1use crate::{
 2    geometry::{rect::RectF, vector::Vector2F},
 3    json::{self, json, ToJson},
 4    DebugContext, Element, ElementBox, Event, EventContext, LayoutContext, PaintContext,
 5    SizeConstraint,
 6};
 7
 8pub struct Stack {
 9    children: Vec<ElementBox>,
10}
11
12impl Stack {
13    pub fn new() -> Self {
14        Stack {
15            children: Vec::new(),
16        }
17    }
18}
19
20impl Element for Stack {
21    type LayoutState = ();
22    type PaintState = ();
23
24    fn layout(
25        &mut self,
26        constraint: SizeConstraint,
27        cx: &mut LayoutContext,
28    ) -> (Vector2F, Self::LayoutState) {
29        let mut size = constraint.min;
30        for child in &mut self.children {
31            size = size.max(child.layout(constraint, cx));
32        }
33        (size, ())
34    }
35
36    fn paint(
37        &mut self,
38        bounds: RectF,
39        _: &mut Self::LayoutState,
40        cx: &mut PaintContext,
41    ) -> Self::PaintState {
42        for child in &mut self.children {
43            cx.scene.push_layer(None);
44            child.paint(bounds.origin(), cx);
45            cx.scene.pop_layer();
46        }
47    }
48
49    fn dispatch_event(
50        &mut self,
51        event: &Event,
52        _: RectF,
53        _: &mut Self::LayoutState,
54        _: &mut Self::PaintState,
55        cx: &mut EventContext,
56    ) -> bool {
57        for child in self.children.iter_mut().rev() {
58            if child.dispatch_event(event, cx) {
59                return true;
60            }
61        }
62        false
63    }
64
65    fn debug(
66        &self,
67        bounds: RectF,
68        _: &Self::LayoutState,
69        _: &Self::PaintState,
70        cx: &DebugContext,
71    ) -> json::Value {
72        json!({
73            "type": "Stack",
74            "bounds": bounds.to_json(),
75            "children": self.children.iter().map(|child| child.debug(cx)).collect::<Vec<json::Value>>()
76        })
77    }
78}
79
80impl Extend<ElementBox> for Stack {
81    fn extend<T: IntoIterator<Item = ElementBox>>(&mut self, children: T) {
82        self.children.extend(children)
83    }
84}