1use crate::{px, FontId, FontRun, Pixels, PlatformTextSystem, SharedString};
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 line: &'a str,
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 char_indices = line.char_indices();
46 iter::from_fn(move || {
47 for (ix, c) in char_indices.by_ref() {
48 if c == '\n' {
49 continue;
50 }
51
52 if Self::is_word_char(c) {
53 if prev_c == ' ' && c != ' ' && first_non_whitespace_ix.is_some() {
54 last_candidate_ix = ix;
55 last_candidate_width = width;
56 }
57 } else {
58 // CJK may not be space separated, e.g.: `Hello world你好世界`
59 if c != ' ' && first_non_whitespace_ix.is_some() {
60 last_candidate_ix = ix;
61 last_candidate_width = width;
62 }
63 }
64
65 if c != ' ' && first_non_whitespace_ix.is_none() {
66 first_non_whitespace_ix = Some(ix);
67 }
68
69 let char_width = self.width_for_char(c);
70 width += char_width;
71 if width > wrap_width && ix > last_wrap_ix {
72 if let (None, Some(first_non_whitespace_ix)) = (indent, first_non_whitespace_ix)
73 {
74 indent = Some(
75 Self::MAX_INDENT.min((first_non_whitespace_ix - last_wrap_ix) as u32),
76 );
77 }
78
79 if last_candidate_ix > 0 {
80 last_wrap_ix = last_candidate_ix;
81 width -= last_candidate_width;
82 last_candidate_ix = 0;
83 } else {
84 last_wrap_ix = ix;
85 width = char_width;
86 }
87
88 if let Some(indent) = indent {
89 width += self.width_for_char(' ') * indent as f32;
90 }
91
92 return Some(Boundary::new(last_wrap_ix, indent.unwrap_or(0)));
93 }
94 prev_c = c;
95 }
96
97 None
98 })
99 }
100
101 /// Truncate a line of text to the given width with this wrapper's font and font size.
102 pub fn truncate_line(
103 &mut self,
104 line: SharedString,
105 truncate_width: Pixels,
106 ellipsis: Option<&str>,
107 ) -> SharedString {
108 let mut width = px(0.);
109 let mut ellipsis_width = px(0.);
110 if let Some(ellipsis) = ellipsis {
111 for c in ellipsis.chars() {
112 ellipsis_width += self.width_for_char(c);
113 }
114 }
115
116 let mut char_indices = line.char_indices();
117 let mut truncate_ix = 0;
118 for (ix, c) in char_indices {
119 if width + ellipsis_width <= truncate_width {
120 truncate_ix = ix;
121 }
122
123 let char_width = self.width_for_char(c);
124 width += char_width;
125
126 if width.floor() > truncate_width {
127 return SharedString::from(format!(
128 "{}{}",
129 &line[..truncate_ix],
130 ellipsis.unwrap_or("")
131 ));
132 }
133 }
134
135 line.clone()
136 }
137
138 pub(crate) fn is_word_char(c: char) -> bool {
139 // ASCII alphanumeric characters, for English, numbers: `Hello123`, etc.
140 c.is_ascii_alphanumeric() ||
141 // Latin script in Unicode for French, German, Spanish, etc.
142 // Latin-1 Supplement
143 // https://en.wikipedia.org/wiki/Latin-1_Supplement
144 matches!(c, '\u{00C0}'..='\u{00FF}') ||
145 // Latin Extended-A
146 // https://en.wikipedia.org/wiki/Latin_Extended-A
147 matches!(c, '\u{0100}'..='\u{017F}') ||
148 // Latin Extended-B
149 // https://en.wikipedia.org/wiki/Latin_Extended-B
150 matches!(c, '\u{0180}'..='\u{024F}') ||
151 // Cyrillic for Russian, Ukrainian, etc.
152 // https://en.wikipedia.org/wiki/Cyrillic_script_in_Unicode
153 matches!(c, '\u{0400}'..='\u{04FF}') ||
154 // Some other known special characters that should be treated as word characters,
155 // e.g. `a-b`, `var_name`, `I'm`, '@mention`, `#hashtag`, `100%`, `3.1415`, `2^3`, `a~b`, etc.
156 matches!(c, '-' | '_' | '.' | '\'' | '$' | '%' | '@' | '#' | '^' | '~' | ',') ||
157 // Characters that used in URL, e.g. `https://github.com/zed-industries/zed?a=1&b=2` for better wrapping a long URL.
158 matches!(c, '/' | ':' | '?' | '&' | '=') ||
159 // `⋯` character is special used in Zed, to keep this at the end of the line.
160 matches!(c, '⋯')
161 }
162
163 #[inline(always)]
164 fn width_for_char(&mut self, c: char) -> Pixels {
165 if (c as u32) < 128 {
166 if let Some(cached_width) = self.cached_ascii_char_widths[c as usize] {
167 cached_width
168 } else {
169 let width = self.compute_width_for_char(c);
170 self.cached_ascii_char_widths[c as usize] = Some(width);
171 width
172 }
173 } else if let Some(cached_width) = self.cached_other_char_widths.get(&c) {
174 *cached_width
175 } else {
176 let width = self.compute_width_for_char(c);
177 self.cached_other_char_widths.insert(c, width);
178 width
179 }
180 }
181
182 fn compute_width_for_char(&self, c: char) -> Pixels {
183 let mut buffer = [0; 4];
184 let buffer = c.encode_utf8(&mut buffer);
185 self.platform_text_system
186 .layout_line(
187 buffer,
188 self.font_size,
189 &[FontRun {
190 len: buffer.len(),
191 font_id: self.font_id,
192 }],
193 )
194 .width
195 }
196}
197
198/// A boundary between two lines of text.
199#[derive(Copy, Clone, Debug, PartialEq, Eq)]
200pub struct Boundary {
201 /// The index of the last character in a line
202 pub ix: usize,
203 /// The indent of the next line.
204 pub next_indent: u32,
205}
206
207impl Boundary {
208 fn new(ix: usize, next_indent: u32) -> Self {
209 Self { ix, next_indent }
210 }
211}
212
213#[cfg(test)]
214mod tests {
215 use super::*;
216 use crate::{font, TestAppContext, TestDispatcher};
217 #[cfg(target_os = "macos")]
218 use crate::{TextRun, WindowTextSystem, WrapBoundary};
219 use rand::prelude::*;
220
221 fn build_wrapper() -> LineWrapper {
222 let dispatcher = TestDispatcher::new(StdRng::seed_from_u64(0));
223 let cx = TestAppContext::new(dispatcher, None);
224 cx.text_system()
225 .add_fonts(vec![std::fs::read(
226 "../../assets/fonts/plex-mono/ZedPlexMono-Regular.ttf",
227 )
228 .unwrap()
229 .into()])
230 .unwrap();
231 let id = cx.text_system().font_id(&font("Zed Plex Mono")).unwrap();
232 LineWrapper::new(id, px(16.), cx.text_system().platform_text_system.clone())
233 }
234
235 #[test]
236 fn test_wrap_line() {
237 let mut wrapper = build_wrapper();
238
239 assert_eq!(
240 wrapper
241 .wrap_line("aa bbb cccc ddddd eeee", px(72.))
242 .collect::<Vec<_>>(),
243 &[
244 Boundary::new(7, 0),
245 Boundary::new(12, 0),
246 Boundary::new(18, 0)
247 ],
248 );
249 assert_eq!(
250 wrapper
251 .wrap_line("aaa aaaaaaaaaaaaaaaaaa", px(72.0))
252 .collect::<Vec<_>>(),
253 &[
254 Boundary::new(4, 0),
255 Boundary::new(11, 0),
256 Boundary::new(18, 0)
257 ],
258 );
259 assert_eq!(
260 wrapper
261 .wrap_line(" aaaaaaa", px(72.))
262 .collect::<Vec<_>>(),
263 &[
264 Boundary::new(7, 5),
265 Boundary::new(9, 5),
266 Boundary::new(11, 5),
267 ]
268 );
269 assert_eq!(
270 wrapper
271 .wrap_line(" ", px(72.))
272 .collect::<Vec<_>>(),
273 &[
274 Boundary::new(7, 0),
275 Boundary::new(14, 0),
276 Boundary::new(21, 0)
277 ]
278 );
279 assert_eq!(
280 wrapper
281 .wrap_line(" aaaaaaaaaaaaaa", px(72.))
282 .collect::<Vec<_>>(),
283 &[
284 Boundary::new(7, 0),
285 Boundary::new(14, 3),
286 Boundary::new(18, 3),
287 Boundary::new(22, 3),
288 ]
289 );
290 }
291
292 #[test]
293 fn test_truncate_line() {
294 let mut wrapper = build_wrapper();
295
296 assert_eq!(
297 wrapper.truncate_line("aa bbb cccc ddddd eeee ffff gggg".into(), px(220.), None),
298 "aa bbb cccc ddddd eeee"
299 );
300 assert_eq!(
301 wrapper.truncate_line(
302 "aa bbb cccc ddddd eeee ffff gggg".into(),
303 px(220.),
304 Some("…")
305 ),
306 "aa bbb cccc ddddd eee…"
307 );
308 assert_eq!(
309 wrapper.truncate_line(
310 "aa bbb cccc ddddd eeee ffff gggg".into(),
311 px(220.),
312 Some("......")
313 ),
314 "aa bbb cccc dddd......"
315 );
316 }
317
318 #[test]
319 fn test_is_word_char() {
320 #[track_caller]
321 fn assert_word(word: &str) {
322 for c in word.chars() {
323 assert!(LineWrapper::is_word_char(c), "assertion failed for '{}'", c);
324 }
325 }
326
327 #[track_caller]
328 fn assert_not_word(word: &str) {
329 let found = word.chars().any(|c| !LineWrapper::is_word_char(c));
330 assert!(found, "assertion failed for '{}'", word);
331 }
332
333 assert_word("Hello123");
334 assert_word("non-English");
335 assert_word("var_name");
336 assert_word("123456");
337 assert_word("3.1415");
338 assert_word("10^2");
339 assert_word("1~2");
340 assert_word("100%");
341 assert_word("@mention");
342 assert_word("#hashtag");
343 assert_word("$variable");
344 assert_word("more⋯");
345
346 // Space
347 assert_not_word("foo bar");
348
349 // URL case
350 assert_word("https://github.com/zed-industries/zed/");
351 assert_word("github.com");
352 assert_word("a=1&b=2");
353
354 // Latin-1 Supplement
355 assert_word("ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏ");
356 // Latin Extended-A
357 assert_word("ĀāĂ㥹ĆćĈĉĊċČčĎď");
358 // Latin Extended-B
359 assert_word("ƀƁƂƃƄƅƆƇƈƉƊƋƌƍƎƏ");
360 // Cyrillic
361 assert_word("АБВГДЕЖЗИЙКЛМНОП");
362
363 // non-word characters
364 assert_not_word("你好");
365 assert_not_word("안녕하세요");
366 assert_not_word("こんにちは");
367 assert_not_word("😀😁😂");
368 assert_not_word("()[]{}<>");
369 }
370
371 // For compatibility with the test macro
372 #[cfg(target_os = "macos")]
373 use crate as gpui;
374
375 // These seem to vary wildly based on the text system.
376 #[cfg(target_os = "macos")]
377 #[crate::test]
378 fn test_wrap_shaped_line(cx: &mut TestAppContext) {
379 cx.update(|cx| {
380 let text_system = WindowTextSystem::new(cx.text_system().clone());
381
382 let normal = TextRun {
383 len: 0,
384 font: font("Helvetica"),
385 color: Default::default(),
386 underline: Default::default(),
387 strikethrough: None,
388 background_color: None,
389 };
390 let bold = TextRun {
391 len: 0,
392 font: font("Helvetica").bold(),
393 color: Default::default(),
394 underline: Default::default(),
395 strikethrough: None,
396 background_color: None,
397 };
398
399 impl TextRun {
400 fn with_len(&self, len: usize) -> Self {
401 let mut this = self.clone();
402 this.len = len;
403 this
404 }
405 }
406
407 let text = "aa bbb cccc ddddd eeee".into();
408 let lines = text_system
409 .shape_text(
410 text,
411 px(16.),
412 &[
413 normal.with_len(4),
414 bold.with_len(5),
415 normal.with_len(6),
416 bold.with_len(1),
417 normal.with_len(7),
418 ],
419 Some(px(72.)),
420 )
421 .unwrap();
422
423 assert_eq!(
424 lines[0].layout.wrap_boundaries(),
425 &[
426 WrapBoundary {
427 run_ix: 1,
428 glyph_ix: 3
429 },
430 WrapBoundary {
431 run_ix: 2,
432 glyph_ix: 3
433 },
434 WrapBoundary {
435 run_ix: 4,
436 glyph_ix: 2
437 }
438 ],
439 );
440 });
441 }
442}