Drag and scratch

1

Hi, I’d like to add a click and drag function where I have a coin that scratches off a mask (like a lotto ticket)
Where would I add the Drag?
This is the AS on the masked clip it works but needs repeated clicking


onClipEvent(load)
{
        _root.createEmptyMovieClip('scratch',0);
        function drawScratch()
        {
                x = _root._xmouse;
                y = _root._ymouse;
                with(_root.scratch)
                {
                       // clear();  <!--scratches aren't erased, adding to the clip and creating a bigger mask!
                        moveTo(x-50,y-50);
                        beginFill(0x000000)
                        lineTo(x+10,y-10);
                        lineTo(x+10,y+10);
                        lineTo(x-10,y+10);
                        endFill(); // change 10's to 50 for square
                }
        }
        this.setMask (_root.scratch)
}
onClipEvent(mouseMove)  //mouseDown= has to be clicked everytime
{
        drawScratch();
        updateAfterEvent();
}