code: def pi_zoom_origin(self, viewer, event, msg=True):
          
          origin = (event.data_x, event.data_y)
          return self._pinch_zoom_rotate(viewer, event.state, event.rot_deg,
                                         event.scale, msg=msg, origin=origin)
docs: Like pi_zoom(), but pans the image as well to keep the
          coordinate under the cursor in that same position relative
          to the window.