scale_gesture.java

class ScaleGestureListener implements ScaleGestureDetector.OnScaleGestureListener
{
    @Override
    public boolean onScale(ScaleGestureDetector detector)
    {
        // do smth with scale
    }

    @Override
    public boolean onScaleBegin(ScaleGestureDetector detector)
    {
        // do smth when scale begin
    }

    @Override
    public void onScaleEnd(ScaleGestureDetector detector)
    {
        // do smth when scale end
    }
}