ensureVisualUpdate method

void ensureVisualUpdate ()

Schedules a new frame using scheduleFrame if this object is not currently producing a frame.

Calling this method ensures that handleDrawFrame will eventually be called, unless it's already in progress.

This has no effect if schedulerPhase is SchedulerPhase.transientCallbacks or SchedulerPhase.midFrameMicrotasks (because a frame is already being prepared in that case), or SchedulerPhase.persistentCallbacks (because a frame is actively being rendered in that case). It will schedule a frame if the schedulerPhase is SchedulerPhase.idle (in between frames) or SchedulerPhase.postFrameCallbacks (after a frame).

Implementation 

void ensureVisualUpdate() {
  switch (schedulerPhase) {
    case SchedulerPhase.idle:
    case SchedulerPhase.postFrameCallbacks:
      scheduleFrame();
      return;
    case SchedulerPhase.transientCallbacks:
    case SchedulerPhase.midFrameMicrotasks:
    case SchedulerPhase.persistentCallbacks:
      return;
  }
}