Thursday, May 19, 2011

Changing Mimetex fonts

An example of Mimetex in action
Mimetex is a handy little add-on for web applications that will render math expressions in TeX/LaTeX syntax and convert them directly to GIF images. It's just one binary executable file which is normally deposited into the "/cgi-bin" directory of the web server. Everything is compiled into the executable, including the fonts. Which is nice: no configuration... no font directories... Simple!

The mimetex distribution comes with the default Computer Modern fonts built in. I was recently asked to change these fonts to a sans-serif font. In case anyone else needs to do something similar I'm documenting what I did in this post.

I'm assuming a Ubuntu Linux distibution (although it should work with other Linux/BSD distros) and you'll need a full TeX/LaTeX distribution installed.

Then download this script. It's good practice to review it first before running it.

The script will:

1) Download Mimetex (if you have not already done so)
2) Render the sans-serif version of Computer Modern to a format that can be used by mimetex
3) Patch mimetex.h to use the sans-serif fonts instead of the default Computer Modern font
4) Compile a new mimetex binary executable file

The results?



What's going on under the hood?

The starting point is a Metafont description of the new font. Fortunately there is a sans-serif variant of computer modern available in Metafont format (cmss and cmssi) included in the TeX distribution.

The process of adding new fonts involves rendering the Metafont file into a bitmaps (.gf) files. Those binary .gf files are then converted into a ASCII printable format using "gftype -i" and then the gfuntype utility (shipped with Mimetex) will convert that to a C header (.h) file. The fonts are run off at various sizes and all the resulting .h files are concatenated together to form 'texfonts.h' which is compiled into the executable.

Is it possible to compile in Type1?

As far as I can tell, there is no easy way to use fonts in formats other than Metafont. And I can't find any way to convert Type1 and other formats to either Metafont or the intermediate .gf bitmap files. I'd be delighted to hear about any suggestions if this is possible.

Also it should be pointed out, there are probably better alternatives to Mimetex available nowadays, eg Mathtex and Mathjax.

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