max / makeover-immediate

41.7 KB · 1012 lines History Blame Raw

1	//! The immediate-mode renderer for [`makeover_layout`].
2	//!
3	//! <!-- wiki: makeover-immediate -->
4	//!
5	//! Named for the mode, not the library, the way `makeover-tui` is named for
6	//! the target and not for ratatui. Immediate mode is the constraint that
7	//! actually separates this renderer from the other two, and egui is the
8	//! backend it is written against.
9	//!
10	//! It is the harshest renderer the description has to survive: no
11	//! `box-shadow`, no `inset`, no cascade, no retained tree to mutate, and
12	//! `Visuals.widgets.*.bg_stroke` is a single stroke with no per-side control.
13	//! A two-tone lit edge is not something egui can be configured into producing,
14	//! so it gets painted by hand here, once, instead of in every consuming app.
15	//!
16	//! # What this crate does and does not own
17	//!
18	//! It owns the expression: two mitred polylines for a bevel and a `Frame`
19	//! for a filled region. It owns no colours and no sizes, and no longer owns a
20	//! substitution: it briefly supplied the page for a well, which was a stand-in
21	//! for `surface-well` before makeover derived it, and every consumer reads the
22	//! real token now. [`Palette`] is supplied by the caller,
23	//! already resolved, and every radius, margin and stroke width arrives in
24	//! [`FrameStyle`].
25	//!
26	//! That split is why the crate has no dependency on `makeover` itself: the app
27	//! already resolves a theme, and coupling a renderer to a colour crate's
28	//! version would buy nothing.
29	//!
30	//! # The cascade is the real difference
31	//!
32	//! A stylesheet can say "a pressed button inverts its bevel" once and let the
33	//! cascade carry it. An immediate-mode renderer has nowhere to put that, so
34	//! every call site decides. [`makeover_layout::Depth::pressed`] is what keeps
35	//! the decision from being re-derived per widget.
36	//!
37	//! # 0.11.0: the overlay becomes reachable
38	//!
39	//! 0.10.0 answered what overlaying means in immediate mode with
40	//! [`Palette::cast`], and nothing could ask: the description had no
41	//! `Depth::Overlay` until `makeover-layout` 0.14.0, so the answer sat beside a
42	//! question that could not be posed. [`frame`] now hands the cast shadow to the
43	//! `egui::Frame` for any depth whose fill is [`Fill::Overlay`], keyed off the
44	//! fill rather than the variant.
45	//!
46	//! The same release brings `makeover_layout::CellPart`, which 0.11.0 carried
47	//! and did not draw. [`table`] draws it, below.
48	//!
49	//! # 0.12.0: the table
50	//!
51	//! [`table`] is the vocabulary 0.11.0 took without using. The consumer is
52	//! audiofiles, whose file list is the only table in the tree exercising all four
53	//! of what the description says about one at once: sortable headings with
54	//! carets, fixed and remainder tracks, and buttons inside cells.
55	//!
56	//! Two things it forces, both named where they land:
57	//!
58	//! - `egui_extras`, this crate's first dependency past egui. egui has no
59	//! table, and `Grid` gives no per-column sizing, no sticky header and no
60	//! scroll sync, which is why audiofiles reached for `egui_extras` rather than
61	//! building on `Grid`. A third answer here would reimplement that crate worse.
62	//! - [`Palette::action`], on the footing [`Palette::content`] arrived on: a
63	//! link in a cell is the first thing here needing the action intent.
64	//!
65	//! Narrowing works differently from the terminal's and the module header says
66	//! why: a content column cannot be measured before the app's closure has drawn
67	//! it, so `egui_extras` sizes it and the declared floor budgets it.
68	//!
69	//! # 0.13.0: what the adoption found missing
70	//!
71	//! 0.12.0 shipped [`table`] before audiofiles had taken it, and taking it found
72	//! three things the file list already did that the function could not say. All
73	//! three are host idiom rather than description, which is why they land here and
74	//! not in `makeover-layout`, and all three are answered on a handle the app
75	//! never sees: the `egui_extras` row and builder this crate owns. That is
76	//! [`table::cell`]'s reasoning again: what the app cannot reach, the renderer
77	//! owes it.
78	//!
79	//! - A selected row. [`table::Body::selected`], a predicate asked per row,
80	//! because `set_selected` is a method on the row. Without it a file list has
81	//! no way to show what is selected, which is most of what a file list does.
82	//! - Scrolling a row into view. [`table::Body::scroll_to`], because
83	//! `scroll_to_row` is a method on the builder. A keyboard cursor that moves
84	//! off-screen and stays there is the bug this prevents.
85	//! - Dragging a divider. [`table::TableStyle::resizable`], which passes the
86	//! test `sticky_header` failed in 0.12.0: egui_extras offers two settings here
87	//! and a renderer can honestly make either choice.
88	//!
89	//! A fourth was found and is not a knob. Cells are centred on the row's centre
90	//! line, always, because there is no second honest answer and egui's own default
91	//! (top-aligned) is the one thing it cannot be.
92	//!
93	//! [`table::Body`] is also what splits a table's per-frame facts from its
94	//! description and from its style. A row count, a selection and a scroll request
95	//! are none of them style, and none of them survive the frame.
96	//!
97	//! # Forms
98	//!
99	//! 0.5.0 adds the field vocabulary on top of the depth vocabulary:
100	//! [`makeover_layout::Field`] rendered to egui widgets, in [`field`], and a set
101	//! of them laid down a column in [`group`]. Before it, a description saying
102	//! "text field, labelled, required, with this hint" had no way to become a
103	//! widget here, and audiofiles' forms stayed hand-rolled.
104	//!
105	//! `makeover-webview` got there first and its form emitter is the precedent
106	//! followed rather than re-derived, including the parts that are bug fixes: a
107	//! select handed a value none of its options carries keeps that value visible
108	//! instead of silently reading as the first option, which is a save-the-wrong-
109	//! thing bug goingson hit for real.
110	//!
111	//! What differs is forced by the mode and not chosen:
112	//!
113	//! - The value arrives as a `&mut`. [`Filling`] borrows the app's own field
114	//! and the widget writes through it. There is no DOM to read back out of,
115	//! which is also why the description deliberately does not carry the value.
116	//! - A text control is drawn as a well and a select is not. The description
117	//! holds that a well is for anything the user looks into, and a text field
118	//! is its own example; a select and a checkbox are pressed rather than looked
119	//! into, so they keep egui's own control painting.
120	//! - Focus is not describable, and egui owns all of it here. Reach,
121	//! focus and the focus ring are this renderer's three answers and
122	//! egui already has all three: its own id stack decides what is reachable,
123	//! its own state decides what holds the keyboard, and it paints exactly one
124	//! ring. A description states none of them — `makeover_layout` removed the
125	//! member that used to try in 0.19.0 — and drawing a second ring on top of
126	//! egui's would break the one-ring rule it would have come from. The terms
127	//! are defined once in `makeover_layout`'s crate header, "Reach, focus and
128	//! the focus ring". [`makeover_layout::State::Disabled`] is drawn, because
129	//! egui has no opinion about it until told.
130	//! - **App-level chrome is not drawn here yet, and that is an omission rather
131	//! than a decision.** `quasi-router` names the affordances that outlive one
132	//! screen — a `Chrome` of key bindings, and an `Outcome::Over` for a screen
133	//! drawn over another — and the webview and terminal renderers both answer
134	//! them. This one does not: an egui host wanting a command palette still
135	//! writes its own. Written down because the silent version of this reads as
136	//! "egui does not need one", and it does; nothing has asked for it yet. The
137	//! shape it would take is not in doubt — egui has `Area` and `Order`, which
138	//! is what an overlay is — so this is work, not a design question.
139
140	#![forbid(unsafe_code)]
141
142	use egui::{
143	Color32, ComboBox, CornerRadius, Margin, Painter, Rect, Response, RichText, Shape, Stroke,
144	TextEdit, Ui,
145	};
146	use makeover_layout::{Bevel, Choice, Depth, Edge, Field, FieldKind, Fill, State};
147
148	/// Columns, narrowing, cell parts and the sort caret, over `egui_extras`.
149	pub mod table;
150
151	/// The resolved colours this renderer needs, as flat values.
152	///
153	/// Built by the app from whatever it already uses to resolve a theme, then
154	/// held and reused. Deliberately not a trait and not string-keyed: a bevel is
155	/// painted per widget per frame, and a map lookup per edge is a cost with
156	/// nothing to show for it.
157	#[derive(Debug, Clone, Copy, PartialEq, Eq)]
158	pub struct Palette {
159	/// `surface-page`.
160	pub page: Color32,
161	/// `surface-raised`.
162	pub raised: Color32,
163	/// `surface-overlay`.
164	pub overlay: Color32,
165	/// `surface-well`.
166	///
167	/// Required, not optional. makeover derives it for every theme from 2.3.0,
168	/// so a resolved palette without a well is not a thing that exists here.
169	/// It was an `Option` while that was untrue, and this renderer substituted
170	/// the page; `makeover-tui` keeps its own `Option` for a different reason,
171	/// since a terminal can have the colour and still be unable to show it.
172	pub well: Color32,
173	/// `surface-sunken`.
174	///
175	/// A surface set back from the one it sits on, by colour and nothing else.
176	/// Not a well: a well is a hole with an edge, and this has no edge. An
177	/// immediate-mode renderer paints an arbitrary rect, so unlike
178	/// `makeover-tui` it has no excuse for declining this one.
179	///
180	/// Required rather than optional, on the same footing as `well`: all 31
181	/// themes makeover embeds author it.
182	pub sunken: Color32,
183	/// `bevel-light`.
184	pub bevel_light: Color32,
185	/// `bevel-dark`.
186	pub bevel_dark: Color32,
187	/// `elevation`.
188	///
189	/// What a surface that floats OVER the page is cast onto it with. The one
190	/// intent here that is about a surface's relationship to the page rather
191	/// than about the surface, which is why it is a translucent near-black on
192	/// every theme rather than something read off the palette's own ramp.
193	///
194	/// Only for a surface that overlays. A menu, a tooltip, a modal. A
195	/// surface in the layout takes a bevel, and reaching for this on a panel
196	/// or a card is how a pre-Platinum look survives a conversion under a new
197	/// name.
198	///
199	/// egui has a real answer for this where a terminal does not: see
200	/// [`Palette::cast`], which is the shadow to hand an
201	/// [`egui::Frame`](egui::Frame).
202	pub elevation: Color32,
203	/// `content`.
204	///
205	/// Ordinary text. Added 0.5.0 with the field renderer, which is the first
206	/// thing here that draws any: until then this crate painted surfaces and
207	/// edges and let the caller's own egui visuals answer for text.
208	pub content: Color32,
209	/// `content-muted`.
210	///
211	/// A field's hint, and what
212	/// [`makeover_layout::State::Disabled`](makeover_layout::State::Disabled)
213	/// resolves to. Both readings come from the description rather than from
214	/// here: `State::Disabled` names this intent by token.
215	pub content_muted: Color32,
216	/// `action-primary`.
217	///
218	/// What a control is drawn in. Added 0.12.0 with the table renderer, for the
219	/// reason `content` was added 0.5.0 with the field renderer: a link in a
220	/// cell is the first thing here that needs the action intent, and a palette
221	/// should carry what is used.
222	///
223	/// This is the intent [`CellPart`](makeover_layout::CellPart) exists to
224	/// separate. A cell holding a control took the cell's text colour until the
225	/// description could say otherwise, which is the drift `makeover-layout`
226	/// 0.14.0 named and `makeover-webview` 0.25.0 fixed on its own side.
227	pub action: Color32,
228	/// `danger`.
229	///
230	/// A field's error message. The one [`makeover_layout::Tone`] this renderer
231	/// needs so far, and it is here rather than as a whole resolved tone set
232	/// because notices are not drawn here yet and a palette should carry what
233	/// is used.
234	pub danger: Color32,
235	}
236
237	impl Palette {
238	/// Resolve a surface intent, or `None` for one this renderer does not know.
239	///
240	/// A plain lookup. There is still no substitution: the old one existed only
241	/// while `surface-well` was underived, and every consumer reads the real
242	/// token now.
243	///
244	/// `Option` since 0.3.0, because [`Fill`] became `#[non_exhaustive]` in
245	/// `makeover-layout` 0.4.0 and a total function over an open enum can only
246	/// stay total by inventing a colour for a member it has never heard of.
247	/// That is the substitution this crate spent 0.2.0 removing, so the return
248	/// type moved instead. Every member the description has today is answered
249	/// with `Some`.
250	#[must_use]
251	pub const fn fill(&self, fill: Fill) -> Option<Color32> {
252	match fill {
253	Fill::Page => Some(self.page),
254	Fill::Raised => Some(self.raised),
255	Fill::Overlay => Some(self.overlay),
256	Fill::Well => Some(self.well),
257	Fill::Sunken => Some(self.sunken),
258	_ => None,
259	}
260	}
261
262	/// The cast shadow for a surface that overlays the page.
263	///
264	/// What "overlaying" means in immediate mode, answered rather than skipped.
265	/// egui already paints shadows for its menus and windows through
266	/// [`egui::Frame::shadow`], so the honest port is to hand that machinery the
267	/// theme's tone instead of egui's own default, not to invent a painter here
268	/// the way [`paint_bevel`] had to.
269	///
270	/// The geometry matches what `makeover-webview` composes, in points rather
271	/// than pixels: a small downward offset and a wide soft blur. A Platinum-era
272	/// menu sits just off the page rather than hovering above it.
273	///
274	/// ```no_run
275	/// # let palette: makeover_immediate::Palette = unimplemented!();
276	/// # let ui: &mut egui::Ui = unimplemented!();
277	/// egui::Frame::popup(ui.style())
278	/// .shadow(palette.cast())
279	/// .show(ui, \|ui\| { ui.label("over the page"); });
280	/// ```
281	#[must_use]
282	pub const fn cast(&self) -> egui::Shadow {
283	egui::Shadow {
284	offset: [0, 2],
285	blur: 24,
286	spread: 0,
287	color: self.elevation,
288	}
289	}
290
291	/// Resolve a bevel edge intent.
292	#[must_use]
293	pub const fn edge(&self, edge: Edge) -> Color32 {
294	match edge {
295	Edge::Light => self.bevel_light,
296	Edge::Dark => self.bevel_dark,
297	}
298	}
299	}
300
301	/// The geometry a framed region is drawn with.
302	///
303	/// Every field is a value, which is why they all arrive from the caller:
304	/// radius and border width belong to `makeover-geometry`, and margins come
305	/// from its relational gaps.
306	#[derive(Debug, Clone, Copy, PartialEq)]
307	pub struct FrameStyle {
308	/// Corner radius. Square under the Platinum default.
309	pub radius: CornerRadius,
310	/// Inner margin between the frame and its contents.
311	pub margin: Margin,
312	/// Bevel stroke width, in points.
313	pub stroke: f32,
314	}
315
316	impl Default for FrameStyle {
317	/// A one-point square frame with no inner margin.
318	fn default() -> Self {
319	Self {
320	radius: CornerRadius::ZERO,
321	margin: Margin::ZERO,
322	stroke: 1.0,
323	}
324	}
325	}
326
327	/// Paint a two-tone edge just inside `rect`.
328	///
329	/// Fill first, bevel after: this adds two polylines and nothing else, so it
330	/// composes over whatever is already there. That is what lets it go over an
331	/// [`egui::TextEdit`] after `ui.add`, where the widget's own fill has landed.
332	///
333	/// Two three-point polylines meeting at opposite corners, rather than four
334	/// segments, so egui mitres the corner joins instead of leaving a notch.
335	///
336	/// The dark polyline is drawn second, so the two corners where the runs meet
337	/// take its tone. That is the right answer here rather than a concession.
338	/// [`makeover_layout::Bevel`] holds those corners to belong to both edges, and
339	/// a renderer with room to divide one should; at the default one-point stroke
340	/// the corner is a one-point square, so the division is sub-pixel and
341	/// antialiasing resolves it to the same blend the mitre already gives. Splitting
342	/// it would add a seam and no information. `makeover-tui` does split, because a
343	/// terminal cell is large enough that not splitting costs a visible cell of edge
344	/// weight — the same rule, at a resolution where it has something to say.
345	pub fn paint_bevel(painter: &Painter, rect: Rect, bevel: Bevel, palette: &Palette, stroke: f32) {
346	let (top_left, bottom_right) = bevel.edges();
347
348	// Inset by half a stroke so the line lands inside `rect` rather than
349	// straddling its edge, which on a fractional-scale display is the
350	// difference between one crisp pixel and two dim ones.
351	let r = rect.shrink(stroke / 2.0);
352
353	painter.add(Shape::line(
354	vec![r.left_bottom(), r.left_top(), r.right_top()],
355	Stroke::new(stroke, palette.edge(top_left)),
356	));
357	painter.add(Shape::line(
358	vec![r.right_top(), r.right_bottom(), r.left_bottom()],
359	Stroke::new(stroke, palette.edge(bottom_right)),
360	));
361	}
362
363	/// Draw a region at a given [`Depth`]: its fill and its edge, together.
364	///
365	/// [`Depth::Flat`] gets neither, and inherits whatever it sits on. That is the
366	/// difference between level-with and painted-the-same-colour, and it is the
367	/// reason `Depth::fill` returns an [`Option`] rather than defaulting to the
368	/// page.
369	pub fn frame<R>(
370	ui: &mut Ui,
371	depth: Depth,
372	palette: &Palette,
373	style: FrameStyle,
374	add_contents: impl FnOnce(&mut Ui) -> R,
375	) -> R {
376	let mut f = egui::Frame::new()
377	.corner_radius(style.radius)
378	.inner_margin(style.margin);
379	// Two ways there is no fill to paint, and they collapse to the same
380	// outcome: the depth names none (Depth::Flat), or it names one this
381	// renderer cannot resolve. Either way the frame goes unfilled and the
382	// bevel below carries the depth on its own, which is the rule this
383	// module already documents for Flat.
384	if let Some(fill) = depth.fill().and_then(\|f\| palette.fill(f)) {
385	f = f.fill(fill);
386	}
387	// A surface that overlays the page is cast onto it. [`Palette::cast`] has
388	// answered what that means here since 0.10.0 and nothing could reach it: a
389	// description had no way to say Overlay until makeover-layout 0.14.0, so
390	// the answer sat beside the question. Keyed off the fill rather than the
391	// variant, so it stays right for whatever else the description calls an
392	// overlay later.
393	if depth.fill() == Some(Fill::Overlay) {
394	f = f.shadow(palette.cast());
395	}
396	let framed = f.show(ui, add_contents);
397	if let Some(bevel) = depth.bevel() {
398	paint_bevel(
399	ui.painter(),
400	framed.response.rect,
401	bevel,
402	palette,
403	style.stroke,
404	);
405	}
406	framed.inner
407	}
408
409	/// The geometry a field group is drawn with.
410	///
411	/// Values again, for the reason [`FrameStyle`] is: every number here belongs to
412	/// `makeover-geometry` and arrives already resolved.
413	#[derive(Debug, Clone, Copy, PartialEq)]
414	pub struct FieldStyle {
415	/// The well a text control sits in.
416	pub frame: FrameStyle,
417	/// Between a field's own parts: its label, its control, its hint and its
418	/// error.
419	pub gap: f32,
420	/// Between one field and the next.
421	pub group_gap: f32,
422	/// What marks a required field, appended to its label.
423	///
424	/// A knob rather than a constant, because it is the one piece of copy in
425	/// this crate and copy is not a renderer's call. A webview does not need it
426	/// at all — it emits the `required` attribute and the browser answers — so
427	/// this renderer is the first place where a compulsory field either shows
428	/// that it is or silently does not.
429	pub required_marker: &'static str,
430	}
431
432	impl Default for FieldStyle {
433	/// The default frame, no gaps, and an asterisk.
434	fn default() -> Self {
435	Self {
436	frame: FrameStyle::default(),
437	gap: 0.0,
438	group_gap: 0.0,
439	required_marker: "*",
440	}
441	}
442	}
443
444	/// What the field currently holds, borrowed from wherever the app keeps it.
445	///
446	/// The immediate-mode counterpart of `makeover_webview::form::Value`, and the
447	/// place the two renderers are forced apart: there the value is read back out
448	/// of the DOM after the fact, and here the widget writes through this borrow as
449	/// it is edited. Same reason the description carries neither.
450	///
451	/// An enum rather than a bag of options, on the reasoning
452	/// `makeover_webview::form::Value` records: a checkbox holding a string is
453	/// unsayable here, where a struct would let it be said and then have to cope.
454	#[derive(Debug, Default)]
455	pub enum Filling<'a> {
456	/// Nothing to edit. The control is drawn and does not answer.
457	#[default]
458	Absent,
459	/// The buffer behind anything that takes typed text, a select included:
460	/// what a select holds is the `value` of one of its [`Choice`]s.
461	///
462	/// [`Choice`]: makeover_layout::Choice
463	Text(&'a mut String),
464	/// A checkbox, on or off.
465	On(&'a mut bool),
466	}
467
468	/// The label, marked if the field is compulsory.
469	fn label_text(field: &Field<'_>, style: &FieldStyle) -> String {
470	if field.required {
471	format!("{} {}", field.label, style.required_marker)
472	} else {
473	field.label.to_owned()
474	}
475	}
476
477	/// The four shapes a control comes in here, which is fewer than there are
478	/// kinds.
479	///
480	/// [`FieldKind`] is `#[non_exhaustive]` and grows; this does not, because the
481	/// ways egui has of asking for a value do not. Reducing the open set to this
482	/// closed one in one total function is what keeps a new kind from needing a new
483	/// arm at every match below.
484	#[derive(Debug, Clone, Copy, PartialEq, Eq)]
485	enum Control {
486	/// Typed into, so it is drawn as a well: the user looks into it.
487	Typed,
488	/// Picked from a control that shows one option at a time. Pressed rather
489	/// than looked into, so egui's own control painting stands.
490	Chosen,
491	/// Picked from options that are all on screen at once.
492	///
493	/// Apart from [`Chosen`](Self::Chosen) because the description holds them
494	/// apart, and holding them apart is the whole content of
495	/// [`FieldKind::Radio`]: same question, and an answer the user can read
496	/// without opening anything.
497	Listed,
498	/// Held on or off.
499	Toggled,
500	}
501
502	/// Which shape a kind takes.
503	///
504	/// The wildcard falls to [`Control::Typed`] on purpose: a kind added to the
505	/// description since this renderer was built degrades to a text box, which
506	/// accepts any value the others would, rather than to nothing drawn at all.
507	///
508	/// `FieldKind::File` lands there as of makeover-layout 0.11.0, and it is left
509	/// there rather than grown a shape of its own. egui's honest answer is a button
510	/// that opens a native picker, which is a fifth control and a file-dialog
511	/// dependency; no consumer of this crate asks for a file field yet. Same
512	/// position this crate took on `Meter` at 0.10.0: the membership test is that
513	/// every renderer could answer honestly, not that each one does on the day.
514	/// A path in a text box is not nothing, and it is what an app that needs this
515	/// tomorrow gets today.
516	///
517	/// `FieldKind::Date` and `FieldKind::DateTime` land there too, as of
518	/// makeover-layout 0.15.0, on the same footing and with one thing owed. A
519	/// calendar is a sixth control and bare `egui` has none, so a typed value is
520	/// the honest answer here; what the app gets is the format the description
521	/// names, `makeover_layout::DATE_FORMAT` and `DATETIME_FORMAT`, which is why
522	/// those are constants rather than a sentence. audiofiles is the only consumer
523	/// of this crate and asks for neither today. A calendar popup is the upgrade
524	/// whenever one does.
525	const fn control_shape(kind: FieldKind) -> Control {
526	match kind {
527	FieldKind::Select => Control::Chosen,
528	FieldKind::Radio => Control::Listed,
529	FieldKind::Checkbox => Control::Toggled,
530	_ => Control::Typed,
531	}
532	}
533
534	/// What a select shows for the value it currently holds.
535	///
536	/// A value no option carries stays on screen as itself rather than reading as
537	/// whichever option happens to be first. goingson saved a backup retention of
538	/// 10 against a 1/3/7/14/0 list and the browser silently showed it as 1, so the
539	/// next save wrote a value nobody chose; `makeover-webview` grew the fix as a
540	/// stray `<option>` and this is the same fix in the shape egui allows.
541	fn shown_label<'a>(options: &'a [Choice<'a>], value: &'a str) -> &'a str {
542	options
543	.iter()
544	.find(\|opt\| opt.value == value)
545	.map_or(value, \|opt\| opt.label)
546	}
547
548	/// The control alone, without its label, hint or error.
549	fn control(
550	ui: &mut Ui,
551	field: &Field<'_>,
552	filling: Filling<'_>,
553	palette: &Palette,
554	style: &FieldStyle,
555	) -> Response {
556	// The mismatch path: described as one thing and filled as another. Nothing
557	// here can fix it, so it is drawn as the empty, inert version of what was
558	// described — visible on screen, in the way an empty select is at the
559	// webview renderer, rather than reported in a log nobody reads.
560	let mut discard = String::new();
561	let mut off = false;
562
563	match control_shape(field.kind) {
564	Control::Typed => {
565	let text = match filling {
566	Filling::Text(text) => text,
567	_ => &mut discard,
568	};
569	// An empty frame and no margin: the well is this crate's, and egui's
570	// own control background and padding would sit underneath it saying
571	// something different about both.
572	let mut edit = if matches!(field.kind, FieldKind::Textarea) {
573	TextEdit::multiline(text)
574	} else {
575	TextEdit::singleline(text)
576	}
577	.frame(egui::Frame::NONE)
578	.margin(Margin::ZERO)
579	.text_color(palette.content)
580	.password(field.kind.confidential());
581	if let Some(ghost) = field.placeholder {
582	edit = edit.hint_text(RichText::new(ghost).color(palette.content_muted));
583	}
584	frame(ui, Depth::Well, palette, style.frame, \|ui\| ui.add(edit))
585	}
586	Control::Toggled => {
587	let on = match filling {
588	Filling::On(on) => on,
589	_ => &mut off,
590	};
591	ui.checkbox(on, RichText::new(field.label).color(palette.content))
592	}
593	Control::Listed => {
594	let value = match filling {
595	Filling::Text(text) => text,
596	_ => &mut discard,
597	};
598	// No `shown_label` counterpart, and none is needed: a value no
599	// option carries leaves every button unfilled, which is already
600	// the honest report on screen. The select needs the fix because it
601	// has one slot and must put something in it.
602	let group = ui.vertical(\|ui\| {
603	let mut answered: Option<Response> = None;
604	for opt in field.options {
605	let picked = ui.radio_value(
606	value,
607	opt.value.to_owned(),
608	RichText::new(opt.label).color(palette.content),
609	);
610	answered = Some(match answered {
611	Some(prev) => prev.union(picked),
612	None => picked,
613	});
614	}
615	answered
616	});
617	// A group described with no options answers as its own empty area
618	// rather than as no response at all, which keeps the caller's
619	// `.changed()` chain working on a field whose option list has not
620	// loaded yet.
621	group.inner.unwrap_or(group.response)
622	}
623	Control::Chosen => {
624	let value = match filling {
625	Filling::Text(text) => text,
626	_ => &mut discard,
627	};
628	let shown = shown_label(field.options, value);
629	ComboBox::from_id_salt(field.name)
630	.selected_text(RichText::new(shown).color(palette.content))
631	.show_ui(ui, \|ui\| {
632	for opt in field.options {
633	ui.selectable_value(
634	value,
635	opt.value.to_owned(),
636	RichText::new(opt.label).color(palette.content),
637	);
638	}
639	})
640	.response
641	}
642	}
643	}
644
645	/// One field, as the column the app drops into its form.
646	///
647	/// The anatomy is `makeover-webview`'s, so the two renderers put a form
648	/// together the same way: label, control, hint, error, top to bottom, with a
649	/// checkbox labelling itself instead of taking a label above.
650	///
651	/// Returns [`None`] for a [`FieldKind::Hidden`] field, which is what
652	/// [`FieldKind::visible`] means and is the honest answer here: a webview still
653	/// emits an input for it because the form submits, and an immediate-mode
654	/// renderer has no form and no submission, so a hidden field is a value the app
655	/// already holds and there is nothing to draw or to respond to.
656	///
657	/// `state` is the description's interaction axis.
658	/// [`State::Disabled`] greys the field and stops it answering, through
659	/// [`State::suppresses_interaction`] rather than through a second reading of
660	/// what disabled means. Focus is not on that axis and never reaches here: egui
661	/// owns reach, focus and the ring for this renderer, and one ring means not a
662	/// second one per renderer that happens to have opinions.
663	pub fn field(
664	ui: &mut Ui,
665	field: &Field<'_>,
666	filling: Filling<'_>,
667	state: Option<State>,
668	palette: &Palette,
669	style: &FieldStyle,
670	) -> Option<Response> {
671	if !field.kind.visible() {
672	return None;
673	}
674	let enabled = !state.is_some_and(State::suppresses_interaction);
675	let text = if enabled {
676	palette.content
677	} else {
678	palette.content_muted
679	};
680
681	let response = ui
682	.vertical(\|ui\| {
683	ui.spacing_mut().item_spacing.y = style.gap;
684
685	// A checkbox labels itself, on the right of the box.
686	// `FieldKind::labels_itself` is the description saying so, and both
687	// webview apps special-cased it inline before it did.
688	if !field.kind.labels_itself() {
689	ui.label(RichText::new(label_text(field, style)).color(text));
690	}
691
692	let response = ui
693	.add_enabled_ui(enabled, \|ui\| control(ui, field, filling, palette, style))
694	.inner;
695
696	// Standing help first, then what is wrong now. Both, in that order,
697	// for the reason the webview renderer names both in
698	// `aria-describedby`: an error appearing must not take the hint
699	// away with it.
700	if let Some(hint) = field.hint {
701	ui.label(RichText::new(hint).color(palette.content_muted));
702	}
703	if let Some(error) = field.error {
704	ui.label(RichText::new(error).color(palette.danger));
705	}
706	response
707	})
708	.inner;
709
710	Some(response)
711	}
712
713	/// A set of fields, laid down a column.
714	///
715	/// `show_extended` is the disclosure, and it is a parameter rather than state
716	/// held here because the disclosure belongs to the form and not to any field:
717	/// [`Field::extended`] marks which fields are behind one, and the app owns
718	/// whether it is open. That is the same division `makeover-webview` draws when
719	/// it marks the group `data-extended` and emits no control to toggle it.
720	///
721	/// `draw` is called once per field that should be visible, in order. Taking a
722	/// callback rather than a slice of [`Filling`]s is what keeps the app's own
723	/// values borrowed one at a time: a form's fields usually live in different
724	/// structs, and a parallel array would have to be built each frame and kept in
725	/// step with the description by hand.
726	pub fn group<'a>(
727	ui: &mut Ui,
728	fields: &'a [Field<'a>],
729	show_extended: bool,
730	style: &FieldStyle,
731	mut draw: impl FnMut(&mut Ui, &'a Field<'a>),
732	) {
733	ui.vertical(\|ui\| {
734	ui.spacing_mut().item_spacing.y = style.group_gap;
735	for f in fields {
736	if f.extended && !show_extended {
737	continue;
738	}
739	draw(ui, f);
740	}
741	});
742	}
743
744	#[cfg(test)]
745	mod tests {
746	use super::*;
747
748	fn palette(well: Color32) -> Palette {
749	Palette {
750	page: Color32::from_rgb(1, 1, 1),
751	raised: Color32::from_rgb(2, 2, 2),
752	overlay: Color32::from_rgb(3, 3, 3),
753	well,
754	sunken: Color32::from_rgb(4, 4, 4),
755	bevel_light: Color32::WHITE,
756	bevel_dark: Color32::BLACK,
757	elevation: Color32::from_black_alpha(46),
758	content: Color32::from_rgb(5, 5, 5),
759	content_muted: Color32::from_rgb(6, 6, 6),
760	action: Color32::from_rgb(7, 7, 7),
761	danger: Color32::from_rgb(8, 8, 8),
762	}
763	}
764
765	/// The cast is egui's own shadow type carrying the theme's tone, which is
766	/// the whole of what this crate had to decide for it: unlike a bevel, egui
767	/// already knows how to paint one.
768	#[test]
769	fn the_cast_hands_egui_the_themes_tone() {
770	let p = palette(Color32::from_rgb(9, 9, 9));
771	let cast = p.cast();
772	assert_eq!(cast.color, p.elevation);
773	assert!(cast.blur > 0, "a cast shadow is soft");
774	assert_eq!(cast.offset, [0, 2], "it falls downward and only a little");
775	}
776
777	#[test]
778	fn a_well_resolves_to_its_own_token() {
779	// No substitution left. The page-filled well was a stand-in for a
780	// token that did not exist yet; it exists now.
781	let w = Color32::from_rgb(9, 9, 9);
782	let p = palette(w);
783	assert_eq!(p.fill(Fill::Well), Some(w));
784	assert_ne!(p.fill(Fill::Well), Some(p.page));
785	}
786
787	#[test]
788	fn every_intent_is_a_plain_lookup() {
789	let p = palette(Color32::from_rgb(9, 9, 9));
790	assert_eq!(p.fill(Fill::Page), Some(p.page));
791	assert_eq!(p.fill(Fill::Raised), Some(p.raised));
792	assert_eq!(p.fill(Fill::Overlay), Some(p.overlay));
793	}
794
795	/// Sunken is its own colour, not the well's and not the page's. The two
796	/// are authored in opposite directions and an earlier cut of the
797	/// description conflated them.
798	#[test]
799	fn sunken_is_neither_the_well_nor_the_page() {
800	let p = palette(Color32::from_rgb(9, 9, 9));
801	assert_eq!(p.fill(Fill::Sunken), Some(p.sunken));
802	assert_ne!(p.fill(Fill::Sunken), p.fill(Fill::Well));
803	assert_ne!(p.fill(Fill::Sunken), p.fill(Fill::Page));
804	}
805
806	#[test]
807	fn a_raised_region_never_resolves_to_the_well_fill() {
808	// The cross-app bug, asserted at the renderer boundary this time.
809	let p = palette(Color32::from_rgb(9, 9, 9));
810	let raised = Depth::Raised.fill().and_then(\|f\| p.fill(f));
811	let well = Depth::Well.fill().and_then(\|f\| p.fill(f));
812	assert_eq!(raised, Some(p.raised));
813	assert_ne!(raised, well);
814	}
815
816	#[test]
817	fn an_overlay_is_cast_onto_the_page_and_takes_no_edge() {
818	// makeover-layout 0.14.0 is what made this reachable. The answer was
819	// already here at 0.10.0 and the question could not be asked.
820	let p = palette(Color32::from_rgb(9, 9, 9));
821	assert_eq!(
822	Depth::Overlay.fill().and_then(\|f\| p.fill(f)),
823	Some(p.overlay)
824	);
825	assert_eq!(Depth::Overlay.bevel(), None);
826	// The shadow `frame` reaches for is the theme's tone rather than
827	// egui's default, which is the whole reason `cast` exists.
828	assert_eq!(p.cast().color, p.elevation);
829	}
830
831	#[test]
832	fn the_lit_edge_swaps_when_a_card_is_pressed() {
833	let p = palette(Color32::from_rgb(9, 9, 9));
834	let (tl, _) = Depth::Raised.bevel().unwrap().edges();
835	let (ptl, _) = Depth::Raised.pressed().bevel().unwrap().edges();
836	assert_eq!(p.edge(tl), p.bevel_light);
837	assert_eq!(p.edge(ptl), p.bevel_dark);
838	}
839
840	#[test]
841	fn flat_asks_for_neither_fill_nor_edge() {
842	assert!(Depth::Flat.fill().is_none());
843	assert!(Depth::Flat.bevel().is_none());
844	}
845
846	#[test]
847	fn a_select_keeps_a_value_none_of_its_options_carries() {
848	// The save-the-wrong-thing bug, asserted at the second renderer so it
849	// is not re-found there. goingson's own numbers.
850	let options = [
851	Choice::plain("1"),
852	Choice::plain("3"),
853	Choice::plain("7"),
854	Choice::plain("14"),
855	];
856	assert_eq!(shown_label(&options, "10"), "10");
857	// And a value that does match reads as its label, not as itself.
858	let spelled = [Choice {
859	value: "7",
860	label: "One week",
861	}];
862	assert_eq!(shown_label(&spelled, "7"), "One week");
863	}
864
865	#[test]
866	fn only_a_required_field_is_marked() {
867	let style = FieldStyle::default();
868	let plain = Field::new(FieldKind::Text, "title", "Title");
869	assert_eq!(label_text(&plain, &style), "Title");
870
871	let required = Field {
872	required: true,
873	..plain
874	};
875	assert_eq!(label_text(&required, &style), "Title *");
876
877	// The marker is copy and the app owns it, which is why it is a knob.
878	let house = FieldStyle {
879	required_marker: "(required)",
880	..style
881	};
882	assert_eq!(label_text(&required, &house), "Title (required)");
883	}
884
885	#[test]
886	fn a_select_and_a_checkbox_are_pressed_and_everything_else_is_typed_into() {
887	// What decides whether the control gets a well. A well is for what the
888	// user looks into, and only one of these is.
889	assert_eq!(control_shape(FieldKind::Select), Control::Chosen);
890	assert_eq!(control_shape(FieldKind::Radio), Control::Listed);
891	assert_eq!(control_shape(FieldKind::Checkbox), Control::Toggled);
892	for k in [
893	FieldKind::Text,
894	FieldKind::Secret,
895	FieldKind::Number,
896	FieldKind::Email,
897	FieldKind::Url,
898	FieldKind::Tel,
899	FieldKind::Textarea,
900	] {
901	assert_eq!(control_shape(k), Control::Typed, "{k:?} is typed into");
902	}
903	}
904
905	#[test]
906	fn the_two_option_taking_kinds_are_drawn_differently_on_purpose() {
907	// The description holds Select and Radio apart, and a renderer that
908	// collapsed them would silently answer a question the app did not ask:
909	// audiofiles' storage style is irreversible and its alternatives have
910	// to be readable without opening anything. Asserting the two shapes
911	// differ is asserting that distinction survives the trip.
912	assert!(FieldKind::Select.offers_options());
913	assert!(FieldKind::Radio.offers_options());
914	assert_ne!(
915	control_shape(FieldKind::Select),
916	control_shape(FieldKind::Radio)
917	);
918	}
919
920	#[test]
921	fn a_hidden_field_draws_nothing_and_answers_nothing() {
922	// Where the two renderers legitimately part: a webview still emits an
923	// input because the form submits, and there is no form here.
924	let f = Field::new(FieldKind::Hidden, "id", "Id");
925	let p = palette(Color32::from_rgb(9, 9, 9));
926	egui::__run_test_ui(\|ui\| {
927	let drawn = field(ui, &f, Filling::Absent, None, &p, &FieldStyle::default());
928	assert!(drawn.is_none());
929	});
930	}
931
932	#[test]
933	fn a_disabled_field_stops_answering_and_an_unstated_one_does_not() {
934	let f = Field::new(FieldKind::Text, "title", "Title");
935	let p = palette(Color32::from_rgb(9, 9, 9));
936	let style = FieldStyle::default();
937	egui::__run_test_ui(\|ui\| {
938	let mut text = String::from("x");
939	let disabled = field(
940	ui,
941	&f,
942	Filling::Text(&mut text),
943	Some(State::Disabled),
944	&p,
945	&style,
946	)
947	.unwrap();
948	assert!(!disabled.enabled());
949
950	// Stating no state is the ordinary case and answers. Focus used to
951	// be the counter-example here; it is egui's now and a description
952	// cannot state it at all.
953	let mut text = String::from("x");
954	let plain = field(ui, &f, Filling::Text(&mut text), None, &p, &style).unwrap();
955	assert!(plain.enabled(), "an unstated field still answers");
956	});
957	}
958
959	#[test]
960	fn a_field_described_one_way_and_filled_another_is_drawn_inert() {
961	// No panic and no write-through. A checkbox handed a string cannot be
962	// filled, so it is drawn off and left alone.
963	let f = Field::new(FieldKind::Checkbox, "done", "Done");
964	let p = palette(Color32::from_rgb(9, 9, 9));
965	let mut text = String::from("untouched");
966	egui::__run_test_ui(\|ui\| {
967	let drawn = field(
968	ui,
969	&f,
970	Filling::Text(&mut text),
971	None,
972	&p,
973	&FieldStyle::default(),
974	);
975	assert!(drawn.is_some());
976	});
977	assert_eq!(text, "untouched");
978	}
979
980	#[test]
981	fn the_disclosure_belongs_to_the_form_and_not_to_the_field() {
982	let fields = [
983	Field::new(FieldKind::Text, "title", "Title"),
984	Field {
985	extended: true,
986	..Field::new(FieldKind::Text, "notes", "Notes")
987	},
988	];
989	let style = FieldStyle::default();
990
991	let mut closed = Vec::new();
992	egui::__run_test_ui(\|ui\| {
993	group(ui, &fields, false, &style, \|_, f\| closed.push(f.name));
994	});
995	assert_eq!(closed, ["title"]);
996
997	let mut open = Vec::new();
998	egui::__run_test_ui(\|ui\| {
999	group(ui, &fields, true, &style, \|_, f\| open.push(f.name));
1000	});
1001	assert_eq!(open, ["title", "notes"]);
1002	}
1003
1004	#[test]
1005	fn the_default_frame_is_square_and_one_point() {
1006	let d = FrameStyle::default();
1007	assert_eq!(d.radius, CornerRadius::ZERO);
1008	assert_eq!(d.margin, Margin::ZERO);
1009	assert!((d.stroke - 1.0).abs() < f32::EPSILON);
1010	}
1011	}
1012