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