def on_mouse_wheel(self, event):
        '''handle mouse wheel zoom changes'''
        rotation = event.GetWheelRotation() / event.GetWheelDelta()
        if rotation > 0:
            zoom = 1.0/(1.1 * rotation)
        elif rotation < 0:
            zoom = 1.1 * (-rotation)
        self.change_zoom(zoom)
        self.redraw_map()
def on_mouse_wheel ( self , event ) : rotation = event . GetWheelRotation ( ) / event . GetWheelDelta ( ) if rotation > 0 : zoom = 1.0 / ( 1.1 * rotation ) elif rotation < 0 : zoom = 1.1 * ( - rotation ) self . change_zoom ( zoom ) self . redraw_map ( )
handle mouse wheel zoom changes