1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
//! `CollapsingHeader` — a clickable header that shows/hides child content.
//!
//! # Composition
//!
//! ```text
//! CollapsingHeader
//! ├── Label (header text, drawn manually)
//! └── child widget (shown when expanded, hidden when collapsed)
//! ```
//!
//! The triangle indicator is drawn as a path. Clicking anywhere on the header
//! row toggles the collapsed/expanded state.
use std::sync::Arc;
use crate::color::Color;
use crate::draw_ctx::DrawCtx;
use crate::event::{Event, EventResult, MouseButton};
use crate::geometry::{Point, Rect, Size};
use crate::text::Font;
use crate::widget::{paint_subtree, Widget};
use crate::widgets::label::Label;
const HEADER_H: f64 = 22.0;
const TRIANGLE_SIZE: f64 = 6.0;
const INDENT: f64 = 12.0;
/// A collapsible section header. When expanded, the child widget is visible
/// below the header row. When collapsed, only the header row is shown.
pub struct CollapsingHeader {
bounds: Rect,
children: Vec<Box<dyn Widget>>,
label: Label,
open: bool,
hovered: bool,
/// The content shown when expanded.
content: Option<Box<dyn Widget>>,
}
impl CollapsingHeader {
/// Create a new header with the given text, using the provided font.
/// Starts expanded by default.
pub fn new(text: impl Into<String>, font: Arc<Font>) -> Self {
let label = Label::new(text, Arc::clone(&font)).with_font_size(13.0);
Self {
bounds: Rect::default(),
children: Vec::new(),
label,
open: true,
hovered: false,
content: None,
}
}
/// Set whether the section is open (expanded) by default.
pub fn default_open(mut self, open: bool) -> Self {
self.open = open;
self
}
/// Set the child content widget shown when expanded.
pub fn with_content(mut self, content: Box<dyn Widget>) -> Self {
self.content = Some(content);
self
}
}
impl Widget for CollapsingHeader {
fn type_name(&self) -> &'static str {
"CollapsingHeader"
}
fn bounds(&self) -> Rect {
self.bounds
}
fn set_bounds(&mut self, b: Rect) {
self.bounds = b;
}
fn children(&self) -> &[Box<dyn Widget>] {
&self.children
}
fn children_mut(&mut self) -> &mut Vec<Box<dyn Widget>> {
&mut self.children
}
fn layout(&mut self, available: Size) -> Size {
let w = available.width;
// Sync `children` with `open` state so the framework dispatches events
// to the content only when it is visible. When closed the content
// lives in `self.content`; when open it lives in `self.children[0]`.
if self.open && self.children.is_empty() {
if let Some(c) = self.content.take() {
self.children.push(c);
}
} else if !self.open && !self.children.is_empty() {
if let Some(c) = self.children.pop() {
self.content = Some(c);
}
}
// Layout label inside the header row.
let label_available = Size::new(w - INDENT - TRIANGLE_SIZE * 2.0, HEADER_H);
let ls = self.label.layout(label_available);
let ly = (HEADER_H - ls.height) * 0.5;
self.label.set_bounds(Rect::new(
INDENT + TRIANGLE_SIZE * 2.0 + 4.0,
ly,
ls.width,
ls.height,
));
// Layout content if open — as a child so the framework paints and
// dispatches events normally. Content is inset from the left by
// INDENT * 0.5 for visual hierarchy.
let content_h = if self.open && !self.children.is_empty() {
let inset = INDENT * 0.5;
let avail_w = (w - inset).max(0.0);
let child = &mut self.children[0];
let cs = child.layout(Size::new(avail_w, available.height - HEADER_H));
// Content sits at the bottom of our bounds (Y-up: y = 0).
child.set_bounds(Rect::new(inset, 0.0, cs.width, cs.height));
cs.height
} else {
0.0
};
let total_h = HEADER_H + content_h;
self.bounds = Rect::new(0.0, 0.0, w, total_h);
Size::new(w, total_h)
}
fn paint(&mut self, ctx: &mut dyn DrawCtx) {
let v = ctx.visuals();
let w = self.bounds.width;
let h = self.bounds.height;
// Header row background — always shown at a subtle tint so the header
// reads as a distinct section boundary even when not hovered. Hover
// deepens the tint slightly as click affordance. Sits just below the
// top divider line so the line remains crisp.
let alpha = if self.hovered { 0.10 } else { 0.06 };
ctx.set_fill_color(Color::rgba(
v.text_color.r,
v.text_color.g,
v.text_color.b,
alpha,
));
ctx.begin_path();
ctx.rect(0.0, h - HEADER_H, w, HEADER_H - 1.0);
ctx.fill();
// Top divider line — 1px, full-width, in the shared separator colour
// so a vertical stack of headers forms consistent section boundaries
// matching any `Separator` widgets elsewhere in the UI.
ctx.set_fill_color(v.separator);
ctx.begin_path();
ctx.rect(0.0, h - 1.0, w, 1.0);
ctx.fill();
// Triangle indicator (▶ collapsed, ▼ expanded).
// In Y-up: the header row occupies y = h - HEADER_H .. h.
let center_y = h - HEADER_H * 0.5;
let tx = INDENT;
let ts = TRIANGLE_SIZE * 0.5;
ctx.set_fill_color(v.text_dim);
ctx.begin_path();
if self.open {
// Pointing down (▼): triangle with point at bottom.
ctx.move_to(tx, center_y + ts * 0.5);
ctx.line_to(tx + ts * 2.0, center_y + ts * 0.5);
ctx.line_to(tx + ts, center_y - ts * 0.8);
} else {
// Pointing right (▶): triangle with point to the right.
ctx.move_to(tx, center_y + ts);
ctx.line_to(tx, center_y - ts);
ctx.line_to(tx + ts * 1.6, center_y);
}
ctx.fill();
// Label.
self.label.set_color(v.text_color);
let lb = self.label.bounds();
// Label y is in header-local coords, but header is at top of our bounds (in Y-up).
let label_offset_y = h - HEADER_H + lb.y;
ctx.save();
ctx.translate(lb.x, label_offset_y);
paint_subtree(&mut self.label, ctx);
ctx.restore();
// Content is painted by the framework via normal child recursion —
// it lives in `self.children[0]` (when open) and has its own bounds
// so `dispatch_event` reaches it without manual forwarding.
}
fn on_event(&mut self, event: &Event) -> EventResult {
let h = self.bounds.height;
match event {
Event::MouseMove { pos } => {
// Header row: top portion in Y-up = y from (h - HEADER_H) to h.
let in_header = pos.x >= 0.0
&& pos.x <= self.bounds.width
&& pos.y >= h - HEADER_H
&& pos.y <= h;
let was = self.hovered;
self.hovered = in_header;
if self.hovered != was {
crate::animation::request_draw();
return EventResult::Consumed;
}
EventResult::Ignored
}
Event::MouseDown {
button: MouseButton::Left,
pos,
..
} => {
let in_header = pos.x >= 0.0
&& pos.x <= self.bounds.width
&& pos.y >= h - HEADER_H
&& pos.y <= h;
if in_header {
self.open = !self.open;
crate::animation::request_draw();
return EventResult::Consumed;
}
EventResult::Ignored
}
_ => EventResult::Ignored,
}
}
fn hit_test(&self, local_pos: Point) -> bool {
local_pos.x >= 0.0
&& local_pos.x <= self.bounds.width
&& local_pos.y >= 0.0
&& local_pos.y <= self.bounds.height
}
}