as3 [flex]旋轉選單

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 
      xmlns:s="library://ns.adobe.com/flex/spark" 
      xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="955" minHeight="600"
      creationComplete="application1_creationCompleteHandler(event)" >
 <fx:Script>
  <![CDATA[
   import caurina.transitions.Tweener;
   import mx.events.FlexEvent;
   private var initX:int=500;
   private var initY:int=200;
   private var gap:int=30;
   private var _scale:Number=.6;
   private var _current:int;
   private var time:Number=0.5;
   protected function application1_creationCompleteHandler(event:FlexEvent):void
   {
    setCurrent(3,false);
   }
   
   private function currentInd(offset:int,len:uint):int
   {
    var temp:int=_current+offset;
    if(temp>=len)
     return temp%len;
    else if(temp<0)
     return len+temp;
    else return temp;
   }
   
   private function setCurrent(ind:int,move:Boolean=true):void
   {
    var len:uint=menu_group.numElements;
    _current=ind;
    if(_current>=len)_current=0;
    else if(_current<0)_current=len-1;
    var _canvas:Canvas;
    for(var i:int=-2;i<=2;i++)
    {
     var v:int=(Math.abs(i)==2)?0:1;
     var t:Number=(Math.abs(i)==2)?.1:time;
     var c:Number=Math.pow(_scale,Math.abs(i));
     var x:Number;
     var y:Number;
     _canvas=menu_group.getChildAt(currentInd(i,len)) as Canvas;
     y=(i==0)?initY:initY+(_canvas.height/2)-(_canvas.height*_scale/(2*Math.abs(i)));
     switch(i)
     {
      case 0:x=initX;break;
      case 1:x=initX+_canvas.width+gap;break;
      case 2:x=initX+_canvas.width+gap*1.5;break;
      case -1:x=initX-(_canvas.width*_scale)-gap;break;
      case -2:x=initX-(_canvas.width*_scale)-gap*.5;break;
     }
     if(move)
      Tweener.addTween(_canvas, {visible:v,scaleX:c,scaleY:c,x:x,y:y,time:t});
     else
     {
      _canvas.x=x;
      _canvas.y=y;
      _canvas.scaleX=_canvas.scaleY=c;
      _canvas.visible=Boolean(v);
      
     }
    }
   }
   
   protected function button1_clickHandler(event:MouseEvent):void
   {
    setCurrent(_current+1);
   }
   protected function button2_clickHandler(event:MouseEvent):void
   {
    setCurrent(_current-1);
   }
   
   
   protected function type_1_clickHandler(event:MouseEvent):void
   {
    // TODO Auto-generated method stub
   }
   
  ]]>
 </fx:Script>
 <s:Group id="menu_group">
  <mx:Canvas visible="false" backgroundColor="0xff0000" width="100" height="100" click="type_1_clickHandler(event)"/>
  <mx:Canvas visible="false" backgroundColor="0x00ff00" width="100" height="100" click="type_1_clickHandler(event)"/>
  <mx:Canvas visible="false" backgroundColor="0x0000ff" width="100" height="100" click="type_1_clickHandler(event)"/>
  <mx:Canvas visible="false" backgroundColor="0xffff00" width="100" height="100" click="type_1_clickHandler(event)"/>
  <mx:Canvas visible="false" backgroundColor="0x00ffff" width="100" height="100" click="type_1_clickHandler(event)"/>
  <mx:Canvas visible="false" backgroundColor="0xff00ff" width="100" height="100" click="type_1_clickHandler(event)"/>
  <mx:Canvas visible="false" backgroundColor="0x123456" width="100" height="100" click="type_1_clickHandler(event)"/>
  <mx:Canvas visible="false" backgroundColor="0x654321" width="100" height="100" click="type_1_clickHandler(event)"/>
 </s:Group>
 <mx:HBox>  
  <s:Button click="button2_clickHandler(event)"/>
  <s:Button click="button1_clickHandler(event)"/>
 </mx:HBox>
</s:Application>