def METHOD_NAME(self, event):
    """Update rotation parmeters based on mouse movement"""
    p1 = event.mouse_event.press_event.pos
    p2 = event.mouse_event.pos
    if self._event_value is None:
        self._event_value = self.azimuth, self.elevation
    self.azimuth = self._event_value[0] - (p2 - p1)[0] * 0.5
    self.elevation = self._event_value[1] + (p2 - p1)[1] * 0.5