Gesture zoom depending on the center of touch points

Hi,
When I use gesture zoom myMC object (movie clip) scaling depending on center of touch points. How can I make this?

PHP Code:

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function zoom(e:TransformGestureEvent):void
       if (myMC.scaleX < 2 && myMC.scaleX > 0.5)
    {
        myMC.scaleX *=  e.scaleX * e.scaleY;
        myMC.scaleY *=  e.scaleX * e.scaleY;
    }
    else if (myMC.scaleX>=2)
    {
        myMC.scaleX = myMC.scaleY = 1.99;
    }
    else if (myMC.scaleX<=0.6)
    {
        myMC.scaleX = myMC.scaleY = 0.61;
    }
    } 


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