1use std::{borrow::Cow, ops::Range};
2
3use crate::{
4 fonts::TextStyle,
5 geometry::{
6 rect::RectF,
7 vector::{vec2f, Vector2F},
8 },
9 json::{ToJson, Value},
10 text_layout::{Line, RunStyle},
11 Element, LayoutContext, SceneBuilder, SizeConstraint, View, ViewContext,
12};
13use serde::Deserialize;
14use serde_json::json;
15use smallvec::{smallvec, SmallVec};
16
17pub struct Label {
18 text: Cow<'static, str>,
19 style: LabelStyle,
20 highlight_indices: Vec<usize>,
21}
22
23#[derive(Clone, Debug, Deserialize, Default)]
24pub struct LabelStyle {
25 pub text: TextStyle,
26 pub highlight_text: Option<TextStyle>,
27}
28
29impl From<TextStyle> for LabelStyle {
30 fn from(text: TextStyle) -> Self {
31 LabelStyle {
32 text,
33 highlight_text: None,
34 }
35 }
36}
37
38impl LabelStyle {
39 pub fn with_font_size(mut self, font_size: f32) -> Self {
40 self.text.font_size = font_size;
41 self
42 }
43}
44
45impl Label {
46 pub fn new<I: Into<Cow<'static, str>>>(text: I, style: impl Into<LabelStyle>) -> Self {
47 Self {
48 text: text.into(),
49 highlight_indices: Default::default(),
50 style: style.into(),
51 }
52 }
53
54 pub fn with_highlights(mut self, indices: Vec<usize>) -> Self {
55 self.highlight_indices = indices;
56 self
57 }
58
59 fn compute_runs(&self) -> SmallVec<[(usize, RunStyle); 8]> {
60 let font_id = self.style.text.font_id;
61 if self.highlight_indices.is_empty() {
62 return smallvec![(
63 self.text.len(),
64 RunStyle {
65 font_id,
66 color: self.style.text.color,
67 underline: self.style.text.underline,
68 }
69 )];
70 }
71
72 let highlight_font_id = self
73 .style
74 .highlight_text
75 .as_ref()
76 .map_or(font_id, |style| style.font_id);
77
78 let mut highlight_indices = self.highlight_indices.iter().copied().peekable();
79 let mut runs = SmallVec::new();
80 let highlight_style = self
81 .style
82 .highlight_text
83 .as_ref()
84 .unwrap_or(&self.style.text);
85
86 for (char_ix, c) in self.text.char_indices() {
87 let mut font_id = font_id;
88 let mut color = self.style.text.color;
89 let mut underline = self.style.text.underline;
90 if let Some(highlight_ix) = highlight_indices.peek() {
91 if char_ix == *highlight_ix {
92 font_id = highlight_font_id;
93 color = highlight_style.color;
94 underline = highlight_style.underline;
95 highlight_indices.next();
96 }
97 }
98
99 let last_run: Option<&mut (usize, RunStyle)> = runs.last_mut();
100 let push_new_run = if let Some((last_len, last_style)) = last_run {
101 if font_id == last_style.font_id
102 && color == last_style.color
103 && underline == last_style.underline
104 {
105 *last_len += c.len_utf8();
106 false
107 } else {
108 true
109 }
110 } else {
111 true
112 };
113
114 if push_new_run {
115 runs.push((
116 c.len_utf8(),
117 RunStyle {
118 font_id,
119 color,
120 underline,
121 },
122 ));
123 }
124 }
125
126 runs
127 }
128}
129
130impl<V: View> Element<V> for Label {
131 type LayoutState = Line;
132 type PaintState = ();
133
134 fn layout(
135 &mut self,
136 constraint: SizeConstraint,
137 _: &mut V,
138 cx: &mut LayoutContext<V>,
139 ) -> (Vector2F, Self::LayoutState) {
140 let runs = self.compute_runs();
141 let line = cx.text_layout_cache().layout_str(
142 &self.text,
143 self.style.text.font_size,
144 runs.as_slice(),
145 );
146
147 let size = vec2f(
148 line.width()
149 .ceil()
150 .max(constraint.min.x())
151 .min(constraint.max.x()),
152 cx.font_cache.line_height(self.style.text.font_size),
153 );
154
155 (size, line)
156 }
157
158 fn paint(
159 &mut self,
160 scene: &mut SceneBuilder,
161 bounds: RectF,
162 visible_bounds: RectF,
163 line: &mut Self::LayoutState,
164 _: &mut V,
165 cx: &mut ViewContext<V>,
166 ) -> Self::PaintState {
167 let visible_bounds = bounds.intersection(visible_bounds).unwrap_or_default();
168 line.paint(
169 scene,
170 bounds.origin(),
171 visible_bounds,
172 bounds.size().y(),
173 cx,
174 )
175 }
176
177 fn rect_for_text_range(
178 &self,
179 _: Range<usize>,
180 _: RectF,
181 _: RectF,
182 _: &Self::LayoutState,
183 _: &Self::PaintState,
184 _: &V,
185 _: &ViewContext<V>,
186 ) -> Option<RectF> {
187 None
188 }
189
190 fn debug(
191 &self,
192 bounds: RectF,
193 _: &Self::LayoutState,
194 _: &Self::PaintState,
195 _: &V,
196 _: &ViewContext<V>,
197 ) -> Value {
198 json!({
199 "type": "Label",
200 "bounds": bounds.to_json(),
201 "text": &self.text,
202 "highlight_indices": self.highlight_indices,
203 "style": self.style.to_json(),
204 })
205 }
206}
207
208impl ToJson for LabelStyle {
209 fn to_json(&self) -> Value {
210 json!({
211 "text": self.text.to_json(),
212 "highlight_text": self.highlight_text
213 .as_ref()
214 .map_or(serde_json::Value::Null, |style| style.to_json())
215 })
216 }
217}
218
219#[cfg(test)]
220mod tests {
221 use super::*;
222 use crate::color::Color;
223 use crate::fonts::{Properties as FontProperties, Weight};
224
225 #[crate::test(self)]
226 fn test_layout_label_with_highlights(cx: &mut crate::AppContext) {
227 let default_style = TextStyle::new(
228 "Menlo",
229 12.,
230 Default::default(),
231 Default::default(),
232 Default::default(),
233 Color::black(),
234 cx.font_cache(),
235 )
236 .unwrap();
237 let highlight_style = TextStyle::new(
238 "Menlo",
239 12.,
240 *FontProperties::new().weight(Weight::BOLD),
241 Default::default(),
242 Default::default(),
243 Color::new(255, 0, 0, 255),
244 cx.font_cache(),
245 )
246 .unwrap();
247 let label = Label::new(
248 ".αβγδε.ⓐⓑⓒⓓⓔ.abcde.".to_string(),
249 LabelStyle {
250 text: default_style.clone(),
251 highlight_text: Some(highlight_style.clone()),
252 },
253 )
254 .with_highlights(vec![
255 ".α".len(),
256 ".αβ".len(),
257 ".αβγδ".len(),
258 ".αβγδε.ⓐ".len(),
259 ".αβγδε.ⓐⓑ".len(),
260 ]);
261
262 let default_run_style = RunStyle {
263 font_id: default_style.font_id,
264 color: default_style.color,
265 underline: default_style.underline,
266 };
267 let highlight_run_style = RunStyle {
268 font_id: highlight_style.font_id,
269 color: highlight_style.color,
270 underline: highlight_style.underline,
271 };
272 let runs = label.compute_runs();
273 assert_eq!(
274 runs.as_slice(),
275 &[
276 (".α".len(), default_run_style),
277 ("βγ".len(), highlight_run_style),
278 ("δ".len(), default_run_style),
279 ("ε".len(), highlight_run_style),
280 (".ⓐ".len(), default_run_style),
281 ("ⓑⓒ".len(), highlight_run_style),
282 ("ⓓⓔ.abcde.".len(), default_run_style),
283 ]
284 );
285 }
286}