1use crate::{
2 color::Color,
3 fonts::{FontId, GlyphId},
4 geometry::{
5 rect::RectF,
6 vector::{vec2f, Vector2F},
7 },
8 platform, scene, FontSystem, PaintContext,
9};
10use ordered_float::OrderedFloat;
11use parking_lot::{Mutex, RwLock, RwLockUpgradableReadGuard};
12use smallvec::SmallVec;
13use std::{
14 borrow::Borrow,
15 collections::HashMap,
16 hash::{Hash, Hasher},
17 iter,
18 sync::Arc,
19};
20
21pub struct TextLayoutCache {
22 prev_frame: Mutex<HashMap<CacheKeyValue, Arc<LineLayout>>>,
23 curr_frame: RwLock<HashMap<CacheKeyValue, Arc<LineLayout>>>,
24 fonts: Arc<dyn platform::FontSystem>,
25}
26
27#[derive(Copy, Clone, Debug, PartialEq, Eq)]
28pub struct RunStyle {
29 pub color: Color,
30 pub font_id: FontId,
31 pub underline: Option<Color>,
32}
33
34impl TextLayoutCache {
35 pub fn new(fonts: Arc<dyn platform::FontSystem>) -> Self {
36 Self {
37 prev_frame: Mutex::new(HashMap::new()),
38 curr_frame: RwLock::new(HashMap::new()),
39 fonts,
40 }
41 }
42
43 pub fn finish_frame(&self) {
44 let mut prev_frame = self.prev_frame.lock();
45 let mut curr_frame = self.curr_frame.write();
46 std::mem::swap(&mut *prev_frame, &mut *curr_frame);
47 curr_frame.clear();
48 }
49
50 pub fn layout_str<'a>(
51 &'a self,
52 text: &'a str,
53 font_size: f32,
54 runs: &'a [(usize, RunStyle)],
55 ) -> Line {
56 let key = &CacheKeyRef {
57 text,
58 font_size: OrderedFloat(font_size),
59 runs,
60 } as &dyn CacheKey;
61 let curr_frame = self.curr_frame.upgradable_read();
62 if let Some(layout) = curr_frame.get(key) {
63 return Line::new(layout.clone(), runs);
64 }
65
66 let mut curr_frame = RwLockUpgradableReadGuard::upgrade(curr_frame);
67 if let Some((key, layout)) = self.prev_frame.lock().remove_entry(key) {
68 curr_frame.insert(key, layout.clone());
69 Line::new(layout.clone(), runs)
70 } else {
71 let layout = Arc::new(self.fonts.layout_line(text, font_size, runs));
72 let key = CacheKeyValue {
73 text: text.into(),
74 font_size: OrderedFloat(font_size),
75 runs: SmallVec::from(runs),
76 };
77 curr_frame.insert(key, layout.clone());
78 Line::new(layout, runs)
79 }
80 }
81}
82
83trait CacheKey {
84 fn key<'a>(&'a self) -> CacheKeyRef<'a>;
85}
86
87impl<'a> PartialEq for (dyn CacheKey + 'a) {
88 fn eq(&self, other: &dyn CacheKey) -> bool {
89 self.key() == other.key()
90 }
91}
92
93impl<'a> Eq for (dyn CacheKey + 'a) {}
94
95impl<'a> Hash for (dyn CacheKey + 'a) {
96 fn hash<H: Hasher>(&self, state: &mut H) {
97 self.key().hash(state)
98 }
99}
100
101#[derive(Eq, PartialEq)]
102struct CacheKeyValue {
103 text: String,
104 font_size: OrderedFloat<f32>,
105 runs: SmallVec<[(usize, RunStyle); 1]>,
106}
107
108impl CacheKey for CacheKeyValue {
109 fn key<'a>(&'a self) -> CacheKeyRef<'a> {
110 CacheKeyRef {
111 text: &self.text.as_str(),
112 font_size: self.font_size,
113 runs: self.runs.as_slice(),
114 }
115 }
116}
117
118impl Hash for CacheKeyValue {
119 fn hash<H: Hasher>(&self, state: &mut H) {
120 self.key().hash(state);
121 }
122}
123
124impl<'a> Borrow<dyn CacheKey + 'a> for CacheKeyValue {
125 fn borrow(&self) -> &(dyn CacheKey + 'a) {
126 self as &dyn CacheKey
127 }
128}
129
130#[derive(Copy, Clone)]
131struct CacheKeyRef<'a> {
132 text: &'a str,
133 font_size: OrderedFloat<f32>,
134 runs: &'a [(usize, RunStyle)],
135}
136
137impl<'a> CacheKey for CacheKeyRef<'a> {
138 fn key<'b>(&'b self) -> CacheKeyRef<'b> {
139 *self
140 }
141}
142
143impl<'a> PartialEq for CacheKeyRef<'a> {
144 fn eq(&self, other: &Self) -> bool {
145 self.text == other.text
146 && self.font_size == other.font_size
147 && self.runs.len() == other.runs.len()
148 && self.runs.iter().zip(other.runs.iter()).all(
149 |((len_a, style_a), (len_b, style_b))| {
150 len_a == len_b && style_a.font_id == style_b.font_id
151 },
152 )
153 }
154}
155
156impl<'a> Hash for CacheKeyRef<'a> {
157 fn hash<H: Hasher>(&self, state: &mut H) {
158 self.text.hash(state);
159 self.font_size.hash(state);
160 for (len, style_id) in self.runs {
161 len.hash(state);
162 style_id.font_id.hash(state);
163 }
164 }
165}
166
167#[derive(Default, Debug)]
168pub struct Line {
169 layout: Arc<LineLayout>,
170 style_runs: SmallVec<[(u32, Color, Option<Color>); 32]>,
171}
172
173#[derive(Default, Debug)]
174pub struct LineLayout {
175 pub width: f32,
176 pub ascent: f32,
177 pub descent: f32,
178 pub runs: Vec<Run>,
179 pub len: usize,
180 pub font_size: f32,
181}
182
183#[derive(Debug)]
184pub struct Run {
185 pub font_id: FontId,
186 pub glyphs: Vec<Glyph>,
187}
188
189#[derive(Debug)]
190pub struct Glyph {
191 pub id: GlyphId,
192 pub position: Vector2F,
193 pub index: usize,
194}
195
196impl Line {
197 fn new(layout: Arc<LineLayout>, runs: &[(usize, RunStyle)]) -> Self {
198 let mut style_runs = SmallVec::new();
199 for (len, style) in runs {
200 style_runs.push((*len as u32, style.color, style.underline));
201 }
202 Self { layout, style_runs }
203 }
204
205 pub fn runs(&self) -> &[Run] {
206 &self.layout.runs
207 }
208
209 pub fn width(&self) -> f32 {
210 self.layout.width
211 }
212
213 pub fn x_for_index(&self, index: usize) -> f32 {
214 for run in &self.layout.runs {
215 for glyph in &run.glyphs {
216 if glyph.index == index {
217 return glyph.position.x();
218 }
219 }
220 }
221 self.layout.width
222 }
223
224 pub fn index_for_x(&self, x: f32) -> Option<usize> {
225 if x >= self.layout.width {
226 None
227 } else {
228 for run in self.layout.runs.iter().rev() {
229 for glyph in run.glyphs.iter().rev() {
230 if glyph.position.x() <= x {
231 return Some(glyph.index);
232 }
233 }
234 }
235 Some(0)
236 }
237 }
238
239 pub fn paint(
240 &self,
241 origin: Vector2F,
242 visible_bounds: RectF,
243 line_height: f32,
244 cx: &mut PaintContext,
245 ) {
246 let padding_top = (line_height - self.layout.ascent - self.layout.descent) / 2.;
247 let baseline_offset = vec2f(0., padding_top + self.layout.ascent);
248
249 let mut style_runs = self.style_runs.iter();
250 let mut run_end = 0;
251 let mut color = Color::black();
252 let mut underline = None;
253
254 for run in &self.layout.runs {
255 let max_glyph_width = cx
256 .font_cache
257 .bounding_box(run.font_id, self.layout.font_size)
258 .x();
259
260 for glyph in &run.glyphs {
261 let glyph_origin = origin + baseline_offset + glyph.position;
262 if glyph_origin.x() > visible_bounds.upper_right().x() {
263 break;
264 }
265
266 let mut finished_underline = None;
267 if glyph.index >= run_end {
268 if let Some((run_len, run_color, run_underline_color)) = style_runs.next() {
269 if let Some((_, underline_color)) = underline {
270 if *run_underline_color != Some(underline_color) {
271 finished_underline = underline.take();
272 }
273 }
274 if let Some(run_underline_color) = run_underline_color {
275 underline.get_or_insert((glyph_origin, *run_underline_color));
276 }
277
278 run_end += *run_len as usize;
279 color = *run_color;
280 } else {
281 run_end = self.layout.len;
282 color = Color::black();
283 finished_underline = underline.take();
284 }
285 }
286
287 if glyph_origin.x() + max_glyph_width < visible_bounds.origin().x() {
288 continue;
289 }
290
291 if let Some((underline_origin, underline_color)) = finished_underline {
292 cx.scene.push_underline(scene::Quad {
293 bounds: RectF::from_points(underline_origin, glyph_origin + vec2f(0., 1.)),
294 background: Some(underline_color),
295 border: Default::default(),
296 corner_radius: 0.,
297 });
298 }
299
300 cx.scene.push_glyph(scene::Glyph {
301 font_id: run.font_id,
302 font_size: self.layout.font_size,
303 id: glyph.id,
304 origin: glyph_origin,
305 color,
306 });
307 }
308 }
309
310 if let Some((underline_start, underline_color)) = underline.take() {
311 let line_end = origin + baseline_offset + vec2f(self.layout.width, 0.);
312
313 cx.scene.push_underline(scene::Quad {
314 bounds: RectF::from_points(underline_start, line_end + vec2f(0., 1.)),
315 background: Some(underline_color),
316 border: Default::default(),
317 corner_radius: 0.,
318 });
319 }
320 }
321
322 pub fn paint_wrapped(
323 &self,
324 origin: Vector2F,
325 visible_bounds: RectF,
326 line_height: f32,
327 boundaries: impl IntoIterator<Item = ShapedBoundary>,
328 cx: &mut PaintContext,
329 ) {
330 let padding_top = (line_height - self.layout.ascent - self.layout.descent) / 2.;
331 let baseline_origin = vec2f(0., padding_top + self.layout.ascent);
332
333 let mut boundaries = boundaries.into_iter().peekable();
334 let mut color_runs = self.style_runs.iter();
335 let mut color_end = 0;
336 let mut color = Color::black();
337
338 let mut glyph_origin = vec2f(0., 0.);
339 let mut prev_position = 0.;
340 for run in &self.layout.runs {
341 for (glyph_ix, glyph) in run.glyphs.iter().enumerate() {
342 if boundaries.peek().map_or(false, |b| b.glyph_ix == glyph_ix) {
343 boundaries.next();
344 glyph_origin = vec2f(0., glyph_origin.y() + line_height);
345 } else {
346 glyph_origin.set_x(glyph_origin.x() + glyph.position.x() - prev_position);
347 }
348 prev_position = glyph.position.x();
349
350 if glyph.index >= color_end {
351 if let Some(next_run) = color_runs.next() {
352 color_end += next_run.0 as usize;
353 color = next_run.1;
354 } else {
355 color_end = self.layout.len;
356 color = Color::black();
357 }
358 }
359
360 let glyph_bounds = RectF::new(
361 origin + glyph_origin,
362 cx.font_cache
363 .bounding_box(run.font_id, self.layout.font_size),
364 );
365 if glyph_bounds.intersects(visible_bounds) {
366 cx.scene.push_glyph(scene::Glyph {
367 font_id: run.font_id,
368 font_size: self.layout.font_size,
369 id: glyph.id,
370 origin: glyph_bounds.origin() + baseline_origin,
371 color,
372 });
373 }
374 }
375 }
376 }
377}
378
379impl Run {
380 pub fn glyphs(&self) -> &[Glyph] {
381 &self.glyphs
382 }
383}
384
385#[derive(Copy, Clone, Debug, PartialEq, Eq)]
386pub struct Boundary {
387 pub ix: usize,
388 pub next_indent: u32,
389}
390
391#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
392pub struct ShapedBoundary {
393 pub run_ix: usize,
394 pub glyph_ix: usize,
395}
396
397impl Boundary {
398 fn new(ix: usize, next_indent: u32) -> Self {
399 Self { ix, next_indent }
400 }
401}
402
403pub struct LineWrapper {
404 font_system: Arc<dyn FontSystem>,
405 pub(crate) font_id: FontId,
406 pub(crate) font_size: f32,
407 cached_ascii_char_widths: [f32; 128],
408 cached_other_char_widths: HashMap<char, f32>,
409}
410
411impl LineWrapper {
412 pub const MAX_INDENT: u32 = 256;
413
414 pub fn new(font_id: FontId, font_size: f32, font_system: Arc<dyn FontSystem>) -> Self {
415 Self {
416 font_system,
417 font_id,
418 font_size,
419 cached_ascii_char_widths: [f32::NAN; 128],
420 cached_other_char_widths: HashMap::new(),
421 }
422 }
423
424 pub fn wrap_line<'a>(
425 &'a mut self,
426 line: &'a str,
427 wrap_width: f32,
428 ) -> impl Iterator<Item = Boundary> + 'a {
429 let mut width = 0.0;
430 let mut first_non_whitespace_ix = None;
431 let mut indent = None;
432 let mut last_candidate_ix = 0;
433 let mut last_candidate_width = 0.0;
434 let mut last_wrap_ix = 0;
435 let mut prev_c = '\0';
436 let mut char_indices = line.char_indices();
437 iter::from_fn(move || {
438 while let Some((ix, c)) = char_indices.next() {
439 if c == '\n' {
440 continue;
441 }
442
443 if self.is_boundary(prev_c, c) && first_non_whitespace_ix.is_some() {
444 last_candidate_ix = ix;
445 last_candidate_width = width;
446 }
447
448 if c != ' ' && first_non_whitespace_ix.is_none() {
449 first_non_whitespace_ix = Some(ix);
450 }
451
452 let char_width = self.width_for_char(c);
453 width += char_width;
454 if width > wrap_width && ix > last_wrap_ix {
455 if let (None, Some(first_non_whitespace_ix)) = (indent, first_non_whitespace_ix)
456 {
457 indent = Some(
458 Self::MAX_INDENT.min((first_non_whitespace_ix - last_wrap_ix) as u32),
459 );
460 }
461
462 if last_candidate_ix > 0 {
463 last_wrap_ix = last_candidate_ix;
464 width -= last_candidate_width;
465 last_candidate_ix = 0;
466 } else {
467 last_wrap_ix = ix;
468 width = char_width;
469 }
470
471 let indent_width =
472 indent.map(|indent| indent as f32 * self.width_for_char(' '));
473 width += indent_width.unwrap_or(0.);
474
475 return Some(Boundary::new(last_wrap_ix, indent.unwrap_or(0)));
476 }
477 prev_c = c;
478 }
479
480 None
481 })
482 }
483
484 pub fn wrap_shaped_line<'a>(
485 &'a mut self,
486 str: &'a str,
487 line: &'a Line,
488 wrap_width: f32,
489 ) -> impl Iterator<Item = ShapedBoundary> + 'a {
490 let mut first_non_whitespace_ix = None;
491 let mut last_candidate_ix = None;
492 let mut last_candidate_x = 0.0;
493 let mut last_wrap_ix = ShapedBoundary {
494 run_ix: 0,
495 glyph_ix: 0,
496 };
497 let mut last_wrap_x = 0.;
498 let mut prev_c = '\0';
499 let mut glyphs = line
500 .runs()
501 .iter()
502 .enumerate()
503 .flat_map(move |(run_ix, run)| {
504 run.glyphs()
505 .iter()
506 .enumerate()
507 .map(move |(glyph_ix, glyph)| {
508 let character = str[glyph.index..].chars().next().unwrap();
509 (
510 ShapedBoundary { run_ix, glyph_ix },
511 character,
512 glyph.position.x(),
513 )
514 })
515 })
516 .peekable();
517
518 iter::from_fn(move || {
519 while let Some((ix, c, x)) = glyphs.next() {
520 if c == '\n' {
521 continue;
522 }
523
524 if self.is_boundary(prev_c, c) && first_non_whitespace_ix.is_some() {
525 last_candidate_ix = Some(ix);
526 last_candidate_x = x;
527 }
528
529 if c != ' ' && first_non_whitespace_ix.is_none() {
530 first_non_whitespace_ix = Some(ix);
531 }
532
533 let next_x = glyphs.peek().map_or(line.width(), |(_, _, x)| *x);
534 let width = next_x - last_wrap_x;
535 if width > wrap_width && ix > last_wrap_ix {
536 if let Some(last_candidate_ix) = last_candidate_ix.take() {
537 last_wrap_ix = last_candidate_ix;
538 last_wrap_x = last_candidate_x;
539 } else {
540 last_wrap_ix = ix;
541 last_wrap_x = x;
542 }
543
544 return Some(last_wrap_ix);
545 }
546 prev_c = c;
547 }
548
549 None
550 })
551 }
552
553 fn is_boundary(&self, prev: char, next: char) -> bool {
554 (prev == ' ') && (next != ' ')
555 }
556
557 #[inline(always)]
558 fn width_for_char(&mut self, c: char) -> f32 {
559 if (c as u32) < 128 {
560 let mut width = self.cached_ascii_char_widths[c as usize];
561 if width.is_nan() {
562 width = self.compute_width_for_char(c);
563 self.cached_ascii_char_widths[c as usize] = width;
564 }
565 width
566 } else {
567 let mut width = self
568 .cached_other_char_widths
569 .get(&c)
570 .copied()
571 .unwrap_or(f32::NAN);
572 if width.is_nan() {
573 width = self.compute_width_for_char(c);
574 self.cached_other_char_widths.insert(c, width);
575 }
576 width
577 }
578 }
579
580 fn compute_width_for_char(&self, c: char) -> f32 {
581 self.font_system
582 .layout_line(
583 &c.to_string(),
584 self.font_size,
585 &[(
586 1,
587 RunStyle {
588 font_id: self.font_id,
589 color: Default::default(),
590 underline: None,
591 },
592 )],
593 )
594 .width
595 }
596}
597
598#[cfg(test)]
599mod tests {
600 use super::*;
601 use crate::fonts::{Properties, Weight};
602
603 #[crate::test(self)]
604 fn test_wrap_line(cx: &mut crate::MutableAppContext) {
605 let font_cache = cx.font_cache().clone();
606 let font_system = cx.platform().fonts();
607 let family = font_cache.load_family(&["Courier"]).unwrap();
608 let font_id = font_cache.select_font(family, &Default::default()).unwrap();
609
610 let mut wrapper = LineWrapper::new(font_id, 16., font_system);
611 assert_eq!(
612 wrapper
613 .wrap_line("aa bbb cccc ddddd eeee", 72.0)
614 .collect::<Vec<_>>(),
615 &[
616 Boundary::new(7, 0),
617 Boundary::new(12, 0),
618 Boundary::new(18, 0)
619 ],
620 );
621 assert_eq!(
622 wrapper
623 .wrap_line("aaa aaaaaaaaaaaaaaaaaa", 72.0)
624 .collect::<Vec<_>>(),
625 &[
626 Boundary::new(4, 0),
627 Boundary::new(11, 0),
628 Boundary::new(18, 0)
629 ],
630 );
631 assert_eq!(
632 wrapper.wrap_line(" aaaaaaa", 72.).collect::<Vec<_>>(),
633 &[
634 Boundary::new(7, 5),
635 Boundary::new(9, 5),
636 Boundary::new(11, 5),
637 ]
638 );
639 assert_eq!(
640 wrapper
641 .wrap_line(" ", 72.)
642 .collect::<Vec<_>>(),
643 &[
644 Boundary::new(7, 0),
645 Boundary::new(14, 0),
646 Boundary::new(21, 0)
647 ]
648 );
649 assert_eq!(
650 wrapper
651 .wrap_line(" aaaaaaaaaaaaaa", 72.)
652 .collect::<Vec<_>>(),
653 &[
654 Boundary::new(7, 0),
655 Boundary::new(14, 3),
656 Boundary::new(18, 3),
657 Boundary::new(22, 3),
658 ]
659 );
660 }
661
662 #[crate::test(self, retries = 5)]
663 fn test_wrap_shaped_line(cx: &mut crate::MutableAppContext) {
664 // This is failing intermittently on CI and we don't have time to figure it out
665 let font_cache = cx.font_cache().clone();
666 let font_system = cx.platform().fonts();
667 let text_layout_cache = TextLayoutCache::new(font_system.clone());
668
669 let family = font_cache.load_family(&["Helvetica"]).unwrap();
670 let font_id = font_cache.select_font(family, &Default::default()).unwrap();
671 let normal = RunStyle {
672 font_id,
673 color: Default::default(),
674 underline: None,
675 };
676 let bold = RunStyle {
677 font_id: font_cache
678 .select_font(
679 family,
680 &Properties {
681 weight: Weight::BOLD,
682 ..Default::default()
683 },
684 )
685 .unwrap(),
686 color: Default::default(),
687 underline: None,
688 };
689
690 let text = "aa bbb cccc ddddd eeee";
691 let line = text_layout_cache.layout_str(
692 text,
693 16.0,
694 &[(4, normal), (5, bold), (6, normal), (1, bold), (7, normal)],
695 );
696
697 let mut wrapper = LineWrapper::new(font_id, 16., font_system);
698 assert_eq!(
699 wrapper
700 .wrap_shaped_line(&text, &line, 72.0)
701 .collect::<Vec<_>>(),
702 &[
703 ShapedBoundary {
704 run_ix: 1,
705 glyph_ix: 3
706 },
707 ShapedBoundary {
708 run_ix: 2,
709 glyph_ix: 3
710 },
711 ShapedBoundary {
712 run_ix: 4,
713 glyph_ix: 2
714 }
715 ],
716 );
717 }
718}