AS3给显示对象拖动支持的工具类

public class DragUtil
	{
		private static var _objVec:Vector.<Sprite> = new Vector.<Sprite>();
		private static function addToVec(obj:Sprite):Boolean{
			if(_objVec.indexOf(obj)==-1){
				_objVec.push(obj);
				return true;
			}
			return false;
		}
		private static function removeFromVec(obj:Sprite):void{
			for(var i:int=0; i<_objVec.length; i++){
				var sp:Sprite = _objVec[i];
				if(sp!=null && sp == obj){
					_objVec.splice(i,1);
				}
			}
		}
		public static function enableDrag(obj:Sprite):void{
			if(obj){
				if(!addToVec(obj)){
					return;//已存在Drag列表
				}
				if(!obj.hasEventListener(MouseEvent.MOUSE_DOWN)){
					obj.addEventListener(MouseEvent.MOUSE_DOWN, onMouseDown);
				}
				if(!obj.hasEventListener(MouseEvent.MOUSE_MOVE)){
					obj.addEventListener(MouseEvent.MOUSE_MOVE, onMouseMove);
				}
				if(!obj.hasEventListener(MouseEvent.MOUSE_UP)){
					obj.addEventListener(MouseEvent.MOUSE_UP, onMouseUp);
				}
				if(!obj.hasEventListener(MouseEvent.MOUSE_OUT)){
					obj.addEventListener(MouseEvent.MOUSE_OUT, onMouseOut);
				}
			}
		}
		public static function disableDrag(obj:Sprite):void{
			if(obj){
				removeFromVec(obj);
				if(obj.hasEventListener(MouseEvent.MOUSE_DOWN)){
					obj.removeEventListener(MouseEvent.MOUSE_DOWN, onMouseDown);
				}
				if(obj.hasEventListener(MouseEvent.MOUSE_MOVE)){
					obj.removeEventListener(MouseEvent.MOUSE_MOVE, onMouseMove);
				}
				if(obj.hasEventListener(MouseEvent.MOUSE_UP)){
					obj.removeEventListener(MouseEvent.MOUSE_UP, onMouseUp);
				}
				if(obj.hasEventListener(MouseEvent.MOUSE_OUT)){
					obj.removeEventListener(MouseEvent.MOUSE_OUT, onMouseOut);
				}
			}
		}
		private static function onMouseDown(evt:MouseEvent):void {
			var obj:Sprite = evt.target as Sprite;
			if(obj!=null && _objVec.indexOf(obj)!=-1){
				obj.startDrag(false, new Rectangle(0,0, StageProxy.stageWidth()-obj.width, StageProxy.stageHeight()-obj.height));
			}
		}
		
		private static function onMouseMove(evt:MouseEvent):void {
			if(evt.buttonDown == false) {
				var obj:Sprite = evt.target as Sprite;
				if(obj!=null && _objVec.indexOf(obj)!=-1){
					obj.stopDrag();
				}
			}
		}
		
		private static function onMouseUp(evt:MouseEvent):void {
			var obj:Sprite = evt.target as Sprite;
			if(obj!=null && _objVec.indexOf(obj)!=-1){
				obj.stopDrag();
			}
		}
		
		private static function onMouseOut(evt:MouseEvent):void {
			var obj:Sprite = evt.target as Sprite;
			if(obj!=null && _objVec.indexOf(obj)!=-1){
				obj.stopDrag();
			}
		}
	}