On Web, use requestAnimationFrame for RedrawRequested

src/platform_impl/web/web_sys/animation_frame.rs

@@ -0,0 +1,62 @@
+use std::cell::Cell;
+use std::rc::Rc;
+use wasm_bindgen::closure::Closure;
+use wasm_bindgen::JsCast;
+
+pub struct AnimationFrameHandler {
+    window: web_sys::Window,
+    closure: Closure<dyn FnMut()>,
+    handle: Rc<Cell<Option<i32>>>,
+}
+
+impl AnimationFrameHandler {
+    pub fn new(window: web_sys::Window) -> Self {
+        let handle = Rc::new(Cell::new(None));
+        let closure = Closure::new({
+            let handle = handle.clone();
+            move || handle.set(None)
+        });
+
+        Self {
+            window,
+            closure,
+            handle,
+        }
+    }
+
+    pub fn on_animation_frame<F>(&mut self, mut f: F)
+    where
+        F: 'static + FnMut(),
+    {
+        let handle = self.handle.clone();
+        self.closure = Closure::new(move || {
+            handle.set(None);
+            f();
+        })
+    }
+
+    pub fn request(&self) {
+        if let Some(handle) = self.handle.take() {
+            self.window
+                .cancel_animation_frame(handle)
+                .expect("Failed to cancel animation frame");
+        }
+
+        let handle = self
+            .window
+            .request_animation_frame(self.closure.as_ref().unchecked_ref())
+            .expect("Failed to request animation frame");
+
+        self.handle.set(Some(handle));
+    }
+}
+
+impl Drop for AnimationFrameHandler {
+    fn drop(&mut self) {
+        if let Some(handle) = self.handle.take() {
+            self.window
+                .cancel_animation_frame(handle)
+                .expect("Failed to cancel animation frame");
+        }
+    }
+}