def METHOD_NAME(self, ev):
    # Mouse released, add dragging offset the view variables
    self.view_centre += np.array(self.view_centre_difference)
    self.view_elevation += self.view_elevation_difference
    self.view_azimuth += self.view_azimuth_difference
    self.view_centre_difference = np.array([0.0,0.0,0.0])
    self.view_azimuth_difference = 0.0
    self.view_elevation_difference = 0.0
    self.update()