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From: doyle@b11.ingr.com (Doyle Davidson)
Newsgroups: comp.windows.x
Subject: Re: Contents of windows
Message-ID: <5059@b11.ingr.com>
Date: 10 May 89 22:14:32 GMT
References: <4037@ficc.uu.net> <1306@esunix.UUCP> <4089@ficc.uu.net>
Organization: Intergraph Corp. Huntsville, AL
Lines: 34

In article <4089@ficc.uu.net>, peter@ficc.uu.net (Peter da Silva) writes:
> In article <1306@esunix.UUCP>, bpendlet@esunix.UUCP (Bob Pendleton) writes:
> > A bit of backing store? Lets see, my default xterm window size is
> > 80x60 using an 8x13 font so that is 499200 pixels. On a machine with
> > 32 bits/pixel (yes, such machines exist and run X) thats 1,996,800
> > bytes or 1.95 megabytes.
> 
> And any half-bright implementation of layers on a machine with that deep
> a display should track the colors used. An XTERM window uses at most four
> colors (fg, bg, cursor, and pointer), so if it backs up more than two
> bitplanes it's horribly inefficient.

That is of course assuming your 4 colors landed on just two planes
(i.e. color indices 0 1 2 3)  They could be indices 5, 19, 31, 
and 4923!!!   Or what about some sort of 32 bit true-color display.  
I suppose you could keep track of the color values used
by a window in a private structure and do some sort of mapping
when you did the backing store.  Ouch!  And what happens when the client
decides it wants another color.  Malloc another private bit plane or
something.  And what if the client...  Hmmm... Maybe that's why we 
kinda decided not to do backing store in our server [yet] (Not to mention 
that 1.95 megabytes just to save 80x60 (4800 bytes) of data :-)

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Doyle C. Davidson              |
Intergraph Corp.               |  These comments are...
Workstation Graphics Standards |
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