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