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1 //! The terminal renderer for [`makeover_layout`].
2 //!
3 //! <!-- wiki: makeover-tui -->
4 //!
5 //! Named for the target and not for ratatui, the same way
6 //! `makeover-immediate` is named for the mode and not for egui.
7 //!
8 //! # What a terminal actually costs you
9 //!
10 //! Not colour. That was the original assumption here and it is wrong on any
11 //! terminal built this decade. Measured across the 31 shipped themes
12 //! (`makeover`'s `well_fidelity` example):
13 //!
14 //! | | ANSI-16 | ANSI-256 | truecolor |
15 //! |---|---|---|---|
16 //! | a well collapses onto its face | 18/31 | 4/31 | 2/31 |
17 //! | at least one bevel edge vanishes into its face | 31/31 | 4/31 | 0 |
18 //!
19 //! The threshold is 256, not 24-bit, and the two failures that survive at
20 //! truecolor are not terminal failures at all: they are the themes whose
21 //! raised surface is already white, so the lightening clamps and the well
22 //! lands exactly on its face. Those render identically in a browser.
23 //! `makeover`'s own `well_is_distinct_from_its_face` test already names them.
24 //!
25 //! **What a terminal costs is geometry, and no amount of colour fixes it.**
26 //! An edge occupies a whole cell on each side. A cell is roughly 8x17 pixels,
27 //! so a one-pixel bevel becomes something an order of magnitude heavier, which
28 //! is why [`frame`] hands back a shrunk [`Rect`] instead of pretending the
29 //! region survived intact. There is nowhere to put a corner radius, so
30 //! `radius_control` and `radius_container` mean the same thing here. A fill
31 //! can only begin and end on a cell boundary.
32 //!
33 //! That is the constraint worth designing against. It does not improve, it is
34 //! not detectable, and it applies equally to the best terminal ever written.
35 //!
36 //! What it does not mean is that the shape inside the cell stops mattering.
37 //! Half of a cell is still addressable, and a bevel drawn in half-blocks reads
38 //! as a lit edge where the same bevel in box-drawing reads as a line: `─` and
39 //! `│` are one stroke through the middle, identical on all four sides, saying
40 //! nothing about where the light is. Half-blocks also make the two corners
41 //! where light meets shadow expressible, since a glyph that fills half a cell
42 //! leaves the other half to the second tone.
43 //!
44 //! # Where fidelity does matter
45 //!
46 //! At [`Fidelity::Ansi16`] the depth vocabulary collapses outright: a well
47 //! cannot be filled distinctly on most themes *and* a bevel loses an edge on
48 //! every one of them, so a raised card and a well both read as a single-tone
49 //! box. Colour cannot carry the distinction, so [`frame`] carries it with the
50 //! glyphs instead.
51 //!
52 //! Above that, colour carries it and the glyph fallback never fires.
53 //!
54 //! [`Palette::shows`] is worth reading correctly in light of the numbers: it
55 //! is **not** a low-colour workaround. It is a correctness check that a fill
56 //! will be visible against what is behind it, and at truecolor it fires on
57 //! exactly the two clamping themes, which is precisely when it should.
58 //!
59 //! # 0.13.0: a modal, and two cues four ports were about to each invent
60 //!
61 //! [`Depth::Overlay`](makeover_layout::Depth::Overlay) arrives in
62 //! makeover-layout 0.14.0 and needed nothing here: [`Palette::fill`] has
63 //! answered `Fill::Overlay` since this crate had a palette, so what was missing
64 //! was the route from a description rather than the drawing. A test asserts it,
65 //! because a route nothing exercises is one a refactor can quietly lose.
66 //!
67 //! [`Theme::selection_on`] and [`Theme::focus_ring`] are the other half, and
68 //! both are DERIVED rather than authored. Every consumer measured did selection
69 //! with `REVERSED`, for want of an on-accent foreground; every one that wanted
70 //! a focus ring either spent makeover's `border-strong` on it, which is a
71 //! divider at 1.63:1 on Akari Dawn, or derived its own the way `alloy_tui`
72 //! does. Four terminal ports were each about to answer that separately.
73 //!
74 //! Derived, not authored, because the direction is one-way. An authored key can
75 //! fall back to a derivation and break no theme on disk; a key this crate
76 //! started requiring would break every theme that lacks it. So the theme format
77 //! does not change and nothing on disk grows, and the promotion stays available
78 //! for a theme that ever needs to tune either.
79 //!
80 //! # 0.14.0: the first structural widget
81 //!
82 //! [`table`] is the first thing here that draws content rather than a surface,
83 //! and it exists because 14 call sites across `mnw-cli` and `viewer` were
84 //! already drawing one. `mnw-cli` had written the mapping layer by hand
85 //! (`src/tui/widgets.rs`: a muted bold header, a selected row carried by the
86 //! background alone) and `viewer` had written a smaller one, which is two
87 //! answers to a question this crate is supposed to answer once.
88 //!
89 //! It is a mapping layer over [`ratatui::widgets::Table`] rather than a table
90 //! implementation, because ratatui already lays tracks out, draws a header,
91 //! highlights a row and scrolls. What it has no answer for is content
92 //! measurement and narrowing, and those are what the module is.
93 //!
94 //! # 0.19.0: `widget` is [`piece`], because the word went to the description
95 //!
96 //! `makeover-layout` 0.20.0 added `Region::Widget`, the third tier between a
97 //! primitive and `Region::Bespoke`: a named assembly of primitives that each
98 //! renderer draws its own way. That is host-agnostic and sits *above* every
99 //! renderer.
100 //!
101 //! This crate's `widget` module is the opposite end of the same stack —
102 //! renderer-local, the answer to what a meter looks like in cells, taking a
103 //! description plus what only a terminal knows. Two different things wearing
104 //! one word, and the collision would have been worst exactly here, in a crate
105 //! that has to implement the tier.
106 //!
107 //! So this half moved and the description's half kept the word. That direction
108 //! is not arbitrary: a second or third party naming a widget is naming the
109 //! layout kind, and nothing outside this tree ever needed a word for a drawing
110 //! routine. `WidgetStyle` is `PieceStyle`.
111 //!
112 //! # 0.27.0: a bar for a bounded number, and an option that is not offered yet
113 //!
114 //! `makeover-layout` 0.28.0's form findings, at the renderer that has the bar
115 //! already. A [`makeover_layout::FieldKind::Range`] is drawn as [`piece::meter`]'s
116 //! cells with its two ends read out either side, because the ends are what the
117 //! question means and a terminal is where it would be easiest to quietly show a
118 //! figure instead. An unbounded range falls back to the text path rather than
119 //! to bounds this crate invented.
120 //!
121 //! `Choice::unavailable` is the one place the three-tone convention's muted is
122 //! the truth rather than the lie it warns about: that option will not answer,
123 //! and the reason it will not now sits on its row.
124 //!
125 //! `Choice::detail` (makeover-layout 0.39.0) takes a row of its own under the
126 //! option, inset by the width of the mark and muted for the same reason: the
127 //! line is not a thing to press. This is the host with the most room of the
128 //! three -- a browser's `<select>` has to run the line into its option's text
129 //! and a terminal does not, so it does not.
130 //!
131 //! `Field::placeholder` on a chooser, the third finding, is already answered
132 //! here and needed nothing: this renderer draws every option of a select at
133 //! once, so an unanswered one is a list with no mark against any row rather
134 //! than an empty box with nothing in it.
135 //!
136 //! # 0.33.0: an interval is one line
137 //!
138 //! `makeover-layout` 0.34.0's [`makeover_layout::FieldKind::Interval`], drawn
139 //! as the low end, the word `to`, and the high end. One line because it is one
140 //! question: two rows would read as two questions, which is exactly what the
141 //! kind exists to stop the description saying, and a terminal has no
142 //! side-by-side boxes to fall back on.
143 //!
144 //! - **An open end draws the bound it falls back to**, muted, because that is
145 //! where the axis ends rather than a value anybody set. With no bound to fall
146 //! back on the end stays blank, which is [`piece::field`]'s standing position
147 //! on a value this crate would have to invent.
148 //! - **The word rather than a dash.** A dash between two numbers is a minus
149 //! sign to anyone reading a signed axis, and half the measured axes are
150 //! signed: audiofiles filters loudness in dBFS.
151 //! - The unit rides on each end, through the same `measured` the typed path
152 //! uses, so `90 BPM to 130 BPM` reads without the label being consulted.
153 //!
154 //! [`piece::Held::Between`] is the second value, for the reason the description
155 //! states both names: a separator inside one string would make this crate own a
156 //! delimiter either end could contain.
157 //!
158 //! # 0.32.0: a number reads with its unit
159 //!
160 //! `makeover-layout` 0.33.0's `Field::unit`, drawn on the value rather than in
161 //! the label. A terminal has one line the eye is on -- the number -- and the
162 //! label is a line above it, so `0.05 s` is the reading and `Attack (s)` two
163 //! rows up is not. A range shows it after the readout beside the bar; a typed
164 //! number after the value. Every other kind ignores it, and which those are is
165 //! `FieldKind::measurable`'s answer rather than a `matches!` kept here.
166 //!
167 //! # 0.31.0: the bar fills along the curve
168 //!
169 //! `makeover-layout` 0.32.0's [`Curve`](makeover_layout::Curve). Where a value
170 //! sits on the bar is the curve's answer now, not its proportion of the extent.
171 //! Under `Curve::Linear` those are the same number, so every range drawn before
172 //! this is unchanged; under a constant ratio they are not, and a bar filled
173 //! linearly would put an envelope's whole useful half inside its first cell.
174 //!
175 //! The two ends beside the bar do not move: they are `f(0)` and `f(1)`, which
176 //! is what they always were and is now what the description calls them.
177 //!
178 //! # The correction this renderer forced
179 //!
180 //! [`makeover_layout::Fill`] briefly carried a `fallback` method, returning
181 //! `Page` for `Well` so a consumer without `surface-well` had something to
182 //! use. That is an answer for a renderer that can always paint a colour. Here
183 //! it is actively wrong: page *is* the surface a well is usually cut into, so
184 //! falling back to it produces the exact invisibility the fallback was meant
185 //! to avoid.
186 //!
187 //! Substituting one intent for another is renderer policy, not description.
188 //! The fallback moved out of the description and into
189 //! `makeover-immediate`, where it belongs, which is the first thing a second
190 //! renderer was built to find.
191
192 #![forbid(unsafe_code)]
193
194 use makeover_layout::{Bevel, Depth, Edge, Fill};
195 use ratatui::buffer::Buffer;
196 use ratatui::layout::Rect;
197 use ratatui::style::Color;
198
199 /// The description this crate renders, re-exported.
200 ///
201 /// Every entry point here takes a type from it, so a consumer would otherwise
202 /// have to depend on the description separately and keep two version
203 /// requirements in step to name the argument it is already being handed.
204 pub use makeover_layout;
205
206 /// A loaded makeover theme, resolved to the colours ratatui draws with.
207 ///
208 /// Behind the `theme` feature: it is the only thing here that needs `makeover`
209 /// itself, and that crate embeds the shipped theme files. A consumer that wants
210 /// [`frame`] and nothing else should not carry them.
211 #[cfg(feature = "theme")]
212 pub mod theme;
213
214 #[cfg(feature = "theme")]
215 pub use theme::{Mode, Quantize, Theme, ThemeError};
216
217 /// Columns, narrowing, cell parts and the sort caret, over ratatui's own
218 /// [`Table`](ratatui::widgets::Table).
219 ///
220 /// Not feature-gated. It needs no theme: [`TableStyle`](table::TableStyle)
221 /// carries the tones, and a caller with a loaded theme gets them from
222 /// `TableStyle::from_theme` instead of supplying them.
223 pub mod table;
224
225 /// Word wrapping that answers a height and a drawing from the same measurement.
226 ///
227 /// The half ratatui's `Paragraph` leaves out. A flow layout asks for rows at a
228 /// width and then draws into the rect it was given, and if the two disagree by
229 /// one row a node draws over the one under it.
230 pub mod text;
231
232 /// A meter, a badge, a control, a figure and a form field.
233 ///
234 /// The pieces below the level [`table`] works at. Not feature-gated, on
235 /// [`table`]'s footing: [`PieceStyle`](piece::PieceStyle) carries the tones,
236 /// and a caller with a loaded theme reaches for `PieceStyle::from_theme`.
237 pub mod piece;
238
239 /// How many colours the terminal can actually show.
240 ///
241 /// Only [`Fidelity::Ansi16`] changes what this crate draws. Above it, colour
242 /// separates a raised surface from a well on every shipped theme, and the
243 /// glyph fallback below never fires. Recorded rather than inferred, because a
244 /// caller that quantised its palette knows the answer and this crate cannot
245 /// recover it from the colours afterwards.
246 #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
247 pub enum Fidelity {
248 /// Sixteen colours. Depth cannot be carried by colour: a well collapses
249 /// onto its face on 18 of 31 themes and a bevel loses an edge on all 31.
250 Ansi16,
251 /// The 6x6x6 cube and the grey ramp. Enough on 27 of 31 themes.
252 Ansi256,
253 /// 24-bit. The only failures left belong to the theme, not the terminal.
254 #[default]
255 TrueColor,
256 }
257
258 impl Fidelity {
259 /// Read the terminal's own claim, from `COLORTERM` then `TERM`.
260 ///
261 /// Deliberately credulous, and the fall-through is where that is decided.
262 /// An unrecognised `TERM` is assumed capable, because the two wrong answers
263 /// do not cost the same: guessing [`TrueColor`](Self::TrueColor) on a
264 /// limited terminal costs some fidelity, and guessing
265 /// [`Ansi16`](Self::Ansi16) on a capable one throws away colour the user
266 /// paid for — and, for a caller that quantises its palette off this answer,
267 /// throws away the whole theme. `COLORTERM` is routinely stripped by ssh
268 /// and by multiplexers, so an unrecognised name is the common case rather
269 /// than the exotic one: `foot`, `xterm` and `screen` all land here.
270 ///
271 /// So sixteen colours is reached by naming the terminals that really have
272 /// them. The list is short and it does not grow: these are the fixed
273 /// consoles, and `TERM=linux` is the case this exists for — the Linux
274 /// virtual console, which is what an installer and a machine with no
275 /// desktop draw on.
276 #[must_use]
277 pub fn detect() -> Self {
278 Self::from_env(
279 &std::env::var("COLORTERM").unwrap_or_default(),
280 &std::env::var("TERM").unwrap_or_default(),
281 )
282 }
283
284 /// [`detect`](Self::detect) with the environment passed in, so the decision
285 /// can be tested without mutating a process-wide variable from a parallel
286 /// test.
287 #[must_use]
288 pub fn from_env(colorterm: &str, term: &str) -> Self {
289 if colorterm.contains("truecolor") || colorterm.contains("24bit") {
290 return Self::TrueColor;
291 }
292 match term {
293 "linux" | "vt100" | "vt220" | "ansi" | "dumb" => Self::Ansi16,
294 _ if term.contains("256color") || term.contains("direct") => Self::Ansi256,
295 _ => Self::TrueColor,
296 }
297 }
298
299 /// Whether colour alone can tell a raised surface from a well here.
300 #[must_use]
301 pub const fn separates_depth(self) -> bool {
302 !matches!(self, Self::Ansi16)
303 }
304 }
305
306 /// The resolved colours this renderer needs.
307 ///
308 /// Supply them already quantised to whatever the terminal can show. That is
309 /// what makes [`Palette::shows`] a plain inequality rather than a colour-space
310 /// calculation: by the time a colour reaches here, the question of what the
311 /// terminal will actually paint has been answered.
312 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
313 pub struct Palette {
314 /// `surface-page`.
315 pub page: Color,
316 /// `surface-raised`.
317 pub raised: Color,
318 /// `surface-overlay`.
319 pub overlay: Color,
320 /// `surface-well`, absent on makeover before 2.3.0.
321 pub well: Option<Color>,
322 /// `bevel-light`.
323 pub bevel_light: Color,
324 /// `bevel-dark`.
325 pub bevel_dark: Color,
326 /// What the terminal can show. Defaults to [`Fidelity::TrueColor`].
327 pub fidelity: Fidelity,
328 }
329
330 impl Palette {
331 /// Resolve a surface intent, or `None` where this renderer has no colour
332 /// for it.
333 ///
334 /// No substitution happens here. A missing intent stays missing, and
335 /// [`frame`] answers it with structure instead of with a different colour.
336 /// That rule is what lets the wildcard below be a real answer rather than
337 /// a hole: [`Fill`] is `#[non_exhaustive]` from `makeover-layout` 0.4.0
338 /// onward, so the description can name a surface this renderer has not
339 /// learned to paint, and saying so is better than failing to build.
340 #[must_use]
341 pub const fn fill(&self, fill: Fill) -> Option<Color> {
342 match fill {
343 Fill::Page => Some(self.page),
344 Fill::Raised => Some(self.raised),
345 Fill::Overlay => Some(self.overlay),
346 Fill::Well => self.well,
347 // Includes Fill::Sunken, which this renderer has no tone for: a
348 // terminal cell has one background, so a surface set back by
349 // colour alone is not a thing it can say. The chosen tab is drawn
350 // forward instead.
351 _ => None,
352 }
353 }
354
355 /// Resolve a bevel edge intent.
356 #[must_use]
357 pub const fn edge(&self, edge: Edge) -> Color {
358 match edge {
359 Edge::Light => self.bevel_light,
360 Edge::Dark => self.bevel_dark,
361 }
362 }
363
364 /// Whether painting `fill` over `behind` would show anything.
365 ///
366 /// The whole of the terminal's problem in one predicate. On a truecolor
367 /// terminal this is almost always true; in sixteen colours it is false
368 /// often enough that a design relying on fills is a design that vanishes.
369 #[must_use]
370 pub fn shows(fill: Color, behind: Color) -> bool {
371 fill != behind
372 }
373
374 /// Whether this palette can express a bevel as two distinct edges.
375 ///
376 /// Measured, this is the wrong thing to worry about: the two edge colours
377 /// never quantise onto each other, at any depth, on any shipped theme.
378 /// What does happen is an edge vanishing into the *face* it is drawn on,
379 /// on every theme at sixteen colours. Kept because a hand-built palette
380 /// can still collide, and cheap to ask.
381 #[must_use]
382 pub fn two_tone(&self) -> bool {
383 self.bevel_light != self.bevel_dark
384 }
385
386 /// Whether depth has to be carried by glyphs rather than by colour.
387 ///
388 /// True when the terminal cannot separate the two surfaces, which is the
389 /// sixteen-colour case and nothing else.
390 #[must_use]
391 pub const fn needs_glyph_depth(&self) -> bool {
392 !self.fidelity.separates_depth()
393 }
394 }
395
396 /// The characters a frame's edges and corners are drawn with.
397 ///
398 /// Per side rather than per axis, because the set that reads best as a bevel
399 /// does not use the same glyph on opposite sides: a half-block edge is only
400 /// half a cell, and which half it occupies is what says where the edge is.
401 /// Box-drawing sets fill `top`/`bottom` and `left`/`right` with the same
402 /// character and lose nothing by it.
403 ///
404 /// Three sets. [`BEVEL`] is what a terminal that can show two tones gets. The
405 /// other two exist because at sixteen colours the glyphs are the only thing
406 /// left to carry depth: a well cannot be filled distinctly and a bevel loses
407 /// an edge, so a raised card and a well would otherwise be the same
408 /// single-tone box. A doubled line reads as standing off the page and a light
409 /// one as cut into it, which is the same claim the fill and the bevel make in
410 /// colour.
411 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
412 pub(crate) struct GlyphSet {
413 pub(crate) top: &'static str,
414 pub(crate) bottom: &'static str,
415 pub(crate) left: &'static str,
416 pub(crate) right: &'static str,
417 pub(crate) top_left: &'static str,
418 pub(crate) top_right: &'static str,
419 pub(crate) bottom_left: &'static str,
420 pub(crate) bottom_right: &'static str,
421 /// Whether the two corners where light meets shadow carry both tones in
422 /// one cell, foreground over background.
423 ///
424 /// Only a half-cell glyph can: it already divides the cell, so the split
425 /// costs nothing and the corner reads as a transition rather than as one
426 /// edge overrunning the other. A box-drawing corner is a single stroke
427 /// with no such division, so those sets say `false` and both shared
428 /// corners go to dark — see [`paint_bevel_with`] for why that particular
429 /// fallback and not the other one.
430 pub(crate) split_corners: bool,
431 }
432
433 /// Half-blocks, which is what a bevel actually wants.
434 ///
435 /// A cell is roughly 8x17 device pixels, so a half-block along the top and a
436 /// half-cell column down the side are about the same number of pixels and the
437 /// edge reads as even thickness. Box-drawing cannot do that: `─` and `│` are
438 /// both a thin stroke through the middle of the cell, identical on all four
439 /// sides, which draws a *line* rather than a lit edge and gives up the light
440 /// model that makes a bevel legible.
441 ///
442 /// Adopted from `alloy_tui`, which reached this independently and got there
443 /// first (2026-07-26, two days before this crate existed).
444 pub(crate) const BEVEL: GlyphSet = GlyphSet {
445 top: "",
446 bottom: "",
447 left: "",
448 right: "",
449 top_left: "",
450 // The two shared corners are the split ones: an upper half continues the
451 // lit top edge while the lower half starts the shaded right edge, and the
452 // mirror of that at bottom left.
453 top_right: "",
454 bottom_left: "",
455 bottom_right: "",
456 split_corners: true,
457 };
458
459 pub(crate) const LIGHT: GlyphSet = GlyphSet {
460 top: "",
461 bottom: "",
462 left: "",
463 right: "",
464 top_left: "",
465 top_right: "",
466 bottom_left: "",
467 bottom_right: "",
468 split_corners: false,
469 };
470
471 pub(crate) const DOUBLE: GlyphSet = GlyphSet {
472 top: "",
473 bottom: "",
474 left: "",
475 right: "",
476 top_left: "",
477 top_right: "",
478 bottom_left: "",
479 bottom_right: "",
480 split_corners: false,
481 };
482
483 /// Paint a two-tone edge around the outside of `area`.
484 ///
485 /// Light takes the top and left, dark the bottom and right. What happens at
486 /// the two corners where they meet depends on what the terminal can show.
487 /// Above sixteen colours the edge is drawn in half-blocks and those corners
488 /// carry both tones, one per half-cell. At sixteen it is box-drawing, whose
489 /// single stroke has no half to give, so both shared corners go to dark.
490 ///
491 /// Costs a cell on each side, which a pixel renderer's bevel does not. Use the
492 /// [`Rect`] returned by [`frame`] rather than assuming the area is intact.
493 pub fn paint_bevel(buf: &mut Buffer, area: Rect, bevel: Bevel, palette: &Palette) {
494 paint_bevel_with(buf, area, bevel, palette, set_for(palette, None));
495 }
496
497 /// Whether the activity mark is lit, this far into a wait.
498 ///
499 /// The one place the blink's phase is worked out, so that `piece::activity` can
500 /// stay a pure drawing and this crate can still hold no clock: the caller says
501 /// how long the wait has run and gets back which of the two cells to draw.
502 ///
503 /// The cadence is `makeover_timing::Cadence::Activity`, a half-period, and is
504 /// deliberately not a number chosen here. Three renderers draw this mark and
505 /// one of them is a browser running it off a CSS custom property; a terminal
506 /// that picked its own would be a second heartbeat for one wait.
507 ///
508 /// **`reduced` returns a lit mark, always.** A reader asking for less motion has
509 /// asked for the movement to stop, not for the information to go away, which is
510 /// the whole argument on `makeover_timing::activity_blink`. A terminal has no
511 /// `prefers-reduced-motion` to read, so the preference arrives as a bool from
512 /// whatever the host asked its own platform.
513 ///
514 /// ```
515 /// use makeover_tui::activity_lit;
516 /// use std::time::Duration;
517 ///
518 /// assert!(activity_lit(Duration::from_millis(0), false));
519 /// assert!(!activity_lit(Duration::from_millis(600), false));
520 /// assert!(activity_lit(Duration::from_millis(1100), false));
521 /// // Motion off: lit, and it stays lit.
522 /// assert!(activity_lit(Duration::from_millis(600), true));
523 /// ```
524 #[must_use]
525 pub fn activity_lit(elapsed: std::time::Duration, reduced: bool) -> bool {
526 let Some(half) = makeover_timing::activity_blink(reduced) else {
527 return true;
528 };
529 let half = half.as_millis();
530 // A cadence of zero would divide by nothing, which is the one value the
531 // token cannot mean. Lit and still is the same answer reduced motion gets.
532 if half == 0 {
533 return true;
534 }
535 (elapsed.as_millis() / half).is_multiple_of(2)
536 }
537
538 /// Which glyphs to draw with, given what the terminal can show.
539 ///
540 /// Above sixteen colours the two tones are available and [`BEVEL`] renders
541 /// them as light. At sixteen the tones collapse, so the box-drawing sets carry
542 /// the distinction in weight instead, and `depth` picks which: a doubled frame
543 /// for a raised card and a light one for everything else. `None` means the
544 /// caller is drawing a bevel with no depth behind it, which is never the
545 /// doubled case.
546 fn set_for(palette: &Palette, depth: Option<Depth>) -> GlyphSet {
547 if !palette.needs_glyph_depth() {
548 return BEVEL;
549 }
550 match depth {
551 Some(Depth::Raised) => DOUBLE,
552 _ => LIGHT,
553 }
554 }
555
556 fn paint_bevel_with(buf: &mut Buffer, area: Rect, bevel: Bevel, palette: &Palette, set: GlyphSet) {
557 if area.width < 2 || area.height < 2 {
558 return;
559 }
560 let (top_left, bottom_right) = bevel.edges();
561 let light = palette.edge(top_left);
562 let dark = palette.edge(bottom_right);
563
564 let (x0, y0) = (area.x, area.y);
565 let (x1, y1) = (area.right() - 1, area.bottom() - 1);
566
567 // Light first: top edge and left edge, corners included.
568 for x in x0..=x1 {
569 buf[(x, y0)].set_symbol(set.top).set_fg(light);
570 }
571 for y in y0..=y1 {
572 buf[(x0, y)].set_symbol(set.left).set_fg(light);
573 }
574 // Dark second, so on a set without split corners the two shared ones land
575 // on it by draw order alone.
576 for x in x0..=x1 {
577 buf[(x, y1)].set_symbol(set.bottom).set_fg(dark);
578 }
579 for y in y0..=y1 {
580 buf[(x1, y)].set_symbol(set.right).set_fg(dark);
581 }
582
583 buf[(x0, y0)].set_symbol(set.top_left).set_fg(light);
584 buf[(x1, y1)].set_symbol(set.bottom_right).set_fg(dark);
585
586 if set.split_corners {
587 // Where light meets shadow, both tones share the cell: the half the
588 // glyph fills is the foreground and the half it leaves is the
589 // background, so the corner is a transition rather than one edge
590 // overrunning the other.
591 buf[(x1, y0)]
592 .set_symbol(set.top_right)
593 .set_fg(light)
594 .set_bg(dark);
595 buf[(x0, y1)]
596 .set_symbol(set.bottom_left)
597 .set_fg(dark)
598 .set_bg(light);
599 } else {
600 // Both shared corners to dark. Not arbitrary: it is the same rule
601 // `makeover-immediate` produces by drawing its dark polyline second,
602 // so a control does not change which corner is lit when it moves
603 // between a terminal and a window. A single-stroke corner has no half
604 // to give the other tone, so this is the only rule available to these
605 // sets anyway.
606 buf[(x1, y0)].set_symbol(set.top_right).set_fg(dark);
607 buf[(x0, y1)].set_symbol(set.bottom_left).set_fg(dark);
608 }
609 }
610
611 /// Draw a region at a given [`Depth`] and return the area left for content.
612 ///
613 /// The fill is painted only when it would be visible against what is already
614 /// in the buffer. Everything else is the edge, which is why a well still reads
615 /// as a well on a terminal that cannot colour one.
616 pub fn frame(buf: &mut Buffer, area: Rect, depth: Depth, palette: &Palette) -> Rect {
617 if area.is_empty() {
618 return area;
619 }
620 let behind = buf[(area.x, area.y)].bg;
621
622 if let Some(color) = depth.fill().and_then(|f| palette.fill(f))
623 && Palette::shows(color, behind)
624 {
625 for y in area.top()..area.bottom() {
626 for x in area.left()..area.right() {
627 buf[(x, y)].set_bg(color);
628 }
629 }
630 }
631
632 match depth.bevel() {
633 Some(bevel) if area.width >= 2 && area.height >= 2 => {
634 // Colour separates raised from well wherever it can. Where it
635 // cannot, the glyphs do, and only then: a doubled frame on every
636 // terminal would be shouting.
637 let set = set_for(palette, Some(depth));
638 paint_bevel_with(buf, area, bevel, palette, set);
639 Rect::new(area.x + 1, area.y + 1, area.width - 2, area.height - 2)
640 }
641 _ => area,
642 }
643 }
644
645 #[cfg(test)]
646 mod tests {
647 use super::*;
648
649 fn palette(well: Option<Color>) -> Palette {
650 Palette {
651 page: Color::Indexed(7),
652 raised: Color::Indexed(15),
653 overlay: Color::Indexed(8),
654 well,
655 bevel_light: Color::Indexed(15),
656 bevel_dark: Color::Indexed(0),
657 fidelity: Fidelity::TrueColor,
658 }
659 }
660
661 fn buffer() -> Buffer {
662 Buffer::empty(Rect::new(0, 0, 6, 4))
663 }
664
665 #[test]
666 fn a_well_that_cannot_be_coloured_is_still_drawn() {
667 // The 18-of-31 case: no surface-well token at all.
668 let p = palette(None);
669 let mut buf = buffer();
670 frame(&mut buf, Rect::new(0, 0, 6, 4), Depth::Well, &p);
671 // No fill was available, but the region still reads as recessed.
672 assert_eq!(buf[(0, 0)].symbol(), BEVEL.top_left);
673 assert_eq!(buf[(0, 0)].bg, Color::Reset);
674 }
675
676 #[test]
677 fn a_fill_that_matches_its_surroundings_is_not_painted() {
678 let p = palette(Some(Color::Indexed(7)));
679 let mut buf = buffer();
680 // Everything behind is already page-coloured, and the well quantised
681 // onto it. Painting it would be a no-op that hides the real problem.
682 for y in 0..4 {
683 for x in 0..6 {
684 buf[(x, y)].set_bg(Color::Indexed(7));
685 }
686 }
687 frame(&mut buf, Rect::new(0, 0, 6, 4), Depth::Well, &p);
688 assert!(!Palette::shows(Color::Indexed(7), Color::Indexed(7)));
689 // The edge is what carries the meaning here.
690 assert_eq!(buf[(5, 3)].symbol(), BEVEL.bottom_right);
691 }
692
693 #[test]
694 fn a_visible_fill_is_painted() {
695 let p = palette(Some(Color::Indexed(4)));
696 let mut buf = buffer();
697 frame(&mut buf, Rect::new(0, 0, 6, 4), Depth::Well, &p);
698 assert_eq!(buf[(2, 2)].bg, Color::Indexed(4));
699 }
700
701 #[test]
702 fn an_overlay_is_painted_and_left_unedged() {
703 // makeover-layout 0.14.0's Depth::Overlay, and the wiring under it was
704 // already here: `Palette::fill` has answered `Fill::Overlay` since this
705 // crate had a palette. So this asserts the route rather than building
706 // one, and it is the assertion that would catch the route being lost.
707 let p = palette(None);
708 let mut buf = buffer();
709 let inner = frame(&mut buf, Rect::new(0, 0, 6, 4), Depth::Overlay, &p);
710
711 assert_eq!(buf[(2, 2)].bg, p.overlay);
712 // A surface over the page is separated by the lift and by what sits
713 // behind it, so it takes no edge -- and with no edge drawn, nothing is
714 // given up to one: the content area is the whole region.
715 assert_eq!(buf[(0, 0)].symbol(), " ");
716 assert_eq!(inner, Rect::new(0, 0, 6, 4));
717 }
718
719 #[test]
720 fn the_light_falls_from_the_top_left() {
721 let p = palette(None);
722 let mut buf = buffer();
723 paint_bevel(&mut buf, Rect::new(0, 0, 6, 4), Bevel::Raised, &p);
724 assert_eq!(buf[(0, 0)].fg, p.bevel_light); // top-left
725 assert_eq!(buf[(3, 0)].fg, p.bevel_light); // top edge
726 assert_eq!(buf[(0, 2)].fg, p.bevel_light); // left edge
727 assert_eq!(buf[(5, 3)].fg, p.bevel_dark); // bottom-right
728 assert_eq!(buf[(3, 3)].fg, p.bevel_dark); // bottom edge
729 assert_eq!(buf[(5, 2)].fg, p.bevel_dark); // right edge
730 }
731
732 // Half-cell glyphs divide the cell already, so the corner where light
733 // meets shadow can hold both rather than picking one.
734 #[test]
735 fn the_shared_corners_carry_both_tones_when_the_glyph_can_split() {
736 let p = palette(None);
737 let mut buf = buffer();
738 paint_bevel(&mut buf, Rect::new(0, 0, 6, 4), Bevel::Raised, &p);
739 let top_right = &buf[(5, 0)];
740 assert_eq!(top_right.fg, p.bevel_light);
741 assert_eq!(top_right.bg, p.bevel_dark);
742 let bottom_left = &buf[(0, 3)];
743 assert_eq!(bottom_left.fg, p.bevel_dark);
744 assert_eq!(bottom_left.bg, p.bevel_light);
745 }
746
747 // A single-stroke corner has no half to give the second tone, so the
748 // box-drawing sets keep the old rule: both shared corners to dark, which
749 // is what makeover-immediate produces by drawing its dark polyline second.
750 // Changing that would move the lit corner between a terminal and a window.
751 #[test]
752 fn box_drawing_corners_stay_dark_and_match_the_immediate_renderer() {
753 let p = Palette {
754 fidelity: Fidelity::Ansi16,
755 ..palette(None)
756 };
757 let mut buf = buffer();
758 paint_bevel(&mut buf, Rect::new(0, 0, 6, 4), Bevel::Raised, &p);
759 assert_eq!(buf[(5, 0)].symbol(), LIGHT.top_right);
760 assert_eq!(buf[(5, 0)].fg, p.bevel_dark);
761 assert_eq!(buf[(5, 0)].bg, Color::Reset, "a stroke has no second tone");
762 assert_eq!(buf[(0, 3)].fg, p.bevel_dark);
763 }
764
765 // The whole outline, as a reader sees it. Asserted as glyphs because the
766 // shape is the point: an even-weight edge on all four sides, which is what
767 // box-drawing could not give.
768 #[test]
769 fn a_bevel_draws_an_even_outline_and_leaves_the_middle_alone() {
770 let p = palette(None);
771 let mut buf = Buffer::empty(Rect::new(0, 0, 5, 4));
772 paint_bevel(&mut buf, Rect::new(0, 0, 5, 4), Bevel::Raised, &p);
773 let rows: Vec<String> = (0..4)
774 .map(|y| (0..5).map(|x| buf[(x, y)].symbol()).collect())
775 .collect();
776 assert_eq!(rows, vec!["▛▀▀▀▀", "▌ ▐", "▌ ▐", "▄▄▄▄▟"]);
777 }
778
779 #[test]
780 fn pressing_swaps_the_lit_side() {
781 let p = palette(None);
782 let mut buf = buffer();
783 paint_bevel(&mut buf, Rect::new(0, 0, 6, 4), Bevel::Raised.pressed(), &p);
784 assert_eq!(buf[(0, 0)].fg, p.bevel_dark);
785 }
786
787 #[test]
788 fn a_sixteen_colour_terminal_can_lose_the_second_tone() {
789 // Not a failure: one box is still a boundary. The palette says so
790 // rather than the renderer pretending otherwise.
791 let flat = Palette {
792 bevel_dark: Color::Indexed(15),
793 ..palette(None)
794 };
795 assert!(!flat.two_tone());
796 assert!(palette(None).two_tone());
797 }
798
799 #[test]
800 fn an_edge_costs_a_cell_on_every_side() {
801 let p = palette(None);
802 let mut buf = buffer();
803 let inner = frame(&mut buf, Rect::new(0, 0, 6, 4), Depth::Raised, &p);
804 assert_eq!(inner, Rect::new(1, 1, 4, 2));
805 // Flat takes no cells, because it draws no edge.
806 let same = frame(&mut buf, Rect::new(0, 0, 6, 4), Depth::Flat, &p);
807 assert_eq!(same, Rect::new(0, 0, 6, 4));
808 }
809
810 #[test]
811 fn sixteen_colours_carries_depth_in_the_glyphs_instead() {
812 // Colour cannot separate raised from well here: the fill collapses on
813 // most themes and an edge vanishes on all of them. The frame has to
814 // say it some other way or the two become the same box.
815 let p = Palette {
816 fidelity: Fidelity::Ansi16,
817 ..palette(None)
818 };
819 assert!(p.needs_glyph_depth());
820 let mut raised = buffer();
821 frame(&mut raised, Rect::new(0, 0, 6, 4), Depth::Raised, &p);
822 let mut well = buffer();
823 frame(&mut well, Rect::new(0, 0, 6, 4), Depth::Well, &p);
824 assert_eq!(raised[(0, 0)].symbol(), DOUBLE.top_left);
825 assert_eq!(well[(0, 0)].symbol(), LIGHT.top_left);
826 assert_ne!(raised[(0, 0)].symbol(), well[(0, 0)].symbol());
827 }
828
829 #[test]
830 fn above_sixteen_colours_the_glyphs_stay_out_of_it() {
831 // The doubled fallback must not fire where colour already works, or
832 // every modern terminal gets a heavier frame it did not need. What it
833 // gets instead is the half-block bevel.
834 for f in [Fidelity::Ansi256, Fidelity::TrueColor] {
835 let p = Palette {
836 fidelity: f,
837 ..palette(Some(Color::Indexed(4)))
838 };
839 assert!(!p.needs_glyph_depth());
840 let mut buf = buffer();
841 frame(&mut buf, Rect::new(0, 0, 6, 4), Depth::Raised, &p);
842 assert_eq!(
843 buf[(0, 0)].symbol(),
844 BEVEL.top_left,
845 "{f:?} got a heavier frame"
846 );
847 assert_ne!(buf[(0, 0)].symbol(), DOUBLE.top_left);
848 }
849 }
850
851 // Raised and well are both bevels and differ only in which way they are
852 // lit, so above sixteen colours they draw the same glyphs and the tones
853 // carry the difference. That is exactly what stops holding at Ansi16, and
854 // why the doubled set exists.
855 #[test]
856 fn colour_alone_separates_raised_from_well_where_it_can() {
857 let p = palette(Some(Color::Indexed(4)));
858 let mut raised = buffer();
859 frame(&mut raised, Rect::new(0, 0, 6, 4), Depth::Raised, &p);
860 let mut well = buffer();
861 frame(&mut well, Rect::new(0, 0, 6, 4), Depth::Well, &p);
862 assert_eq!(raised[(0, 0)].symbol(), well[(0, 0)].symbol());
863 assert_eq!(raised[(0, 0)].fg, p.bevel_light);
864 assert_eq!(well[(0, 0)].fg, p.bevel_dark);
865 }
866
867 #[test]
868 fn detection_defaults_generously_and_only_downgrades_on_evidence() {
869 assert!(Fidelity::default().separates_depth());
870 assert!(Fidelity::TrueColor.separates_depth());
871 assert!(Fidelity::Ansi256.separates_depth());
872 assert!(!Fidelity::Ansi16.separates_depth());
873 }
874
875 // Sixteen colours is reached by naming a console, never by failing to
876 // recognise a terminal. `COLORTERM` is stripped by ssh and by every
877 // multiplexer, so an unrecognised name carries no evidence at all, and a
878 // caller quantising its palette off this answer would flatten a whole theme
879 // on the strength of it.
880 #[test]
881 fn an_unrecognised_terminal_is_assumed_capable() {
882 let f = Fidelity::from_env;
883 assert_eq!(f("", "foot"), Fidelity::TrueColor);
884 assert_eq!(f("", "xterm"), Fidelity::TrueColor);
885 assert_eq!(f("", "screen"), Fidelity::TrueColor);
886 assert_eq!(f("", ""), Fidelity::TrueColor);
887 }
888
889 #[test]
890 fn a_console_that_really_has_sixteen_colours_is_named() {
891 let f = Fidelity::from_env;
892 assert_eq!(f("", "linux"), Fidelity::Ansi16);
893 assert_eq!(f("", "vt100"), Fidelity::Ansi16);
894 assert_eq!(f("", "dumb"), Fidelity::Ansi16);
895 }
896
897 #[test]
898 fn a_terminal_naming_its_depth_is_taken_at_its_word() {
899 let f = Fidelity::from_env;
900 assert_eq!(f("", "xterm-256color"), Fidelity::Ansi256);
901 assert_eq!(f("", "screen-256color"), Fidelity::Ansi256);
902 assert_eq!(f("", "xterm-direct"), Fidelity::Ansi256);
903 // And a claim of 24-bit beats the name, which is only ever a floor.
904 assert_eq!(f("truecolor", "xterm-256color"), Fidelity::TrueColor);
905 assert_eq!(f("24bit", "linux"), Fidelity::TrueColor);
906 }
907
908 #[test]
909 fn a_region_too_small_for_an_edge_is_left_alone() {
910 let p = palette(None);
911 let mut buf = buffer();
912 let inner = frame(&mut buf, Rect::new(0, 0, 1, 1), Depth::Raised, &p);
913 assert_eq!(inner, Rect::new(0, 0, 1, 1));
914 }
915 }
916