     
     private var tempShadowRadius: CGFloat = 0
     private var tempShadowOpacity: Float = 0
+    private var touchCenterLocation: CGPoint?
     
     private var rippleMask: CAShapeLayer? {
         get {

    override func layoutSubviews() {
        super.layoutSubviews()
        
        let oldCenter = rippleView.center
        setupRippleView()
        rippleView.center = oldCenter
        
        rippleBackgroundView.layer.frame = bounds
        rippleBackgroundView.layer.mask = rippleMask

    
    override func beginTrackingWithTouch(touch: UITouch, withEvent event: UIEvent?) -> Bool {
        if trackTouchLocation {
            touchCenterLocation = touch.locationInView(self)
        } else {
            touchCenterLocation = nil
        }
        
        UIView.animateWithDuration(0.1,
