Thursday, July 17, 2008

Thumbnails and TeX support for MediaWiki on Mac OS X

After you have setup a new MediaWiki installation you will likely want to enable some extra functionality which requires additional software.

First off to create thumbnails of images you need to install ImageMagick, which gives you the incredibly handy convert program.

Second you can add maths support, using TeX, for this you need ocaml, latex and dvipng. Grab the required programs from MacPorts, they are available from Fink as well.
  • sudo port install ImageMagick
  • sudo port install ocaml
  • sudo port install tetex
  • sudo port install ghostscript
Texvc will convert your TeX into whatever MediaWiki wants to display (HTML, MathML or PNG), but it needs to know where several programs are. Given you are probably running your webserver as the www user, who has no $PATH settings how do you tell Texvc where to find the files? In an unusal move, hardcode them! Edit <mediawiki>/math/, prefixing /opt/local/bin to the four commands
let cmd_dvips tmpprefix = "/opt/local/bin/dvips -R -E " ^ tmpprefix ^ ".dvi -f >" ^ tmpprefix ^ ".ps"
let cmd_latex tmpprefix = "/opt/local/bin/latex " ^ tmpprefix ^ ".tex >/dev/null"
let cmd_convert tmpprefix finalpath = "/usr/local/bin/convert -quality 100 -density 120 " ^ tmpprefix ^ ".ps " ^ finalpath ^ " >/dev/null 2>/dev/null"
let cmd_dvipng tmpprefix finalpath = "/opt/local/bin/dvipng -gamma 1.5 -D 120 -T tight --strict " ^ tmpprefix ^ ".dvi -o " ^ finalpath ^ " >/dev/null 2>/dev/null"
Them recompile texvc with make, ocaml will take over here.

Tell ImageMagick where gs is, by editing /opt/local/lib/ImageMagick-X.X.X/config/delegates.xml, where X.X.X is version number. Replaces every "gs" with "/opt/local/bin/gs", only edit "gs" entries, about half a dozen.

Finally tell MediaWiki to use TeX, by editing your LocalSettings.php with $wgUseTeX = true;

Now math support should be good to go. Thank to this compilation of advice for assistance.

So now this wikitext will produce the following:

== Magical latex in action ==
<math>\left \{ \frac{a}{b} \right \} \quad \left \lbrace \frac{a}{b} \right \rbrace</math>

<math>x \implies y</math> an AMS command

<math>f(n) =
n/2, & \mbox{if }n\mbox{ is even} \\
3n+1, & \mbox{if }n\mbox{ is odd}

== Image thumbnail ==

[[Image:OpenSUSE.png|frame|Full size|center]]
[[Image:OpenSUSE.png|thumb|A thumbnail|center]]