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List:       kwin
Subject:    Re: Using UnredirectFullscreen=false by default in distributions
From:       Thomas =?utf-8?q?L=C3=BCbking?= <thomas.luebking () web ! de>
Date:       2010-06-03 13:24:17
Message-ID: 201006031524.18238.thomas.luebking () web ! de
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Am Thursday 03 June 2010 schrieb alekcejk@googlemail.com:
> So, KWin developers do not recommend distros to change default value of
> UnredirectFullscreen?

_I_ (single opinion) recommanded to think about your targetbase likely 
usecase, nothing else (and explained mine an why i therefore prefere 
unredirection taking place)

- When will your users use fullscreen* applications.
- What kind of fullscreen applications will that be.
- Will your users rather suspend compositing on heavy load single window tasks 
(games, videos) anyway?

There is no general right answer to this, the only certain thing is that 
compositing does not come for free. o figure the best experience for your 
users, you'll have to know your users, sorry :-(

Apparently the opinion among kwin devs leans towards unredirection, but again: 
for eg. a distro targeting office systems, namely text processing and table 
calculations ("excel") in FS mode, this would be just wrong.

*not(!) maximized windows, though.
 
> Thomas Lübking wrote:
> > IMO this is far more usecase than distro related.
> > 
> > If you're on an office box and tend to use fullscreen text processing,
> > then the unredirection sucks because of all the tooltips and popups.
> > 
> > If you're on a home or mixed mode client (and maybe think that using
> > maximized/fullscreen applications is plain wrong anyway ;-) then
> > unredirection will usually take place on video playback and/or gaming.
> > 
> > As the cpu overhead for the redirected painting heavily scales with the
> > update frequency and those usecases are cpu/gpu intense anyway, you
> > really want a) the unredirection to take place, or
> > b) suspend compositing while playing movies/gaming (for even more
> > performance)
> > 
> > (a third case are screensavers, but fancy screensavers are "nonsense"
> > anyway and also the re-redirection causes flicker and therefore a
> > bugreport as you can glimpse the desktop/root window when promted the
> > password dialog.)
> > 
> > So: personally i'd keep unredirection as
> > a) i think maximizing windows is plain wrong ;-)
> > b) i don't have to actively suspend/resume compositing when playing some
> > HD movie.
> > 
> > The solution is however to prevent the flicker.
> > => HACKISH (?) FIX:
> > I think storing the root (pixmap), dumping the fullscreen window into the
> > root, re-redirecting and restoring the original root (pixmap) would do
> > the job - never tested though and this also might be HW/driver related
> > (Does everybody else see the root pixmap on re-redirection?!)
> > 
> > Thomas
> > 
> > Am Tuesday 01 June 2010 schrieb alekcejk@googlemail.com:
> >> Hi,
> >> 
> >> I have read solution from
> >> https://bugs.kde.org/show_bug.cgi?id=177495#c2
> >> that fixes windows flickering in fullscreen mode.
> >> 
> >> Kubuntu uses UnredirectFullscreen=false in default KWin settings
> >> https://bugs.launchpad.net/ubuntu/+source/kubuntu-default-
> 
> settings/+bug/327
> 
> >> 199
> >> 
> >> Is this solution good enough for all distributions?
> >> Is there many issues related with performance hit when
> >> UnredirectFullscreen=false used?
> >> 
> >> Alexey Kurov <nucleo@fedoraproject.org>
> >> _______________________________________________
> >> kwin mailing list
> >> kwin@kde.org
> >> https://mail.kde.org/mailman/listinfo/kwin
> 
> _______________________________________________
> kwin mailing list
> kwin@kde.org
> https://mail.kde.org/mailman/listinfo/kwin

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