1use crate::{
2 color::Color,
3 fonts::{HighlightStyle, TextStyle},
4 geometry::{
5 rect::RectF,
6 vector::{vec2f, Vector2F},
7 },
8 json::{ToJson, Value},
9 presenter::MeasurementContext,
10 text_layout::{Line, RunStyle, ShapedBoundary},
11 DebugContext, Element, FontCache, LayoutContext, PaintContext, SizeConstraint, TextLayoutCache,
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: Vec<(Range<usize>, HighlightStyle)>,
22}
23
24pub struct LayoutState {
25 shaped_lines: Vec<Line>,
26 wrap_boundaries: Vec<Vec<ShapedBoundary>>,
27 line_height: f32,
28}
29
30impl Text {
31 pub fn new<I: Into<Cow<'static, str>>>(text: I, style: TextStyle) -> Self {
32 Self {
33 text: text.into(),
34 style,
35 soft_wrap: true,
36 highlights: Vec::new(),
37 }
38 }
39
40 pub fn with_default_color(mut self, color: Color) -> Self {
41 self.style.color = color;
42 self
43 }
44
45 pub fn with_highlights(mut self, runs: Vec<(Range<usize>, HighlightStyle)>) -> Self {
46 self.highlights = runs;
47 self
48 }
49
50 pub fn with_soft_wrap(mut self, soft_wrap: bool) -> Self {
51 self.soft_wrap = soft_wrap;
52 self
53 }
54}
55
56impl Element for Text {
57 type LayoutState = LayoutState;
58 type PaintState = ();
59
60 fn layout(
61 &mut self,
62 constraint: SizeConstraint,
63 cx: &mut LayoutContext,
64 ) -> (Vector2F, Self::LayoutState) {
65 // Convert the string and highlight ranges into an iterator of highlighted chunks.
66
67 let mut offset = 0;
68 let mut highlight_ranges = self.highlights.iter().peekable();
69 let chunks = std::iter::from_fn(|| {
70 let result;
71 if let Some((range, highlight_style)) = highlight_ranges.peek() {
72 if offset < range.start {
73 result = Some((&self.text[offset..range.start], None));
74 offset = range.start;
75 } else if range.end <= self.text.len() {
76 result = Some((&self.text[range.clone()], Some(*highlight_style)));
77 highlight_ranges.next();
78 offset = range.end;
79 } else {
80 warn!(
81 "Highlight out of text range. Text len: {}, Highlight range: {}..{}",
82 self.text.len(),
83 range.start,
84 range.end
85 );
86 result = None;
87 }
88 } else if offset < self.text.len() {
89 result = Some((&self.text[offset..], None));
90 offset = self.text.len();
91 } else {
92 result = None;
93 }
94 result
95 });
96
97 // Perform shaping on these highlighted chunks
98 let shaped_lines = layout_highlighted_chunks(
99 chunks,
100 &self.style,
101 cx.text_layout_cache,
102 cx.font_cache,
103 usize::MAX,
104 self.text.matches('\n').count() + 1,
105 );
106
107 // If line wrapping is enabled, wrap each of the shaped lines.
108 let font_id = self.style.font_id;
109 let mut line_count = 0;
110 let mut max_line_width = 0_f32;
111 let mut wrap_boundaries = Vec::new();
112 let mut wrapper = cx.font_cache.line_wrapper(font_id, self.style.font_size);
113 for (line, shaped_line) in self.text.split('\n').zip(&shaped_lines) {
114 if self.soft_wrap {
115 let boundaries = wrapper
116 .wrap_shaped_line(line, shaped_line, constraint.max.x())
117 .collect::<Vec<_>>();
118 line_count += boundaries.len() + 1;
119 wrap_boundaries.push(boundaries);
120 } else {
121 line_count += 1;
122 }
123 max_line_width = max_line_width.max(shaped_line.width());
124 }
125
126 let line_height = cx.font_cache.line_height(self.style.font_size);
127 let size = vec2f(
128 max_line_width
129 .ceil()
130 .max(constraint.min.x())
131 .min(constraint.max.x()),
132 (line_height * line_count as f32).ceil(),
133 );
134 (
135 size,
136 LayoutState {
137 shaped_lines,
138 wrap_boundaries,
139 line_height,
140 },
141 )
142 }
143
144 fn paint(
145 &mut self,
146 bounds: RectF,
147 visible_bounds: RectF,
148 layout: &mut Self::LayoutState,
149 cx: &mut PaintContext,
150 ) -> Self::PaintState {
151 let mut origin = bounds.origin();
152 let empty = Vec::new();
153 for (ix, line) in layout.shaped_lines.iter().enumerate() {
154 let wrap_boundaries = layout.wrap_boundaries.get(ix).unwrap_or(&empty);
155 let boundaries = RectF::new(
156 origin,
157 vec2f(
158 bounds.width(),
159 (wrap_boundaries.len() + 1) as f32 * layout.line_height,
160 ),
161 );
162
163 if boundaries.intersects(visible_bounds) {
164 if self.soft_wrap {
165 line.paint_wrapped(
166 origin,
167 visible_bounds,
168 layout.line_height,
169 wrap_boundaries.iter().copied(),
170 cx,
171 );
172 } else {
173 line.paint(origin, visible_bounds, layout.line_height, cx);
174 }
175 }
176 origin.set_y(boundaries.max_y());
177 }
178 }
179
180 fn rect_for_text_range(
181 &self,
182 _: Range<usize>,
183 _: RectF,
184 _: RectF,
185 _: &Self::LayoutState,
186 _: &Self::PaintState,
187 _: &MeasurementContext,
188 ) -> Option<RectF> {
189 None
190 }
191
192 fn debug(
193 &self,
194 bounds: RectF,
195 _: &Self::LayoutState,
196 _: &Self::PaintState,
197 _: &DebugContext,
198 ) -> Value {
199 json!({
200 "type": "Text",
201 "bounds": bounds.to_json(),
202 "text": &self.text,
203 "style": self.style.to_json(),
204 })
205 }
206}
207
208/// Perform text layout on a series of highlighted chunks of text.
209pub fn layout_highlighted_chunks<'a>(
210 chunks: impl Iterator<Item = (&'a str, Option<HighlightStyle>)>,
211 text_style: &'a TextStyle,
212 text_layout_cache: &'a TextLayoutCache,
213 font_cache: &'a Arc<FontCache>,
214 max_line_len: usize,
215 max_line_count: usize,
216) -> Vec<Line> {
217 let mut layouts = Vec::with_capacity(max_line_count);
218 let mut line = String::new();
219 let mut styles = Vec::new();
220 let mut row = 0;
221 let mut line_exceeded_max_len = false;
222 for (chunk, highlight_style) in chunks.chain([("\n", Default::default())]) {
223 for (ix, mut line_chunk) in chunk.split('\n').enumerate() {
224 if ix > 0 {
225 layouts.push(text_layout_cache.layout_str(&line, text_style.font_size, &styles));
226 line.clear();
227 styles.clear();
228 row += 1;
229 line_exceeded_max_len = false;
230 if row == max_line_count {
231 return layouts;
232 }
233 }
234
235 if !line_chunk.is_empty() && !line_exceeded_max_len {
236 let text_style = if let Some(style) = highlight_style {
237 text_style
238 .clone()
239 .highlight(style, font_cache)
240 .map(Cow::Owned)
241 .unwrap_or_else(|_| Cow::Borrowed(text_style))
242 } else {
243 Cow::Borrowed(text_style)
244 };
245
246 if line.len() + line_chunk.len() > max_line_len {
247 let mut chunk_len = max_line_len - line.len();
248 while !line_chunk.is_char_boundary(chunk_len) {
249 chunk_len -= 1;
250 }
251 line_chunk = &line_chunk[..chunk_len];
252 line_exceeded_max_len = true;
253 }
254
255 line.push_str(line_chunk);
256 styles.push((
257 line_chunk.len(),
258 RunStyle {
259 font_id: text_style.font_id,
260 color: text_style.color,
261 underline: text_style.underline,
262 },
263 ));
264 }
265 }
266 }
267
268 layouts
269}
270
271#[cfg(test)]
272mod tests {
273 use super::*;
274 use crate::{
275 elements::Empty, fonts, ElementBox, Entity, MutableAppContext, RenderContext, View,
276 };
277
278 #[crate::test(self)]
279 fn test_soft_wrapping_with_carriage_returns(cx: &mut MutableAppContext) {
280 let (window_id, _) = cx.add_window(Default::default(), |_| TestView);
281 let mut presenter = cx.build_presenter(window_id, Default::default(), Default::default());
282 fonts::with_font_cache(cx.font_cache().clone(), || {
283 let mut text = Text::new("Hello\r\n", Default::default()).with_soft_wrap(true);
284 let (_, state) = text.layout(
285 SizeConstraint::new(Default::default(), vec2f(f32::INFINITY, f32::INFINITY)),
286 &mut presenter.build_layout_context(Default::default(), false, cx),
287 );
288 assert_eq!(state.shaped_lines.len(), 2);
289 assert_eq!(state.wrap_boundaries.len(), 2);
290 });
291 }
292
293 struct TestView;
294
295 impl Entity for TestView {
296 type Event = ();
297 }
298
299 impl View for TestView {
300 fn ui_name() -> &'static str {
301 "TestView"
302 }
303
304 fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
305 Empty::new().boxed()
306 }
307 }
308}