Re: [Groff] Drawing filled circle segments

[Ted Harding]

On 28-Oct-05 Werner LEMBERG wrote:
> 
>> I need to use drawing requests (\D'...') directly (without
>> using PIC) to make pie-chart segments that can be filled with
>> color.
> 
> This isn't possible directly in groff (nor it is possible directly
> with pic).  It is not too difficult to write a macro which constructs
> the segment itself with \D'l...' and \D'a...', but there's no way to
> fill it.  The only solution is to approximate the segment with a
> filled polygon.
> 
> Let's see what Ted will cook :-)
> 
> 
>     Werner

Well, here's a skeleton with an example of use. Basically, as it is,
you invoke in-line it with

\*[wedge radius(pts) Red Green Blue Angle1 Angle2]

and carry on from there ... I was toying with the idea of building
a full macro out of this, but then I thought that different people
will want to arrange things in different ways, so provided you
have the basic "wedge" building-block you can build your own.
And of course you can tweak its functionality.

Here's the sample troff code (".LP" from ms macros; vary to taste):



\X'ps: def \
/wedge { gsave \
  currentpoint translate 1 -1 scale \
  /ang2 exch def \
  /ang1 exch def \
  /B exch def /G exch def /R exch def \
  /rad exch def \
  R G B setrgbcolor \
  newpath \
  0 0 moveto \
  0 0   rad ang1 ang2 arc \
  closepath \
  fill stroke \
  grestore \
} def
.ds wedge \Z'\X'ps: exec \\$1 \\$2 \\$3 \\$4 \\$5 \\$6 wedge''
.LP
\&
.sp 1i
This is a line with_\h'0.5i'\
\*[wedge 36 1.0 0.0 0.0 000 045]\
\*[wedge 36 0.5 0.5 0.0 045 100]\
\*[wedge 36 0.0 1.0 0.0 100 170]\
\*[wedge 36 0.0 0.5 0.5 170 250]\
\*[wedge 36 0.0 0.0 1.0 250 360]\
\h'0.5i'_in the middle of it.
.sp 1i
That was a line with a bar-chart.



Best wishes to all,
Ted.


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Date: 28-Oct-05                                       Time: 14:49:05
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