1use crate::{
2 color::Color,
3 fonts::{FontId, GlyphId, Underline},
4 geometry::{
5 rect::RectF,
6 vector::{vec2f, Vector2F},
7 },
8 platform,
9 platform::FontSystem,
10 scene,
11 window::WindowContext,
12 SceneBuilder,
13};
14use ordered_float::OrderedFloat;
15use parking_lot::{Mutex, RwLock, RwLockUpgradableReadGuard};
16use smallvec::SmallVec;
17use std::{
18 borrow::Borrow,
19 collections::HashMap,
20 hash::{Hash, Hasher},
21 iter,
22 sync::Arc,
23};
24
25pub struct TextLayoutCache {
26 prev_frame: Mutex<HashMap<CacheKeyValue, Arc<LineLayout>>>,
27 curr_frame: RwLock<HashMap<CacheKeyValue, Arc<LineLayout>>>,
28 fonts: Arc<dyn platform::FontSystem>,
29}
30
31#[derive(Copy, Clone, Debug, PartialEq, Eq)]
32pub struct RunStyle {
33 pub color: Color,
34 pub font_id: FontId,
35 pub underline: Underline,
36}
37
38impl TextLayoutCache {
39 pub fn new(fonts: Arc<dyn platform::FontSystem>) -> Self {
40 Self {
41 prev_frame: Mutex::new(HashMap::new()),
42 curr_frame: RwLock::new(HashMap::new()),
43 fonts,
44 }
45 }
46
47 pub fn finish_frame(&self) {
48 let mut prev_frame = self.prev_frame.lock();
49 let mut curr_frame = self.curr_frame.write();
50 std::mem::swap(&mut *prev_frame, &mut *curr_frame);
51 curr_frame.clear();
52 }
53
54 pub fn layout_str<'a>(
55 &'a self,
56 text: &'a str,
57 font_size: f32,
58 runs: &'a [(usize, RunStyle)],
59 ) -> Line {
60 let key = &CacheKeyRef {
61 text,
62 font_size: OrderedFloat(font_size),
63 runs,
64 } as &dyn CacheKey;
65 let curr_frame = self.curr_frame.upgradable_read();
66 if let Some(layout) = curr_frame.get(key) {
67 return Line::new(layout.clone(), runs);
68 }
69
70 let mut curr_frame = RwLockUpgradableReadGuard::upgrade(curr_frame);
71 if let Some((key, layout)) = self.prev_frame.lock().remove_entry(key) {
72 curr_frame.insert(key, layout.clone());
73 Line::new(layout, runs)
74 } else {
75 let layout = Arc::new(self.fonts.layout_line(text, font_size, runs));
76 let key = CacheKeyValue {
77 text: text.into(),
78 font_size: OrderedFloat(font_size),
79 runs: SmallVec::from(runs),
80 };
81 curr_frame.insert(key, layout.clone());
82 Line::new(layout, runs)
83 }
84 }
85}
86
87trait CacheKey {
88 fn key(&self) -> CacheKeyRef;
89}
90
91impl<'a> PartialEq for (dyn CacheKey + 'a) {
92 fn eq(&self, other: &dyn CacheKey) -> bool {
93 self.key() == other.key()
94 }
95}
96
97impl<'a> Eq for (dyn CacheKey + 'a) {}
98
99impl<'a> Hash for (dyn CacheKey + 'a) {
100 fn hash<H: Hasher>(&self, state: &mut H) {
101 self.key().hash(state)
102 }
103}
104
105#[derive(Eq)]
106struct CacheKeyValue {
107 text: String,
108 font_size: OrderedFloat<f32>,
109 runs: SmallVec<[(usize, RunStyle); 1]>,
110}
111
112impl CacheKey for CacheKeyValue {
113 fn key(&self) -> CacheKeyRef {
114 CacheKeyRef {
115 text: self.text.as_str(),
116 font_size: self.font_size,
117 runs: self.runs.as_slice(),
118 }
119 }
120}
121
122impl PartialEq for CacheKeyValue {
123 fn eq(&self, other: &Self) -> bool {
124 self.key().eq(&other.key())
125 }
126}
127
128impl Hash for CacheKeyValue {
129 fn hash<H: Hasher>(&self, state: &mut H) {
130 self.key().hash(state);
131 }
132}
133
134impl<'a> Borrow<dyn CacheKey + 'a> for CacheKeyValue {
135 fn borrow(&self) -> &(dyn CacheKey + 'a) {
136 self as &dyn CacheKey
137 }
138}
139
140#[derive(Copy, Clone)]
141struct CacheKeyRef<'a> {
142 text: &'a str,
143 font_size: OrderedFloat<f32>,
144 runs: &'a [(usize, RunStyle)],
145}
146
147impl<'a> CacheKey for CacheKeyRef<'a> {
148 fn key(&self) -> CacheKeyRef {
149 *self
150 }
151}
152
153impl<'a> PartialEq for CacheKeyRef<'a> {
154 fn eq(&self, other: &Self) -> bool {
155 self.text == other.text
156 && self.font_size == other.font_size
157 && self.runs.len() == other.runs.len()
158 && self.runs.iter().zip(other.runs.iter()).all(
159 |((len_a, style_a), (len_b, style_b))| {
160 len_a == len_b && style_a.font_id == style_b.font_id
161 },
162 )
163 }
164}
165
166impl<'a> Hash for CacheKeyRef<'a> {
167 fn hash<H: Hasher>(&self, state: &mut H) {
168 self.text.hash(state);
169 self.font_size.hash(state);
170 for (len, style_id) in self.runs {
171 len.hash(state);
172 style_id.font_id.hash(state);
173 }
174 }
175}
176
177#[derive(Default, Debug, Clone)]
178pub struct Line {
179 layout: Arc<LineLayout>,
180 style_runs: SmallVec<[(u32, Color, Underline); 32]>,
181}
182
183#[derive(Default, Debug)]
184pub struct LineLayout {
185 pub width: f32,
186 pub ascent: f32,
187 pub descent: f32,
188 pub runs: Vec<Run>,
189 pub len: usize,
190 pub font_size: f32,
191}
192
193#[derive(Debug)]
194pub struct Run {
195 pub font_id: FontId,
196 pub glyphs: Vec<Glyph>,
197}
198
199#[derive(Clone, Debug)]
200pub struct Glyph {
201 pub id: GlyphId,
202 pub position: Vector2F,
203 pub index: usize,
204 pub is_emoji: bool,
205}
206
207impl Line {
208 fn new(layout: Arc<LineLayout>, runs: &[(usize, RunStyle)]) -> Self {
209 let mut style_runs = SmallVec::new();
210 for (len, style) in runs {
211 style_runs.push((*len as u32, style.color, style.underline));
212 }
213 Self { layout, style_runs }
214 }
215
216 pub fn runs(&self) -> &[Run] {
217 &self.layout.runs
218 }
219
220 pub fn width(&self) -> f32 {
221 self.layout.width
222 }
223
224 pub fn font_size(&self) -> f32 {
225 self.layout.font_size
226 }
227
228 pub fn x_for_index(&self, index: usize) -> f32 {
229 for run in &self.layout.runs {
230 for glyph in &run.glyphs {
231 if glyph.index >= index {
232 return glyph.position.x();
233 }
234 }
235 }
236 self.layout.width
237 }
238
239 pub fn font_for_index(&self, index: usize) -> Option<FontId> {
240 for run in &self.layout.runs {
241 for glyph in &run.glyphs {
242 if glyph.index >= index {
243 return Some(run.font_id);
244 }
245 }
246 }
247
248 None
249 }
250
251 pub fn len(&self) -> usize {
252 self.layout.len
253 }
254
255 pub fn is_empty(&self) -> bool {
256 self.layout.len == 0
257 }
258
259 pub fn index_for_x(&self, x: f32) -> Option<usize> {
260 if x >= self.layout.width {
261 None
262 } else {
263 for run in self.layout.runs.iter().rev() {
264 for glyph in run.glyphs.iter().rev() {
265 if glyph.position.x() <= x {
266 return Some(glyph.index);
267 }
268 }
269 }
270 Some(0)
271 }
272 }
273
274 pub fn paint(
275 &self,
276 scene: &mut SceneBuilder,
277 origin: Vector2F,
278 visible_bounds: RectF,
279 line_height: f32,
280 cx: &mut WindowContext,
281 ) {
282 let padding_top = (line_height - self.layout.ascent - self.layout.descent) / 2.;
283 let baseline_offset = vec2f(0., padding_top + self.layout.ascent);
284
285 let mut style_runs = self.style_runs.iter();
286 let mut run_end = 0;
287 let mut color = Color::black();
288 let mut underline = None;
289
290 for run in &self.layout.runs {
291 let max_glyph_width = cx
292 .font_cache
293 .bounding_box(run.font_id, self.layout.font_size)
294 .x();
295
296 for glyph in &run.glyphs {
297 let glyph_origin = origin + baseline_offset + glyph.position;
298 if glyph_origin.x() > visible_bounds.upper_right().x() {
299 break;
300 }
301
302 let mut finished_underline = None;
303 if glyph.index >= run_end {
304 if let Some((run_len, run_color, run_underline)) = style_runs.next() {
305 if let Some((_, underline_style)) = underline {
306 if *run_underline != underline_style {
307 finished_underline = underline.take();
308 }
309 }
310 if run_underline.thickness.into_inner() > 0. {
311 underline.get_or_insert((
312 vec2f(
313 glyph_origin.x(),
314 origin.y() + baseline_offset.y() + 0.618 * self.layout.descent,
315 ),
316 Underline {
317 color: Some(run_underline.color.unwrap_or(*run_color)),
318 thickness: run_underline.thickness,
319 squiggly: run_underline.squiggly,
320 },
321 ));
322 }
323
324 run_end += *run_len as usize;
325 color = *run_color;
326 } else {
327 run_end = self.layout.len;
328 finished_underline = underline.take();
329 }
330 }
331
332 if glyph_origin.x() + max_glyph_width < visible_bounds.origin().x() {
333 continue;
334 }
335
336 if let Some((underline_origin, underline_style)) = finished_underline {
337 scene.push_underline(scene::Underline {
338 origin: underline_origin,
339 width: glyph_origin.x() - underline_origin.x(),
340 thickness: underline_style.thickness.into(),
341 color: underline_style.color.unwrap(),
342 squiggly: underline_style.squiggly,
343 });
344 }
345
346 if glyph.is_emoji {
347 scene.push_image_glyph(scene::ImageGlyph {
348 font_id: run.font_id,
349 font_size: self.layout.font_size,
350 id: glyph.id,
351 origin: glyph_origin,
352 });
353 } else {
354 scene.push_glyph(scene::Glyph {
355 font_id: run.font_id,
356 font_size: self.layout.font_size,
357 id: glyph.id,
358 origin: glyph_origin,
359 color,
360 });
361 }
362 }
363 }
364
365 if let Some((underline_start, underline_style)) = underline.take() {
366 let line_end_x = origin.x() + self.layout.width;
367 scene.push_underline(scene::Underline {
368 origin: underline_start,
369 width: line_end_x - underline_start.x(),
370 color: underline_style.color.unwrap(),
371 thickness: underline_style.thickness.into(),
372 squiggly: underline_style.squiggly,
373 });
374 }
375 }
376
377 pub fn paint_wrapped(
378 &self,
379 scene: &mut SceneBuilder,
380 origin: Vector2F,
381 visible_bounds: RectF,
382 line_height: f32,
383 boundaries: impl IntoIterator<Item = ShapedBoundary>,
384 cx: &mut WindowContext,
385 ) {
386 let padding_top = (line_height - self.layout.ascent - self.layout.descent) / 2.;
387 let baseline_origin = vec2f(0., padding_top + self.layout.ascent);
388
389 let mut boundaries = boundaries.into_iter().peekable();
390 let mut color_runs = self.style_runs.iter();
391 let mut color_end = 0;
392 let mut color = Color::black();
393
394 let mut glyph_origin = vec2f(0., 0.);
395 let mut prev_position = 0.;
396 for run in &self.layout.runs {
397 for (glyph_ix, glyph) in run.glyphs.iter().enumerate() {
398 if boundaries.peek().map_or(false, |b| b.glyph_ix == glyph_ix) {
399 boundaries.next();
400 glyph_origin = vec2f(0., glyph_origin.y() + line_height);
401 } else {
402 glyph_origin.set_x(glyph_origin.x() + glyph.position.x() - prev_position);
403 }
404 prev_position = glyph.position.x();
405
406 if glyph.index >= color_end {
407 if let Some(next_run) = color_runs.next() {
408 color_end += next_run.0 as usize;
409 color = next_run.1;
410 } else {
411 color_end = self.layout.len;
412 color = Color::black();
413 }
414 }
415
416 let glyph_bounds = RectF::new(
417 origin + glyph_origin,
418 cx.font_cache
419 .bounding_box(run.font_id, self.layout.font_size),
420 );
421 if glyph_bounds.intersects(visible_bounds) {
422 if glyph.is_emoji {
423 scene.push_image_glyph(scene::ImageGlyph {
424 font_id: run.font_id,
425 font_size: self.layout.font_size,
426 id: glyph.id,
427 origin: glyph_bounds.origin() + baseline_origin,
428 });
429 } else {
430 scene.push_glyph(scene::Glyph {
431 font_id: run.font_id,
432 font_size: self.layout.font_size,
433 id: glyph.id,
434 origin: glyph_bounds.origin() + baseline_origin,
435 color,
436 });
437 }
438 }
439 }
440 }
441 }
442}
443
444impl Run {
445 pub fn glyphs(&self) -> &[Glyph] {
446 &self.glyphs
447 }
448}
449
450#[derive(Copy, Clone, Debug, PartialEq, Eq)]
451pub struct Boundary {
452 pub ix: usize,
453 pub next_indent: u32,
454}
455
456#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
457pub struct ShapedBoundary {
458 pub run_ix: usize,
459 pub glyph_ix: usize,
460}
461
462impl Boundary {
463 fn new(ix: usize, next_indent: u32) -> Self {
464 Self { ix, next_indent }
465 }
466}
467
468pub struct LineWrapper {
469 font_system: Arc<dyn FontSystem>,
470 pub(crate) font_id: FontId,
471 pub(crate) font_size: f32,
472 cached_ascii_char_widths: [f32; 128],
473 cached_other_char_widths: HashMap<char, f32>,
474}
475
476impl LineWrapper {
477 pub const MAX_INDENT: u32 = 256;
478
479 pub fn new(font_id: FontId, font_size: f32, font_system: Arc<dyn FontSystem>) -> Self {
480 Self {
481 font_system,
482 font_id,
483 font_size,
484 cached_ascii_char_widths: [f32::NAN; 128],
485 cached_other_char_widths: HashMap::new(),
486 }
487 }
488
489 pub fn wrap_line<'a>(
490 &'a mut self,
491 line: &'a str,
492 wrap_width: f32,
493 ) -> impl Iterator<Item = Boundary> + 'a {
494 let mut width = 0.0;
495 let mut first_non_whitespace_ix = None;
496 let mut indent = None;
497 let mut last_candidate_ix = 0;
498 let mut last_candidate_width = 0.0;
499 let mut last_wrap_ix = 0;
500 let mut prev_c = '\0';
501 let mut char_indices = line.char_indices();
502 iter::from_fn(move || {
503 for (ix, c) in char_indices.by_ref() {
504 if c == '\n' {
505 continue;
506 }
507
508 if self.is_boundary(prev_c, c) && first_non_whitespace_ix.is_some() {
509 last_candidate_ix = ix;
510 last_candidate_width = width;
511 }
512
513 if c != ' ' && first_non_whitespace_ix.is_none() {
514 first_non_whitespace_ix = Some(ix);
515 }
516
517 let char_width = self.width_for_char(c);
518 width += char_width;
519 if width > wrap_width && ix > last_wrap_ix {
520 if let (None, Some(first_non_whitespace_ix)) = (indent, first_non_whitespace_ix)
521 {
522 indent = Some(
523 Self::MAX_INDENT.min((first_non_whitespace_ix - last_wrap_ix) as u32),
524 );
525 }
526
527 if last_candidate_ix > 0 {
528 last_wrap_ix = last_candidate_ix;
529 width -= last_candidate_width;
530 last_candidate_ix = 0;
531 } else {
532 last_wrap_ix = ix;
533 width = char_width;
534 }
535
536 let indent_width =
537 indent.map(|indent| indent as f32 * self.width_for_char(' '));
538 width += indent_width.unwrap_or(0.);
539
540 return Some(Boundary::new(last_wrap_ix, indent.unwrap_or(0)));
541 }
542 prev_c = c;
543 }
544
545 None
546 })
547 }
548
549 pub fn wrap_shaped_line<'a>(
550 &'a mut self,
551 str: &'a str,
552 line: &'a Line,
553 wrap_width: f32,
554 ) -> impl Iterator<Item = ShapedBoundary> + 'a {
555 let mut first_non_whitespace_ix = None;
556 let mut last_candidate_ix = None;
557 let mut last_candidate_x = 0.0;
558 let mut last_wrap_ix = ShapedBoundary {
559 run_ix: 0,
560 glyph_ix: 0,
561 };
562 let mut last_wrap_x = 0.;
563 let mut prev_c = '\0';
564 let mut glyphs = line
565 .runs()
566 .iter()
567 .enumerate()
568 .flat_map(move |(run_ix, run)| {
569 run.glyphs()
570 .iter()
571 .enumerate()
572 .map(move |(glyph_ix, glyph)| {
573 let character = str[glyph.index..].chars().next().unwrap();
574 (
575 ShapedBoundary { run_ix, glyph_ix },
576 character,
577 glyph.position.x(),
578 )
579 })
580 })
581 .peekable();
582
583 iter::from_fn(move || {
584 while let Some((ix, c, x)) = glyphs.next() {
585 if c == '\n' {
586 continue;
587 }
588
589 if self.is_boundary(prev_c, c) && first_non_whitespace_ix.is_some() {
590 last_candidate_ix = Some(ix);
591 last_candidate_x = x;
592 }
593
594 if c != ' ' && first_non_whitespace_ix.is_none() {
595 first_non_whitespace_ix = Some(ix);
596 }
597
598 let next_x = glyphs.peek().map_or(line.width(), |(_, _, x)| *x);
599 let width = next_x - last_wrap_x;
600 if width > wrap_width && ix > last_wrap_ix {
601 if let Some(last_candidate_ix) = last_candidate_ix.take() {
602 last_wrap_ix = last_candidate_ix;
603 last_wrap_x = last_candidate_x;
604 } else {
605 last_wrap_ix = ix;
606 last_wrap_x = x;
607 }
608
609 return Some(last_wrap_ix);
610 }
611 prev_c = c;
612 }
613
614 None
615 })
616 }
617
618 fn is_boundary(&self, prev: char, next: char) -> bool {
619 (prev == ' ') && (next != ' ')
620 }
621
622 #[inline(always)]
623 fn width_for_char(&mut self, c: char) -> f32 {
624 if (c as u32) < 128 {
625 let mut width = self.cached_ascii_char_widths[c as usize];
626 if width.is_nan() {
627 width = self.compute_width_for_char(c);
628 self.cached_ascii_char_widths[c as usize] = width;
629 }
630 width
631 } else {
632 let mut width = self
633 .cached_other_char_widths
634 .get(&c)
635 .copied()
636 .unwrap_or(f32::NAN);
637 if width.is_nan() {
638 width = self.compute_width_for_char(c);
639 self.cached_other_char_widths.insert(c, width);
640 }
641 width
642 }
643 }
644
645 fn compute_width_for_char(&self, c: char) -> f32 {
646 self.font_system
647 .layout_line(
648 &c.to_string(),
649 self.font_size,
650 &[(
651 1,
652 RunStyle {
653 font_id: self.font_id,
654 color: Default::default(),
655 underline: Default::default(),
656 },
657 )],
658 )
659 .width
660 }
661}
662
663#[cfg(test)]
664mod tests {
665 use super::*;
666 use crate::fonts::{Properties, Weight};
667
668 #[crate::test(self)]
669 fn test_wrap_line(cx: &mut crate::AppContext) {
670 let font_cache = cx.font_cache().clone();
671 let font_system = cx.platform().fonts();
672 let family = font_cache
673 .load_family(&["Courier"], &Default::default())
674 .unwrap();
675 let font_id = font_cache.select_font(family, &Default::default()).unwrap();
676
677 let mut wrapper = LineWrapper::new(font_id, 16., font_system);
678 assert_eq!(
679 wrapper
680 .wrap_line("aa bbb cccc ddddd eeee", 72.0)
681 .collect::<Vec<_>>(),
682 &[
683 Boundary::new(7, 0),
684 Boundary::new(12, 0),
685 Boundary::new(18, 0)
686 ],
687 );
688 assert_eq!(
689 wrapper
690 .wrap_line("aaa aaaaaaaaaaaaaaaaaa", 72.0)
691 .collect::<Vec<_>>(),
692 &[
693 Boundary::new(4, 0),
694 Boundary::new(11, 0),
695 Boundary::new(18, 0)
696 ],
697 );
698 assert_eq!(
699 wrapper.wrap_line(" aaaaaaa", 72.).collect::<Vec<_>>(),
700 &[
701 Boundary::new(7, 5),
702 Boundary::new(9, 5),
703 Boundary::new(11, 5),
704 ]
705 );
706 assert_eq!(
707 wrapper
708 .wrap_line(" ", 72.)
709 .collect::<Vec<_>>(),
710 &[
711 Boundary::new(7, 0),
712 Boundary::new(14, 0),
713 Boundary::new(21, 0)
714 ]
715 );
716 assert_eq!(
717 wrapper
718 .wrap_line(" aaaaaaaaaaaaaa", 72.)
719 .collect::<Vec<_>>(),
720 &[
721 Boundary::new(7, 0),
722 Boundary::new(14, 3),
723 Boundary::new(18, 3),
724 Boundary::new(22, 3),
725 ]
726 );
727 }
728
729 #[crate::test(self, retries = 5)]
730 fn test_wrap_shaped_line(cx: &mut crate::AppContext) {
731 // This is failing intermittently on CI and we don't have time to figure it out
732 let font_cache = cx.font_cache().clone();
733 let font_system = cx.platform().fonts();
734 let text_layout_cache = TextLayoutCache::new(font_system.clone());
735
736 let family = font_cache
737 .load_family(&["Helvetica"], &Default::default())
738 .unwrap();
739 let font_id = font_cache.select_font(family, &Default::default()).unwrap();
740 let normal = RunStyle {
741 font_id,
742 color: Default::default(),
743 underline: Default::default(),
744 };
745 let bold = RunStyle {
746 font_id: font_cache
747 .select_font(
748 family,
749 &Properties {
750 weight: Weight::BOLD,
751 ..Default::default()
752 },
753 )
754 .unwrap(),
755 color: Default::default(),
756 underline: Default::default(),
757 };
758
759 let text = "aa bbb cccc ddddd eeee";
760 let line = text_layout_cache.layout_str(
761 text,
762 16.0,
763 &[(4, normal), (5, bold), (6, normal), (1, bold), (7, normal)],
764 );
765
766 let mut wrapper = LineWrapper::new(font_id, 16., font_system);
767 assert_eq!(
768 wrapper
769 .wrap_shaped_line(text, &line, 72.0)
770 .collect::<Vec<_>>(),
771 &[
772 ShapedBoundary {
773 run_ix: 1,
774 glyph_ix: 3
775 },
776 ShapedBoundary {
777 run_ix: 2,
778 glyph_ix: 3
779 },
780 ShapedBoundary {
781 run_ix: 4,
782 glyph_ix: 2
783 }
784 ],
785 );
786 }
787}