AS3.0 設置sprite的錨點，不改變註冊點的的函數

function RegPoint($obj:Sprite , $point:Point):void
{
 var tmp_point:Point = $obj.parent.globalToLocal($obj.localToGlobal($point));
 var len:int = $obj.numChildren;
 while (len--)
 {
  var tmp_obj:DisplayObject = $obj.getChildAt(len);
  tmp_obj.x -=  $point.x;
  tmp_obj.y -=  $point.y;
  }
	 $obj.x = tmp_point.x;
 	$obj.y = tmp_point.y;
}