MovieClip设置以中心点旋转

1. var transtimer:Timer=new Timer(50,150);
2. transtimer.addEventListener("timer",timeChange);
3. transtimer.addEventListener("timerComplete",timeComplete);
4. var objMatrix3:Matrix=parMC.childMC.transform.matrix;
5. var step:Number=Math.PI/2;
6. var rX = parMC.width/2;
7. var rY = parMC.height/2;
8. transtimer.start();
9. function childRotation():void 
10. {
11.         objMatrix3.tx-=rX;
12.         objMatrix3.ty-=rY;
13.         objMatrix3.rotate(step/100);
14.         objMatrix3.tx+=rX;
15.         objMatrix3.ty+=rY;
16.         parMC.childMC.transform.matrix=objMatrix3;
17. }
18. function timeChange(event:TimerEvent):void 
19. {
20.         childRotation();
21. }
22. function timeComplete(event:TimerEvent):void 
23. {
24.         transtimer.reset();
25.         transtimer.start();
26. }