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
27impl TextLayoutCache {
28 pub fn new(fonts: Arc<dyn platform::FontSystem>) -> Self {
29 Self {
30 prev_frame: Mutex::new(HashMap::new()),
31 curr_frame: RwLock::new(HashMap::new()),
32 fonts,
33 }
34 }
35
36 pub fn finish_frame(&self) {
37 let mut prev_frame = self.prev_frame.lock();
38 let mut curr_frame = self.curr_frame.write();
39 std::mem::swap(&mut *prev_frame, &mut *curr_frame);
40 curr_frame.clear();
41 }
42
43 pub fn layout_str<'a>(
44 &'a self,
45 text: &'a str,
46 font_size: f32,
47 runs: &'a [(usize, FontId, Color)],
48 ) -> Line {
49 let key = &CacheKeyRef {
50 text,
51 font_size: OrderedFloat(font_size),
52 runs,
53 } as &dyn CacheKey;
54 let curr_frame = self.curr_frame.upgradable_read();
55 if let Some(layout) = curr_frame.get(key) {
56 return Line::new(layout.clone(), runs);
57 }
58
59 let mut curr_frame = RwLockUpgradableReadGuard::upgrade(curr_frame);
60 if let Some((key, layout)) = self.prev_frame.lock().remove_entry(key) {
61 curr_frame.insert(key, layout.clone());
62 Line::new(layout.clone(), runs)
63 } else {
64 let layout = Arc::new(self.fonts.layout_line(text, font_size, runs));
65 let key = CacheKeyValue {
66 text: text.into(),
67 font_size: OrderedFloat(font_size),
68 runs: SmallVec::from(runs),
69 };
70 curr_frame.insert(key, layout.clone());
71 Line::new(layout, runs)
72 }
73 }
74}
75
76trait CacheKey {
77 fn key<'a>(&'a self) -> CacheKeyRef<'a>;
78}
79
80impl<'a> PartialEq for (dyn CacheKey + 'a) {
81 fn eq(&self, other: &dyn CacheKey) -> bool {
82 self.key() == other.key()
83 }
84}
85
86impl<'a> Eq for (dyn CacheKey + 'a) {}
87
88impl<'a> Hash for (dyn CacheKey + 'a) {
89 fn hash<H: Hasher>(&self, state: &mut H) {
90 self.key().hash(state)
91 }
92}
93
94#[derive(Eq, PartialEq)]
95struct CacheKeyValue {
96 text: String,
97 font_size: OrderedFloat<f32>,
98 runs: SmallVec<[(usize, FontId, Color); 1]>,
99}
100
101impl CacheKey for CacheKeyValue {
102 fn key<'a>(&'a self) -> CacheKeyRef<'a> {
103 CacheKeyRef {
104 text: &self.text.as_str(),
105 font_size: self.font_size,
106 runs: self.runs.as_slice(),
107 }
108 }
109}
110
111impl Hash for CacheKeyValue {
112 fn hash<H: Hasher>(&self, state: &mut H) {
113 self.key().hash(state);
114 }
115}
116
117impl<'a> Borrow<dyn CacheKey + 'a> for CacheKeyValue {
118 fn borrow(&self) -> &(dyn CacheKey + 'a) {
119 self as &dyn CacheKey
120 }
121}
122
123#[derive(Copy, Clone, PartialEq, Eq, Hash)]
124struct CacheKeyRef<'a> {
125 text: &'a str,
126 font_size: OrderedFloat<f32>,
127 runs: &'a [(usize, FontId, Color)],
128}
129
130impl<'a> CacheKey for CacheKeyRef<'a> {
131 fn key<'b>(&'b self) -> CacheKeyRef<'b> {
132 *self
133 }
134}
135
136#[derive(Default, Debug)]
137pub struct Line {
138 layout: Arc<LineLayout>,
139 color_runs: SmallVec<[(u32, Color); 32]>,
140}
141
142#[derive(Default, Debug)]
143pub struct LineLayout {
144 pub width: f32,
145 pub ascent: f32,
146 pub descent: f32,
147 pub runs: Vec<Run>,
148 pub len: usize,
149 pub font_size: f32,
150}
151
152#[derive(Debug)]
153pub struct Run {
154 pub font_id: FontId,
155 pub glyphs: Vec<Glyph>,
156}
157
158#[derive(Debug)]
159pub struct Glyph {
160 pub id: GlyphId,
161 pub position: Vector2F,
162 pub index: usize,
163}
164
165impl Line {
166 fn new(layout: Arc<LineLayout>, runs: &[(usize, FontId, Color)]) -> Self {
167 let mut color_runs = SmallVec::new();
168 for (len, _, color) in runs {
169 color_runs.push((*len as u32, *color));
170 }
171 Self { layout, color_runs }
172 }
173
174 pub fn runs(&self) -> &[Run] {
175 &self.layout.runs
176 }
177
178 pub fn width(&self) -> f32 {
179 self.layout.width
180 }
181
182 pub fn x_for_index(&self, index: usize) -> f32 {
183 for run in &self.layout.runs {
184 for glyph in &run.glyphs {
185 if glyph.index == index {
186 return glyph.position.x();
187 }
188 }
189 }
190 self.layout.width
191 }
192
193 pub fn index_for_x(&self, x: f32) -> Option<usize> {
194 if x >= self.layout.width {
195 None
196 } else {
197 for run in self.layout.runs.iter().rev() {
198 for glyph in run.glyphs.iter().rev() {
199 if glyph.position.x() <= x {
200 return Some(glyph.index);
201 }
202 }
203 }
204 Some(0)
205 }
206 }
207
208 pub fn paint(&self, origin: Vector2F, visible_bounds: RectF, cx: &mut PaintContext) {
209 let padding_top = (visible_bounds.height() - self.layout.ascent - self.layout.descent) / 2.;
210 let baseline_origin = vec2f(0., padding_top + self.layout.ascent);
211
212 let mut color_runs = self.color_runs.iter();
213 let mut color_end = 0;
214 let mut color = Color::black();
215
216 for run in &self.layout.runs {
217 let max_glyph_width = cx
218 .font_cache
219 .bounding_box(run.font_id, self.layout.font_size)
220 .x();
221
222 for glyph in &run.glyphs {
223 let glyph_origin = baseline_origin + glyph.position;
224
225 if glyph_origin.x() + max_glyph_width < visible_bounds.origin().x() {
226 continue;
227 }
228 if glyph_origin.x() > visible_bounds.upper_right().x() {
229 break;
230 }
231
232 if glyph.index >= color_end {
233 if let Some(next_run) = color_runs.next() {
234 color_end += next_run.0 as usize;
235 color = next_run.1;
236 } else {
237 color_end = self.layout.len;
238 color = Color::black();
239 }
240 }
241
242 cx.scene.push_glyph(scene::Glyph {
243 font_id: run.font_id,
244 font_size: self.layout.font_size,
245 id: glyph.id,
246 origin: origin + glyph_origin,
247 color,
248 });
249 }
250 }
251 }
252
253 pub fn paint_wrapped(
254 &self,
255 origin: Vector2F,
256 line_height: f32,
257 boundaries: impl IntoIterator<Item = ShapedBoundary>,
258 cx: &mut PaintContext,
259 ) {
260 let padding_top = (line_height - self.layout.ascent - self.layout.descent) / 2.;
261 let baseline_origin = vec2f(0., padding_top + self.layout.ascent);
262
263 let mut boundaries = boundaries.into_iter().peekable();
264 let mut color_runs = self.color_runs.iter();
265 let mut color_end = 0;
266 let mut color = Color::black();
267
268 let mut glyph_origin = baseline_origin;
269 let mut prev_position = 0.;
270 for run in &self.layout.runs {
271 for (glyph_ix, glyph) in run.glyphs.iter().enumerate() {
272 if boundaries.peek().map_or(false, |b| b.glyph_ix == glyph_ix) {
273 boundaries.next();
274 glyph_origin = vec2f(0., glyph_origin.y() + line_height);
275 } else {
276 glyph_origin.set_x(glyph_origin.x() + glyph.position.x() - prev_position);
277 }
278 prev_position = glyph.position.x();
279
280 if glyph.index >= color_end {
281 if let Some(next_run) = color_runs.next() {
282 color_end += next_run.0 as usize;
283 color = next_run.1;
284 } else {
285 color_end = self.layout.len;
286 color = Color::black();
287 }
288 }
289
290 cx.scene.push_glyph(scene::Glyph {
291 font_id: run.font_id,
292 font_size: self.layout.font_size,
293 id: glyph.id,
294 origin: origin + glyph_origin,
295 color,
296 });
297 }
298 }
299 }
300}
301
302impl Run {
303 pub fn glyphs(&self) -> &[Glyph] {
304 &self.glyphs
305 }
306}
307
308#[derive(Copy, Clone, Debug, PartialEq, Eq)]
309pub struct Boundary {
310 pub ix: usize,
311 pub next_indent: u32,
312}
313
314#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
315pub struct ShapedBoundary {
316 pub run_ix: usize,
317 pub glyph_ix: usize,
318}
319
320impl Boundary {
321 fn new(ix: usize, next_indent: u32) -> Self {
322 Self { ix, next_indent }
323 }
324}
325
326pub struct LineWrapper {
327 font_system: Arc<dyn FontSystem>,
328 pub(crate) font_id: FontId,
329 pub(crate) font_size: f32,
330 cached_ascii_char_widths: [f32; 128],
331 cached_other_char_widths: HashMap<char, f32>,
332}
333
334impl LineWrapper {
335 pub const MAX_INDENT: u32 = 256;
336
337 pub fn new(font_id: FontId, font_size: f32, font_system: Arc<dyn FontSystem>) -> Self {
338 Self {
339 font_system,
340 font_id,
341 font_size,
342 cached_ascii_char_widths: [f32::NAN; 128],
343 cached_other_char_widths: HashMap::new(),
344 }
345 }
346
347 pub fn wrap_line<'a>(
348 &'a mut self,
349 line: &'a str,
350 wrap_width: f32,
351 ) -> impl Iterator<Item = Boundary> + 'a {
352 let mut width = 0.0;
353 let mut first_non_whitespace_ix = None;
354 let mut indent = None;
355 let mut last_candidate_ix = 0;
356 let mut last_candidate_width = 0.0;
357 let mut last_wrap_ix = 0;
358 let mut prev_c = '\0';
359 let mut char_indices = line.char_indices();
360 iter::from_fn(move || {
361 while let Some((ix, c)) = char_indices.next() {
362 if c == '\n' {
363 continue;
364 }
365
366 if self.is_boundary(prev_c, c) && first_non_whitespace_ix.is_some() {
367 last_candidate_ix = ix;
368 last_candidate_width = width;
369 }
370
371 if c != ' ' && first_non_whitespace_ix.is_none() {
372 first_non_whitespace_ix = Some(ix);
373 }
374
375 let char_width = self.width_for_char(c);
376 width += char_width;
377 if width > wrap_width && ix > last_wrap_ix {
378 if let (None, Some(first_non_whitespace_ix)) = (indent, first_non_whitespace_ix)
379 {
380 indent = Some(
381 Self::MAX_INDENT.min((first_non_whitespace_ix - last_wrap_ix) as u32),
382 );
383 }
384
385 if last_candidate_ix > 0 {
386 last_wrap_ix = last_candidate_ix;
387 width -= last_candidate_width;
388 last_candidate_ix = 0;
389 } else {
390 last_wrap_ix = ix;
391 width = char_width;
392 }
393
394 let indent_width =
395 indent.map(|indent| indent as f32 * self.width_for_char(' '));
396 width += indent_width.unwrap_or(0.);
397
398 return Some(Boundary::new(last_wrap_ix, indent.unwrap_or(0)));
399 }
400 prev_c = c;
401 }
402
403 None
404 })
405 }
406
407 pub fn wrap_shaped_line<'a>(
408 &'a mut self,
409 str: &'a str,
410 line: &'a Line,
411 wrap_width: f32,
412 ) -> impl Iterator<Item = ShapedBoundary> + 'a {
413 let mut first_non_whitespace_ix = None;
414 let mut last_candidate_ix = None;
415 let mut last_candidate_x = 0.0;
416 let mut last_wrap_ix = ShapedBoundary {
417 run_ix: 0,
418 glyph_ix: 0,
419 };
420 let mut last_wrap_x = 0.;
421 let mut prev_c = '\0';
422 let mut glyphs = line
423 .runs()
424 .iter()
425 .enumerate()
426 .flat_map(move |(run_ix, run)| {
427 run.glyphs()
428 .iter()
429 .enumerate()
430 .map(move |(glyph_ix, glyph)| {
431 let character = str[glyph.index..].chars().next().unwrap();
432 (
433 ShapedBoundary { run_ix, glyph_ix },
434 character,
435 glyph.position.x(),
436 )
437 })
438 })
439 .peekable();
440
441 iter::from_fn(move || {
442 while let Some((ix, c, x)) = glyphs.next() {
443 if c == '\n' {
444 continue;
445 }
446
447 if self.is_boundary(prev_c, c) && first_non_whitespace_ix.is_some() {
448 last_candidate_ix = Some(ix);
449 last_candidate_x = x;
450 }
451
452 if c != ' ' && first_non_whitespace_ix.is_none() {
453 first_non_whitespace_ix = Some(ix);
454 }
455
456 let next_x = glyphs.peek().map_or(line.width(), |(_, _, x)| *x);
457 let width = next_x - last_wrap_x;
458 if width > wrap_width && ix > last_wrap_ix {
459 if let Some(last_candidate_ix) = last_candidate_ix.take() {
460 last_wrap_ix = last_candidate_ix;
461 last_wrap_x = last_candidate_x;
462 } else {
463 last_wrap_ix = ix;
464 last_wrap_x = x;
465 }
466
467 return Some(last_wrap_ix);
468 }
469 prev_c = c;
470 }
471
472 None
473 })
474 }
475
476 fn is_boundary(&self, prev: char, next: char) -> bool {
477 (prev == ' ') && (next != ' ')
478 }
479
480 #[inline(always)]
481 fn width_for_char(&mut self, c: char) -> f32 {
482 if (c as u32) < 128 {
483 let mut width = self.cached_ascii_char_widths[c as usize];
484 if width.is_nan() {
485 width = self.compute_width_for_char(c);
486 self.cached_ascii_char_widths[c as usize] = width;
487 }
488 width
489 } else {
490 let mut width = self
491 .cached_other_char_widths
492 .get(&c)
493 .copied()
494 .unwrap_or(f32::NAN);
495 if width.is_nan() {
496 width = self.compute_width_for_char(c);
497 self.cached_other_char_widths.insert(c, width);
498 }
499 width
500 }
501 }
502
503 fn compute_width_for_char(&self, c: char) -> f32 {
504 self.font_system
505 .layout_line(
506 &c.to_string(),
507 self.font_size,
508 &[(1, self.font_id, Default::default())],
509 )
510 .width
511 }
512}
513
514#[cfg(test)]
515mod tests {
516 use super::*;
517 use crate::{
518 color::Color,
519 fonts::{Properties, Weight},
520 };
521
522 #[crate::test(self)]
523 fn test_wrap_line(cx: &mut crate::MutableAppContext) {
524 let font_cache = cx.font_cache().clone();
525 let font_system = cx.platform().fonts();
526 let family = font_cache.load_family(&["Courier"]).unwrap();
527 let font_id = font_cache.select_font(family, &Default::default()).unwrap();
528
529 let mut wrapper = LineWrapper::new(font_id, 16., font_system);
530 assert_eq!(
531 wrapper
532 .wrap_line("aa bbb cccc ddddd eeee", 72.0)
533 .collect::<Vec<_>>(),
534 &[
535 Boundary::new(7, 0),
536 Boundary::new(12, 0),
537 Boundary::new(18, 0)
538 ],
539 );
540 assert_eq!(
541 wrapper
542 .wrap_line("aaa aaaaaaaaaaaaaaaaaa", 72.0)
543 .collect::<Vec<_>>(),
544 &[
545 Boundary::new(4, 0),
546 Boundary::new(11, 0),
547 Boundary::new(18, 0)
548 ],
549 );
550 assert_eq!(
551 wrapper.wrap_line(" aaaaaaa", 72.).collect::<Vec<_>>(),
552 &[
553 Boundary::new(7, 5),
554 Boundary::new(9, 5),
555 Boundary::new(11, 5),
556 ]
557 );
558 assert_eq!(
559 wrapper
560 .wrap_line(" ", 72.)
561 .collect::<Vec<_>>(),
562 &[
563 Boundary::new(7, 0),
564 Boundary::new(14, 0),
565 Boundary::new(21, 0)
566 ]
567 );
568 assert_eq!(
569 wrapper
570 .wrap_line(" aaaaaaaaaaaaaa", 72.)
571 .collect::<Vec<_>>(),
572 &[
573 Boundary::new(7, 0),
574 Boundary::new(14, 3),
575 Boundary::new(18, 3),
576 Boundary::new(22, 3),
577 ]
578 );
579 }
580
581 #[crate::test(self)]
582 fn test_wrap_shaped_line(cx: &mut crate::MutableAppContext) {
583 let font_cache = cx.font_cache().clone();
584 let font_system = cx.platform().fonts();
585 let text_layout_cache = TextLayoutCache::new(font_system.clone());
586
587 let family = font_cache.load_family(&["Helvetica"]).unwrap();
588 let font_id = font_cache.select_font(family, &Default::default()).unwrap();
589 let normal = font_cache.select_font(family, &Default::default()).unwrap();
590 let bold = font_cache
591 .select_font(
592 family,
593 &Properties {
594 weight: Weight::BOLD,
595 ..Default::default()
596 },
597 )
598 .unwrap();
599
600 let text = "aa bbb cccc ddddd eeee";
601 let line = text_layout_cache.layout_str(
602 text,
603 16.0,
604 &[
605 (4, normal, Color::default()),
606 (5, bold, Color::default()),
607 (6, normal, Color::default()),
608 (1, bold, Color::default()),
609 (7, normal, Color::default()),
610 ],
611 );
612
613 let mut wrapper = LineWrapper::new(font_id, 16., font_system);
614 assert_eq!(
615 wrapper
616 .wrap_shaped_line(&text, &line, 72.0)
617 .collect::<Vec<_>>(),
618 &[
619 ShapedBoundary {
620 run_ix: 1,
621 glyph_ix: 3
622 },
623 ShapedBoundary {
624 run_ix: 2,
625 glyph_ix: 3
626 },
627 ShapedBoundary {
628 run_ix: 4,
629 glyph_ix: 2
630 }
631 ],
632 );
633 }
634}