // to reorder and not doing it now is `content-secondary`, because it still
1807 // answers a press; a column that is not sortable emits no caret at all and
1808 // takes nothing. The idle arm used to hide its glyph and reserve the box,
1809 // which cost a reflow-free press and said nothing. It draws now, and the
1810 // reservation stops being a thing to get right.
1811 //
1812 // The glyph is `Sort::glyph`, escaped rather than written: a CSS `content`
1813 // string cannot carry the character literally through this file's own
1814 // escaping, and spelling it here as well would put the third copy back that
1815 // `makeover-layout` 0.27.5 exists to remove.
1816 let _ = writeln!(
1817 css,
1818 ".{heading}[data-sortable]::after \
1819 {{\n content: \" {}\";\n color: var(--content-secondary);\n}}",
1820 css_escape(Sort::Ascending.glyph())
1821 );
1822 for direction in [Sort::Ascending, Sort::Descending] {
1823 let _ = writeln!(
1824 css,
1825 ".{heading}[aria-sort=\"{}\"]::after \
1826 {{\n content: \" {}\";\n color: var(--content);\n}}",
1827 direction.as_str(),
1828 css_escape(direction.glyph())
1829 );
1830 }
1831 css
1832 }
1833
1834 /// The frame a table sits in.
1835 ///
1836 /// # Why this is a CSS table and not the grid the rest of the module assumes
1837 ///
1838 /// A grid row needs `grid-template-columns`, which has to name every column in
1839 /// order, so it cannot be written without knowing the columns. That is what
1840 /// [`list::narrowing_css`] is for, and it works: goingson builds `tables.css` in
1841 /// its own `build.rs` out of it, and nothing here changes that.
1842 ///
1843 /// It does not work for a table a *description* produced. Those columns are
1844 /// known at render time rather than at build time, and the rules would have to
1845 /// travel with the markup: a `<style>` element per table, which needs
1846 /// `style-src 'unsafe-inline'` and so blocks the MNW server's standing plan to
1847 /// drop it. The head is not an escape: a table swapped in by htmx after a
1848 /// delete arrives as a fragment with no head at all.
1849 ///
1850 /// A CSS table aligns its columns across rows knowing nothing about how many
1851 /// there are, so there is no track list to emit and nothing per-table to carry.
1852 /// The cost is that a described table cannot take a per-column fixed length,
1853 /// which costs nothing today: [`Sizing`](list::Sizing) is looked up by column
1854 /// name and a description carries no lengths to put in it, so every track a
1855 /// described table could ask for is already content, fill or auto.
1856 ///
1857 /// [`Priority`] hiding is unchanged in kind. It moves from a generated
1858 /// `display: none` per dropped column to one rule per drop class, which is the
1859 /// same fact addressed by class rather than by cutoff, and still never by
1860 /// position.
1861 fn table_rules(opts: &Emit) -> String {
1862 let table = class("table", opts);
1863 let head = class("table-head", opts);
1864 let row = class("table-row", opts);
1865 let heading = class("table-heading", opts);
1866 let cell = class("cell", opts);
1867 let mut css = String::new();
1868
1869 let _ = writeln!(
1870 css,
1871 ".{table} {{\n display: table;\n width: 100%;\n}}"
1872 );
1873 let _ = writeln!(css, ".{head},\n.{row} {{\n display: table-row;\n}}");
1874 // Scoped under `.{table}` rather than keyed on the classes alone. The
1875 // table model is what a cell takes *by being in a table*, and only there:
1876 // goingson's task headings are `.table-heading` inside a CSS grid, so the
1877 // unscoped rule reached them, and the sort caret and the sortable cursor
1878 // -- which `state_rules` keys on `.table-heading` and rightly still does
1879 // -- came with a `display` the grid had to blockify away.
1880 //
1881 // It costs no markup anywhere: quasi-webview always nests the heading
1882 // inside the table (`quasi-webview/src/node.rs:1591`, `:1605`, `:1615`).
1883 let _ = writeln!(
1884 css,
1885 ".{table} .{heading},\n.{table} .{cell} {{\n display: table-cell;\n}}"
1886 );
1887
1888 // A content column shrinks to what is in it. `width: 1%` is how a CSS table
1889 // is told that: auto layout hands the slack to the columns that asked for
1890 // room, and a column asking for almost none gets what it needs and no more.
1891 // The `nowrap` is what stops it being given less by wrapping.
1892 let _ = writeln!(
1893 css,
1894 ".{} {{\n white-space: nowrap;\n width: 1%;\n}}",
1895 class("cell-content", opts)
1896 );
1897
1898 // A fixed column has no length to be fixed to. The description carries none
1899 // and `Sizing` is not reachable from here, so it behaves as content: the
1900 // honest answer to a width nobody supplied, and the same one `Sizing::track`
1901 // gives it.
1902 let _ = writeln!(
1903 css,
1904 ".{} {{\n white-space: nowrap;\n}}",
1905 class("cell-fixed", opts)
1906 );
1907
1908 // Optional columns go at the narrowest class, secondary ones go with them,
1909 // which is the cutoff walk `kept_at` describes said as two media queries.
1910 // Essential columns have no rule at all, because never dropping is what not
1911 // being mentioned already means.
1912 for (size, drops) in [
1913 (
1914 SizeClass::Compact,
1915 &["cell-drops-first", "cell-drops-next"][..],
1916 ),
1917 (SizeClass::Medium, &["cell-drops-first"][..]),
1918 ] {
1919 let selectors: Vec<String> = drops
1920 .iter()
1921 .map(|drop| format!(".{}", class(drop, opts)))
1922 .collect();
1923 css.push_str(&gated(
1924 Some(&size.media_condition()),
1925 &format!("{} {{\n display: none;\n}}\n", selectors.join(",\n")),
1926 ));
1927 }
1928
1929 // What is inside a cell, which the table side could not say until
1930 // makeover-layout 0.14.0. Every cell was one `.cell` and one content
1931 // colour, so a button in a cell was painted as text -- the drift
1932 // `RowPart::intent` has prevented for list rows since 0.2.0 and prevented
1933 // for nothing here.
1934 //
1935 // The colour goes on `.cell-value` rather than on `.cell`, and that
1936 // placement is the whole fix. On the container it would cascade into the
1937 // tokens and the controls sitting beside the text, which is the bug said
1938 // in one rule; on the part that is text, it reaches text and stops.
1939 for part in [
1940 CellPart::Value,
1941 CellPart::Tokens,
1942 CellPart::Actions,
1943 CellPart::Link,
1944 ] {
1945 // Three of the four inherit, each for its own reason: a token carries
1946 // its own tone, an action is a control rather than text, and a link
1947 // takes the action colour from the anchor it is. `CellPart::intent`
1948 // says so by answering with the intent inheriting already gives, and
1949 // pinning that would be louder than saying nothing.
1950 //
1951 // Written as a skip-list rather than as a match on Value, so a member
1952 // added upstream gets its intent emitted rather than being silently
1953 // dropped. That is the same trade `part_class`'s fallback makes: land
1954 // plainly, never land as nothing.
1955 if !matches!(part, CellPart::Tokens | CellPart::Actions | CellPart::Link) {
1956 let _ = writeln!(
1957 css,
1958 ".{} {{\n color: var(--{});\n}}",
1959 class(cell_part_class(part), opts),
1960 part.intent()
1961 );
1962 }
1963 }
1964
1965 css
1966 }
1967
1968 /// The component layer: every named thing phase A emits.
1969 ///
1970 /// No scrollbar track. It was on the phase A list and came off: eight lines of
1971 /// `::-webkit-scrollbar` with no shape a terminal or an immediate-mode painter
1972 /// would want handed to it, so it stays with the apps.
1973 #[must_use]
1974 pub fn component_rules(opts: &Emit) -> String {
1975 let mut css = String::new();
1976 css.push_str(&surface_rules(opts));
1977 css.push_str(&link_rules(opts));
1978 css.push_str(&token_rules(opts));
1979 css.push_str(&selector_rules(opts));
1980 css.push_str(&row_rules(opts));
1981 css.push_str(&run_rules(opts));
1982 css.push_str(&progress_rules(opts));
1983 css.push_str(&awaiting_rules(opts));
1984 css.push_str(&figure_rules(opts));
1985 css.push_str(&picture_rules(opts));
1986 css.push_str(&showing_rules(opts));
1987 css.push_str(&track_rules(opts));
1988 css.push_str(&state_rules(opts));
1989 css.push_str(&table_rules(opts));
1990 css.push_str(&facet::facet_rules(opts));
1991 css.push_str(&form::editor_rules(opts));
1992 css.push_str(&form::suggestion_rules(opts));
1993 css.push_str(&form::unit_rules(opts));
1994 css.push_str(&form::option_detail_rules(opts));
1995 css.push_str(&form::note_rules(opts));
1996 css.push_str(&leaving_rules());
1997 css
1998 }
1999
2000 /// How a transient notice goes away.
2001 ///
2002 /// `makeover-timing` says that `Intent::Dismiss` is how long a notice lives
2003 /// *before it starts to leave*, and that the leaving itself is `Motion::Fade`.
2004 /// `makeover-build` writes `--motion-fade` into every consumer's `timing.css`,
2005 /// and this is the rule that reads it. Removing the node the moment the dismiss
2006 /// is up skips the leaving entirely.
2007 ///
2008 /// # Why an attribute and not a class
2009 ///
2010 /// [`Emit`]'s prefix moves every class this crate writes, so a class here would
2011 /// have to be resolved through `class()` by whoever sets it -- and the party
2012 /// setting it is a script, which has no prefix to hand. `data-leaving` is
2013 /// outside that namespace, so a renderer can set it from JavaScript with no
2014 /// coordination.
2015 ///
2016 /// The transition sits on the notice and the opacity on the leaving state, so
2017 /// the element is transitionable before the attribute arrives; a transition
2018 /// declared in the same rule as the value it changes has nothing to animate
2019 /// from.
2020 ///
2021 /// # Reduced motion is handled by the token, not by a second rule here
2022 ///
2023 /// `timing.css` already zeroes `--motion-fade` under `prefers-reduced-motion`.
2024 /// The reader who asked for less motion gets an instant change rather than a
2025 /// fade, and the renderer that sets the attribute must still remove the node on
2026 /// a timer rather than on `transitionend` -- a zero-length transition may fire
2027 /// no event at all, and a node waiting on one that never comes stays forever.
2028 ///
2029 /// The fallback is `0ms` and not a guessed duration: a page with no timing
2030 /// sheet has not opted into this vocabulary, and the honest answer there is the
2031 /// behaviour it had before, which is the notice going away at once.
2032 fn leaving_rules() -> String {
2033 let mut css = String::new();
2034 let _ = writeln!(
2035 css,
2036 "[data-notice] {{\n transition: opacity var(--motion-fade, 0ms) \
2037 ease-out;\n}}"
2038 );
2039 let _ = writeln!(css, "[data-notice][data-leaving] {{\n opacity: 0;\n}}");
2040 css
2041 }
2042
2043 /// The whole phase-A stylesheet: properties, depth rules and components, in
2044 /// [`CSS_LAYER`], under a generated-file banner.
2045 ///
2046 /// The banner sits outside the layer, because a comment participates in no
2047 /// cascade and a reader opening the file should see what it is before seeing
2048 /// an at-rule.
2049 #[must_use]
2050 pub fn stylesheet(opts: &Emit) -> String {
2051 let body = in_css_layer(&format!(
2052 ":root {{\n{}}}\n\n{}\n{}",
2053 bevel_properties(opts),
2054 depth_rules(opts),
2055 component_rules(opts)
2056 ));
2057 // Counted from the body rather than through `vocabulary::names`, which
2058 // calls back into here.
2059 let classes = vocabulary::classes_in_css(&body).len();
2060 let version = VERSION;
2061 format!(
2062 "/* Generated by makeover-webview {version} from makeover-layout, \
2063 {classes} classes.\n \
2064 Do not edit. The version and the count are here because a stale\n \
2065 lockfile fails silently: an older emitter writes a well-formed sheet\n \
2066 with components missing, and nothing else in the file says so. If\n \
2067 this version trails what the manifest asks for, re-resolve.\n\n \
2068 Depth is a fill and an edge together; naming them apart is what let\n \
2069 them disagree. See the crate's README and wiki note makeover-layout.\n\n \
2070 Everything below is in the `{CSS_LAYER}` cascade layer. Declare the\n \
2071 order once in your own stylesheet, or this layer's position is decided\n \
2072 by whichever generated file the browser happens to see first:\n\n \
2073 @layer {CSS_LAYER}, base, components, responsive; */\n{body}"
2074 )
2075 }
2076
2077 #[cfg(test)]
2078 mod tests;
2079