I followed the tutorial on techbase to write a wallpaper plugin. The paint method basically blits a fullscreen Pixmap 10 times per second and produces a heavy cpu load (half a 3 GHZ core). Now i removed all apps and widgets from the desktop and even the panel, so that the desktop was completely empty, only the wallpaper needed to be drawn. Still the heavy load.
Now what is happening, that a simple pixmap copy of about 100 MByte per second keeps a strong pc so busy, and what to do about it ?
I am using Pixmaps that are copied untransformed and without compositing.
Even if the data would be copied from main memory, 100 MByte/ second are really not much.
I know this is a simple program and i don't understand the details of the graphics pipeline and whatever is going on behind the scene. Maybe i overlooked something.
Please don't tell me that there is no good solution.

ps : i am referring to the wallpaper plugin "Fly Mode" on kde-look.org

You may wish to check the source of the Image plugin as shipped with Plasma.

It can be found at trunk/KDE/kdebase/workspace/plasma/generic/wallpapers/image/

I actually have the kdebase-workspace source and checked the image plugin to learn from it.
I checked the cpu load when using the standard kde plugin Slidshow, because it does a smooth transition effect between the current and the new wallpaper. And the cpu load is also large : http://www.flickr.com/photos/46811114@N07/4324213587/

Before i dive into the opernGL world i just wanted to be sure that there is no way to do a fullscreen animation with the QPainter class and reasonable cpu load. Even though i can't understand why that would be the case.

Which way to go ?
Could someone please link me to some page where this issue has been discussed before, as i am sure it has been talked about a thousand times ?

Yes it has been brought up before, but this was all I could find at the moment: http://mail.kde.org/pipermail/plasma-de ... 09797.html

Thanks
The help you linked me to answers my questions.