[Interest] speeding up QListView scrolling

Bo Thorsen bthorsen at ics.com
Thu Aug 22 10:31:31 CEST 2013

Den 22-08-2013 04:58, Hamish Moffatt skrev:
> I'm using a QListWidget in an embedded application and I'm finding it
> quite slow to scroll. There's not many items on the list, but it is in a
> custom QWidget with a translucent background displayed over the top of
> some other widgets (all of which are static and not animated or anything).
> Another QListWidget which isn't part of a pop-up translucent widget
> performs somewhat better. Same for another QScrollArea I have containing
> some more custom widgets.
> Are there any tricks for speeding it up? I don't know anything about
> OpenGL or the graphics framework but I read some suggestion that it
> could help. This -
> http://lists.qt.nokia.com/public/qt-interest/2010-February/019575.html -
> suggests the QAbstractScrollArea viewport can be set to a QGLWidget, but
> all I got was a flickering mess.

Forget OpenGL when you're not using something that clearly benefits from 
it. It's *not* a magic optimization wand we can add over our widgets. If 
it was, we would all be using it as the standard painting engine.

You probably have to look at your own code and make the list faster. The 
way to do that is to make the items faster. If they are just text, then 
you're out of luck. But a well written model with QListView instead of 
QListWidget is usually very fast.

And of course, the obvious answer: Doing optimization without numbers is 
almost impossible. Start by figuring out what it is that takes up the 
time instead of guessing.


Bo Thorsen, European Qt Manager, Integrated Computer Solutions
ICS - Delivering World-Class Applications for Embedded & Mobile Devices

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