1use crate::{
2 color::Color,
3 fonts::{HighlightStyle, TextStyle},
4 geometry::{
5 rect::RectF,
6 vector::{vec2f, Vector2F},
7 },
8 json::{ToJson, Value},
9 text_layout::{Line, RunStyle, ShapedBoundary},
10 AppContext, Element, FontCache, LayoutContext, SceneBuilder, SizeConstraint, TextLayoutCache,
11 View, ViewContext,
12};
13use log::warn;
14use serde_json::json;
15use std::{borrow::Cow, ops::Range, sync::Arc};
16
17pub struct Text {
18 text: Cow<'static, str>,
19 style: TextStyle,
20 soft_wrap: bool,
21 highlights: Option<Box<[(Range<usize>, HighlightStyle)]>>,
22 custom_runs: Option<(
23 Box<[Range<usize>]>,
24 Box<dyn FnMut(usize, RectF, &mut SceneBuilder, &mut AppContext)>,
25 )>,
26}
27
28pub struct LayoutState {
29 shaped_lines: Vec<Line>,
30 wrap_boundaries: Vec<Vec<ShapedBoundary>>,
31 line_height: f32,
32}
33
34impl Text {
35 pub fn new<I: Into<Cow<'static, str>>>(text: I, style: TextStyle) -> Self {
36 Self {
37 text: text.into(),
38 style,
39 soft_wrap: true,
40 highlights: None,
41 custom_runs: None,
42 }
43 }
44
45 pub fn with_default_color(mut self, color: Color) -> Self {
46 self.style.color = color;
47 self
48 }
49
50 pub fn with_highlights(
51 mut self,
52 runs: impl Into<Box<[(Range<usize>, HighlightStyle)]>>,
53 ) -> Self {
54 self.highlights = Some(runs.into());
55 self
56 }
57
58 pub fn with_custom_runs(
59 mut self,
60 runs: impl Into<Box<[Range<usize>]>>,
61 callback: impl 'static + FnMut(usize, RectF, &mut SceneBuilder, &mut AppContext),
62 ) -> Self {
63 self.custom_runs = Some((runs.into(), Box::new(callback)));
64 self
65 }
66
67 pub fn with_soft_wrap(mut self, soft_wrap: bool) -> Self {
68 self.soft_wrap = soft_wrap;
69 self
70 }
71}
72
73impl<V: View> Element<V> for Text {
74 type LayoutState = LayoutState;
75 type PaintState = ();
76
77 fn layout(
78 &mut self,
79 constraint: SizeConstraint,
80 _: &mut V,
81 cx: &mut LayoutContext<V>,
82 ) -> (Vector2F, Self::LayoutState) {
83 // Convert the string and highlight ranges into an iterator of highlighted chunks.
84
85 let mut offset = 0;
86 let mut highlight_ranges = self
87 .highlights
88 .as_ref()
89 .map_or(Default::default(), AsRef::as_ref)
90 .iter()
91 .peekable();
92 let chunks = std::iter::from_fn(|| {
93 let result;
94 if let Some((range, highlight_style)) = highlight_ranges.peek() {
95 if offset < range.start {
96 result = Some((&self.text[offset..range.start], None));
97 offset = range.start;
98 } else if range.end <= self.text.len() {
99 result = Some((&self.text[range.clone()], Some(*highlight_style)));
100 highlight_ranges.next();
101 offset = range.end;
102 } else {
103 warn!(
104 "Highlight out of text range. Text len: {}, Highlight range: {}..{}",
105 self.text.len(),
106 range.start,
107 range.end
108 );
109 result = None;
110 }
111 } else if offset < self.text.len() {
112 result = Some((&self.text[offset..], None));
113 offset = self.text.len();
114 } else {
115 result = None;
116 }
117 result
118 });
119
120 // Perform shaping on these highlighted chunks
121 let shaped_lines = layout_highlighted_chunks(
122 chunks,
123 &self.style,
124 cx.text_layout_cache(),
125 &cx.font_cache,
126 usize::MAX,
127 self.text.matches('\n').count() + 1,
128 );
129
130 // If line wrapping is enabled, wrap each of the shaped lines.
131 let font_id = self.style.font_id;
132 let mut line_count = 0;
133 let mut max_line_width = 0_f32;
134 let mut wrap_boundaries = Vec::new();
135 let mut wrapper = cx.font_cache.line_wrapper(font_id, self.style.font_size);
136 for (line, shaped_line) in self.text.split('\n').zip(&shaped_lines) {
137 if self.soft_wrap {
138 let boundaries = wrapper
139 .wrap_shaped_line(line, shaped_line, constraint.max.x())
140 .collect::<Vec<_>>();
141 line_count += boundaries.len() + 1;
142 wrap_boundaries.push(boundaries);
143 } else {
144 line_count += 1;
145 }
146 max_line_width = max_line_width.max(shaped_line.width());
147 }
148
149 let line_height = cx.font_cache.line_height(self.style.font_size);
150 let size = vec2f(
151 max_line_width
152 .ceil()
153 .max(constraint.min.x())
154 .min(constraint.max.x()),
155 (line_height * line_count as f32).ceil(),
156 );
157 (
158 size,
159 LayoutState {
160 shaped_lines,
161 wrap_boundaries,
162 line_height,
163 },
164 )
165 }
166
167 fn paint(
168 &mut self,
169 scene: &mut SceneBuilder,
170 bounds: RectF,
171 visible_bounds: RectF,
172 layout: &mut Self::LayoutState,
173 _: &mut V,
174 cx: &mut ViewContext<V>,
175 ) -> Self::PaintState {
176 let mut origin = bounds.origin();
177 let empty = Vec::new();
178 let mut callback = |_, _, _: &mut SceneBuilder, _: &mut AppContext| {};
179
180 let mouse_runs;
181 let custom_run_callback;
182 if let Some((runs, build_region)) = &mut self.custom_runs {
183 mouse_runs = runs.iter();
184 custom_run_callback = build_region.as_mut();
185 } else {
186 mouse_runs = [].iter();
187 custom_run_callback = &mut callback;
188 }
189 let mut custom_runs = mouse_runs.enumerate().peekable();
190
191 let mut offset = 0;
192 for (ix, line) in layout.shaped_lines.iter().enumerate() {
193 let wrap_boundaries = layout.wrap_boundaries.get(ix).unwrap_or(&empty);
194 let boundaries = RectF::new(
195 origin,
196 vec2f(
197 bounds.width(),
198 (wrap_boundaries.len() + 1) as f32 * layout.line_height,
199 ),
200 );
201
202 if boundaries.intersects(visible_bounds) {
203 if self.soft_wrap {
204 line.paint_wrapped(
205 scene,
206 origin,
207 visible_bounds,
208 layout.line_height,
209 wrap_boundaries,
210 cx,
211 );
212 } else {
213 line.paint(scene, origin, visible_bounds, layout.line_height, cx);
214 }
215 }
216
217 // Paint any custom runs that intersect this line.
218 let end_offset = offset + line.len();
219 if let Some((custom_run_ix, custom_run_range)) = custom_runs.peek().cloned() {
220 if custom_run_range.start < end_offset {
221 let mut current_custom_run = None;
222 if custom_run_range.start <= offset {
223 current_custom_run = Some((custom_run_ix, custom_run_range.end, origin));
224 }
225
226 let mut glyph_origin = origin;
227 let mut prev_position = 0.;
228 let mut wrap_boundaries = wrap_boundaries.iter().copied().peekable();
229 for (run_ix, glyph_ix, glyph) in
230 line.runs().iter().enumerate().flat_map(|(run_ix, run)| {
231 run.glyphs()
232 .iter()
233 .enumerate()
234 .map(move |(ix, glyph)| (run_ix, ix, glyph))
235 })
236 {
237 glyph_origin.set_x(glyph_origin.x() + glyph.position.x() - prev_position);
238 prev_position = glyph.position.x();
239
240 // If we've reached a soft wrap position, move down one line. If there
241 // is a custom run in-progress, paint it.
242 if wrap_boundaries
243 .peek()
244 .map_or(false, |b| b.run_ix == run_ix && b.glyph_ix == glyph_ix)
245 {
246 if let Some((run_ix, _, run_origin)) = &mut current_custom_run {
247 let bounds = RectF::from_points(
248 *run_origin,
249 glyph_origin + vec2f(0., layout.line_height),
250 );
251 custom_run_callback(*run_ix, bounds, scene, cx);
252 *run_origin =
253 vec2f(origin.x(), glyph_origin.y() + layout.line_height);
254 }
255 wrap_boundaries.next();
256 glyph_origin = vec2f(origin.x(), glyph_origin.y() + layout.line_height);
257 }
258
259 // If we've reached the end of the current custom run, paint it.
260 if let Some((run_ix, run_end_offset, run_origin)) = current_custom_run {
261 if offset + glyph.index == run_end_offset {
262 current_custom_run.take();
263 let bounds = RectF::from_points(
264 run_origin,
265 glyph_origin + vec2f(0., layout.line_height),
266 );
267 custom_run_callback(run_ix, bounds, scene, cx);
268 custom_runs.next();
269 }
270
271 if let Some((_, run_range)) = custom_runs.peek() {
272 if run_range.start >= end_offset {
273 break;
274 }
275 if run_range.start == offset + glyph.index {
276 current_custom_run =
277 Some((run_ix, run_range.end, glyph_origin));
278 }
279 }
280 }
281
282 // If we've reached the start of a new custom run, start tracking it.
283 if let Some((run_ix, run_range)) = custom_runs.peek() {
284 if offset + glyph.index == run_range.start {
285 current_custom_run = Some((*run_ix, run_range.end, glyph_origin));
286 }
287 }
288 }
289
290 // If a custom run extends beyond the end of the line, paint it.
291 if let Some((run_ix, run_end_offset, run_origin)) = current_custom_run {
292 let line_end = glyph_origin + vec2f(line.width() - prev_position, 0.);
293 let bounds = RectF::from_points(
294 run_origin,
295 line_end + vec2f(0., layout.line_height),
296 );
297 custom_run_callback(run_ix, bounds, scene, cx);
298 if end_offset == run_end_offset {
299 custom_runs.next();
300 }
301 }
302 }
303 }
304
305 offset = end_offset + 1;
306 origin.set_y(boundaries.max_y());
307 }
308 }
309
310 fn rect_for_text_range(
311 &self,
312 _: Range<usize>,
313 _: RectF,
314 _: RectF,
315 _: &Self::LayoutState,
316 _: &Self::PaintState,
317 _: &V,
318 _: &ViewContext<V>,
319 ) -> Option<RectF> {
320 None
321 }
322
323 fn debug(
324 &self,
325 bounds: RectF,
326 _: &Self::LayoutState,
327 _: &Self::PaintState,
328 _: &V,
329 _: &ViewContext<V>,
330 ) -> Value {
331 json!({
332 "type": "Text",
333 "bounds": bounds.to_json(),
334 "text": &self.text,
335 "style": self.style.to_json(),
336 })
337 }
338}
339
340/// Perform text layout on a series of highlighted chunks of text.
341fn layout_highlighted_chunks<'a>(
342 chunks: impl Iterator<Item = (&'a str, Option<HighlightStyle>)>,
343 text_style: &TextStyle,
344 text_layout_cache: &TextLayoutCache,
345 font_cache: &Arc<FontCache>,
346 max_line_len: usize,
347 max_line_count: usize,
348) -> Vec<Line> {
349 let mut layouts = Vec::with_capacity(max_line_count);
350 let mut line = String::new();
351 let mut styles = Vec::new();
352 let mut row = 0;
353 let mut line_exceeded_max_len = false;
354 for (chunk, highlight_style) in chunks.chain([("\n", Default::default())]) {
355 for (ix, mut line_chunk) in chunk.split('\n').enumerate() {
356 if ix > 0 {
357 layouts.push(text_layout_cache.layout_str(&line, text_style.font_size, &styles));
358 line.clear();
359 styles.clear();
360 row += 1;
361 line_exceeded_max_len = false;
362 if row == max_line_count {
363 return layouts;
364 }
365 }
366
367 if !line_chunk.is_empty() && !line_exceeded_max_len {
368 let text_style = if let Some(style) = highlight_style {
369 text_style
370 .clone()
371 .highlight(style, font_cache)
372 .map(Cow::Owned)
373 .unwrap_or_else(|_| Cow::Borrowed(text_style))
374 } else {
375 Cow::Borrowed(text_style)
376 };
377
378 if line.len() + line_chunk.len() > max_line_len {
379 let mut chunk_len = max_line_len - line.len();
380 while !line_chunk.is_char_boundary(chunk_len) {
381 chunk_len -= 1;
382 }
383 line_chunk = &line_chunk[..chunk_len];
384 line_exceeded_max_len = true;
385 }
386
387 line.push_str(line_chunk);
388 styles.push((
389 line_chunk.len(),
390 RunStyle {
391 font_id: text_style.font_id,
392 color: text_style.color,
393 underline: text_style.underline,
394 },
395 ));
396 }
397 }
398 }
399
400 layouts
401}
402
403#[cfg(test)]
404mod tests {
405 use super::*;
406 use crate::{elements::Empty, fonts, AnyElement, AppContext, Entity, View, ViewContext};
407
408 #[crate::test(self)]
409 fn test_soft_wrapping_with_carriage_returns(cx: &mut AppContext) {
410 cx.add_window(Default::default(), |cx| {
411 let mut view = TestView;
412 fonts::with_font_cache(cx.font_cache().clone(), || {
413 let mut text = Text::new("Hello\r\n", Default::default()).with_soft_wrap(true);
414 let mut new_parents = Default::default();
415 let mut notify_views_if_parents_change = Default::default();
416 let mut layout_cx = LayoutContext::new(
417 cx,
418 &mut new_parents,
419 &mut notify_views_if_parents_change,
420 false,
421 );
422 let (_, state) = text.layout(
423 SizeConstraint::new(Default::default(), vec2f(f32::INFINITY, f32::INFINITY)),
424 &mut view,
425 &mut layout_cx,
426 );
427 assert_eq!(state.shaped_lines.len(), 2);
428 assert_eq!(state.wrap_boundaries.len(), 2);
429 });
430 view
431 });
432 }
433
434 struct TestView;
435
436 impl Entity for TestView {
437 type Event = ();
438 }
439
440 impl View for TestView {
441 fn ui_name() -> &'static str {
442 "TestView"
443 }
444
445 fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
446 Empty::new().into_any()
447 }
448 }
449}