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

[Bart van Deenen]

On Wednesday 19 November 2008 16:21:43 Gunnar Sletta wrote:
> Bart van Deenen wrote:

> > 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?

> 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.

Hi Gunnar

thanks for the tip. I had already played with this a bit, and must probably 
come to the conclusion that the only way to do really smooth animation is to 
go fullscreen, so that nothing else interrupts the communication with the 
graphics server. Otherwise I'll always have somewhat erratic/unsmooth 
animation.

Any chance that the new animation features in Qt4.5 will help me get really 
smooth multi-object animation?

What about the Java overhead? Would we get significant gains with going to 
C++? At least we wouldn't have occasional garbage collection to mess up our 
animation.

Thanks

Bart
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