Defines the PanTool class.
A tool that enables the user to pan around a viewport by clicking a mouse button and dragging.
Called when a mouse event causes the drag operation to end.
A drag is ended when a user releases the mouse, or by receiving a mouse_leave event when on_drag_leave is ‘end’.
Called when the drag operation starts.
The event parameter is the mouse event that established the drag operation; its x and y attributes correspond to the current location of the mouse, and not to the position of the mouse when the initial left_down or right_down event happened.
Handles the mouse being moved when the tool is in the ‘panning’ state.