Flex ActionScript实例代码之定时器控制的动画效果

package {
    import flash.display.Sprite;
    import flash.events.Event;
    import flash.events.TimerEvent;
    import flash.utils.Timer;

    public class Main extends Sprite {
        private var _sprite:Sprite = new Sprite(  );
        private var _vx:Number = 1;
        private var _vy:Number = 1;
        private var _timer:Timer;

        public function Main(  ) {
            _sprite.graphics.beginFill(0x0000ff, 100);
            _sprite.graphics.drawCircle(0, 0, 25);
            _sprite.graphics.endFill(  );
            _sprite.x = 50;
            _sprite.y = 100;
            addChild(_sprite);
            _timer = new Timer(30);
            _timer.addEventListener("timer", onTimer);
            _timer.start(  );
        }

        public function onTimer(event:TimerEvent):void {
            _sprite.x += _vx;
            _sprite.y += _vy;
        }
    }
}