Code example for OvershootInterpolator

     * Interface to be implemented to add and remove PopupZoomer to/from the view hierarchy. 
    public static interface OnVisibilityChangedListener { 
        public void onPopupZoomerShown(PopupZoomer zoomer);
        public void onPopupZoomerHidden(PopupZoomer zoomer);
    private OnVisibilityChangedListener mOnVisibilityChangedListener = null;
    // Cached drawable used to frame the zooming popup. 
    // TODO(tonyg): This should be marked purgeable so that if the system wants to recover this 
    // memory, we can just reload it from the resource ID next time it is needed. 
    // See 
    private static Drawable sOverlayDrawable;
    // The padding used for drawing the overlay around the content, instead of directly above it. 
    private static Rect sOverlayPadding;
    // The radius of the overlay bubble, used for rounding the bitmap to draw underneath it. 
    private static float sOverlayCornerRadius;