Path: utzoo!attcan!uunet!snorkelwacker!bloom-beacon!LARRY.MCRCIM.MCGILL.EDU!mouse
From: mouse@LARRY.MCRCIM.MCGILL.EDU (der Mouse)
Newsgroups: comp.windows.x
Subject: Re:  XCopyPlane() on color Vaxstation 2000s
Message-ID: <8911010656.AA19525@Larry.McRCIM.McGill.EDU>
Date: 1 Nov 89 06:56:55 GMT
Sender: root@bloom-beacon.MIT.EDU
Organization: The Internet
Lines: 35

> I have a simple client which just displays a bitmap file in a window.
> I call XReadBitmapFile() and create a GC with BlackPixel and
> WhitePixel as foreground and background respectively.  Then, AFTER
> RECEIVING AN EXPOSE EVENT, I just use XCopyPlane to display the
> exposed part of the pixmap.

Good, you've avoided the first problem.  (But you've already created
another, probably without realizing it.)

>        gcval.foreground=BlackPixel(disp,0);
>        gcval.background=WhitePixel(disp,0);

Not that it's related to your problem, but this sort of assumption is a
common headache of mine.  Not everybody runs black-on-white!

>        XMapRaised(disp,win);

>        XSelectInput(disp, win, ExposureMask|ButtonPressMask|KeyPressMask);
>        for (;;)
> [...read events and redraw stuff upon an Expose event...]

Suppose the server generates Expose events from the MapRaised before it
acts on the SelectInput?  Guess what that will do...

By the way, you needn't XFlush after drawing; XNextEvent will flush for
you if necessary.

Why is there a difference?  I can only guess, and it wouldn't even be
an informed guess, because I've never even seen a DEC server.  So your
guess is at least as good as and probably better than mine.

					der Mouse

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			new: mouse@larry.mcrcim.mcgill.edu