code: def viewbox_mouse_event(self, event):
          
          BaseCamera.viewbox_mouse_event(self, event)
          if event.type == 'mouse_wheel':
              s = 1.1 ** - event.delta[1]
              self._scale_factor *= s
              if self._distance is not None:
                  self._distance *= s
              self.view_changed()
docs: The ViewBox received a mouse event; update transform
          accordingly.
          Default implementation adjusts scale factor when scolling.
  
          Parameters
          ----------
          event : instance of Event
              The event.