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