public interface OnGestureListener
void
onDrag(float dx, float dy)
onFling(float startX, float startY, float velocityX, float velocityY)
onScale(float scaleFactor, float focusX, float focusY)
void onDrag(float dx, float dy)
void onFling(float startX, float startY, float velocityX, float velocityY)
void onScale(float scaleFactor, float focusX, float focusY)