flex怎么实现百叶窗特效

flex如何实现百叶窗特效？
在flash中很容易能实现百叶窗效果，不知道flex中能否同样实现该效果？


[解决办法]
effects\Blinds.as

JScript code

package effects{        import effects.effectClasses.BlindsInstance;        import mx.controls.scrollClasses.ScrollBarDirection;    import mx.effects.IEffectInstance;    import mx.effects.TweenEffect;        public class Blinds extends TweenEffect    {                private static var AFFECTED_PROPERTIES:Array = ["mask"];                public function Blinds(target:Object=null)        {            super(target);            instanceClass = BlindsInstance;        }                public var direction:String = ScrollBarDirection.VERTICAL;                public var blindsFrom:Number;                public var blindsTo:Number;                public var gapFrom:Number;                public var gapTo:Number;                override public function getAffectedProperties():Array        {            return AFFECTED_PROPERTIES;        }                override protected function initInstance(instance:IEffectInstance):void        {            super.initInstance(instance);            var blindsInstance:BlindsInstance = BlindsInstance(instance);            blindsInstance.direction = direction;            blindsInstance.blindsFrom = blindsFrom;            blindsInstance.blindsTo = blindsTo;            blindsInstance.gapFrom = gapFrom;            blindsInstance.gapTo = gapTo;        }            }    }