See revision 9682.

I made this change because I think it is a better way to support our cgm
device driver. CGM format is a long-established (since 1987) open standard
for vector graphics that is supported by w3c (see
http://www.w3.org/Graphics/WebCGM/). Despite its openness, CGM has never
gotten much support within the free software community (probably because it
was ahead of its time).  But that doesn't mean we have to continue that
trend. I doubt many were using our cgm device before because it depends on
the public domain software library, libcd, which is difficult to find, and
no longer maintained.  OTOH, that library code seems to build without
problems on all platforms that our developers have tried so it makes sense
to do the build ourselves so it is automatically accessible for everybody
who builds PLplot.

I have only lightly tested these changes so far, but if I run the test
executables built in lib/nistcd, I generate identical cgm files to
those supplied with the libcd tarball.

Please give this change a thorough testing.  If you don't know how to view
the resulting cgm files, they should be convertable to other vector graphics
formats such as svg using uniconvertor.  However, Debian Lenny let me down
in this case (See http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=518816).

Another possibility for viewing/converting cgm is ralcgm.  (That is what the
ImageMagick display app uses to view/convert cgm files.) However, Debian let
me down there as well since nobody has packaged ralcmg for Debian. An
unpatched ralcgm is impossible to build on Linux because the package's
configuration is completely Linux unaware. (Yes, that happened back in the
mid 90's when ralcgm was programmed). However, I took a patched source from
a src rpm that filled in all the Linux configuration information properly,
and I got that version to build with no issues.

After that build, the "display" application gave good results for our cgm
plots within the current limitations of the cgm device (Hershey fonts, no
antialising, etc.) Note, if you look at the cgm examples generated by
running the tests in lib/nistcd, the text is done with good looking fonts,
and the text and lines are nicely antialiased.  Thus, it is possible in
theory to overcome these current limitations for our cgm device if anybody
is interested on working on this device (considering that the external libcd
build is no longer a barrier to entry for using -dev cgm).

Alan
__________________________
Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state implementation
for stellar interiors (freeeos.sf.net); PLplot scientific plotting software
package (plplot.org); the libLASi project (unifont.org/lasi); the Loads of
Linux Links project (loll.sf.net); and the Linux Brochure Project
(lbproject.sf.net).
__________________________

Linux-powered Science
__________________________

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