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