Quote Originally Posted by tampstaffs View Post
My problem is ,I have QGraphicsItems in the scene.When I try to update one of them, paint event is generated for it.And when it updates it self, for some reason its generating paint event fpr other items.
This would suggest the boundingRect() for the item is defined incorrectly.

I would like to minimise this, either to one paint event where all of them are updated at one time or that only th eitem I want is updated.
They should all be updated at once (I mean in a single paintEvent() of the viewport). If you experience something different and you are sure about it then there is probably some error in your code.

Aare there any tips and tricks to improve graphics view performance.When i start scrolling for example:
there are about 3 paint for each graphics items which is killing the performance.
Hard to say exactly what is going on without seeing the code. But you may play around with QGraphicsItem::setCacheMode(), maybe it helps.


I have created a scrollable area myself which inherits from QGraphicsWidget, Graphics items are added to this.but this multi paint events on the same items is proving costly during scrolling and even when application is being launched
Can't you use what the graphics view offers? If you make your scene bigger than the view, scrollbars will appear by themselves. The reason for the behaviour you observe might be related to the fact that you use QGraphicsProxyWidget (if you do).