1use crate::{
 2    geometry::vector::Vector2F, AfterLayoutContext, Element, ElementBox, Event, EventContext,
 3    LayoutContext, PaintContext, SizeConstraint,
 4};
 5
 6pub struct EventHandler {
 7    child: ElementBox,
 8    mouse_down: Option<Box<dyn FnMut(&mut EventContext) -> bool>>,
 9}
10
11impl EventHandler {
12    pub fn new(child: ElementBox) -> Self {
13        Self {
14            child,
15            mouse_down: None,
16        }
17    }
18
19    pub fn on_mouse_down<F>(mut self, callback: F) -> Self
20    where
21        F: 'static + FnMut(&mut EventContext) -> bool,
22    {
23        self.mouse_down = Some(Box::new(callback));
24        self
25    }
26}
27
28impl Element for EventHandler {
29    type LayoutState = ();
30    type PaintState = ();
31
32    fn layout(
33        &mut self,
34        constraint: SizeConstraint,
35        ctx: &mut LayoutContext,
36    ) -> (Vector2F, Self::LayoutState) {
37        let size = self.child.layout(constraint, ctx);
38        (size, ())
39    }
40
41    fn after_layout(
42        &mut self,
43        _: Vector2F,
44        _: &mut Self::LayoutState,
45        ctx: &mut AfterLayoutContext,
46    ) {
47        self.child.after_layout(ctx);
48    }
49
50    fn paint(
51        &mut self,
52        bounds: pathfinder_geometry::rect::RectF,
53        _: &mut Self::LayoutState,
54        ctx: &mut PaintContext,
55    ) -> Self::PaintState {
56        self.child.paint(bounds.origin(), ctx);
57    }
58
59    fn dispatch_event(
60        &mut self,
61        event: &Event,
62        bounds: pathfinder_geometry::rect::RectF,
63        _: &mut Self::LayoutState,
64        _: &mut Self::PaintState,
65        ctx: &mut EventContext,
66    ) -> bool {
67        if self.child.dispatch_event(event, ctx) {
68            true
69        } else {
70            match event {
71                Event::LeftMouseDown { position, .. } => {
72                    if let Some(callback) = self.mouse_down.as_mut() {
73                        if bounds.contains_point(*position) {
74                            return callback(ctx);
75                        }
76                    }
77                    false
78                }
79                _ => false,
80            }
81        }
82    }
83}