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List:       kde-core-devel
Subject:    Re: Ann: KPixmapIO
From:       mosfet <mosfet () mandrakesoft ! com>
Date:       2000-02-27 3:06:55
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Richard Moore wrote:
> 
> Geert Jansen wrote:
> >
> > Hi!
> >
> > I created a small class called KPixmapIO which uses MIT-SHM for converting
> > images to pixmaps and vice versa. After some testing, the results are
> > rather pleasing. I measured the following figures, using a 1024x768 test
> > image:
> >
> [snipped benchmark]
> > If you want to check it out, it can be found at
> > ftp://ftp.stack.nl/pub/users/geertj/kpixmapio.tar.gz
> > It contains the test program I used too.
> >
> > If other people want to use it too, I can import it to the CVS.
> > I wrote it to speed up the transparent backgrounds in konsole
> 
> Would this be good for kdeui? It might help the theming code.
> It will certainly be fantastic for kvnc, it needs to tranfer a lot
> of data to the X server to keep the screen up to date.
> 

<IMHO>
I already said this several times but here I go again...

MIT-SHM is great for single multimedia windows, as long as you have code
that will also operate without it. It should not be used for several
potentially large pixmaps. It's a limited resource on many systems (the
maximum for all apps is defined as a kernel parameter), many apps such
as databases also need it, and on some Unix'es very little is allowed by
default ie: ~1/2 meg. After a pixmaps you run out of space. Thus it's
not really usable for themes and should not go in transparent konsole,
but would be potentially cool for a multimedia class. You could simply
allocate it until if fails, but then you end up having to do a recently
used scheme to optimize and code to handle when it fails.

As a ex-sysadmin if KDE used MIT-SHM for pixmaps I would never install
it on any production machine that also runs apps using Unix shared
memory, like Oracle.

</IMHO>

> Rich.
> 
> > (not yet committed).
> >
> > Greetings,
> >  --
> >     Geert Jansen                       email: <g.t.jansen at stud.tue.nl>
> >     Phylosopher, Physicist,                    email: <jansen at kde.org>
> >     KDE enthusiast                                 PGP key ID: 0xD2B5E7CE
> 
> --
>      Richard Moore              rich@ipso-facto.freeserve.co.uk
> http://www.robocast.com/        richard@robocast.com
> http://developer.kde.org/       rich@kde.org

-- 
Daniel M. Duley - Unix developer & sys admin.
http://www.mosfet.org - The place for KDE development news.
mosfet@mandrakesoft.com
mosfet@kde.org

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