问Flex AS3异步精灵(MovieClip)动画

EN

public class Bird extends Sprite
{
    private var bird_mc:MovieClip;

    public function Bird(startFrame:Number = 0)
    {
        super();
        this.addEventListener(starling.events.Event.ADDED_TO_STAGE, onAddedToStage);
    }

    private function onAddedToStage(event:Event):void
    {
        this.removeEventListener(Event.ADDED_TO_STAGE, onAddedToStage);
        createBird_mc();
    }

    private function createBird_mc():void
    {
        bird_mc = new MovieClip(Assets.getAtlas().getTextures("Bird_"), 16);
        bird_mc.x = Math.ceil(-bird_mc.width/2);
        bird_mc.y = Math.ceil(-bird_mc.height/2);
        starling.core.Starling.juggler.add(bird_mc);
        this.addChild(bird_mc);
    }
}