No idea about QGraphicsView

[Shawn]

I used QGraphicsView to draw a diagram like below
this diagram is depending on an xml file
so, the height and the width can be variable acoording to the user
Now I can draw it using a given initial position like (300,300)
My problem is:
1.after I finished drawing this diagram, what should i do to make it in the central of the window, especially when the user change the size of the window?
2.is there any way I can change the size of the scene/view according to the size of the diagram? and this diagram is still in the central of the window?


Thank a lot for help!