Using addPixmap to a QGraphicsView, just let the view handle the zoom, moves.... Just handling all the view events to move the division smoothly.
This time, just paint the background white and then draw the map without divisions (before the first division is asked), then add the divisions as they are asked.
(as always, the red spaces will be gone). The variable "punto" will be translated.

Zoom, move (it behaves like before), with several maps in two computers (one that was not affected by the bug and one that was affected).