Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!sun-barr!decwrl!adobe!gelphman
From: gelphman@adobe.COM (David Gelphman)
Newsgroups: comp.lang.postscript
Subject: Re: The One Page Processor, a PostScript word processor.
Keywords: PostScript, word processor, good software, free
Message-ID: <1502@adobe.UUCP>
Date: 2 Dec 89 21:33:13 GMT
References: <1989Nov29.131039.22368@sgzh.uucp>
Reply-To: gelphman@adobe.UUCP (David Gelphman)
Organization: Adobe Systems Incorporated, Mountain View
Lines: 70

In article <1989Nov29.131039.22368@sgzh.uucp> Bruno Pape, P.O. Box 368, Thomaston CT, 06787, USA writes:
>Have at it.  If your running UNIX here is a shell script you could use.
>

>%
>%	Checks to see if on a color PostScript device.
>%	A real lousy test.  A product name with Color, color, or
>%	COLOR in it means a color device?  I hope.
>%
>
>statusdict begin product end
>(Color) search
>{
>	pop pop pop def_colors
>}{
>	(color) search
>	{
>		pop pop pop def_colors
>	}{
>		(COLOR) search
>		{
>			pop pop pop def_colors
>		}{
>			pop no_colors
>		} ifelse
>	} ifelse
>} ifelse

    This approach of testing for color is STRONGLY discouraged.
The best way to test for extensions or functionality is to look
directly for the feature for which you are interested. In this
case, 'setrgbcolor' is a standard part of the language and has
been in all implementations including the original Apple LaserWriter
printer. If used on a black and white output device, the rgb color is mapped 
into the NTSC gray equivalent. Applications which wish to apply rgb
color to line art and text can do so by using setrgbcolor on all PostScript
output devices.
   The 'setcmykcolor' operator today exists only in color output devices
but one can expect it to exist in future b&w devices. If you need to use
this operator then it is a simple matter to test for the functionality
and emulate it if it isn't available. For example:
   /setcmykcolor where
	{% yes it is known
		pop	% pop the dict found
	}{  % no it isn't
		/setcmykcolor	% c m y k
			{% pick your favorite strategy for mapping cmyk
			% to rgb...here is the way Adobe Illustrator does it
				1 sub 4 1 roll
				3
				{
					3 index add neg dup 0 lt
					{ pop 0 } if
					3 1 roll
				} repeat setrgbcolor pop
			} bind def
	}ifelse
%  see the Color Extensions document on the file server for more detail
%  about mappings between   rgbcolor space and cmykcolor space

Once 'setcmykcolor' has been conditionally defined as above you can
use it with impunity. There is no need to check for product strings,
etc to use specific operators...test for the operators themselves.

David Gelphman
Adobe Systems Incorporated