1 files changed, 79 insertions, 0 deletions
diff --git a/packages/excalidraw/animation-frame-handler.ts b/packages/excalidraw/animation-frame-handler.ts
new file mode 100644
index 0000000..b1a9844
--- /dev/null
+++ b/packages/excalidraw/animation-frame-handler.ts
@@ -0,0 +1,79 @@
+export type AnimationCallback = (timestamp: number) => void | boolean;
+
+export type AnimationTarget = {
+  callback: AnimationCallback;
+  stopped: boolean;
+};
+
+export class AnimationFrameHandler {
+  private targets = new WeakMap<object, AnimationTarget>();
+  private rafIds = new WeakMap<object, number>();
+
+  register(key: object, callback: AnimationCallback) {
+    this.targets.set(key, { callback, stopped: true });
+  }
+
+  start(key: object) {
+    const target = this.targets.get(key);
+
+    if (!target) {
+      return;
+    }
+
+    if (this.rafIds.has(key)) {
+      return;
+    }
+
+    this.targets.set(key, { ...target, stopped: false });
+    this.scheduleFrame(key);
+  }
+
+  stop(key: object) {
+    const target = this.targets.get(key);
+    if (target && !target.stopped) {
+      this.targets.set(key, { ...target, stopped: true });
+    }
+
+    this.cancelFrame(key);
+  }
+
+  private constructFrame(key: object): FrameRequestCallback {
+    return (timestamp: number) => {
+      const target = this.targets.get(key);
+
+      if (!target) {
+        return;
+      }
+
+      const shouldAbort = this.onFrame(target, timestamp);
+
+      if (!target.stopped && !shouldAbort) {
+        this.scheduleFrame(key);
+      } else {
+        this.cancelFrame(key);
+      }
+    };
+  }
+
+  private scheduleFrame(key: object) {
+    const rafId = requestAnimationFrame(this.constructFrame(key));
+
+    this.rafIds.set(key, rafId);
+  }
+
+  private cancelFrame(key: object) {
+    if (this.rafIds.has(key)) {
+      const rafId = this.rafIds.get(key)!;
+
+      cancelAnimationFrame(rafId);
+    }
+
+    this.rafIds.delete(key);
+  }
+
+  private onFrame(target: AnimationTarget, timestamp: number): boolean {
+    const shouldAbort = target.callback(timestamp);
+
+    return shouldAbort ?? false;
+  }
+}