

XOR

When we use XAllocColor, we ask for the color closet to the
requested RGB.  The output is then an integer (pixel) and RGB values flags and pad

The pixel is the value used in an XOR

For example, on the SPARC

Color	Pixel

White	0
Black	1
Red	60

         XOR operation             result maps to color
           Rd Wh Bl             
        Rd  0 60 61                Wh Rd  ?
        Wh 60  0  1                Rd Wh Bl
        Bl 61  1  0                ?  Bl Wh

        The ? means that CALPLOT means that CALPLOT fortunately was able to
        map 61 -> reddish green


For LINUX
Color	Pixel

White	1
Black	0
Red	27

         XOR operation             result maps to color
           Rd Wh Bl             
        Rd  0 26 27                Bl  ? Rd
        Wh 26  0  1                 ? Bl Wh
        Bl 27  1  0                Rd Wh Bl
	
	The ? means that whatever pixel 26 points to, is the color shown

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Conclusion: the use of XOR with color is very dependent on the color server.
Perhaps I should modify XviG to pass back the pixel values -

So on LINUX, if I choose BLACK - I do not see anything different
So on Solaris, if I choose WHITE I do not see anything different

	since anything XOR 0 = anything 
