1use crate::{
2 color::Color,
3 fonts::{FontId, GlyphId, Underline},
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: Underline,
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, Clone)]
168pub struct Line {
169 layout: Arc<LineLayout>,
170 style_runs: SmallVec<[(u32, Color, Underline); 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(Clone, Debug)]
190pub struct Glyph {
191 pub id: GlyphId,
192 pub position: Vector2F,
193 pub index: usize,
194 pub is_emoji: bool,
195}
196
197impl Line {
198 fn new(layout: Arc<LineLayout>, runs: &[(usize, RunStyle)]) -> Self {
199 let mut style_runs = SmallVec::new();
200 for (len, style) in runs {
201 style_runs.push((*len as u32, style.color, style.underline));
202 }
203 Self { layout, style_runs }
204 }
205
206 pub fn runs(&self) -> &[Run] {
207 &self.layout.runs
208 }
209
210 pub fn width(&self) -> f32 {
211 self.layout.width
212 }
213
214 pub fn font_size(&self) -> f32 {
215 self.layout.font_size
216 }
217
218 pub fn x_for_index(&self, index: usize) -> f32 {
219 for run in &self.layout.runs {
220 for glyph in &run.glyphs {
221 if glyph.index >= index {
222 return glyph.position.x();
223 }
224 }
225 }
226 self.layout.width
227 }
228
229 pub fn font_for_index(&self, index: usize) -> Option<FontId> {
230 for run in &self.layout.runs {
231 for glyph in &run.glyphs {
232 if glyph.index >= index {
233 return Some(run.font_id);
234 }
235 }
236 }
237
238 None
239 }
240
241 pub fn index_for_x(&self, x: f32) -> Option<usize> {
242 if x >= self.layout.width {
243 None
244 } else {
245 for run in self.layout.runs.iter().rev() {
246 for glyph in run.glyphs.iter().rev() {
247 if glyph.position.x() <= x {
248 return Some(glyph.index);
249 }
250 }
251 }
252 Some(0)
253 }
254 }
255
256 pub fn paint(
257 &self,
258 origin: Vector2F,
259 visible_bounds: RectF,
260 line_height: f32,
261 cx: &mut PaintContext,
262 ) {
263 let padding_top = (line_height - self.layout.ascent - self.layout.descent) / 2.;
264 let baseline_offset = vec2f(0., padding_top + self.layout.ascent);
265
266 let mut style_runs = self.style_runs.iter();
267 let mut run_end = 0;
268 let mut color = Color::black();
269 let mut underline = None;
270
271 for run in &self.layout.runs {
272 let max_glyph_width = cx
273 .font_cache
274 .bounding_box(run.font_id, self.layout.font_size)
275 .x();
276
277 for glyph in &run.glyphs {
278 let glyph_origin = origin + baseline_offset + glyph.position;
279 if glyph_origin.x() > visible_bounds.upper_right().x() {
280 break;
281 }
282
283 let mut finished_underline = None;
284 if glyph.index >= run_end {
285 if let Some((run_len, run_color, run_underline)) = style_runs.next() {
286 if let Some((_, underline_style)) = underline {
287 if *run_underline != underline_style {
288 finished_underline = underline.take();
289 }
290 }
291 if run_underline.thickness.into_inner() > 0. {
292 underline.get_or_insert((
293 vec2f(
294 glyph_origin.x(),
295 origin.y() + baseline_offset.y() + 0.618 * self.layout.descent,
296 ),
297 Underline {
298 color: Some(run_underline.color.unwrap_or(*run_color)),
299 thickness: run_underline.thickness.into(),
300 squiggly: run_underline.squiggly,
301 },
302 ));
303 }
304
305 run_end += *run_len as usize;
306 color = *run_color;
307 } else {
308 run_end = self.layout.len;
309 finished_underline = underline.take();
310 }
311 }
312
313 if glyph_origin.x() + max_glyph_width < visible_bounds.origin().x() {
314 continue;
315 }
316
317 if let Some((underline_origin, underline_style)) = finished_underline {
318 cx.scene.push_underline(scene::Underline {
319 origin: underline_origin,
320 width: glyph_origin.x() - underline_origin.x(),
321 thickness: underline_style.thickness.into(),
322 color: underline_style.color.unwrap(),
323 squiggly: underline_style.squiggly,
324 });
325 }
326
327 if glyph.is_emoji {
328 cx.scene.push_image_glyph(scene::ImageGlyph {
329 font_id: run.font_id,
330 font_size: self.layout.font_size,
331 id: glyph.id,
332 origin: glyph_origin,
333 });
334 } else {
335 cx.scene.push_glyph(scene::Glyph {
336 font_id: run.font_id,
337 font_size: self.layout.font_size,
338 id: glyph.id,
339 origin: glyph_origin,
340 color,
341 });
342 }
343 }
344 }
345
346 if let Some((underline_start, underline_style)) = underline.take() {
347 let line_end_x = origin.x() + self.layout.width;
348 cx.scene.push_underline(scene::Underline {
349 origin: underline_start,
350 width: line_end_x - underline_start.x(),
351 color: underline_style.color.unwrap(),
352 thickness: underline_style.thickness.into(),
353 squiggly: underline_style.squiggly,
354 });
355 }
356 }
357
358 pub fn paint_wrapped(
359 &self,
360 origin: Vector2F,
361 visible_bounds: RectF,
362 line_height: f32,
363 boundaries: impl IntoIterator<Item = ShapedBoundary>,
364 cx: &mut PaintContext,
365 ) {
366 let padding_top = (line_height - self.layout.ascent - self.layout.descent) / 2.;
367 let baseline_origin = vec2f(0., padding_top + self.layout.ascent);
368
369 let mut boundaries = boundaries.into_iter().peekable();
370 let mut color_runs = self.style_runs.iter();
371 let mut color_end = 0;
372 let mut color = Color::black();
373
374 let mut glyph_origin = vec2f(0., 0.);
375 let mut prev_position = 0.;
376 for run in &self.layout.runs {
377 for (glyph_ix, glyph) in run.glyphs.iter().enumerate() {
378 if boundaries.peek().map_or(false, |b| b.glyph_ix == glyph_ix) {
379 boundaries.next();
380 glyph_origin = vec2f(0., glyph_origin.y() + line_height);
381 } else {
382 glyph_origin.set_x(glyph_origin.x() + glyph.position.x() - prev_position);
383 }
384 prev_position = glyph.position.x();
385
386 if glyph.index >= color_end {
387 if let Some(next_run) = color_runs.next() {
388 color_end += next_run.0 as usize;
389 color = next_run.1;
390 } else {
391 color_end = self.layout.len;
392 color = Color::black();
393 }
394 }
395
396 let glyph_bounds = RectF::new(
397 origin + glyph_origin,
398 cx.font_cache
399 .bounding_box(run.font_id, self.layout.font_size),
400 );
401 if glyph_bounds.intersects(visible_bounds) {
402 if glyph.is_emoji {
403 cx.scene.push_image_glyph(scene::ImageGlyph {
404 font_id: run.font_id,
405 font_size: self.layout.font_size,
406 id: glyph.id,
407 origin: glyph_bounds.origin() + baseline_origin,
408 });
409 } else {
410 cx.scene.push_glyph(scene::Glyph {
411 font_id: run.font_id,
412 font_size: self.layout.font_size,
413 id: glyph.id,
414 origin: glyph_bounds.origin() + baseline_origin,
415 color,
416 });
417 }
418 }
419 }
420 }
421 }
422}
423
424impl Run {
425 pub fn glyphs(&self) -> &[Glyph] {
426 &self.glyphs
427 }
428}
429
430#[derive(Copy, Clone, Debug, PartialEq, Eq)]
431pub struct Boundary {
432 pub ix: usize,
433 pub next_indent: u32,
434}
435
436#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
437pub struct ShapedBoundary {
438 pub run_ix: usize,
439 pub glyph_ix: usize,
440}
441
442impl Boundary {
443 fn new(ix: usize, next_indent: u32) -> Self {
444 Self { ix, next_indent }
445 }
446}
447
448pub struct LineWrapper {
449 font_system: Arc<dyn FontSystem>,
450 pub(crate) font_id: FontId,
451 pub(crate) font_size: f32,
452 cached_ascii_char_widths: [f32; 128],
453 cached_other_char_widths: HashMap<char, f32>,
454}
455
456impl LineWrapper {
457 pub const MAX_INDENT: u32 = 256;
458
459 pub fn new(font_id: FontId, font_size: f32, font_system: Arc<dyn FontSystem>) -> Self {
460 Self {
461 font_system,
462 font_id,
463 font_size,
464 cached_ascii_char_widths: [f32::NAN; 128],
465 cached_other_char_widths: HashMap::new(),
466 }
467 }
468
469 pub fn wrap_line<'a>(
470 &'a mut self,
471 line: &'a str,
472 wrap_width: f32,
473 ) -> impl Iterator<Item = Boundary> + 'a {
474 let mut width = 0.0;
475 let mut first_non_whitespace_ix = None;
476 let mut indent = None;
477 let mut last_candidate_ix = 0;
478 let mut last_candidate_width = 0.0;
479 let mut last_wrap_ix = 0;
480 let mut prev_c = '\0';
481 let mut char_indices = line.char_indices();
482 iter::from_fn(move || {
483 while let Some((ix, c)) = char_indices.next() {
484 if c == '\n' {
485 continue;
486 }
487
488 if self.is_boundary(prev_c, c) && first_non_whitespace_ix.is_some() {
489 last_candidate_ix = ix;
490 last_candidate_width = width;
491 }
492
493 if c != ' ' && first_non_whitespace_ix.is_none() {
494 first_non_whitespace_ix = Some(ix);
495 }
496
497 let char_width = self.width_for_char(c);
498 width += char_width;
499 if width > wrap_width && ix > last_wrap_ix {
500 if let (None, Some(first_non_whitespace_ix)) = (indent, first_non_whitespace_ix)
501 {
502 indent = Some(
503 Self::MAX_INDENT.min((first_non_whitespace_ix - last_wrap_ix) as u32),
504 );
505 }
506
507 if last_candidate_ix > 0 {
508 last_wrap_ix = last_candidate_ix;
509 width -= last_candidate_width;
510 last_candidate_ix = 0;
511 } else {
512 last_wrap_ix = ix;
513 width = char_width;
514 }
515
516 let indent_width =
517 indent.map(|indent| indent as f32 * self.width_for_char(' '));
518 width += indent_width.unwrap_or(0.);
519
520 return Some(Boundary::new(last_wrap_ix, indent.unwrap_or(0)));
521 }
522 prev_c = c;
523 }
524
525 None
526 })
527 }
528
529 pub fn wrap_shaped_line<'a>(
530 &'a mut self,
531 str: &'a str,
532 line: &'a Line,
533 wrap_width: f32,
534 ) -> impl Iterator<Item = ShapedBoundary> + 'a {
535 let mut first_non_whitespace_ix = None;
536 let mut last_candidate_ix = None;
537 let mut last_candidate_x = 0.0;
538 let mut last_wrap_ix = ShapedBoundary {
539 run_ix: 0,
540 glyph_ix: 0,
541 };
542 let mut last_wrap_x = 0.;
543 let mut prev_c = '\0';
544 let mut glyphs = line
545 .runs()
546 .iter()
547 .enumerate()
548 .flat_map(move |(run_ix, run)| {
549 run.glyphs()
550 .iter()
551 .enumerate()
552 .map(move |(glyph_ix, glyph)| {
553 let character = str[glyph.index..].chars().next().unwrap();
554 (
555 ShapedBoundary { run_ix, glyph_ix },
556 character,
557 glyph.position.x(),
558 )
559 })
560 })
561 .peekable();
562
563 iter::from_fn(move || {
564 while let Some((ix, c, x)) = glyphs.next() {
565 if c == '\n' {
566 continue;
567 }
568
569 if self.is_boundary(prev_c, c) && first_non_whitespace_ix.is_some() {
570 last_candidate_ix = Some(ix);
571 last_candidate_x = x;
572 }
573
574 if c != ' ' && first_non_whitespace_ix.is_none() {
575 first_non_whitespace_ix = Some(ix);
576 }
577
578 let next_x = glyphs.peek().map_or(line.width(), |(_, _, x)| *x);
579 let width = next_x - last_wrap_x;
580 if width > wrap_width && ix > last_wrap_ix {
581 if let Some(last_candidate_ix) = last_candidate_ix.take() {
582 last_wrap_ix = last_candidate_ix;
583 last_wrap_x = last_candidate_x;
584 } else {
585 last_wrap_ix = ix;
586 last_wrap_x = x;
587 }
588
589 return Some(last_wrap_ix);
590 }
591 prev_c = c;
592 }
593
594 None
595 })
596 }
597
598 fn is_boundary(&self, prev: char, next: char) -> bool {
599 (prev == ' ') && (next != ' ')
600 }
601
602 #[inline(always)]
603 fn width_for_char(&mut self, c: char) -> f32 {
604 if (c as u32) < 128 {
605 let mut width = self.cached_ascii_char_widths[c as usize];
606 if width.is_nan() {
607 width = self.compute_width_for_char(c);
608 self.cached_ascii_char_widths[c as usize] = width;
609 }
610 width
611 } else {
612 let mut width = self
613 .cached_other_char_widths
614 .get(&c)
615 .copied()
616 .unwrap_or(f32::NAN);
617 if width.is_nan() {
618 width = self.compute_width_for_char(c);
619 self.cached_other_char_widths.insert(c, width);
620 }
621 width
622 }
623 }
624
625 fn compute_width_for_char(&self, c: char) -> f32 {
626 self.font_system
627 .layout_line(
628 &c.to_string(),
629 self.font_size,
630 &[(
631 1,
632 RunStyle {
633 font_id: self.font_id,
634 color: Default::default(),
635 underline: Default::default(),
636 },
637 )],
638 )
639 .width
640 }
641}
642
643#[cfg(test)]
644mod tests {
645 use super::*;
646 use crate::fonts::{Properties, Weight};
647
648 #[crate::test(self)]
649 fn test_wrap_line(cx: &mut crate::MutableAppContext) {
650 let font_cache = cx.font_cache().clone();
651 let font_system = cx.platform().fonts();
652 let family = font_cache.load_family(&["Courier"]).unwrap();
653 let font_id = font_cache.select_font(family, &Default::default()).unwrap();
654
655 let mut wrapper = LineWrapper::new(font_id, 16., font_system);
656 assert_eq!(
657 wrapper
658 .wrap_line("aa bbb cccc ddddd eeee", 72.0)
659 .collect::<Vec<_>>(),
660 &[
661 Boundary::new(7, 0),
662 Boundary::new(12, 0),
663 Boundary::new(18, 0)
664 ],
665 );
666 assert_eq!(
667 wrapper
668 .wrap_line("aaa aaaaaaaaaaaaaaaaaa", 72.0)
669 .collect::<Vec<_>>(),
670 &[
671 Boundary::new(4, 0),
672 Boundary::new(11, 0),
673 Boundary::new(18, 0)
674 ],
675 );
676 assert_eq!(
677 wrapper.wrap_line(" aaaaaaa", 72.).collect::<Vec<_>>(),
678 &[
679 Boundary::new(7, 5),
680 Boundary::new(9, 5),
681 Boundary::new(11, 5),
682 ]
683 );
684 assert_eq!(
685 wrapper
686 .wrap_line(" ", 72.)
687 .collect::<Vec<_>>(),
688 &[
689 Boundary::new(7, 0),
690 Boundary::new(14, 0),
691 Boundary::new(21, 0)
692 ]
693 );
694 assert_eq!(
695 wrapper
696 .wrap_line(" aaaaaaaaaaaaaa", 72.)
697 .collect::<Vec<_>>(),
698 &[
699 Boundary::new(7, 0),
700 Boundary::new(14, 3),
701 Boundary::new(18, 3),
702 Boundary::new(22, 3),
703 ]
704 );
705 }
706
707 #[crate::test(self, retries = 5)]
708 fn test_wrap_shaped_line(cx: &mut crate::MutableAppContext) {
709 // This is failing intermittently on CI and we don't have time to figure it out
710 let font_cache = cx.font_cache().clone();
711 let font_system = cx.platform().fonts();
712 let text_layout_cache = TextLayoutCache::new(font_system.clone());
713
714 let family = font_cache.load_family(&["Helvetica"]).unwrap();
715 let font_id = font_cache.select_font(family, &Default::default()).unwrap();
716 let normal = RunStyle {
717 font_id,
718 color: Default::default(),
719 underline: Default::default(),
720 };
721 let bold = RunStyle {
722 font_id: font_cache
723 .select_font(
724 family,
725 &Properties {
726 weight: Weight::BOLD,
727 ..Default::default()
728 },
729 )
730 .unwrap(),
731 color: Default::default(),
732 underline: Default::default(),
733 };
734
735 let text = "aa bbb cccc ddddd eeee";
736 let line = text_layout_cache.layout_str(
737 text,
738 16.0,
739 &[(4, normal), (5, bold), (6, normal), (1, bold), (7, normal)],
740 );
741
742 let mut wrapper = LineWrapper::new(font_id, 16., font_system);
743 assert_eq!(
744 wrapper
745 .wrap_shaped_line(&text, &line, 72.0)
746 .collect::<Vec<_>>(),
747 &[
748 ShapedBoundary {
749 run_ix: 1,
750 glyph_ix: 3
751 },
752 ShapedBoundary {
753 run_ix: 2,
754 glyph_ix: 3
755 },
756 ShapedBoundary {
757 run_ix: 4,
758 glyph_ix: 2
759 }
760 ],
761 );
762 }
763}