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
use crate::kurbo::{Point, Rect, Size};
use crate::{
BoxConstraints, Data, Env, Event, EventCtx, LayoutCtx, LifeCycle, LifeCycleCtx, PaintCtx,
UpdateCtx, Widget, WidgetPod,
};
pub struct Either<T> {
closure: Box<dyn Fn(&T, &Env) -> bool>,
true_branch: WidgetPod<T, Box<dyn Widget<T>>>,
false_branch: WidgetPod<T, Box<dyn Widget<T>>>,
current: bool,
}
impl<T> Either<T> {
pub fn new(
closure: impl Fn(&T, &Env) -> bool + 'static,
true_branch: impl Widget<T> + 'static,
false_branch: impl Widget<T> + 'static,
) -> Either<T> {
Either {
closure: Box::new(closure),
true_branch: WidgetPod::new(true_branch).boxed(),
false_branch: WidgetPod::new(false_branch).boxed(),
current: false,
}
}
}
impl<T: Data> Widget<T> for Either<T> {
fn event(&mut self, ctx: &mut EventCtx, event: &Event, data: &mut T, env: &Env) {
if self.current {
self.true_branch.event(ctx, event, data, env)
} else {
self.false_branch.event(ctx, event, data, env)
}
}
fn lifecycle(&mut self, ctx: &mut LifeCycleCtx, event: &LifeCycle, data: &T, env: &Env) {
if let LifeCycle::WidgetAdded = event {
self.current = (self.closure)(data, env);
}
self.true_branch.lifecycle(ctx, event, data, env);
self.false_branch.lifecycle(ctx, event, data, env);
}
fn update(&mut self, ctx: &mut UpdateCtx, _old_data: &T, data: &T, env: &Env) {
let current = (self.closure)(data, env);
if current != self.current {
self.current = current;
ctx.request_layout();
}
if self.current {
self.true_branch.update(ctx, data, env);
} else {
self.false_branch.update(ctx, data, env);
}
}
fn layout(&mut self, ctx: &mut LayoutCtx, bc: &BoxConstraints, data: &T, env: &Env) -> Size {
if self.current {
let size = self.true_branch.layout(ctx, bc, data, env);
self.true_branch.set_layout_rect(
ctx,
data,
env,
Rect::from_origin_size(Point::ORIGIN, size),
);
ctx.set_paint_insets(self.true_branch.paint_insets());
size
} else {
let size = self.false_branch.layout(ctx, bc, data, env);
self.false_branch.set_layout_rect(
ctx,
data,
env,
Rect::from_origin_size(Point::ORIGIN, size),
);
ctx.set_paint_insets(self.true_branch.paint_insets());
size
}
}
fn paint(&mut self, ctx: &mut PaintCtx, data: &T, env: &Env) {
if self.current {
self.true_branch.paint_raw(ctx, data, env);
} else {
self.false_branch.paint_raw(ctx, data, env);
}
}
}