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Re: [Traverso-devel] playhead cpu usage, crosshair like implementation n
From: |
Nicola Döbelin |
Subject: |
Re: [Traverso-devel] playhead cpu usage, crosshair like implementation needed ? |
Date: |
Tue, 06 Feb 2007 15:09:58 +0100 |
> > I must admit I'm surprised (or disappointed for that matter) by the poor
> > performance of QGraphicsView. After all it is advertised as a very
> > powerfull framework, designed to work with large numbers of 2D objects.
>
> There has been an extremely lengthy discussion on qt4-preview mailinglist
> on
> exactly this issue.
>
> To clarify things a bit:
>
> QGraphicsView doesn't paint _at all_ !
> It manages in combination with QGraphicsScene the graphics items, and it's
> doing a _great_ job at that, no doubt!
>
> The painting is done by the arthur paint engine, which is called by the
> ViewItems, like painter->drawRect(), painter->drawLines() and so on, so to
> some degree, we have to blame that piece of code ?
> Unfortunately, it's not that simple. We the user want vector based
> drawing, so
> the engine has to be vector based.
> This imposes a certain amount of overhead!
> This overhead is reduced to some very little cpu load in Qt 4.3, so that's
> very good news.
>
> Why does painting then still take so much cpu time?
> What became clear on that lengthy discussion on qt4-prevew ml is that the
> very
> same application that took ~ 80% cpu load in X11 only took ~ 5% max on
> windows .....
Thanks for the explanation. It seems we have to live with it for now. Just out
of curiosity: Do you know if the 3D desktop stuff (Xgl, Aixgl, compiz, beryll
etc.) could solve these problems? If I understood correctly the painting is
hardware accellerated, but I've never tried it out since I don't care that much
about these gimmicks.
Nic
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- [Traverso-devel] playhead cpu usage, crosshair like implementation needed ?, Remon, 2007/02/06
- Re: [Traverso-devel] playhead cpu usage, crosshair like implementation needed ?, Nicola Döbelin, 2007/02/06
- Re: [Traverso-devel] playhead cpu usage, crosshair like implementation needed ?, Remon, 2007/02/06
- Re: [Traverso-devel] playhead cpu usage, crosshair like implementation needed ?,
Nicola Döbelin <=
- Re: [Traverso-devel] playhead cpu usage, crosshair like implementation needed ?, Remon, 2007/02/06
- Re: [Traverso-devel] playhead cpu usage, crosshair like implementation needed ?, Niklas Klügel, 2007/02/06
- Re: [Traverso-devel] playhead cpu usage, crosshair like implementation needed ?, Remon, 2007/02/06
- Re: [Traverso-devel] playhead cpu usage, crosshair like implementation needed ?, Nicola Döbelin, 2007/02/06
Message not available
Re: [Traverso-devel] playhead cpu usage, crosshair like implementation needed ?, Jonatan Liljedahl, 2007/02/07