code: public void updateNoDraw() {
  		if (autoUpdate) {
  			long now = getTime();
  			long delta = now - lastUpdate;
  			if (firstUpdate) {
  				delta = 0;
  				firstUpdate = false;
  			}
  			lastUpdate = now;
  			nextFrame(delta);
  		}
  	}
docs: Update the animation cycle without draw the image, useful
  for keeping two animations in sync
  
  @deprecated