1 files changed, 20 insertions, 0 deletions
diff --git a/wgpu/src/widget/canvas/state.rs b/wgpu/src/widget/canvas/state.rs
new file mode 100644
index 00000000..8388f94d
--- /dev/null
+++ b/wgpu/src/widget/canvas/state.rs
@@ -0,0 +1,20 @@
+use crate::canvas::{Event, Geometry, Size};
+
+pub trait State {
+    fn update(&mut self, _event: Event, _bounds: Size) {}
+
+    fn draw(&self, bounds: Size) -> Vec<Geometry>;
+}
+
+impl<T> State for &mut T
+where
+    T: State,
+{
+    fn update(&mut self, event: Event, bounds: Size) {
+        T::update(self, event, bounds);
+    }
+
+    fn draw(&self, bounds: Size) -> Vec<Geometry> {
+        T::draw(self, bounds)
+    }
+}