There are not many modifications done to the original xdvi except that fonts not available can now be substituted by specifying them in a file. The environmental variable TEXFONTSUB points to this file. For example, TEXFONTSUB=c:/xdvi/texfonts.sub". The filename texfonts.sub is arbitrary. One can rename it to some other name as long as the environmental variable TEXFONTSUB points to it. Format of the font substitute file (ASCII) is as follows:
amr10 -> cmr10
src2 -> dest2
etc.
where src2 is the unavailable font and dest2 is the font we intended to substitute. It is exactly as the font substitution machcanism found in DVIVGA.
For those interested in the image processing features provided by XDVI, please browse through the source and see if I did anything wrong in choosing suitable image quality since I do not know anything about image processing.
Default TEXfont directory is "c:/tex/fonts." However, this can be overridden by specifying another directory through some environmental variable. Please look at the file readme for details.
Finally, I have tested only the "pk" font version of XDVI, therefore the performance of using "gf" and "pxl" is unknown. These two versions of XDVI are however also modified to look up font substitute file. To use the other version one must re-compile the source. To obtain the other versions one must re-compile XDVI with appropiate switches set.