1use crate::{
 2    AfterLayoutContext, Element, ElementBox, Event, EventContext, LayoutContext, PaintContext,
 3    SizeConstraint,
 4};
 5use pathfinder_geometry::vector::{vec2f, Vector2F};
 6
 7pub struct Align {
 8    child: ElementBox,
 9    alignment: Vector2F,
10}
11
12impl Align {
13    pub fn new(child: ElementBox) -> Self {
14        Self {
15            child,
16            alignment: Vector2F::zero(),
17        }
18    }
19
20    pub fn top_center(mut self) -> Self {
21        self.alignment = vec2f(0.0, -1.0);
22        self
23    }
24}
25
26impl Element for Align {
27    type LayoutState = ();
28    type PaintState = ();
29
30    fn layout(
31        &mut self,
32        mut constraint: SizeConstraint,
33        ctx: &mut LayoutContext,
34    ) -> (Vector2F, Self::LayoutState) {
35        let mut size = constraint.max;
36        constraint.min = Vector2F::zero();
37        let child_size = self.child.layout(constraint, ctx);
38        if size.x().is_infinite() {
39            size.set_x(child_size.x());
40        }
41        if size.y().is_infinite() {
42            size.set_y(child_size.y());
43        }
44        (size, ())
45    }
46
47    fn after_layout(
48        &mut self,
49        _: Vector2F,
50        _: &mut Self::LayoutState,
51        ctx: &mut AfterLayoutContext,
52    ) {
53        self.child.after_layout(ctx);
54    }
55
56    fn paint(
57        &mut self,
58        bounds: pathfinder_geometry::rect::RectF,
59        _: &mut Self::LayoutState,
60        ctx: &mut PaintContext,
61    ) -> Self::PaintState {
62        let my_center = bounds.size() / 2.;
63        let my_target = my_center + my_center * self.alignment;
64
65        let child_center = self.child.size() / 2.;
66        let child_target = child_center + child_center * self.alignment;
67
68        self.child
69            .paint(bounds.origin() - (child_target - my_target), ctx);
70    }
71
72    fn dispatch_event(
73        &mut self,
74        event: &Event,
75        _: pathfinder_geometry::rect::RectF,
76        _: &mut Self::LayoutState,
77        _: &mut Self::PaintState,
78        ctx: &mut EventContext,
79    ) -> bool {
80        self.child.dispatch_event(event, ctx)
81    }
82}