1use std::ops::Range;
 2
 3use crate::{
 4    geometry::{rect::RectF, vector::Vector2F},
 5    json::{self, json, ToJson},
 6    presenter::MeasurementContext,
 7    DebugContext, Element, ElementBox, LayoutContext, PaintContext, SizeConstraint,
 8};
 9
10#[derive(Default)]
11pub struct Stack {
12    children: Vec<ElementBox>,
13}
14
15impl Stack {
16    pub fn new() -> Self {
17        Self::default()
18    }
19}
20
21impl Element for Stack {
22    type LayoutState = ();
23    type PaintState = ();
24
25    fn layout(
26        &mut self,
27        mut constraint: SizeConstraint,
28        cx: &mut LayoutContext,
29    ) -> (Vector2F, Self::LayoutState) {
30        let mut size = constraint.min;
31        for child in &mut self.children {
32            size = size.max(child.layout(constraint, cx));
33            constraint.min = size;
34        }
35        (size, ())
36    }
37
38    fn paint(
39        &mut self,
40        bounds: RectF,
41        visible_bounds: RectF,
42        _: &mut Self::LayoutState,
43        cx: &mut PaintContext,
44    ) -> Self::PaintState {
45        for child in &mut self.children {
46            cx.paint_layer(None, |cx| {
47                child.paint(bounds.origin(), visible_bounds, cx);
48            });
49        }
50    }
51
52    fn rect_for_text_range(
53        &self,
54        range_utf16: Range<usize>,
55        _: RectF,
56        _: RectF,
57        _: &Self::LayoutState,
58        _: &Self::PaintState,
59        cx: &MeasurementContext,
60    ) -> Option<RectF> {
61        self.children
62            .iter()
63            .rev()
64            .find_map(|child| child.rect_for_text_range(range_utf16.clone(), cx))
65    }
66
67    fn debug(
68        &self,
69        bounds: RectF,
70        _: &Self::LayoutState,
71        _: &Self::PaintState,
72        cx: &DebugContext,
73    ) -> json::Value {
74        json!({
75            "type": "Stack",
76            "bounds": bounds.to_json(),
77            "children": self.children.iter().map(|child| child.debug(cx)).collect::<Vec<json::Value>>()
78        })
79    }
80}
81
82impl Extend<ElementBox> for Stack {
83    fn extend<T: IntoIterator<Item = ElementBox>>(&mut self, children: T) {
84        self.children.extend(children)
85    }
86}