GraphicsView performance problems

**wysota** · 16th February 2007, 12:31

What if you disable the render hints while painting the background? Do you get a significant performance gain? Could you also please include information about profiling for drawBackground()? It might require a recompilation of Qt!

**Gopala Krishna** · 16th February 2007, 13:20

Originally Posted by wysota

What if you disable the render hints while painting the background? Do you get a significant performance gain?

Disabling render hints didn't improve the performance significantly.

Originally Posted by wysota

Could you also please include information about profiling for drawBackground()?!It might require a recompilation of Qt

I can do that but i may have to do re-recompilation later

Before that, do you see any problems in my code ? Did you see performance difference after commenting the lines ? Atleast I would like to wait till Bitto answers something since compiling qt is time consuming!

**Gopala Krishna** · 17th February 2007, 10:09

As I already pointed out that performance is better without those nodes and textitems as children. Does that mean drawBackground() is being called twice for same area ? Does the framework lack any optimization in calculating this before hand ?

**rajesh** · 17th February 2007, 10:14

drawBackground() get called every time whenever your window painted, means when ever you move window or resize..

**Gopala Krishna** · 17th February 2007, 10:29

Originally Posted by rajesh

drawBackground() get called every time whenever your window painted, means when ever you move window or resize..

No. That is just one of the case. drawBackground() is called always before updating the required item(eg when its moved) with the probably the item's bounding rect. You can check that by just printing something say qDebug() << rect; in the method.