遮罩（手电筒效果）

package
{
    
    import flash.display.Bitmap;
    import flash.display.Loader;
    import flash.display.Sprite;
    import flash.events.Event;
    import flash.net.URLRequest;
    
    [SWF(width = 600,height = 450,backgroundColor = 0x000000)]
    
    public class Main extends Sprite
    {
        private var _bitmap:Bitmap;
        private var _circleMask:Sprite;
        public function Main()
        {
            init();
            startLoad();
        }
        
        private function init():void
        {
            _circleMask = new Sprite();
            _circleMask.graphics.lineStyle(5);
            _circleMask.graphics.beginFill(0xff0000);
            _circleMask.graphics.drawCircle(60,60,60);
            _circleMask.graphics.endFill();
            addChild(_circleMask);
            _circleMask.startDrag(true); // 鼠标跟随          
        }
        
        private function startLoad():void
        {
　　　　　　　//加载照片
            var loader:Loader = new Loader();
            var request:URLRequest = new URLRequest("resource/pic/wuqilong.jpg");
            loader.contentLoaderInfo.addEventListener(Event.COMPLETE,loaded);
            loader.load(request);
        }
        
        private function loaded(evt:Event):void
        {
　　　　　　　//设置遮罩
            _bitmap = Bitmap(evt.target.content);
            addChild(_bitmap);
            _bitmap.mask = _circleMask;
        }
    }
}