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List:       kde-panel-devel
Subject:    Re: painting suggestions
From:       "Aaron J. Seigo" <aseigo () kde ! org>
Date:       2008-09-22 18:07:42
Message-ID: 200809221207.46667.aseigo () kde ! org
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On Sunday 21 September 2008, Riccardo Iaconelli wrote:
> On Monday 22 September 2008 02:04:04 Robert Knight wrote:
> > Fredrik has answered this one on techbase:
> >
> > http://techbase.kde.org/Development/Tutorials/Graphics/Performance#QPaint
> >er
> >
> >::setOpacity.28.29
>
> This changes the opacity of the start pixmap, while I want to decrease
> opacity just for that single painting operation, keeping the cached pixmap
> intact.
>
> So the two options are:
> a) create a copy of the cached pixmap and use the above trick on it.
> b) use QPainter::setOpacity()
>
> Which one is the cheapest?

you could always experiment with either valgrind or using QTimer ... but 
QPainter::setOpacity always defaults to a software path that renders into a 
local image, and so is likely to usually be slower.

-- 
Aaron J. Seigo
humru othro a kohnu se
GPG Fingerprint: 8B8B 2209 0C6F 7C47 B1EA  EE75 D6B7 2EB1 A7F1 DB43

KDE core developer sponsored by Trolltech


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