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From: etaylor@wilkins.iaims.bcm.tmc.edu (Eric Taylor)
Newsgroups: comp.windows.x
Subject: Re: Window Managers
Message-ID: <3055@gazette.bcm.tmc.edu>
Date: 4 Dec 90 19:06:02 GMT
References: <7422@castle.ed.ac.uk>
Sender: usenet@bcm.tmc.edu
Reply-To: etaylor@wilkins.iaims.bcm.tmc.edu (Eric Taylor)
Organization: Baylor College of Medicine, Houston, Tx
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The general concept is that you draw a line using
GXXor.  You draw a line the first time and it inverts
the colors beneath it.  The draw the same line in
exactly the same place again and the colors invert
again giving you the original pixels.

	The GC for drawing this line is as follows :

        Pixel white = WhitePixel(dpy,screen) ;
        Pixel black = BlackPixel(dpy,screen) ;
        values.foreground = black ^ white ;
        values.background = white ;
        values.line_width = 0 ;
        values.function = GXxor ;
        values.plane_mask = values.foreground ;
        values.subwindow_mode = IncludeInferiors ;
        return XtGetGC(w,
                (unsigned long)GCForeground |
                (unsigned long)GCBackground |
                (unsigned long)GCLineWidth  |
                (unsigned long)GCSubwindowMode |
                (unsigned long)GCPlaneMask  |
                (unsigned long)GCFunction,
                &values);
--
					Eric Taylor
					Baylor College of Medicine
					etaylor@wilkins.bcm.tmc.edu
					(713) 798-3776