1use crate::{FontId, FontRun, Pixels, PlatformTextSystem, SharedString, TextRun, px};
2use collections::HashMap;
3use std::{iter, sync::Arc};
4
5/// The GPUI line wrapper, used to wrap lines of text to a given width.
6pub struct LineWrapper {
7 platform_text_system: Arc<dyn PlatformTextSystem>,
8 pub(crate) font_id: FontId,
9 pub(crate) font_size: Pixels,
10 cached_ascii_char_widths: [Option<Pixels>; 128],
11 cached_other_char_widths: HashMap<char, Pixels>,
12}
13
14impl LineWrapper {
15 /// The maximum indent that can be applied to a line.
16 pub const MAX_INDENT: u32 = 256;
17
18 pub(crate) fn new(
19 font_id: FontId,
20 font_size: Pixels,
21 text_system: Arc<dyn PlatformTextSystem>,
22 ) -> Self {
23 Self {
24 platform_text_system: text_system,
25 font_id,
26 font_size,
27 cached_ascii_char_widths: [None; 128],
28 cached_other_char_widths: HashMap::default(),
29 }
30 }
31
32 /// Wrap a line of text to the given width with this wrapper's font and font size.
33 pub fn wrap_line<'a>(
34 &'a mut self,
35 fragments: &'a [LineFragment],
36 wrap_width: Pixels,
37 ) -> impl Iterator<Item = Boundary> + 'a {
38 let mut width = px(0.);
39 let mut first_non_whitespace_ix = None;
40 let mut indent = None;
41 let mut last_candidate_ix = 0;
42 let mut last_candidate_width = px(0.);
43 let mut last_wrap_ix = 0;
44 let mut prev_c = '\0';
45 let mut index = 0;
46 let mut candidates = fragments
47 .iter()
48 .flat_map(move |fragment| fragment.wrap_boundary_candidates())
49 .peekable();
50 iter::from_fn(move || {
51 for candidate in candidates.by_ref() {
52 let ix = index;
53 index += candidate.len_utf8();
54 let mut new_prev_c = prev_c;
55 let item_width = match candidate {
56 WrapBoundaryCandidate::Char { character: c } => {
57 if c == '\n' {
58 continue;
59 }
60
61 if Self::is_word_char(c) {
62 if prev_c == ' ' && c != ' ' && first_non_whitespace_ix.is_some() {
63 last_candidate_ix = ix;
64 last_candidate_width = width;
65 }
66 } else {
67 // CJK may not be space separated, e.g.: `Hello world你好世界`
68 if c != ' ' && first_non_whitespace_ix.is_some() {
69 last_candidate_ix = ix;
70 last_candidate_width = width;
71 }
72 }
73
74 if c != ' ' && first_non_whitespace_ix.is_none() {
75 first_non_whitespace_ix = Some(ix);
76 }
77
78 new_prev_c = c;
79
80 self.width_for_char(c)
81 }
82 WrapBoundaryCandidate::Element {
83 width: element_width,
84 ..
85 } => {
86 if prev_c == ' ' && first_non_whitespace_ix.is_some() {
87 last_candidate_ix = ix;
88 last_candidate_width = width;
89 }
90
91 if first_non_whitespace_ix.is_none() {
92 first_non_whitespace_ix = Some(ix);
93 }
94
95 element_width
96 }
97 };
98
99 width += item_width;
100 if width > wrap_width && ix > last_wrap_ix {
101 if let (None, Some(first_non_whitespace_ix)) = (indent, first_non_whitespace_ix)
102 {
103 indent = Some(
104 Self::MAX_INDENT.min((first_non_whitespace_ix - last_wrap_ix) as u32),
105 );
106 }
107
108 if last_candidate_ix > 0 {
109 last_wrap_ix = last_candidate_ix;
110 width -= last_candidate_width;
111 last_candidate_ix = 0;
112 } else {
113 last_wrap_ix = ix;
114 width = item_width;
115 }
116
117 if let Some(indent) = indent {
118 width += self.width_for_char(' ') * indent as f32;
119 }
120
121 return Some(Boundary::new(last_wrap_ix, indent.unwrap_or(0)));
122 }
123
124 prev_c = new_prev_c;
125 }
126
127 None
128 })
129 }
130
131 /// Truncate a line of text to the given width with this wrapper's font and font size.
132 pub fn truncate_line(
133 &mut self,
134 line: SharedString,
135 truncate_width: Pixels,
136 truncation_suffix: &str,
137 runs: &mut Vec<TextRun>,
138 ) -> SharedString {
139 let mut width = px(0.);
140 let mut suffix_width = truncation_suffix
141 .chars()
142 .map(|c| self.width_for_char(c))
143 .fold(px(0.0), |a, x| a + x);
144 let mut char_indices = line.char_indices();
145 let mut truncate_ix = 0;
146 for (ix, c) in char_indices {
147 if width + suffix_width < truncate_width {
148 truncate_ix = ix;
149 }
150
151 let char_width = self.width_for_char(c);
152 width += char_width;
153
154 if width.floor() > truncate_width {
155 let result =
156 SharedString::from(format!("{}{}", &line[..truncate_ix], truncation_suffix));
157 update_runs_after_truncation(&result, truncation_suffix, runs);
158
159 return result;
160 }
161 }
162
163 line
164 }
165
166 /// Any character in this list should be treated as a word character,
167 /// meaning it can be part of a word that should not be wrapped.
168 pub(crate) fn is_word_char(c: char) -> bool {
169 // ASCII alphanumeric characters, for English, numbers: `Hello123`, etc.
170 c.is_ascii_alphanumeric() ||
171 // Latin script in Unicode for French, German, Spanish, etc.
172 // Latin-1 Supplement
173 // https://en.wikipedia.org/wiki/Latin-1_Supplement
174 matches!(c, '\u{00C0}'..='\u{00FF}') ||
175 // Latin Extended-A
176 // https://en.wikipedia.org/wiki/Latin_Extended-A
177 matches!(c, '\u{0100}'..='\u{017F}') ||
178 // Latin Extended-B
179 // https://en.wikipedia.org/wiki/Latin_Extended-B
180 matches!(c, '\u{0180}'..='\u{024F}') ||
181 // Cyrillic for Russian, Ukrainian, etc.
182 // https://en.wikipedia.org/wiki/Cyrillic_script_in_Unicode
183 matches!(c, '\u{0400}'..='\u{04FF}') ||
184 // Some other known special characters that should be treated as word characters,
185 // e.g. `a-b`, `var_name`, `I'm`, '@mention`, `#hashtag`, `100%`, `3.1415`,
186 // `2^3`, `a~b`, `a=1`, `Self::new`, etc.
187 matches!(c, '-' | '_' | '.' | '\'' | '$' | '%' | '@' | '#' | '^' | '~' | ',' | '=' | ':') ||
188 // `⋯` character is special used in Zed, to keep this at the end of the line.
189 matches!(c, '⋯')
190 }
191
192 #[inline(always)]
193 fn width_for_char(&mut self, c: char) -> Pixels {
194 if (c as u32) < 128 {
195 if let Some(cached_width) = self.cached_ascii_char_widths[c as usize] {
196 cached_width
197 } else {
198 let width = self.compute_width_for_char(c);
199 self.cached_ascii_char_widths[c as usize] = Some(width);
200 width
201 }
202 } else if let Some(cached_width) = self.cached_other_char_widths.get(&c) {
203 *cached_width
204 } else {
205 let width = self.compute_width_for_char(c);
206 self.cached_other_char_widths.insert(c, width);
207 width
208 }
209 }
210
211 fn compute_width_for_char(&self, c: char) -> Pixels {
212 let mut buffer = [0; 4];
213 let buffer = c.encode_utf8(&mut buffer);
214 self.platform_text_system
215 .layout_line(
216 buffer,
217 self.font_size,
218 &[FontRun {
219 len: buffer.len(),
220 font_id: self.font_id,
221 }],
222 )
223 .width
224 }
225}
226
227fn update_runs_after_truncation(result: &str, ellipsis: &str, runs: &mut Vec<TextRun>) {
228 let mut truncate_at = result.len() - ellipsis.len();
229 for (run_index, run) in runs.iter_mut().enumerate() {
230 if run.len <= truncate_at {
231 truncate_at -= run.len;
232 } else {
233 run.len = truncate_at + ellipsis.len();
234 runs.truncate(run_index + 1);
235 break;
236 }
237 }
238}
239
240/// A fragment of a line that can be wrapped.
241pub enum LineFragment<'a> {
242 /// A text fragment consisting of characters.
243 Text {
244 /// The text content of the fragment.
245 text: &'a str,
246 },
247 /// A non-text element with a fixed width.
248 Element {
249 /// The width of the element in pixels.
250 width: Pixels,
251 /// The UTF-8 encoded length of the element.
252 len_utf8: usize,
253 },
254}
255
256impl<'a> LineFragment<'a> {
257 /// Creates a new text fragment from the given text.
258 pub fn text(text: &'a str) -> Self {
259 LineFragment::Text { text }
260 }
261
262 /// Creates a new non-text element with the given width and UTF-8 encoded length.
263 pub fn element(width: Pixels, len_utf8: usize) -> Self {
264 LineFragment::Element { width, len_utf8 }
265 }
266
267 fn wrap_boundary_candidates(&self) -> impl Iterator<Item = WrapBoundaryCandidate> {
268 let text = match self {
269 LineFragment::Text { text } => text,
270 LineFragment::Element { .. } => "\0",
271 };
272 text.chars().map(move |character| {
273 if let LineFragment::Element { width, len_utf8 } = self {
274 WrapBoundaryCandidate::Element {
275 width: *width,
276 len_utf8: *len_utf8,
277 }
278 } else {
279 WrapBoundaryCandidate::Char { character }
280 }
281 })
282 }
283}
284
285enum WrapBoundaryCandidate {
286 Char { character: char },
287 Element { width: Pixels, len_utf8: usize },
288}
289
290impl WrapBoundaryCandidate {
291 pub fn len_utf8(&self) -> usize {
292 match self {
293 WrapBoundaryCandidate::Char { character } => character.len_utf8(),
294 WrapBoundaryCandidate::Element { len_utf8: len, .. } => *len,
295 }
296 }
297}
298
299/// A boundary between two lines of text.
300#[derive(Copy, Clone, Debug, PartialEq, Eq)]
301pub struct Boundary {
302 /// The index of the last character in a line
303 pub ix: usize,
304 /// The indent of the next line.
305 pub next_indent: u32,
306}
307
308impl Boundary {
309 fn new(ix: usize, next_indent: u32) -> Self {
310 Self { ix, next_indent }
311 }
312}
313
314#[cfg(test)]
315mod tests {
316 use super::*;
317 use crate::{
318 Font, FontFeatures, FontStyle, FontWeight, Hsla, TestAppContext, TestDispatcher, font,
319 };
320 #[cfg(target_os = "macos")]
321 use crate::{TextRun, WindowTextSystem, WrapBoundary};
322 use rand::prelude::*;
323
324 fn build_wrapper() -> LineWrapper {
325 let dispatcher = TestDispatcher::new(StdRng::seed_from_u64(0));
326 let cx = TestAppContext::build(dispatcher, None);
327 let id = cx.text_system().resolve_font(&font(".ZedMono"));
328 LineWrapper::new(id, px(16.), cx.text_system().platform_text_system.clone())
329 }
330
331 fn generate_test_runs(input_run_len: &[usize]) -> Vec<TextRun> {
332 input_run_len
333 .iter()
334 .map(|run_len| TextRun {
335 len: *run_len,
336 font: Font {
337 family: "Dummy".into(),
338 features: FontFeatures::default(),
339 fallbacks: None,
340 weight: FontWeight::default(),
341 style: FontStyle::Normal,
342 },
343 color: Hsla::default(),
344 background_color: None,
345 underline: None,
346 strikethrough: None,
347 })
348 .collect()
349 }
350
351 #[test]
352 fn test_wrap_line() {
353 let mut wrapper = build_wrapper();
354
355 assert_eq!(
356 wrapper
357 .wrap_line(&[LineFragment::text("aa bbb cccc ddddd eeee")], px(72.))
358 .collect::<Vec<_>>(),
359 &[
360 Boundary::new(7, 0),
361 Boundary::new(12, 0),
362 Boundary::new(18, 0)
363 ],
364 );
365 assert_eq!(
366 wrapper
367 .wrap_line(&[LineFragment::text("aaa aaaaaaaaaaaaaaaaaa")], px(72.0))
368 .collect::<Vec<_>>(),
369 &[
370 Boundary::new(4, 0),
371 Boundary::new(11, 0),
372 Boundary::new(18, 0)
373 ],
374 );
375 assert_eq!(
376 wrapper
377 .wrap_line(&[LineFragment::text(" aaaaaaa")], px(72.))
378 .collect::<Vec<_>>(),
379 &[
380 Boundary::new(7, 5),
381 Boundary::new(9, 5),
382 Boundary::new(11, 5),
383 ]
384 );
385 assert_eq!(
386 wrapper
387 .wrap_line(
388 &[LineFragment::text(" ")],
389 px(72.)
390 )
391 .collect::<Vec<_>>(),
392 &[
393 Boundary::new(7, 0),
394 Boundary::new(14, 0),
395 Boundary::new(21, 0)
396 ]
397 );
398 assert_eq!(
399 wrapper
400 .wrap_line(&[LineFragment::text(" aaaaaaaaaaaaaa")], px(72.))
401 .collect::<Vec<_>>(),
402 &[
403 Boundary::new(7, 0),
404 Boundary::new(14, 3),
405 Boundary::new(18, 3),
406 Boundary::new(22, 3),
407 ]
408 );
409
410 // Test wrapping multiple text fragments
411 assert_eq!(
412 wrapper
413 .wrap_line(
414 &[
415 LineFragment::text("aa bbb "),
416 LineFragment::text("cccc ddddd eeee")
417 ],
418 px(72.)
419 )
420 .collect::<Vec<_>>(),
421 &[
422 Boundary::new(7, 0),
423 Boundary::new(12, 0),
424 Boundary::new(18, 0)
425 ],
426 );
427
428 // Test wrapping with a mix of text and element fragments
429 assert_eq!(
430 wrapper
431 .wrap_line(
432 &[
433 LineFragment::text("aa "),
434 LineFragment::element(px(20.), 1),
435 LineFragment::text(" bbb "),
436 LineFragment::element(px(30.), 1),
437 LineFragment::text(" cccc")
438 ],
439 px(72.)
440 )
441 .collect::<Vec<_>>(),
442 &[
443 Boundary::new(5, 0),
444 Boundary::new(9, 0),
445 Boundary::new(11, 0)
446 ],
447 );
448
449 // Test with element at the beginning and text afterward
450 assert_eq!(
451 wrapper
452 .wrap_line(
453 &[
454 LineFragment::element(px(50.), 1),
455 LineFragment::text(" aaaa bbbb cccc dddd")
456 ],
457 px(72.)
458 )
459 .collect::<Vec<_>>(),
460 &[
461 Boundary::new(2, 0),
462 Boundary::new(7, 0),
463 Boundary::new(12, 0),
464 Boundary::new(17, 0)
465 ],
466 );
467
468 // Test with a large element that forces wrapping by itself
469 assert_eq!(
470 wrapper
471 .wrap_line(
472 &[
473 LineFragment::text("short text "),
474 LineFragment::element(px(100.), 1),
475 LineFragment::text(" more text")
476 ],
477 px(72.)
478 )
479 .collect::<Vec<_>>(),
480 &[
481 Boundary::new(6, 0),
482 Boundary::new(11, 0),
483 Boundary::new(12, 0),
484 Boundary::new(18, 0)
485 ],
486 );
487 }
488
489 #[test]
490 fn test_truncate_line() {
491 let mut wrapper = build_wrapper();
492
493 fn perform_test(
494 wrapper: &mut LineWrapper,
495 text: &'static str,
496 result: &'static str,
497 ellipsis: &str,
498 ) {
499 let dummy_run_lens = vec![text.len()];
500 let mut dummy_runs = generate_test_runs(&dummy_run_lens);
501 assert_eq!(
502 wrapper.truncate_line(text.into(), px(220.), ellipsis, &mut dummy_runs),
503 result
504 );
505 assert_eq!(dummy_runs.first().unwrap().len, result.len());
506 }
507
508 perform_test(
509 &mut wrapper,
510 "aa bbb cccc ddddd eeee ffff gggg",
511 "aa bbb cccc ddddd eeee",
512 "",
513 );
514 perform_test(
515 &mut wrapper,
516 "aa bbb cccc ddddd eeee ffff gggg",
517 "aa bbb cccc ddddd eee…",
518 "…",
519 );
520 perform_test(
521 &mut wrapper,
522 "aa bbb cccc ddddd eeee ffff gggg",
523 "aa bbb cccc dddd......",
524 "......",
525 );
526 }
527
528 #[test]
529 fn test_truncate_multiple_runs() {
530 let mut wrapper = build_wrapper();
531
532 fn perform_test(
533 wrapper: &mut LineWrapper,
534 text: &'static str,
535 result: &str,
536 run_lens: &[usize],
537 result_run_len: &[usize],
538 line_width: Pixels,
539 ) {
540 let mut dummy_runs = generate_test_runs(run_lens);
541 assert_eq!(
542 wrapper.truncate_line(text.into(), line_width, "…", &mut dummy_runs),
543 result
544 );
545 for (run, result_len) in dummy_runs.iter().zip(result_run_len) {
546 assert_eq!(run.len, *result_len);
547 }
548 }
549 // Case 0: Normal
550 // Text: abcdefghijkl
551 // Runs: Run0 { len: 12, ... }
552 //
553 // Truncate res: abcd… (truncate_at = 4)
554 // Run res: Run0 { string: abcd…, len: 7, ... }
555 perform_test(&mut wrapper, "abcdefghijkl", "abcd…", &[12], &[7], px(50.));
556 // Case 1: Drop some runs
557 // Text: abcdefghijkl
558 // Runs: Run0 { len: 4, ... }, Run1 { len: 4, ... }, Run2 { len: 4, ... }
559 //
560 // Truncate res: abcdef… (truncate_at = 6)
561 // Runs res: Run0 { string: abcd, len: 4, ... }, Run1 { string: ef…, len:
562 // 5, ... }
563 perform_test(
564 &mut wrapper,
565 "abcdefghijkl",
566 "abcdef…",
567 &[4, 4, 4],
568 &[4, 5],
569 px(70.),
570 );
571 // Case 2: Truncate at start of some run
572 // Text: abcdefghijkl
573 // Runs: Run0 { len: 4, ... }, Run1 { len: 4, ... }, Run2 { len: 4, ... }
574 //
575 // Truncate res: abcdefgh… (truncate_at = 8)
576 // Runs res: Run0 { string: abcd, len: 4, ... }, Run1 { string: efgh, len:
577 // 4, ... }, Run2 { string: …, len: 3, ... }
578 perform_test(
579 &mut wrapper,
580 "abcdefghijkl",
581 "abcdefgh…",
582 &[4, 4, 4],
583 &[4, 4, 3],
584 px(90.),
585 );
586 }
587
588 #[test]
589 fn test_update_run_after_truncation() {
590 fn perform_test(result: &str, run_lens: &[usize], result_run_lens: &[usize]) {
591 let mut dummy_runs = generate_test_runs(run_lens);
592 update_runs_after_truncation(result, "…", &mut dummy_runs);
593 for (run, result_len) in dummy_runs.iter().zip(result_run_lens) {
594 assert_eq!(run.len, *result_len);
595 }
596 }
597 // Case 0: Normal
598 // Text: abcdefghijkl
599 // Runs: Run0 { len: 12, ... }
600 //
601 // Truncate res: abcd… (truncate_at = 4)
602 // Run res: Run0 { string: abcd…, len: 7, ... }
603 perform_test("abcd…", &[12], &[7]);
604 // Case 1: Drop some runs
605 // Text: abcdefghijkl
606 // Runs: Run0 { len: 4, ... }, Run1 { len: 4, ... }, Run2 { len: 4, ... }
607 //
608 // Truncate res: abcdef… (truncate_at = 6)
609 // Runs res: Run0 { string: abcd, len: 4, ... }, Run1 { string: ef…, len:
610 // 5, ... }
611 perform_test("abcdef…", &[4, 4, 4], &[4, 5]);
612 // Case 2: Truncate at start of some run
613 // Text: abcdefghijkl
614 // Runs: Run0 { len: 4, ... }, Run1 { len: 4, ... }, Run2 { len: 4, ... }
615 //
616 // Truncate res: abcdefgh… (truncate_at = 8)
617 // Runs res: Run0 { string: abcd, len: 4, ... }, Run1 { string: efgh, len:
618 // 4, ... }, Run2 { string: …, len: 3, ... }
619 perform_test("abcdefgh…", &[4, 4, 4], &[4, 4, 3]);
620 }
621
622 #[test]
623 fn test_is_word_char() {
624 #[track_caller]
625 fn assert_word(word: &str) {
626 for c in word.chars() {
627 assert!(LineWrapper::is_word_char(c), "assertion failed for '{}'", c);
628 }
629 }
630
631 #[track_caller]
632 fn assert_not_word(word: &str) {
633 let found = word.chars().any(|c| !LineWrapper::is_word_char(c));
634 assert!(found, "assertion failed for '{}'", word);
635 }
636
637 assert_word("Hello123");
638 assert_word("non-English");
639 assert_word("var_name");
640 assert_word("123456");
641 assert_word("3.1415");
642 assert_word("10^2");
643 assert_word("1~2");
644 assert_word("100%");
645 assert_word("@mention");
646 assert_word("#hashtag");
647 assert_word("$variable");
648 assert_word("a=1");
649 assert_word("Self::is_word_char");
650 assert_word("more⋯");
651
652 // Space
653 assert_not_word("foo bar");
654
655 // URL case
656 assert_word("github.com");
657 assert_not_word("zed-industries/zed");
658 assert_not_word("zed-industries\\zed");
659 assert_not_word("a=1&b=2");
660 assert_not_word("foo?b=2");
661
662 // Latin-1 Supplement
663 assert_word("ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏ");
664 // Latin Extended-A
665 assert_word("ĀāĂ㥹ĆćĈĉĊċČčĎď");
666 // Latin Extended-B
667 assert_word("ƀƁƂƃƄƅƆƇƈƉƊƋƌƍƎƏ");
668 // Cyrillic
669 assert_word("АБВГДЕЖЗИЙКЛМНОП");
670
671 // non-word characters
672 assert_not_word("你好");
673 assert_not_word("안녕하세요");
674 assert_not_word("こんにちは");
675 assert_not_word("😀😁😂");
676 assert_not_word("()[]{}<>");
677 }
678
679 // For compatibility with the test macro
680 #[cfg(target_os = "macos")]
681 use crate as gpui;
682
683 // These seem to vary wildly based on the text system.
684 #[cfg(target_os = "macos")]
685 #[crate::test]
686 fn test_wrap_shaped_line(cx: &mut TestAppContext) {
687 cx.update(|cx| {
688 let text_system = WindowTextSystem::new(cx.text_system().clone());
689
690 let normal = TextRun {
691 len: 0,
692 font: font("Helvetica"),
693 color: Default::default(),
694 underline: Default::default(),
695 strikethrough: None,
696 background_color: None,
697 };
698 let bold = TextRun {
699 len: 0,
700 font: font("Helvetica").bold(),
701 color: Default::default(),
702 underline: Default::default(),
703 strikethrough: None,
704 background_color: None,
705 };
706
707 let text = "aa bbb cccc ddddd eeee".into();
708 let lines = text_system
709 .shape_text(
710 text,
711 px(16.),
712 &[
713 normal.with_len(4),
714 bold.with_len(5),
715 normal.with_len(6),
716 bold.with_len(1),
717 normal.with_len(7),
718 ],
719 Some(px(72.)),
720 None,
721 )
722 .unwrap();
723
724 assert_eq!(
725 lines[0].layout.wrap_boundaries(),
726 &[
727 WrapBoundary {
728 run_ix: 0,
729 glyph_ix: 7
730 },
731 WrapBoundary {
732 run_ix: 0,
733 glyph_ix: 12
734 },
735 WrapBoundary {
736 run_ix: 0,
737 glyph_ix: 18
738 }
739 ],
740 );
741 });
742 }
743}