1 files changed, 41 insertions, 0 deletions
diff --git a/src/render_loop.rs b/src/render_loop.rs
new file mode 100644
index 0000000..bc6d8a9
--- /dev/null
+++ b/src/render_loop.rs
@@ -0,0 +1,41 @@
+use std::cell::RefCell;
+use std::rc::Rc;
+
+use wasm_bindgen::prelude::*;
+
+pub struct RenderLoop {
+    inner: Rc<RefCell<Closure<dyn FnMut(f64)>>>,
+}
+
+impl RenderLoop {
+    fn request_animation_frame(f: &Closure<dyn FnMut(f64)>) {
+        web_sys::window().expect("no window")
+            .request_animation_frame(f.as_ref().unchecked_ref())
+            .expect("should register `requestAnimationFrame` OK");
+    }
+
+    pub fn new<T: FnMut(f64) -> bool + 'static>(mut fun: T) -> Self {
+        let inner = Rc::new(RefCell::new(Closure::new(|_| {})));
+        let rloop = inner.clone();
+
+        *inner.borrow_mut() = Closure::new(move |t| {
+            if fun(t) {
+                Self::request_animation_frame(&rloop.borrow());
+            }
+        });
+        Self { inner }
+    }
+
+    pub fn start(&self) -> Result<(), JsValue> {
+        Self::request_animation_frame(&self.inner.borrow());
+        Ok(())
+    }
+}
+
+impl Clone for RenderLoop {
+    fn clone(&self) -> Self {
+        Self {
+            inner: self.inner.clone(),
+        }
+    }
+}