1use crate::{FontId, GlyphId, Pixels, PlatformTextSystem, Point, SharedString, Size, point, px};
2use collections::FxHashMap;
3use parking_lot::{Mutex, RwLock, RwLockUpgradableReadGuard};
4use smallvec::SmallVec;
5use std::{
6 borrow::Borrow,
7 hash::{Hash, Hasher},
8 ops::Range,
9 sync::Arc,
10};
11
12use super::LineWrapper;
13
14/// A laid out and styled line of text
15#[derive(Default, Debug)]
16pub struct LineLayout {
17 /// The font size for this line
18 pub font_size: Pixels,
19 /// The width of the line
20 pub width: Pixels,
21 /// The ascent of the line
22 pub ascent: Pixels,
23 /// The descent of the line
24 pub descent: Pixels,
25 /// The shaped runs that make up this line
26 pub runs: Vec<ShapedRun>,
27 /// The length of the line in utf-8 bytes
28 pub len: usize,
29}
30
31/// A run of text that has been shaped .
32#[derive(Debug, Clone)]
33pub struct ShapedRun {
34 /// The font id for this run
35 pub font_id: FontId,
36 /// The glyphs that make up this run
37 pub glyphs: Vec<ShapedGlyph>,
38}
39
40/// A single glyph, ready to paint.
41#[derive(Clone, Debug)]
42pub struct ShapedGlyph {
43 /// The ID for this glyph, as determined by the text system.
44 pub id: GlyphId,
45
46 /// The position of this glyph in its containing line.
47 pub position: Point<Pixels>,
48
49 /// The index of this glyph in the original text.
50 pub index: usize,
51
52 /// Whether this glyph is an emoji
53 pub is_emoji: bool,
54}
55
56impl LineLayout {
57 /// The index for the character at the given x coordinate
58 pub fn index_for_x(&self, x: Pixels) -> Option<usize> {
59 if x >= self.width {
60 None
61 } else {
62 for run in self.runs.iter().rev() {
63 for glyph in run.glyphs.iter().rev() {
64 if glyph.position.x <= x {
65 return Some(glyph.index);
66 }
67 }
68 }
69 Some(0)
70 }
71 }
72
73 /// closest_index_for_x returns the character boundary closest to the given x coordinate
74 /// (e.g. to handle aligning up/down arrow keys)
75 pub fn closest_index_for_x(&self, x: Pixels) -> usize {
76 let mut prev_index = 0;
77 let mut prev_x = px(0.);
78
79 for run in self.runs.iter() {
80 for glyph in run.glyphs.iter() {
81 if glyph.position.x >= x {
82 if glyph.position.x - x < x - prev_x {
83 return glyph.index;
84 } else {
85 return prev_index;
86 }
87 }
88 prev_index = glyph.index;
89 prev_x = glyph.position.x;
90 }
91 }
92
93 if self.len == 1 {
94 if x > self.width / 2. {
95 return 1;
96 } else {
97 return 0;
98 }
99 }
100
101 self.len
102 }
103
104 /// The x position of the character at the given index
105 pub fn x_for_index(&self, index: usize) -> Pixels {
106 for run in &self.runs {
107 for glyph in &run.glyphs {
108 if glyph.index >= index {
109 return glyph.position.x;
110 }
111 }
112 }
113 self.width
114 }
115
116 /// The corresponding Font at the given index
117 pub fn font_id_for_index(&self, index: usize) -> Option<FontId> {
118 for run in &self.runs {
119 for glyph in &run.glyphs {
120 if glyph.index >= index {
121 return Some(run.font_id);
122 }
123 }
124 }
125 None
126 }
127
128 fn compute_wrap_boundaries(
129 &self,
130 text: &str,
131 wrap_width: Pixels,
132 max_lines: Option<usize>,
133 ) -> SmallVec<[WrapBoundary; 1]> {
134 let mut boundaries = SmallVec::new();
135 let mut first_non_whitespace_ix = None;
136 let mut last_candidate_ix = None;
137 let mut last_candidate_x = px(0.);
138 let mut last_boundary = WrapBoundary {
139 run_ix: 0,
140 glyph_ix: 0,
141 };
142 let mut last_boundary_x = px(0.);
143 let mut prev_ch = '\0';
144 let mut glyphs = self
145 .runs
146 .iter()
147 .enumerate()
148 .flat_map(move |(run_ix, run)| {
149 run.glyphs.iter().enumerate().map(move |(glyph_ix, glyph)| {
150 let character = text[glyph.index..].chars().next().unwrap();
151 (
152 WrapBoundary { run_ix, glyph_ix },
153 character,
154 glyph.position.x,
155 )
156 })
157 })
158 .peekable();
159
160 while let Some((boundary, ch, x)) = glyphs.next() {
161 if ch == '\n' {
162 continue;
163 }
164
165 // Here is very similar to `LineWrapper::wrap_line` to determine text wrapping,
166 // but there are some differences, so we have to duplicate the code here.
167 if LineWrapper::is_word_char(ch) {
168 if prev_ch == ' ' && ch != ' ' && first_non_whitespace_ix.is_some() {
169 last_candidate_ix = Some(boundary);
170 last_candidate_x = x;
171 }
172 } else {
173 if ch != ' ' && first_non_whitespace_ix.is_some() {
174 last_candidate_ix = Some(boundary);
175 last_candidate_x = x;
176 }
177 }
178
179 if ch != ' ' && first_non_whitespace_ix.is_none() {
180 first_non_whitespace_ix = Some(boundary);
181 }
182
183 let next_x = glyphs.peek().map_or(self.width, |(_, _, x)| *x);
184 let width = next_x - last_boundary_x;
185
186 if width > wrap_width && boundary > last_boundary {
187 // When used line_clamp, we should limit the number of lines.
188 if let Some(max_lines) = max_lines
189 && boundaries.len() >= max_lines - 1
190 {
191 break;
192 }
193
194 if let Some(last_candidate_ix) = last_candidate_ix.take() {
195 last_boundary = last_candidate_ix;
196 last_boundary_x = last_candidate_x;
197 } else {
198 last_boundary = boundary;
199 last_boundary_x = x;
200 }
201 boundaries.push(last_boundary);
202 }
203 prev_ch = ch;
204 }
205
206 boundaries
207 }
208}
209
210/// A line of text that has been wrapped to fit a given width
211#[derive(Default, Debug)]
212pub struct WrappedLineLayout {
213 /// The line layout, pre-wrapping.
214 pub unwrapped_layout: Arc<LineLayout>,
215
216 /// The boundaries at which the line was wrapped
217 pub wrap_boundaries: SmallVec<[WrapBoundary; 1]>,
218
219 /// The width of the line, if it was wrapped
220 pub wrap_width: Option<Pixels>,
221}
222
223/// A boundary at which a line was wrapped
224#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
225pub struct WrapBoundary {
226 /// The index in the run just before the line was wrapped
227 pub run_ix: usize,
228 /// The index of the glyph just before the line was wrapped
229 pub glyph_ix: usize,
230}
231
232impl WrappedLineLayout {
233 /// The length of the underlying text, in utf8 bytes.
234 #[allow(clippy::len_without_is_empty)]
235 pub fn len(&self) -> usize {
236 self.unwrapped_layout.len
237 }
238
239 /// The width of this line, in pixels, whether or not it was wrapped.
240 pub fn width(&self) -> Pixels {
241 self.wrap_width
242 .unwrap_or(Pixels::MAX)
243 .min(self.unwrapped_layout.width)
244 }
245
246 /// The size of the whole wrapped text, for the given line_height.
247 /// can span multiple lines if there are multiple wrap boundaries.
248 pub fn size(&self, line_height: Pixels) -> Size<Pixels> {
249 Size {
250 width: self.width(),
251 height: line_height * (self.wrap_boundaries.len() + 1),
252 }
253 }
254
255 /// The ascent of a line in this layout
256 pub fn ascent(&self) -> Pixels {
257 self.unwrapped_layout.ascent
258 }
259
260 /// The descent of a line in this layout
261 pub fn descent(&self) -> Pixels {
262 self.unwrapped_layout.descent
263 }
264
265 /// The wrap boundaries in this layout
266 pub fn wrap_boundaries(&self) -> &[WrapBoundary] {
267 &self.wrap_boundaries
268 }
269
270 /// The font size of this layout
271 pub fn font_size(&self) -> Pixels {
272 self.unwrapped_layout.font_size
273 }
274
275 /// The runs in this layout, sans wrapping
276 pub fn runs(&self) -> &[ShapedRun] {
277 &self.unwrapped_layout.runs
278 }
279
280 /// The index corresponding to a given position in this layout for the given line height.
281 ///
282 /// See also [`Self::closest_index_for_position`].
283 pub fn index_for_position(
284 &self,
285 position: Point<Pixels>,
286 line_height: Pixels,
287 ) -> Result<usize, usize> {
288 self._index_for_position(position, line_height, false)
289 }
290
291 /// The closest index to a given position in this layout for the given line height.
292 ///
293 /// Closest means the character boundary closest to the given position.
294 ///
295 /// See also [`LineLayout::closest_index_for_x`].
296 pub fn closest_index_for_position(
297 &self,
298 position: Point<Pixels>,
299 line_height: Pixels,
300 ) -> Result<usize, usize> {
301 self._index_for_position(position, line_height, true)
302 }
303
304 fn _index_for_position(
305 &self,
306 mut position: Point<Pixels>,
307 line_height: Pixels,
308 closest: bool,
309 ) -> Result<usize, usize> {
310 let wrapped_line_ix = (position.y / line_height) as usize;
311
312 let wrapped_line_start_index;
313 let wrapped_line_start_x;
314 if wrapped_line_ix > 0 {
315 let Some(line_start_boundary) = self.wrap_boundaries.get(wrapped_line_ix - 1) else {
316 return Err(0);
317 };
318 let run = &self.unwrapped_layout.runs[line_start_boundary.run_ix];
319 let glyph = &run.glyphs[line_start_boundary.glyph_ix];
320 wrapped_line_start_index = glyph.index;
321 wrapped_line_start_x = glyph.position.x;
322 } else {
323 wrapped_line_start_index = 0;
324 wrapped_line_start_x = Pixels::ZERO;
325 };
326
327 let wrapped_line_end_index;
328 let wrapped_line_end_x;
329 if wrapped_line_ix < self.wrap_boundaries.len() {
330 let next_wrap_boundary_ix = wrapped_line_ix;
331 let next_wrap_boundary = self.wrap_boundaries[next_wrap_boundary_ix];
332 let run = &self.unwrapped_layout.runs[next_wrap_boundary.run_ix];
333 let glyph = &run.glyphs[next_wrap_boundary.glyph_ix];
334 wrapped_line_end_index = glyph.index;
335 wrapped_line_end_x = glyph.position.x;
336 } else {
337 wrapped_line_end_index = self.unwrapped_layout.len;
338 wrapped_line_end_x = self.unwrapped_layout.width;
339 };
340
341 let mut position_in_unwrapped_line = position;
342 position_in_unwrapped_line.x += wrapped_line_start_x;
343 if position_in_unwrapped_line.x < wrapped_line_start_x {
344 Err(wrapped_line_start_index)
345 } else if position_in_unwrapped_line.x >= wrapped_line_end_x {
346 Err(wrapped_line_end_index)
347 } else {
348 if closest {
349 Ok(self
350 .unwrapped_layout
351 .closest_index_for_x(position_in_unwrapped_line.x))
352 } else {
353 Ok(self
354 .unwrapped_layout
355 .index_for_x(position_in_unwrapped_line.x)
356 .unwrap())
357 }
358 }
359 }
360
361 /// Returns the pixel position for the given byte index.
362 pub fn position_for_index(&self, index: usize, line_height: Pixels) -> Option<Point<Pixels>> {
363 let mut line_start_ix = 0;
364 let mut line_end_indices = self
365 .wrap_boundaries
366 .iter()
367 .map(|wrap_boundary| {
368 let run = &self.unwrapped_layout.runs[wrap_boundary.run_ix];
369 let glyph = &run.glyphs[wrap_boundary.glyph_ix];
370 glyph.index
371 })
372 .chain([self.len()])
373 .enumerate();
374 for (ix, line_end_ix) in line_end_indices {
375 let line_y = ix as f32 * line_height;
376 if index < line_start_ix {
377 break;
378 } else if index > line_end_ix {
379 line_start_ix = line_end_ix;
380 continue;
381 } else {
382 let line_start_x = self.unwrapped_layout.x_for_index(line_start_ix);
383 let x = self.unwrapped_layout.x_for_index(index) - line_start_x;
384 return Some(point(x, line_y));
385 }
386 }
387
388 None
389 }
390}
391
392pub(crate) struct LineLayoutCache {
393 previous_frame: Mutex<FrameCache>,
394 current_frame: RwLock<FrameCache>,
395 platform_text_system: Arc<dyn PlatformTextSystem>,
396}
397
398#[derive(Default)]
399struct FrameCache {
400 lines: FxHashMap<Arc<CacheKey>, Arc<LineLayout>>,
401 wrapped_lines: FxHashMap<Arc<CacheKey>, Arc<WrappedLineLayout>>,
402 used_lines: Vec<Arc<CacheKey>>,
403 used_wrapped_lines: Vec<Arc<CacheKey>>,
404}
405
406#[derive(Clone, Default)]
407pub(crate) struct LineLayoutIndex {
408 lines_index: usize,
409 wrapped_lines_index: usize,
410}
411
412impl LineLayoutCache {
413 pub fn new(platform_text_system: Arc<dyn PlatformTextSystem>) -> Self {
414 Self {
415 previous_frame: Mutex::default(),
416 current_frame: RwLock::default(),
417 platform_text_system,
418 }
419 }
420
421 pub fn layout_index(&self) -> LineLayoutIndex {
422 let frame = self.current_frame.read();
423 LineLayoutIndex {
424 lines_index: frame.used_lines.len(),
425 wrapped_lines_index: frame.used_wrapped_lines.len(),
426 }
427 }
428
429 pub fn reuse_layouts(&self, range: Range<LineLayoutIndex>) {
430 let mut previous_frame = &mut *self.previous_frame.lock();
431 let mut current_frame = &mut *self.current_frame.write();
432
433 for key in &previous_frame.used_lines[range.start.lines_index..range.end.lines_index] {
434 if let Some((key, line)) = previous_frame.lines.remove_entry(key) {
435 current_frame.lines.insert(key, line);
436 }
437 current_frame.used_lines.push(key.clone());
438 }
439
440 for key in &previous_frame.used_wrapped_lines
441 [range.start.wrapped_lines_index..range.end.wrapped_lines_index]
442 {
443 if let Some((key, line)) = previous_frame.wrapped_lines.remove_entry(key) {
444 current_frame.wrapped_lines.insert(key, line);
445 }
446 current_frame.used_wrapped_lines.push(key.clone());
447 }
448 }
449
450 pub fn truncate_layouts(&self, index: LineLayoutIndex) {
451 let mut current_frame = &mut *self.current_frame.write();
452 current_frame.used_lines.truncate(index.lines_index);
453 current_frame
454 .used_wrapped_lines
455 .truncate(index.wrapped_lines_index);
456 }
457
458 pub fn finish_frame(&self) {
459 let mut prev_frame = self.previous_frame.lock();
460 let mut curr_frame = self.current_frame.write();
461 std::mem::swap(&mut *prev_frame, &mut *curr_frame);
462 curr_frame.lines.clear();
463 curr_frame.wrapped_lines.clear();
464 curr_frame.used_lines.clear();
465 curr_frame.used_wrapped_lines.clear();
466 }
467
468 pub fn layout_wrapped_line<Text>(
469 &self,
470 text: Text,
471 font_size: Pixels,
472 runs: &[FontRun],
473 wrap_width: Option<Pixels>,
474 max_lines: Option<usize>,
475 ) -> Arc<WrappedLineLayout>
476 where
477 Text: AsRef<str>,
478 SharedString: From<Text>,
479 {
480 let key = &CacheKeyRef {
481 text: text.as_ref(),
482 font_size,
483 runs,
484 wrap_width,
485 force_width: None,
486 } as &dyn AsCacheKeyRef;
487
488 let current_frame = self.current_frame.upgradable_read();
489 if let Some(layout) = current_frame.wrapped_lines.get(key) {
490 return layout.clone();
491 }
492
493 let previous_frame_entry = self.previous_frame.lock().wrapped_lines.remove_entry(key);
494 if let Some((key, layout)) = previous_frame_entry {
495 let mut current_frame = RwLockUpgradableReadGuard::upgrade(current_frame);
496 current_frame
497 .wrapped_lines
498 .insert(key.clone(), layout.clone());
499 current_frame.used_wrapped_lines.push(key);
500 layout
501 } else {
502 drop(current_frame);
503 let text = SharedString::from(text);
504 let unwrapped_layout = self.layout_line::<&SharedString>(&text, font_size, runs, None);
505 let wrap_boundaries = if let Some(wrap_width) = wrap_width {
506 unwrapped_layout.compute_wrap_boundaries(text.as_ref(), wrap_width, max_lines)
507 } else {
508 SmallVec::new()
509 };
510 let layout = Arc::new(WrappedLineLayout {
511 unwrapped_layout,
512 wrap_boundaries,
513 wrap_width,
514 });
515 let key = Arc::new(CacheKey {
516 text,
517 font_size,
518 runs: SmallVec::from(runs),
519 wrap_width,
520 force_width: None,
521 });
522
523 let mut current_frame = self.current_frame.write();
524 current_frame
525 .wrapped_lines
526 .insert(key.clone(), layout.clone());
527 current_frame.used_wrapped_lines.push(key);
528
529 layout
530 }
531 }
532
533 pub fn layout_line<Text>(
534 &self,
535 text: Text,
536 font_size: Pixels,
537 runs: &[FontRun],
538 force_width: Option<Pixels>,
539 ) -> Arc<LineLayout>
540 where
541 Text: AsRef<str>,
542 SharedString: From<Text>,
543 {
544 let key = &CacheKeyRef {
545 text: text.as_ref(),
546 font_size,
547 runs,
548 wrap_width: None,
549 force_width,
550 } as &dyn AsCacheKeyRef;
551
552 let current_frame = self.current_frame.upgradable_read();
553 if let Some(layout) = current_frame.lines.get(key) {
554 return layout.clone();
555 }
556
557 let mut current_frame = RwLockUpgradableReadGuard::upgrade(current_frame);
558 if let Some((key, layout)) = self.previous_frame.lock().lines.remove_entry(key) {
559 current_frame.lines.insert(key.clone(), layout.clone());
560 current_frame.used_lines.push(key);
561 layout
562 } else {
563 let text = SharedString::from(text);
564 let mut layout = self
565 .platform_text_system
566 .layout_line(&text, font_size, runs);
567
568 if let Some(force_width) = force_width {
569 let mut glyph_pos = 0;
570 for run in layout.runs.iter_mut() {
571 for glyph in run.glyphs.iter_mut() {
572 if (glyph.position.x - glyph_pos * force_width).abs() > px(1.) {
573 glyph.position.x = glyph_pos * force_width;
574 }
575 glyph_pos += 1;
576 }
577 }
578 }
579
580 let key = Arc::new(CacheKey {
581 text,
582 font_size,
583 runs: SmallVec::from(runs),
584 wrap_width: None,
585 force_width,
586 });
587 let layout = Arc::new(layout);
588 current_frame.lines.insert(key.clone(), layout.clone());
589 current_frame.used_lines.push(key);
590 layout
591 }
592 }
593}
594
595/// A run of text with a single font.
596#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
597pub struct FontRun {
598 pub(crate) len: usize,
599 pub(crate) font_id: FontId,
600}
601
602trait AsCacheKeyRef {
603 fn as_cache_key_ref(&self) -> CacheKeyRef<'_>;
604}
605
606#[derive(Clone, Debug, Eq)]
607struct CacheKey {
608 text: SharedString,
609 font_size: Pixels,
610 runs: SmallVec<[FontRun; 1]>,
611 wrap_width: Option<Pixels>,
612 force_width: Option<Pixels>,
613}
614
615#[derive(Copy, Clone, PartialEq, Eq, Hash)]
616struct CacheKeyRef<'a> {
617 text: &'a str,
618 font_size: Pixels,
619 runs: &'a [FontRun],
620 wrap_width: Option<Pixels>,
621 force_width: Option<Pixels>,
622}
623
624impl PartialEq for dyn AsCacheKeyRef + '_ {
625 fn eq(&self, other: &dyn AsCacheKeyRef) -> bool {
626 self.as_cache_key_ref() == other.as_cache_key_ref()
627 }
628}
629
630impl Eq for dyn AsCacheKeyRef + '_ {}
631
632impl Hash for dyn AsCacheKeyRef + '_ {
633 fn hash<H: Hasher>(&self, state: &mut H) {
634 self.as_cache_key_ref().hash(state)
635 }
636}
637
638impl AsCacheKeyRef for CacheKey {
639 fn as_cache_key_ref(&self) -> CacheKeyRef<'_> {
640 CacheKeyRef {
641 text: &self.text,
642 font_size: self.font_size,
643 runs: self.runs.as_slice(),
644 wrap_width: self.wrap_width,
645 force_width: self.force_width,
646 }
647 }
648}
649
650impl PartialEq for CacheKey {
651 fn eq(&self, other: &Self) -> bool {
652 self.as_cache_key_ref().eq(&other.as_cache_key_ref())
653 }
654}
655
656impl Hash for CacheKey {
657 fn hash<H: Hasher>(&self, state: &mut H) {
658 self.as_cache_key_ref().hash(state);
659 }
660}
661
662impl<'a> Borrow<dyn AsCacheKeyRef + 'a> for Arc<CacheKey> {
663 fn borrow(&self) -> &(dyn AsCacheKeyRef + 'a) {
664 self.as_ref() as &dyn AsCacheKeyRef
665 }
666}
667
668impl AsCacheKeyRef for CacheKeyRef<'_> {
669 fn as_cache_key_ref(&self) -> CacheKeyRef<'_> {
670 *self
671 }
672}