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
263 if glyph_origin.x() + max_glyph_width < visible_bounds.origin().x() {
264 continue;
265 }
266 if glyph_origin.x() > visible_bounds.upper_right().x() {
267 break;
268 }
269
270 if glyph.index >= run_end {
271 if let Some((run_len, run_color, run_underline_color)) = style_runs.next() {
272 if let Some((underline_origin, underline_color)) = underline {
273 if *run_underline_color != Some(underline_color) {
274 cx.scene.push_underline(scene::Quad {
275 bounds: RectF::from_points(
276 underline_origin,
277 glyph_origin + vec2f(0., 1.),
278 ),
279 background: Some(underline_color),
280 border: Default::default(),
281 corner_radius: 0.,
282 });
283 underline = None;
284 }
285 }
286
287 if let Some(run_underline_color) = run_underline_color {
288 underline.get_or_insert((glyph_origin, *run_underline_color));
289 }
290
291 run_end += *run_len as usize;
292 color = *run_color;
293 } else {
294 run_end = self.layout.len;
295 color = Color::black();
296 if let Some((underline_origin, underline_color)) = underline.take() {
297 cx.scene.push_underline(scene::Quad {
298 bounds: RectF::from_points(
299 underline_origin,
300 glyph_origin + vec2f(0., 1.),
301 ),
302 background: Some(underline_color),
303 border: Default::default(),
304 corner_radius: 0.,
305 });
306 }
307 }
308 }
309
310 cx.scene.push_glyph(scene::Glyph {
311 font_id: run.font_id,
312 font_size: self.layout.font_size,
313 id: glyph.id,
314 origin: glyph_origin,
315 color,
316 });
317 }
318 }
319
320 if let Some((underline_start, underline_color)) = underline.take() {
321 let line_end = origin + baseline_offset + vec2f(self.layout.width, 0.);
322
323 cx.scene.push_underline(scene::Quad {
324 bounds: RectF::from_points(underline_start, line_end + vec2f(0., 1.)),
325 background: Some(underline_color),
326 border: Default::default(),
327 corner_radius: 0.,
328 });
329 }
330 }
331
332 pub fn paint_wrapped(
333 &self,
334 origin: Vector2F,
335 visible_bounds: RectF,
336 line_height: f32,
337 boundaries: impl IntoIterator<Item = ShapedBoundary>,
338 cx: &mut PaintContext,
339 ) {
340 let padding_top = (line_height - self.layout.ascent - self.layout.descent) / 2.;
341 let baseline_origin = vec2f(0., padding_top + self.layout.ascent);
342
343 let mut boundaries = boundaries.into_iter().peekable();
344 let mut color_runs = self.style_runs.iter();
345 let mut color_end = 0;
346 let mut color = Color::black();
347
348 let mut glyph_origin = vec2f(0., 0.);
349 let mut prev_position = 0.;
350 for run in &self.layout.runs {
351 for (glyph_ix, glyph) in run.glyphs.iter().enumerate() {
352 if boundaries.peek().map_or(false, |b| b.glyph_ix == glyph_ix) {
353 boundaries.next();
354 glyph_origin = vec2f(0., glyph_origin.y() + line_height);
355 } else {
356 glyph_origin.set_x(glyph_origin.x() + glyph.position.x() - prev_position);
357 }
358 prev_position = glyph.position.x();
359
360 if glyph.index >= color_end {
361 if let Some(next_run) = color_runs.next() {
362 color_end += next_run.0 as usize;
363 color = next_run.1;
364 } else {
365 color_end = self.layout.len;
366 color = Color::black();
367 }
368 }
369
370 let glyph_bounds = RectF::new(
371 origin + glyph_origin,
372 cx.font_cache
373 .bounding_box(run.font_id, self.layout.font_size),
374 );
375 if glyph_bounds.intersects(visible_bounds) {
376 cx.scene.push_glyph(scene::Glyph {
377 font_id: run.font_id,
378 font_size: self.layout.font_size,
379 id: glyph.id,
380 origin: glyph_bounds.origin() + baseline_origin,
381 color,
382 });
383 }
384 }
385 }
386 }
387}
388
389impl Run {
390 pub fn glyphs(&self) -> &[Glyph] {
391 &self.glyphs
392 }
393}
394
395#[derive(Copy, Clone, Debug, PartialEq, Eq)]
396pub struct Boundary {
397 pub ix: usize,
398 pub next_indent: u32,
399}
400
401#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
402pub struct ShapedBoundary {
403 pub run_ix: usize,
404 pub glyph_ix: usize,
405}
406
407impl Boundary {
408 fn new(ix: usize, next_indent: u32) -> Self {
409 Self { ix, next_indent }
410 }
411}
412
413pub struct LineWrapper {
414 font_system: Arc<dyn FontSystem>,
415 pub(crate) font_id: FontId,
416 pub(crate) font_size: f32,
417 cached_ascii_char_widths: [f32; 128],
418 cached_other_char_widths: HashMap<char, f32>,
419}
420
421impl LineWrapper {
422 pub const MAX_INDENT: u32 = 256;
423
424 pub fn new(font_id: FontId, font_size: f32, font_system: Arc<dyn FontSystem>) -> Self {
425 Self {
426 font_system,
427 font_id,
428 font_size,
429 cached_ascii_char_widths: [f32::NAN; 128],
430 cached_other_char_widths: HashMap::new(),
431 }
432 }
433
434 pub fn wrap_line<'a>(
435 &'a mut self,
436 line: &'a str,
437 wrap_width: f32,
438 ) -> impl Iterator<Item = Boundary> + 'a {
439 let mut width = 0.0;
440 let mut first_non_whitespace_ix = None;
441 let mut indent = None;
442 let mut last_candidate_ix = 0;
443 let mut last_candidate_width = 0.0;
444 let mut last_wrap_ix = 0;
445 let mut prev_c = '\0';
446 let mut char_indices = line.char_indices();
447 iter::from_fn(move || {
448 while let Some((ix, c)) = char_indices.next() {
449 if c == '\n' {
450 continue;
451 }
452
453 if self.is_boundary(prev_c, c) && first_non_whitespace_ix.is_some() {
454 last_candidate_ix = ix;
455 last_candidate_width = width;
456 }
457
458 if c != ' ' && first_non_whitespace_ix.is_none() {
459 first_non_whitespace_ix = Some(ix);
460 }
461
462 let char_width = self.width_for_char(c);
463 width += char_width;
464 if width > wrap_width && ix > last_wrap_ix {
465 if let (None, Some(first_non_whitespace_ix)) = (indent, first_non_whitespace_ix)
466 {
467 indent = Some(
468 Self::MAX_INDENT.min((first_non_whitespace_ix - last_wrap_ix) as u32),
469 );
470 }
471
472 if last_candidate_ix > 0 {
473 last_wrap_ix = last_candidate_ix;
474 width -= last_candidate_width;
475 last_candidate_ix = 0;
476 } else {
477 last_wrap_ix = ix;
478 width = char_width;
479 }
480
481 let indent_width =
482 indent.map(|indent| indent as f32 * self.width_for_char(' '));
483 width += indent_width.unwrap_or(0.);
484
485 return Some(Boundary::new(last_wrap_ix, indent.unwrap_or(0)));
486 }
487 prev_c = c;
488 }
489
490 None
491 })
492 }
493
494 pub fn wrap_shaped_line<'a>(
495 &'a mut self,
496 str: &'a str,
497 line: &'a Line,
498 wrap_width: f32,
499 ) -> impl Iterator<Item = ShapedBoundary> + 'a {
500 let mut first_non_whitespace_ix = None;
501 let mut last_candidate_ix = None;
502 let mut last_candidate_x = 0.0;
503 let mut last_wrap_ix = ShapedBoundary {
504 run_ix: 0,
505 glyph_ix: 0,
506 };
507 let mut last_wrap_x = 0.;
508 let mut prev_c = '\0';
509 let mut glyphs = line
510 .runs()
511 .iter()
512 .enumerate()
513 .flat_map(move |(run_ix, run)| {
514 run.glyphs()
515 .iter()
516 .enumerate()
517 .map(move |(glyph_ix, glyph)| {
518 let character = str[glyph.index..].chars().next().unwrap();
519 (
520 ShapedBoundary { run_ix, glyph_ix },
521 character,
522 glyph.position.x(),
523 )
524 })
525 })
526 .peekable();
527
528 iter::from_fn(move || {
529 while let Some((ix, c, x)) = glyphs.next() {
530 if c == '\n' {
531 continue;
532 }
533
534 if self.is_boundary(prev_c, c) && first_non_whitespace_ix.is_some() {
535 last_candidate_ix = Some(ix);
536 last_candidate_x = x;
537 }
538
539 if c != ' ' && first_non_whitespace_ix.is_none() {
540 first_non_whitespace_ix = Some(ix);
541 }
542
543 let next_x = glyphs.peek().map_or(line.width(), |(_, _, x)| *x);
544 let width = next_x - last_wrap_x;
545 if width > wrap_width && ix > last_wrap_ix {
546 if let Some(last_candidate_ix) = last_candidate_ix.take() {
547 last_wrap_ix = last_candidate_ix;
548 last_wrap_x = last_candidate_x;
549 } else {
550 last_wrap_ix = ix;
551 last_wrap_x = x;
552 }
553
554 return Some(last_wrap_ix);
555 }
556 prev_c = c;
557 }
558
559 None
560 })
561 }
562
563 fn is_boundary(&self, prev: char, next: char) -> bool {
564 (prev == ' ') && (next != ' ')
565 }
566
567 #[inline(always)]
568 fn width_for_char(&mut self, c: char) -> f32 {
569 if (c as u32) < 128 {
570 let mut width = self.cached_ascii_char_widths[c as usize];
571 if width.is_nan() {
572 width = self.compute_width_for_char(c);
573 self.cached_ascii_char_widths[c as usize] = width;
574 }
575 width
576 } else {
577 let mut width = self
578 .cached_other_char_widths
579 .get(&c)
580 .copied()
581 .unwrap_or(f32::NAN);
582 if width.is_nan() {
583 width = self.compute_width_for_char(c);
584 self.cached_other_char_widths.insert(c, width);
585 }
586 width
587 }
588 }
589
590 fn compute_width_for_char(&self, c: char) -> f32 {
591 self.font_system
592 .layout_line(
593 &c.to_string(),
594 self.font_size,
595 &[(
596 1,
597 RunStyle {
598 font_id: self.font_id,
599 color: Default::default(),
600 underline: None,
601 },
602 )],
603 )
604 .width
605 }
606}
607
608#[cfg(test)]
609mod tests {
610 use super::*;
611 use crate::fonts::{Properties, Weight};
612
613 #[crate::test(self)]
614 fn test_wrap_line(cx: &mut crate::MutableAppContext) {
615 let font_cache = cx.font_cache().clone();
616 let font_system = cx.platform().fonts();
617 let family = font_cache.load_family(&["Courier"]).unwrap();
618 let font_id = font_cache.select_font(family, &Default::default()).unwrap();
619
620 let mut wrapper = LineWrapper::new(font_id, 16., font_system);
621 assert_eq!(
622 wrapper
623 .wrap_line("aa bbb cccc ddddd eeee", 72.0)
624 .collect::<Vec<_>>(),
625 &[
626 Boundary::new(7, 0),
627 Boundary::new(12, 0),
628 Boundary::new(18, 0)
629 ],
630 );
631 assert_eq!(
632 wrapper
633 .wrap_line("aaa aaaaaaaaaaaaaaaaaa", 72.0)
634 .collect::<Vec<_>>(),
635 &[
636 Boundary::new(4, 0),
637 Boundary::new(11, 0),
638 Boundary::new(18, 0)
639 ],
640 );
641 assert_eq!(
642 wrapper.wrap_line(" aaaaaaa", 72.).collect::<Vec<_>>(),
643 &[
644 Boundary::new(7, 5),
645 Boundary::new(9, 5),
646 Boundary::new(11, 5),
647 ]
648 );
649 assert_eq!(
650 wrapper
651 .wrap_line(" ", 72.)
652 .collect::<Vec<_>>(),
653 &[
654 Boundary::new(7, 0),
655 Boundary::new(14, 0),
656 Boundary::new(21, 0)
657 ]
658 );
659 assert_eq!(
660 wrapper
661 .wrap_line(" aaaaaaaaaaaaaa", 72.)
662 .collect::<Vec<_>>(),
663 &[
664 Boundary::new(7, 0),
665 Boundary::new(14, 3),
666 Boundary::new(18, 3),
667 Boundary::new(22, 3),
668 ]
669 );
670 }
671
672 #[crate::test(self, retries = 5)]
673 fn test_wrap_shaped_line(cx: &mut crate::MutableAppContext) {
674 // This is failing intermittently on CI and we don't have time to figure it out
675 let font_cache = cx.font_cache().clone();
676 let font_system = cx.platform().fonts();
677 let text_layout_cache = TextLayoutCache::new(font_system.clone());
678
679 let family = font_cache.load_family(&["Helvetica"]).unwrap();
680 let font_id = font_cache.select_font(family, &Default::default()).unwrap();
681 let normal = RunStyle {
682 font_id,
683 color: Default::default(),
684 underline: None,
685 };
686 let bold = RunStyle {
687 font_id: font_cache
688 .select_font(
689 family,
690 &Properties {
691 weight: Weight::BOLD,
692 ..Default::default()
693 },
694 )
695 .unwrap(),
696 color: Default::default(),
697 underline: None,
698 };
699
700 let text = "aa bbb cccc ddddd eeee";
701 let line = text_layout_cache.layout_str(
702 text,
703 16.0,
704 &[(4, normal), (5, bold), (6, normal), (1, bold), (7, normal)],
705 );
706
707 let mut wrapper = LineWrapper::new(font_id, 16., font_system);
708 assert_eq!(
709 wrapper
710 .wrap_shaped_line(&text, &line, 72.0)
711 .collect::<Vec<_>>(),
712 &[
713 ShapedBoundary {
714 run_ix: 1,
715 glyph_ix: 3
716 },
717 ShapedBoundary {
718 run_ix: 2,
719 glyph_ix: 3
720 },
721 ShapedBoundary {
722 run_ix: 4,
723 glyph_ix: 2
724 }
725 ],
726 );
727 }
728}