[Qt-jambi-interest] QPixmap erratic performance depends on size of QPixmap

[Gunnar Sletta]

Bart van Deenen wrote:
> Hi all, Gunnar
> 
> My problem is dependent on the size of the root level QPixmap. When I use a 
> size of 600x1000 the timer becomes erratic, and when I use 400x300 everything 
> is smooth without any problems. Any idea how to get a handle on this? What 
> should I look into to at least be able to predict where the limit is?

Hi Bart,

I had a look at the example and it is as I pointed out in the initial 
mail. The rendering happens on the X server in a different process and 
the timings you do in your app are more or less useless unless you put a 
QApplication.syncX() into the code, which causes Qt to wait for all its 
sent X commands to be processed before continuing.

If you do this, you will see that drawing speed will be more consistent, 
but of course the general performance of the application will go down as 
you have locking in the graphics pipeline now.

best regards,
Gunnar