change bounding of QGraphicsScene

[wysota]

i say you, you imagine you have a svg map like worldmap that you want add that in the center of some circles like radar, you have some target added in this map and you can select or move them and some button outside of this circle for changing zooming and panning and adding target to this map.

Sorry, this description is too vague to make out anything of it. I'm asking about your goals, not methods of achieving them.