Well, hours later, and I still couldn't figure out where Inkscape hides its table of fonts/font properties. Another one of those cases where it is faster to write something from scratch than to figure out where it is buried in existing code. The attached small test case does the desired sort of calculation and works on both linux and Windows (mingw, with devlibs32 installed for freetype and fontconfig.) The first time it ran on Windowx XP it took about 30 seconds, presumably because it was making the font cache. Subsequent runs were fast. Found the cache file(s) in:
C:\Documents and Settings\Local Settings<username>\Apps\Temp\fontconfig\cache
Strange file names, starts with a long string of hexadecimal characters and then ends in ".cache-2" or ".cache-3". Today's was 456KB and one from two days ago was 935KB. Not sure which other application made the older one, nor why that one was twice as large.
Regards,
David Mathog mathog@...1176... Manager, Sequence Analysis Facility, Biology Division, Caltech