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
|
use super::*;
/// A node that adds padding to its child.
#[derive(Debug, Clone, Eq, PartialEq)]
#[cfg_attr(feature = "layout-cache", derive(Hash))]
pub struct PadNode {
/// The amount of padding.
pub padding: Sides<Linear>,
/// The child node whose sides to pad.
pub child: LayoutNode,
}
impl Layout for PadNode {
fn layout(
&self,
ctx: &mut LayoutContext,
regions: &Regions,
) -> Vec<Constrained<Rc<Frame>>> {
let mut frames = self.child.layout(
ctx,
®ions.map(|size| size - self.padding.resolve(size).size()),
);
for (Constrained { item: frame, constraints }, (current, base)) in
frames.iter_mut().zip(regions.iter())
{
fn solve_axis(length: Length, padding: Linear) -> Length {
(length + padding.abs) / (1.0 - padding.rel.get())
}
// Solve for the size `padded` that satisfies (approximately):
// `padded - padding.resolve(padded).size() == size`
let padded = Size::new(
solve_axis(frame.size.width, self.padding.left + self.padding.right),
solve_axis(frame.size.height, self.padding.top + self.padding.bottom),
);
let padding = self.padding.resolve(padded);
let origin = Point::new(padding.left, padding.top);
// Inflate min and max contraints by the padding.
for spec in [&mut constraints.min, &mut constraints.max] {
if let Some(horizontal) = spec.horizontal.as_mut() {
*horizontal += padding.size().width;
}
if let Some(vertical) = spec.vertical.as_mut() {
*vertical += padding.size().height;
}
}
// Set exact and base constraints if the child had them.
constraints.exact.horizontal.and_set(Some(current.width));
constraints.exact.vertical.and_set(Some(current.height));
constraints.base.horizontal.and_set(Some(base.width));
constraints.base.vertical.and_set(Some(base.height));
// Also set base constraints if the padding is relative.
if self.padding.left.is_relative() || self.padding.right.is_relative() {
constraints.base.horizontal = Some(base.width);
}
if self.padding.top.is_relative() || self.padding.bottom.is_relative() {
constraints.base.vertical = Some(base.height);
}
// Create a new larger frame and place the child's frame inside it.
let empty = Frame::new(padded, frame.baseline + origin.y);
let prev = std::mem::replace(frame, Rc::new(empty));
let new = Rc::make_mut(frame);
new.push_frame(origin, prev);
}
frames
}
}
impl From<PadNode> for LayoutNode {
fn from(pad: PadNode) -> Self {
Self::new(pad)
}
}
|
