support manual canvas snapshotting (#108)

See highlight/highlight#6139

Author: Vadman97

packages/rrweb/src/record/index.ts

@@ -323,6 +323,7 @@ function record<T = eventWithTime>(
     blockSelector,
     mirror,
     sampling: sampling?.canvas?.fps,
+    samplingManual: sampling?.canvas?.fpsManual,
     clearWebGLBuffer: sampling?.canvas?.clearWebGLBuffer,
     initialSnapshotDelay: sampling?.canvas?.initialSnapshotDelay,
     dataURLOptions,
@@ -687,6 +688,13 @@ record.takeFullSnapshot = (isCheckout?: boolean) => {
   takeFullSnapshot(isCheckout);
 };
 
+record.snapshotCanvas = async (element: HTMLCanvasElement) => {
+  if (!canvasManager) {
+    throw new Error('canvas manager is not initialized');
+  }
+  await canvasManager.snapshot(element);
+};
+
 record.mirror = mirror;
 
 export default record;