Add conversion functions for winit feature

src/input/button_state.rs

@@ -7,3 +7,17 @@ pub enum ButtonState {
     /// The button is __not__ pressed.
     Released,
 }
+
+#[cfg(feature = "winit")]
+mod winit_conversion {
+    use winit::event::ElementState;
+
+    impl From<ElementState> for super::ButtonState {
+        fn from(element_state: ElementState) -> Self {
+            match element_state {
+                ElementState::Pressed => super::ButtonState::Pressed,
+                ElementState::Released => super::ButtonState::Released,
+            }
+        }
+    }
+}