scale displayobject(等比例缩放偏移)

ScaleDisplayObjectDemo.as

     /**
      * @param resource 
      * align the specfied resource to top-left coordinate
      */
      function handleResetTopLeftPos(resource:Sprite):Sprite{
		var s:Sprite = new Sprite();
		resource.parent.addChildAt(s, resource.parent.getChildIndex(resource));
		s.addChild(resource.parent.removeChild(resource));
		var leftTop:Point = getLeftTopPosition(resource);
		var originX:Number = resource.x;
		var originY:Number = resource.y;
		resource.x = leftTop.x;
		resource.y = leftTop.y;
		s.x = -leftTop.x + originX;
		s.y = -leftTop.y + originY;
		return s;
	}
	
	/**
	 * get the displayobject's topleft position
	 *
	 * @param d
	 * 
	 * @return point
	 *
	 * @see DisplayObjectUtil.as
	 */
	function getLeftTopPosition(d:DisplayObject, scaleX:Number = NaN, scaleY:Number = NaN):Point {
		if(!isNaN(scaleX)){
			d.scaleX = scaleX;
		}
		if(!isNaN(scaleY)){
			d.scaleY = scaleY;
		}
		var rect:Rectangle = d.getBounds(d);
		var m:Matrix = d.transform.matrix;
		/**
		 * the displayobject's scaleX scaleY maybe have problem
		 */
		var scaleX:Number = m.a;
		var scaleY:Number = m.d;
		var rx:Number, ry:Number;
		rx = scaleX >0 ? m.a * rect.left : m.a * rect.right;
		ry = scaleY >0 ? m.d * rect.top : m.d * rect.bottom;
		return new Point(-rx|0, -ry|0);
	}
	

	var t:Sprite = handleResetTopLeftPos(_mc);
	var time:Number;
	var revert:Boolean = false;
	//TODO
	t.addEventListener(MouseEvent.CLICK, function(evt:MouseEvent):void{
		if(!isComplete){
			return;
		}
		var content:Sprite = t.getChildAt(0) as Sprite;
		var mt:Matrix = content.transform.matrix;
		var prevMouseX:Number = content.mouseX;
		var prevMouseY:Number = content.mouseY;
		var leftTop:Point;
		time = getTimer();
		revert = !revert;
		var prevPoint:Point = new Point(prevMouseX, prevMouseY);
		var currentPoint:Point = prevPoint.clone();
		prevPoint = content.localToGlobal(prevPoint);
		isComplete = false;
	        easeing(mt, {"a":revert ? 1 : .2, "d": revert ? 1 : .2}, .2, Sine.easeOut, function():void{
				content.transform.matrix = mt;
                                //等比例缩放调整坐标TODO
				leftTop = getLeftTopPosition(content);
				content.x = leftTop.x;
				content.y = leftTop.y;
				currentPoint.x = prevMouseX;
				currentPoint.y = prevMouseY;
				currentPoint = content.localToGlobal(currentPoint);
				t.x -= currentPoint.x - prevPoint.x;
				t.y -= currentPoint.y - prevPoint.y;
		});
	 });
	
	addChild(t);
	var sx:Number = (stage.stageWidth - t.width) * .5;
	var sy:Number = (stage.stageHeight - t.height) * .5;
	t.x = sx;
	t.y = sy;

        var isComplete:Boolean = true;
	function easeing(t:Object, property:Object, duration:Number, easeFun:Function, updateFun:Function):void{
		var s:Shape = new Shape();
		var ns:Number, d:Number = 0;
		var starts:Object = {}, changes:Object = {};
		for(var it:* in property){
			starts[it] = t[it];
			changes[it] = property[it] - t[it];
		}
		s.addEventListener(Event.ENTER_FRAME, function(evt:Event):void{
				ns = (getTimer() - time) * .001;
				d = ns >= duration ? 1 : easeFun(ns, 0, 1, duration);
				for(var item:* in property){
					t[item] = starts[item] + changes[item] * d;
				}
				updateFun();
				if(d == 1){
					isComplete = true;
					s.removeEventListener(Event.ENTER_FRAME, arguments.callee);
				}
		});
	}