AS 3.0 随鼠标移动

package{
 
 import flash.display.Sprite;
 import flash.events.Event;
 
 
 public class mouse extends Sprite{
  
  private var ball:Sprite;
  
  public function mouse(){
   ball = Ball();   
   addChild(ball);
   ball.x = 50;
   ball.y = 50;   
   ball.addEventListener(Event.ENTER_FRAME,moveball);   
   }
   
  private function Ball():Sprite{
   var sp:Sprite = new Sprite();
   sp.graphics.beginFill(0xffff00);
   sp.graphics.drawCircle(0,0,10);
   sp.graphics.endFill();   
   return sp;  
   }
  //定义事件
  private function moveball(evt:Event):void{
   var dx:Number = mouseX - ball.x;
   var dy:Number = mouseY - ball.y;
   var vx:Number = dx/2;
   var vy:Number = dy/2;
   ball.x += vx;
   ball.y += vy;
   
   }
  
  }
 
 
 
 }