1use std::marker::PhantomData;
 2
 3use super::Element;
 4use crate::{
 5    json::{self, json},
 6    PaintContext, SceneBuilder, ViewContext,
 7};
 8use json::ToJson;
 9use pathfinder_geometry::{
10    rect::RectF,
11    vector::{vec2f, Vector2F},
12};
13
14pub struct Canvas<V, F>(F, PhantomData<V>);
15
16impl<V, F> Canvas<V, F>
17where
18    F: FnMut(&mut SceneBuilder, RectF, RectF, &mut V, &mut ViewContext<V>),
19{
20    pub fn new(f: F) -> Self {
21        Self(f, PhantomData)
22    }
23}
24
25impl<V: 'static, F> Element<V> for Canvas<V, F>
26where
27    F: 'static + FnMut(&mut SceneBuilder, RectF, RectF, &mut V, &mut ViewContext<V>),
28{
29    type LayoutState = ();
30    type PaintState = ();
31
32    fn layout(
33        &mut self,
34        constraint: crate::SizeConstraint,
35        _: &mut V,
36        _: &mut crate::LayoutContext<V>,
37    ) -> (Vector2F, Self::LayoutState) {
38        let x = if constraint.max.x().is_finite() {
39            constraint.max.x()
40        } else {
41            constraint.min.x()
42        };
43        let y = if constraint.max.y().is_finite() {
44            constraint.max.y()
45        } else {
46            constraint.min.y()
47        };
48        (vec2f(x, y), ())
49    }
50
51    fn paint(
52        &mut self,
53        scene: &mut SceneBuilder,
54        bounds: RectF,
55        visible_bounds: RectF,
56        _: &mut Self::LayoutState,
57        view: &mut V,
58        cx: &mut PaintContext<V>,
59    ) -> Self::PaintState {
60        self.0(scene, bounds, visible_bounds, view, cx)
61    }
62
63    fn rect_for_text_range(
64        &self,
65        _: std::ops::Range<usize>,
66        _: RectF,
67        _: RectF,
68        _: &Self::LayoutState,
69        _: &Self::PaintState,
70        _: &V,
71        _: &ViewContext<V>,
72    ) -> Option<RectF> {
73        None
74    }
75
76    fn debug(
77        &self,
78        bounds: RectF,
79        _: &Self::LayoutState,
80        _: &Self::PaintState,
81        _: &V,
82        _: &ViewContext<V>,
83    ) -> json::Value {
84        json!({"type": "Canvas", "bounds": bounds.to_json()})
85    }
86}