Menus: unnecessary repaints?!

[Waldo Bastian]

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On Friday 06 June 2003 09:44, Karl Vogel wrote:
> On 06 Jun 2003, you wrote in kde.kde-optimize:
> > On Thu, Jun 05, 2003 at 05:32:04PM +0200, Waldo Bastian wrote:
> >> and do a scroll+repaint when it has scrolled only a little. Not sure
> >> if you will run into problems with invalid areas that need repainting
> >> before scrolling though.
> >
> > sure you would (and, fwiw, netscape/moz, openoffice and certainly many
> > other apps don't get it right), but invalidating the image if the
> > to-be-scrolled part is (partially) obscured should not be that hard in
> > theory. of course things get somewhat more complicated if you want to
> > do partial scrolls to reuse every single already visible character ...
>
> I've never done any X coding, but doesn't X take care of the layering?! ie.
> can't you just scroll the entire window contents without having to take
> overlapping windows in mind?!

Yes, X takes care of the layering, but X may also destroy your window contents 
as it sees fit (for example because it isn't visible) It will then ask the 
application to repaint the area when it becomes visible again. When you 
scroll a region that needs repainting you basically scroll garbage, so you 
need to detect that somehow. Or keep a copy of the screen buffer around so 
that you can copy form there.

Cheers,
Waldo
- -- 
bastian at kde.org -=|[ SuSE, The Linux Desktop Experts ]|=- bastian at suse.com
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