只用ActionScript实现效果

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
               xmlns:s="library://ns.adobe.com/flex/spark"
               applicationComplete="init()">
  <s:layout>
    <s:VerticalLayout paddingLeft="20" paddingTop="20" />
  </s:layout>
  <fx:Script>
    <![CDATA[
      import flash.utils.Timer;
     
      import spark.effects.AnimateFilter;
      import spark.effects.animation.MotionPath;
      import spark.effects.animation.RepeatBehavior;
      import spark.effects.animation.SimpleMotionPath;
      import spark.filters.GlowFilter;
     
      [Bindable]
      protected var secondsTillDue:int = 5;
      protected var _timer:Timer;
      protected var _effect:AnimateFilter;
     
      protected function init():void{
        var filter:GlowFilter = new GlowFilter(0xde7800, 1, 20, 20);//设置GlowFilter来发出橘黄色的光
        _effect = new AnimateFilter(box, filter);//创建效果实例
        _effect.duration = 1000;
        _effect.repeatCount = 0;
        _effect.repeatBehavior = RepeatBehavior.REVERSE;
        _effect.motionPaths = new <MotionPath>[
                                  new SimpleMotionPath("alpha", 0, 1)];//建立alpha动画的MotionPath
       
        _timer = new Timer(1000); //tick every 1000ms 
        _timer.addEventListener('timer', onTimerTick);
        _timer.start();
      }//将计时器设为每1000ms运行1次
      
      protected function onTimerTick(event:TimerEvent):void{
        secondsTillDue = Math.max(secondsTillDue-1, 0);//更新secondsTillDue的值
        if(secondsTillDue == 0){
          _effect.play();
          _timer.stop();
        }
      }
    ]]>
  </fx:Script>
  <s:Label id="labelField" fontWeight="bold" fontSize="14"
           text="Due in {secondsTillDue} seconds" />
  <s:Rect id="box" width="200" height="200">
    <s:fill>
      <s:SolidColor color="black" />
    </s:fill>
  </s:Rect>
</s:Application>