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 // If round_to_closest, find the closest index to the given x position
242 // If !round_to_closest, find the largest index before the given x position
243 pub fn index_for_x(&self, x: f32) -> Option<usize> {
244 if x >= self.layout.width {
245 None
246 } else {
247 for run in self.layout.runs.iter().rev() {
248 for glyph in run.glyphs.iter().rev() {
249 if glyph.position.x() <= x {
250 return Some(glyph.index);
251 }
252 }
253 }
254 Some(0)
255 }
256 }
257
258 pub fn paint(
259 &self,
260 origin: Vector2F,
261 visible_bounds: RectF,
262 line_height: f32,
263 cx: &mut PaintContext,
264 ) {
265 let padding_top = (line_height - self.layout.ascent - self.layout.descent) / 2.;
266 let baseline_offset = vec2f(0., padding_top + self.layout.ascent);
267
268 let mut style_runs = self.style_runs.iter();
269 let mut run_end = 0;
270 let mut color = Color::black();
271 let mut underline = None;
272
273 for run in &self.layout.runs {
274 let max_glyph_width = cx
275 .font_cache
276 .bounding_box(run.font_id, self.layout.font_size)
277 .x();
278
279 for glyph in &run.glyphs {
280 let glyph_origin = origin + baseline_offset + glyph.position;
281 if glyph_origin.x() > visible_bounds.upper_right().x() {
282 break;
283 }
284
285 let mut finished_underline = None;
286 if glyph.index >= run_end {
287 if let Some((run_len, run_color, run_underline)) = style_runs.next() {
288 if let Some((_, underline_style)) = underline {
289 if *run_underline != underline_style {
290 finished_underline = underline.take();
291 }
292 }
293 if run_underline.thickness.into_inner() > 0. {
294 underline.get_or_insert((
295 vec2f(
296 glyph_origin.x(),
297 origin.y() + baseline_offset.y() + 0.618 * self.layout.descent,
298 ),
299 Underline {
300 color: Some(run_underline.color.unwrap_or(*run_color)),
301 thickness: run_underline.thickness.into(),
302 squiggly: run_underline.squiggly,
303 },
304 ));
305 }
306
307 run_end += *run_len as usize;
308 color = *run_color;
309 } else {
310 run_end = self.layout.len;
311 finished_underline = underline.take();
312 }
313 }
314
315 if glyph_origin.x() + max_glyph_width < visible_bounds.origin().x() {
316 continue;
317 }
318
319 if let Some((underline_origin, underline_style)) = finished_underline {
320 cx.scene.push_underline(scene::Underline {
321 origin: underline_origin,
322 width: glyph_origin.x() - underline_origin.x(),
323 thickness: underline_style.thickness.into(),
324 color: underline_style.color.unwrap(),
325 squiggly: underline_style.squiggly,
326 });
327 }
328
329 if glyph.is_emoji {
330 cx.scene.push_image_glyph(scene::ImageGlyph {
331 font_id: run.font_id,
332 font_size: self.layout.font_size,
333 id: glyph.id,
334 origin: glyph_origin,
335 });
336 } else {
337 cx.scene.push_glyph(scene::Glyph {
338 font_id: run.font_id,
339 font_size: self.layout.font_size,
340 id: glyph.id,
341 origin: glyph_origin,
342 color,
343 });
344 }
345 }
346 }
347
348 if let Some((underline_start, underline_style)) = underline.take() {
349 let line_end_x = origin.x() + self.layout.width;
350 cx.scene.push_underline(scene::Underline {
351 origin: underline_start,
352 width: line_end_x - underline_start.x(),
353 color: underline_style.color.unwrap(),
354 thickness: underline_style.thickness.into(),
355 squiggly: underline_style.squiggly,
356 });
357 }
358 }
359
360 pub fn paint_wrapped(
361 &self,
362 origin: Vector2F,
363 visible_bounds: RectF,
364 line_height: f32,
365 boundaries: impl IntoIterator<Item = ShapedBoundary>,
366 cx: &mut PaintContext,
367 ) {
368 let padding_top = (line_height - self.layout.ascent - self.layout.descent) / 2.;
369 let baseline_origin = vec2f(0., padding_top + self.layout.ascent);
370
371 let mut boundaries = boundaries.into_iter().peekable();
372 let mut color_runs = self.style_runs.iter();
373 let mut color_end = 0;
374 let mut color = Color::black();
375
376 let mut glyph_origin = vec2f(0., 0.);
377 let mut prev_position = 0.;
378 for run in &self.layout.runs {
379 for (glyph_ix, glyph) in run.glyphs.iter().enumerate() {
380 if boundaries.peek().map_or(false, |b| b.glyph_ix == glyph_ix) {
381 boundaries.next();
382 glyph_origin = vec2f(0., glyph_origin.y() + line_height);
383 } else {
384 glyph_origin.set_x(glyph_origin.x() + glyph.position.x() - prev_position);
385 }
386 prev_position = glyph.position.x();
387
388 if glyph.index >= color_end {
389 if let Some(next_run) = color_runs.next() {
390 color_end += next_run.0 as usize;
391 color = next_run.1;
392 } else {
393 color_end = self.layout.len;
394 color = Color::black();
395 }
396 }
397
398 let glyph_bounds = RectF::new(
399 origin + glyph_origin,
400 cx.font_cache
401 .bounding_box(run.font_id, self.layout.font_size),
402 );
403 if glyph_bounds.intersects(visible_bounds) {
404 if glyph.is_emoji {
405 cx.scene.push_image_glyph(scene::ImageGlyph {
406 font_id: run.font_id,
407 font_size: self.layout.font_size,
408 id: glyph.id,
409 origin: glyph_bounds.origin() + baseline_origin,
410 });
411 } else {
412 cx.scene.push_glyph(scene::Glyph {
413 font_id: run.font_id,
414 font_size: self.layout.font_size,
415 id: glyph.id,
416 origin: glyph_bounds.origin() + baseline_origin,
417 color,
418 });
419 }
420 }
421 }
422 }
423 }
424}
425
426impl Run {
427 pub fn glyphs(&self) -> &[Glyph] {
428 &self.glyphs
429 }
430}
431
432#[derive(Copy, Clone, Debug, PartialEq, Eq)]
433pub struct Boundary {
434 pub ix: usize,
435 pub next_indent: u32,
436}
437
438#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
439pub struct ShapedBoundary {
440 pub run_ix: usize,
441 pub glyph_ix: usize,
442}
443
444impl Boundary {
445 fn new(ix: usize, next_indent: u32) -> Self {
446 Self { ix, next_indent }
447 }
448}
449
450pub struct LineWrapper {
451 font_system: Arc<dyn FontSystem>,
452 pub(crate) font_id: FontId,
453 pub(crate) font_size: f32,
454 cached_ascii_char_widths: [f32; 128],
455 cached_other_char_widths: HashMap<char, f32>,
456}
457
458impl LineWrapper {
459 pub const MAX_INDENT: u32 = 256;
460
461 pub fn new(font_id: FontId, font_size: f32, font_system: Arc<dyn FontSystem>) -> Self {
462 Self {
463 font_system,
464 font_id,
465 font_size,
466 cached_ascii_char_widths: [f32::NAN; 128],
467 cached_other_char_widths: HashMap::new(),
468 }
469 }
470
471 pub fn wrap_line<'a>(
472 &'a mut self,
473 line: &'a str,
474 wrap_width: f32,
475 ) -> impl Iterator<Item = Boundary> + 'a {
476 let mut width = 0.0;
477 let mut first_non_whitespace_ix = None;
478 let mut indent = None;
479 let mut last_candidate_ix = 0;
480 let mut last_candidate_width = 0.0;
481 let mut last_wrap_ix = 0;
482 let mut prev_c = '\0';
483 let mut char_indices = line.char_indices();
484 iter::from_fn(move || {
485 while let Some((ix, c)) = char_indices.next() {
486 if c == '\n' {
487 continue;
488 }
489
490 if self.is_boundary(prev_c, c) && first_non_whitespace_ix.is_some() {
491 last_candidate_ix = ix;
492 last_candidate_width = width;
493 }
494
495 if c != ' ' && first_non_whitespace_ix.is_none() {
496 first_non_whitespace_ix = Some(ix);
497 }
498
499 let char_width = self.width_for_char(c);
500 width += char_width;
501 if width > wrap_width && ix > last_wrap_ix {
502 if let (None, Some(first_non_whitespace_ix)) = (indent, first_non_whitespace_ix)
503 {
504 indent = Some(
505 Self::MAX_INDENT.min((first_non_whitespace_ix - last_wrap_ix) as u32),
506 );
507 }
508
509 if last_candidate_ix > 0 {
510 last_wrap_ix = last_candidate_ix;
511 width -= last_candidate_width;
512 last_candidate_ix = 0;
513 } else {
514 last_wrap_ix = ix;
515 width = char_width;
516 }
517
518 let indent_width =
519 indent.map(|indent| indent as f32 * self.width_for_char(' '));
520 width += indent_width.unwrap_or(0.);
521
522 return Some(Boundary::new(last_wrap_ix, indent.unwrap_or(0)));
523 }
524 prev_c = c;
525 }
526
527 None
528 })
529 }
530
531 pub fn wrap_shaped_line<'a>(
532 &'a mut self,
533 str: &'a str,
534 line: &'a Line,
535 wrap_width: f32,
536 ) -> impl Iterator<Item = ShapedBoundary> + 'a {
537 let mut first_non_whitespace_ix = None;
538 let mut last_candidate_ix = None;
539 let mut last_candidate_x = 0.0;
540 let mut last_wrap_ix = ShapedBoundary {
541 run_ix: 0,
542 glyph_ix: 0,
543 };
544 let mut last_wrap_x = 0.;
545 let mut prev_c = '\0';
546 let mut glyphs = line
547 .runs()
548 .iter()
549 .enumerate()
550 .flat_map(move |(run_ix, run)| {
551 run.glyphs()
552 .iter()
553 .enumerate()
554 .map(move |(glyph_ix, glyph)| {
555 let character = str[glyph.index..].chars().next().unwrap();
556 (
557 ShapedBoundary { run_ix, glyph_ix },
558 character,
559 glyph.position.x(),
560 )
561 })
562 })
563 .peekable();
564
565 iter::from_fn(move || {
566 while let Some((ix, c, x)) = glyphs.next() {
567 if c == '\n' {
568 continue;
569 }
570
571 if self.is_boundary(prev_c, c) && first_non_whitespace_ix.is_some() {
572 last_candidate_ix = Some(ix);
573 last_candidate_x = x;
574 }
575
576 if c != ' ' && first_non_whitespace_ix.is_none() {
577 first_non_whitespace_ix = Some(ix);
578 }
579
580 let next_x = glyphs.peek().map_or(line.width(), |(_, _, x)| *x);
581 let width = next_x - last_wrap_x;
582 if width > wrap_width && ix > last_wrap_ix {
583 if let Some(last_candidate_ix) = last_candidate_ix.take() {
584 last_wrap_ix = last_candidate_ix;
585 last_wrap_x = last_candidate_x;
586 } else {
587 last_wrap_ix = ix;
588 last_wrap_x = x;
589 }
590
591 return Some(last_wrap_ix);
592 }
593 prev_c = c;
594 }
595
596 None
597 })
598 }
599
600 fn is_boundary(&self, prev: char, next: char) -> bool {
601 (prev == ' ') && (next != ' ')
602 }
603
604 #[inline(always)]
605 fn width_for_char(&mut self, c: char) -> f32 {
606 if (c as u32) < 128 {
607 let mut width = self.cached_ascii_char_widths[c as usize];
608 if width.is_nan() {
609 width = self.compute_width_for_char(c);
610 self.cached_ascii_char_widths[c as usize] = width;
611 }
612 width
613 } else {
614 let mut width = self
615 .cached_other_char_widths
616 .get(&c)
617 .copied()
618 .unwrap_or(f32::NAN);
619 if width.is_nan() {
620 width = self.compute_width_for_char(c);
621 self.cached_other_char_widths.insert(c, width);
622 }
623 width
624 }
625 }
626
627 fn compute_width_for_char(&self, c: char) -> f32 {
628 self.font_system
629 .layout_line(
630 &c.to_string(),
631 self.font_size,
632 &[(
633 1,
634 RunStyle {
635 font_id: self.font_id,
636 color: Default::default(),
637 underline: Default::default(),
638 },
639 )],
640 )
641 .width
642 }
643}
644
645#[cfg(test)]
646mod tests {
647 use super::*;
648 use crate::fonts::{Properties, Weight};
649
650 #[crate::test(self)]
651 fn test_wrap_line(cx: &mut crate::MutableAppContext) {
652 let font_cache = cx.font_cache().clone();
653 let font_system = cx.platform().fonts();
654 let family = font_cache.load_family(&["Courier"]).unwrap();
655 let font_id = font_cache.select_font(family, &Default::default()).unwrap();
656
657 let mut wrapper = LineWrapper::new(font_id, 16., font_system);
658 assert_eq!(
659 wrapper
660 .wrap_line("aa bbb cccc ddddd eeee", 72.0)
661 .collect::<Vec<_>>(),
662 &[
663 Boundary::new(7, 0),
664 Boundary::new(12, 0),
665 Boundary::new(18, 0)
666 ],
667 );
668 assert_eq!(
669 wrapper
670 .wrap_line("aaa aaaaaaaaaaaaaaaaaa", 72.0)
671 .collect::<Vec<_>>(),
672 &[
673 Boundary::new(4, 0),
674 Boundary::new(11, 0),
675 Boundary::new(18, 0)
676 ],
677 );
678 assert_eq!(
679 wrapper.wrap_line(" aaaaaaa", 72.).collect::<Vec<_>>(),
680 &[
681 Boundary::new(7, 5),
682 Boundary::new(9, 5),
683 Boundary::new(11, 5),
684 ]
685 );
686 assert_eq!(
687 wrapper
688 .wrap_line(" ", 72.)
689 .collect::<Vec<_>>(),
690 &[
691 Boundary::new(7, 0),
692 Boundary::new(14, 0),
693 Boundary::new(21, 0)
694 ]
695 );
696 assert_eq!(
697 wrapper
698 .wrap_line(" aaaaaaaaaaaaaa", 72.)
699 .collect::<Vec<_>>(),
700 &[
701 Boundary::new(7, 0),
702 Boundary::new(14, 3),
703 Boundary::new(18, 3),
704 Boundary::new(22, 3),
705 ]
706 );
707 }
708
709 #[crate::test(self, retries = 5)]
710 fn test_wrap_shaped_line(cx: &mut crate::MutableAppContext) {
711 // This is failing intermittently on CI and we don't have time to figure it out
712 let font_cache = cx.font_cache().clone();
713 let font_system = cx.platform().fonts();
714 let text_layout_cache = TextLayoutCache::new(font_system.clone());
715
716 let family = font_cache.load_family(&["Helvetica"]).unwrap();
717 let font_id = font_cache.select_font(family, &Default::default()).unwrap();
718 let normal = RunStyle {
719 font_id,
720 color: Default::default(),
721 underline: Default::default(),
722 };
723 let bold = RunStyle {
724 font_id: font_cache
725 .select_font(
726 family,
727 &Properties {
728 weight: Weight::BOLD,
729 ..Default::default()
730 },
731 )
732 .unwrap(),
733 color: Default::default(),
734 underline: Default::default(),
735 };
736
737 let text = "aa bbb cccc ddddd eeee";
738 let line = text_layout_cache.layout_str(
739 text,
740 16.0,
741 &[(4, normal), (5, bold), (6, normal), (1, bold), (7, normal)],
742 );
743
744 let mut wrapper = LineWrapper::new(font_id, 16., font_system);
745 assert_eq!(
746 wrapper
747 .wrap_shaped_line(&text, &line, 72.0)
748 .collect::<Vec<_>>(),
749 &[
750 ShapedBoundary {
751 run_ix: 1,
752 glyph_ix: 3
753 },
754 ShapedBoundary {
755 run_ix: 2,
756 glyph_ix: 3
757 },
758 ShapedBoundary {
759 run_ix: 4,
760 glyph_ix: 2
761 }
762 ],
763 );
764 }
765}