Re: [Groff] Writing in gray with groff... possible?

[Ted Harding]

On 25-Jun-00 baruchel wrote:
> Brest, le samedi 24 juin
>> 
>> Yes in principle, but not all easily.
>> 
>> There is no provision at present in tbl for cell-background-filling,
>> so
>> you would have to fake it.
>> 
> Thank you for this. Is it possible to do the second thing I asked
> (write with gray characters)? I am not afraid of doing some job in the
> troff output
> ;-)
> 
> -- 
>    .~.   Thomas Baruchel

This one is easy (if the output device is PostScript). You don't need
to edit the output. The following is an entire input file:

  .ps 36
  .vs 36p
  .ce 3
  \X'ps: exec 0.7 setgray'GREY
  \X'ps: exec 0 setgray'BLACK
  \X'ps: exec 0.4 setgray'DARK GREY

(Note that in PostScript gray = 0 means "black", gray = 1 means "white").

You could define strings or macros for this, e.g.

  .de grch
  .ds ngr \\$1
  .shift
  \X'ps: exec \\*[ngr] setgray'\\$*
  ..
  .ps 36
  .vs 36p
  .ce 3
  .grch 0.7 GREY
  .grch 0 BLACK
  .grch 0.4 DARK GREY

This also works for coloured text, e.g.

  .ds RED "\X'ps: exec 1 0 0 setrgbcolor'
  .ds BLACK "\X'ps: exec 0 0 0 setrgbcolor'
  .ps 36
  .vs 36p
  .ce 3
  THIS IS BLACK
  \*[RED]THIS IS RED
  \*[BLACK]THIS IS BLACK AGAIN

  .nr bwd \w'\0WHITE ON GREY\0'u
  .ce
  \D'f 400u'\h'-400u'\
  \Z'\v'0.5m'\D'P 0 -1.7m \n[bwd]u 0 0 1.7m -\n[bwd]u 0'\v'-0.5m''\
  \X'ps: exec 1 1 1 setgray'\0WHITE ON GREY\0


If you view the output in a colour PostScript renderer such
as ghostscript or ghostview, you should see the colour changes.

The last item above shows how to print white on grey.

Ted.

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Date: 25-Jun-00                                       Time: 01:06:07
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