1use crate::{
 2    fonts::TextStyle,
 3    geometry::{
 4        rect::RectF,
 5        vector::{vec2f, Vector2F},
 6    },
 7    json::{json, ToJson},
 8    DebugContext, Element, ElementBox, Event, EventContext, LayoutContext, PaintContext,
 9    SizeConstraint,
10};
11
12pub struct LineBox {
13    child: ElementBox,
14    style: TextStyle,
15}
16
17impl LineBox {
18    pub fn new(child: ElementBox, style: TextStyle) -> Self {
19        Self { child, style }
20    }
21}
22
23impl Element for LineBox {
24    type LayoutState = f32;
25    type PaintState = ();
26
27    fn layout(
28        &mut self,
29        constraint: SizeConstraint,
30        cx: &mut LayoutContext,
31    ) -> (Vector2F, Self::LayoutState) {
32        let line_height = cx
33            .font_cache
34            .line_height(self.style.font_id, self.style.font_size);
35        let character_height = cx
36            .font_cache
37            .ascent(self.style.font_id, self.style.font_size)
38            + cx.font_cache
39                .descent(self.style.font_id, self.style.font_size);
40        let child_max = vec2f(constraint.max.x(), character_height);
41        let child_size = self.child.layout(
42            SizeConstraint::new(constraint.min.min(child_max), child_max),
43            cx,
44        );
45        let size = vec2f(child_size.x(), line_height);
46        (size, (line_height - character_height) / 2.)
47    }
48
49    fn paint(
50        &mut self,
51        bounds: RectF,
52        visible_bounds: RectF,
53        padding_top: &mut f32,
54        cx: &mut PaintContext,
55    ) -> Self::PaintState {
56        self.child.paint(
57            bounds.origin() + vec2f(0., *padding_top),
58            visible_bounds,
59            cx,
60        );
61    }
62
63    fn dispatch_event(
64        &mut self,
65        event: &Event,
66        _: RectF,
67        _: &mut Self::LayoutState,
68        _: &mut Self::PaintState,
69        cx: &mut EventContext,
70    ) -> bool {
71        self.child.dispatch_event(event, cx)
72    }
73
74    fn debug(
75        &self,
76        bounds: RectF,
77        _: &Self::LayoutState,
78        _: &Self::PaintState,
79        cx: &DebugContext,
80    ) -> serde_json::Value {
81        json!({
82            "bounds": bounds.to_json(),
83            "style": self.style.to_json(),
84            "child": self.child.debug(cx),
85        })
86    }
87}