Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!rutgers!mit-eddie!bloom-beacon!LARRY.MCRCIM.MCGILL.EDU!mouse
From: mouse@LARRY.MCRCIM.MCGILL.EDU
Newsgroups: comp.windows.x
Subject: Re:  Short circuiting network communication
Message-ID: <9012091641.AA14521@Larry.McRCIM.McGill.EDU>
Date: 9 Dec 90 16:41:31 GMT
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
Lines: 42

> We are using X11R4 to write some application software.  Two problems
> have arisen that I need pointers to solutions.

> (1) When server and client are resident on the same machine, is there
>     a reasonable way to NOT pass messages over the net, but directly
>     (e.g. memory-to-memory ??) to enhance performance ?

The MIT-SHM extension does this, but (as I understand it) only for
pixmaps.  (Of course, images are typically the largest things to be
shipped back and forth over the communication channel.)

It probably would not be hard to build a server and a matching version
of Xlib that speak via a shared memory segment.  If you can come up
with a way to layer a reliable byte-stream interface on top of the
shared memory (not difficult), that's all you need....

I have a very hazy memory that someone may have done this.  I have no
idea who, or the status of the resulting code; I'm not even sure the
memory isn't just an amalgam of other things.

> (2) We are using 256 colors in specific windows.  In several window
>     managers that we have tried, when the cursor leaves the color
>     window, the window goes black.  We assume this is due to color
>     table swapping.  Is there a wm that provides a mechanism for
>     avoiding this ?

Not that I know of.  But notice that if your hardware provides the
hardware analogue of a single 256-entry PseudoColor lookup table (which
is the commonest sort of color machine around, I feel sure), you can't
really avoid this entirely, without giving up some of those 256 colors.
(In general the window won't go black but rather will go "technicolor"
when some other window's colormap gets installed.)

When this swapping happens depends on the window manager's colormap
focus policy.  I feel sure gwm can be configured to support different
colormap policies; perhaps twm can as well.  (No, I haven't the
foggiest clue how in either case.)

					der Mouse

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