linuxcaffe; distros and desktops

[Anton Markov]

The new X.Org 6.8.1 xserver includes the "composite" extention which 
supports "True transparency":

Taavi Burns wrote:
> On Fri, 29 Oct 2004 00:02:12 -0400 (EDT), Robert Brockway
> <rbrockway-wgAaPJgzrDxH4x6Dk/4f9A at public.gmane.org> wrote:
> 
>>Hi Taavi.  What do you mean by True transparency composited on the client?
>
> AFAIK all of the currently implemented transparency schemes involve heavy
> communication between the X server and the X client: the X client does the
> rendering, fetching current screen state from the X server, and then dumps
> the composited image back to the X server.  I wouldn't want to do that on
> the wire.
> 
> When things get to the point where the X client program just says "This is my
> alpha channel" and the X server composites everything, then the speed will
> be quite acceptable.  Using proper compositing like this has other advantages,
> too (like the elimination of 'tearing' when dragging one window across another,
> because no application ever has to redraw itself because as far as
> it's concerned it's never obscured.

This is exactly what the composite extention does. Actually the 
composite extention only provides an RGBA visual (alpha channel). A 
separate program called the "composite manager" (such as X.Org's 
"xcompmgr") is responsible for doing the composing. The output of 
programs is redirected to the composite manager, which can then do 
transparency, shadows, fading, etc. It is also possible to use the 
graphics card to accelerate the effects.

Unfortunately it's not stable, and has various problems with DRI, 
openGL, xv, and other X extentions, but it does address the points Taavi 
  mentions above. It's a good start; I have OSX-like shadows and 
smooth-moving windows right now :).

> Nope, the WM can run on the terminal server.  I was only speaking of
> transparency
> being computed on the thin client (X server) vs the
> server+lotsofchatteronthewire
> (X client).
When "xcompmgr" is ran on the same computer as the x-server, all 
compsing can be done right on the thin-client itself. I've tried it over 
SSH, and  it causes no slowdown since the programs don't even know 
xcompmgr is running, but I still get shadows under the window and the 
menus; cool :).

-- 
Anton Markov <("anton" + "@" + "truxtar" + "." + "com")>

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