QGraphicsItem meaning of pos(), scenePos()

[wysota]

Program I develop is interactive editor. So, setPos() and rotate() are used frequently in the order which user decides.

But how is that related to other items on the scene?

By sceneBoundingRect() I detect item position in scene relating to other items to estimate correct user's interactive move by mouse.

But why? If you want scene coordinates, handle the event in the scene and not in the item. Anyway I see no point in knowing scene coordinates while handling mouse move.

So, how to setPos() correctly after rotating item around its center? setPos() I mean to set item position programmatically.

Should I decrease value by item->transform().dx() and item->transform().dy() ?
Also it is necessary to take care of signs (decrease or increase)

You shouldn't need to do anything. Can you provide a snippet of code (or better yet a small compilable example) to show us what you are trying to do? Basically if we want to correct item position, we tend to do it in itemChange() not in mouse move events.