1use std::marker::PhantomData;
 2
 3use super::Element;
 4use crate::{
 5    json::{self, json},
 6    PaintContext, SceneBuilder, View, 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    V: View,
19    F: FnMut(&mut SceneBuilder, RectF, RectF, &mut V, &mut ViewContext<V>),
20{
21    pub fn new(f: F) -> Self {
22        Self(f, PhantomData)
23    }
24}
25
26impl<V: View, F> Element<V> for Canvas<V, F>
27where
28    F: 'static + FnMut(&mut SceneBuilder, RectF, RectF, &mut V, &mut ViewContext<V>),
29{
30    type LayoutState = ();
31    type PaintState = ();
32
33    fn layout(
34        &mut self,
35        constraint: crate::SizeConstraint,
36        _: &mut V,
37        _: &mut crate::LayoutContext<V>,
38    ) -> (Vector2F, Self::LayoutState) {
39        let x = if constraint.max.x().is_finite() {
40            constraint.max.x()
41        } else {
42            constraint.min.x()
43        };
44        let y = if constraint.max.y().is_finite() {
45            constraint.max.y()
46        } else {
47            constraint.min.y()
48        };
49        (vec2f(x, y), ())
50    }
51
52    fn paint(
53        &mut self,
54        scene: &mut SceneBuilder,
55        bounds: RectF,
56        visible_bounds: RectF,
57        _: &mut Self::LayoutState,
58        view: &mut V,
59        cx: &mut PaintContext<V>,
60    ) -> Self::PaintState {
61        self.0(scene, bounds, visible_bounds, view, cx)
62    }
63
64    fn rect_for_text_range(
65        &self,
66        _: std::ops::Range<usize>,
67        _: RectF,
68        _: RectF,
69        _: &Self::LayoutState,
70        _: &Self::PaintState,
71        _: &V,
72        _: &ViewContext<V>,
73    ) -> Option<RectF> {
74        None
75    }
76
77    fn debug(
78        &self,
79        bounds: RectF,
80        _: &Self::LayoutState,
81        _: &Self::PaintState,
82        _: &V,
83        _: &ViewContext<V>,
84    ) -> json::Value {
85        json!({"type": "Canvas", "bounds": bounds.to_json()})
86    }
87}