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