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 Element, FontCache, LayoutContext, PaintContext, SizeConstraint, TextLayoutCache, ViewContext,
11 WindowContext,
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 WindowContext)>,
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 WindowContext),
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: 'static> 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 bounds: RectF,
170 visible_bounds: RectF,
171 layout: &mut Self::LayoutState,
172 _: &mut V,
173 cx: &mut PaintContext<V>,
174 ) -> Self::PaintState {
175 let mut origin = bounds.origin();
176 let empty = Vec::new();
177 let mut callback = |_, _, _: &mut WindowContext| {};
178
179 let mouse_runs;
180 let custom_run_callback;
181 if let Some((runs, build_region)) = &mut self.custom_runs {
182 mouse_runs = runs.iter();
183 custom_run_callback = build_region.as_mut();
184 } else {
185 mouse_runs = [].iter();
186 custom_run_callback = &mut callback;
187 }
188 let mut custom_runs = mouse_runs.enumerate().peekable();
189
190 let mut offset = 0;
191 for (ix, line) in layout.shaped_lines.iter().enumerate() {
192 let wrap_boundaries = layout.wrap_boundaries.get(ix).unwrap_or(&empty);
193 let boundaries = RectF::new(
194 origin,
195 vec2f(
196 bounds.width(),
197 (wrap_boundaries.len() + 1) as f32 * layout.line_height,
198 ),
199 );
200
201 if boundaries.intersects(visible_bounds) {
202 if self.soft_wrap {
203 line.paint_wrapped(
204 origin,
205 visible_bounds,
206 layout.line_height,
207 wrap_boundaries,
208 cx,
209 );
210 } else {
211 line.paint(origin, visible_bounds, layout.line_height, cx);
212 }
213 }
214
215 // Paint any custom runs that intersect this line.
216 let end_offset = offset + line.len();
217 if let Some((custom_run_ix, custom_run_range)) = custom_runs.peek().cloned() {
218 if custom_run_range.start < end_offset {
219 let mut current_custom_run = None;
220 if custom_run_range.start <= offset {
221 current_custom_run = Some((custom_run_ix, custom_run_range.end, origin));
222 }
223
224 let mut glyph_origin = origin;
225 let mut prev_position = 0.;
226 let mut wrap_boundaries = wrap_boundaries.iter().copied().peekable();
227 for (run_ix, glyph_ix, glyph) in
228 line.runs().iter().enumerate().flat_map(|(run_ix, run)| {
229 run.glyphs()
230 .iter()
231 .enumerate()
232 .map(move |(ix, glyph)| (run_ix, ix, glyph))
233 })
234 {
235 glyph_origin.set_x(glyph_origin.x() + glyph.position.x() - prev_position);
236 prev_position = glyph.position.x();
237
238 // If we've reached a soft wrap position, move down one line. If there
239 // is a custom run in-progress, paint it.
240 if wrap_boundaries
241 .peek()
242 .map_or(false, |b| b.run_ix == run_ix && b.glyph_ix == glyph_ix)
243 {
244 if let Some((run_ix, _, run_origin)) = &mut current_custom_run {
245 let bounds = RectF::from_points(
246 *run_origin,
247 glyph_origin + vec2f(0., layout.line_height),
248 );
249 custom_run_callback(*run_ix, bounds, cx);
250 *run_origin =
251 vec2f(origin.x(), glyph_origin.y() + layout.line_height);
252 }
253 wrap_boundaries.next();
254 glyph_origin = vec2f(origin.x(), glyph_origin.y() + layout.line_height);
255 }
256
257 // If we've reached the end of the current custom run, paint it.
258 if let Some((run_ix, run_end_offset, run_origin)) = current_custom_run {
259 if offset + glyph.index == run_end_offset {
260 current_custom_run.take();
261 let bounds = RectF::from_points(
262 run_origin,
263 glyph_origin + vec2f(0., layout.line_height),
264 );
265 custom_run_callback(run_ix, bounds, cx);
266 custom_runs.next();
267 }
268
269 if let Some((_, run_range)) = custom_runs.peek() {
270 if run_range.start >= end_offset {
271 break;
272 }
273 if run_range.start == offset + glyph.index {
274 current_custom_run =
275 Some((run_ix, run_range.end, glyph_origin));
276 }
277 }
278 }
279
280 // If we've reached the start of a new custom run, start tracking it.
281 if let Some((run_ix, run_range)) = custom_runs.peek() {
282 if offset + glyph.index == run_range.start {
283 current_custom_run = Some((*run_ix, run_range.end, glyph_origin));
284 }
285 }
286 }
287
288 // If a custom run extends beyond the end of the line, paint it.
289 if let Some((run_ix, run_end_offset, run_origin)) = current_custom_run {
290 let line_end = glyph_origin + vec2f(line.width() - prev_position, 0.);
291 let bounds = RectF::from_points(
292 run_origin,
293 line_end + vec2f(0., layout.line_height),
294 );
295 custom_run_callback(run_ix, bounds, cx);
296 if end_offset == run_end_offset {
297 custom_runs.next();
298 }
299 }
300 }
301 }
302
303 offset = end_offset + 1;
304 origin.set_y(boundaries.max_y());
305 }
306 }
307
308 fn rect_for_text_range(
309 &self,
310 _: Range<usize>,
311 _: RectF,
312 _: RectF,
313 _: &Self::LayoutState,
314 _: &Self::PaintState,
315 _: &V,
316 _: &ViewContext<V>,
317 ) -> Option<RectF> {
318 None
319 }
320
321 fn debug(
322 &self,
323 bounds: RectF,
324 _: &Self::LayoutState,
325 _: &Self::PaintState,
326 _: &V,
327 _: &ViewContext<V>,
328 ) -> Value {
329 json!({
330 "type": "Text",
331 "bounds": bounds.to_json(),
332 "text": &self.text,
333 "style": self.style.to_json(),
334 })
335 }
336}
337
338/// Perform text layout on a series of highlighted chunks of text.
339pub fn layout_highlighted_chunks<'a>(
340 chunks: impl Iterator<Item = (&'a str, Option<HighlightStyle>)>,
341 text_style: &TextStyle,
342 text_layout_cache: &TextLayoutCache,
343 font_cache: &Arc<FontCache>,
344 max_line_len: usize,
345 max_line_count: usize,
346) -> Vec<Line> {
347 let mut layouts = Vec::with_capacity(max_line_count);
348 let mut line = String::new();
349 let mut styles = Vec::new();
350 let mut row = 0;
351 let mut line_exceeded_max_len = false;
352 for (chunk, highlight_style) in chunks.chain([("\n", Default::default())]) {
353 for (ix, mut line_chunk) in chunk.split('\n').enumerate() {
354 if ix > 0 {
355 layouts.push(text_layout_cache.layout_str(&line, text_style.font_size, &styles));
356 line.clear();
357 styles.clear();
358 row += 1;
359 line_exceeded_max_len = false;
360 if row == max_line_count {
361 return layouts;
362 }
363 }
364
365 if !line_chunk.is_empty() && !line_exceeded_max_len {
366 let text_style = if let Some(style) = highlight_style {
367 text_style
368 .clone()
369 .highlight(style, font_cache)
370 .map(Cow::Owned)
371 .unwrap_or_else(|_| Cow::Borrowed(text_style))
372 } else {
373 Cow::Borrowed(text_style)
374 };
375
376 if line.len() + line_chunk.len() > max_line_len {
377 let mut chunk_len = max_line_len - line.len();
378 while !line_chunk.is_char_boundary(chunk_len) {
379 chunk_len -= 1;
380 }
381 line_chunk = &line_chunk[..chunk_len];
382 line_exceeded_max_len = true;
383 }
384
385 line.push_str(line_chunk);
386 styles.push((
387 line_chunk.len(),
388 RunStyle {
389 font_id: text_style.font_id,
390 color: text_style.color,
391 underline: text_style.underline,
392 },
393 ));
394 }
395 }
396 }
397
398 layouts
399}
400
401#[cfg(test)]
402mod tests {
403 use super::*;
404 use crate::{elements::Empty, fonts, AnyElement, AppContext, Entity, View, ViewContext};
405
406 #[crate::test(self)]
407 fn test_soft_wrapping_with_carriage_returns(cx: &mut AppContext) {
408 cx.add_window(Default::default(), |cx| {
409 let mut view = TestView;
410 fonts::with_font_cache(cx.font_cache().clone(), || {
411 let mut text = Text::new("Hello\r\n", Default::default()).with_soft_wrap(true);
412 let mut layout_cx = LayoutContext::new(cx);
413 let (_, state) = text.layout(
414 SizeConstraint::new(Default::default(), vec2f(f32::INFINITY, f32::INFINITY)),
415 &mut view,
416 &mut layout_cx,
417 );
418 assert_eq!(state.shaped_lines.len(), 2);
419 assert_eq!(state.wrap_boundaries.len(), 2);
420 });
421 view
422 });
423 }
424
425 struct TestView;
426
427 impl Entity for TestView {
428 type Event = ();
429 }
430
431 impl View for TestView {
432 fn ui_name() -> &'static str {
433 "TestView"
434 }
435
436 fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
437 Empty::new().into_any()
438 }
439 }
440}