There was an attempt a while ago to allow modules from
the Scribunto
extension (which are written in Lua, not plain wikitext, though) to
render as images:
https://gerrit.wikimedia.org/r/#/c/113759/
There's also
https://www.mediawiki.org/wiki/Extension:GraphViz (not
to be confused with Extension:Graph), which renders images from
wikitext and uploads them back to the wiki as regular files in File:
namespace.
Perhaps one of these will serve as inspiration :)
Thanks for the tip! GraphViz looks like you have to embed the code in
the page itself, in between <graphviz/> tags, so that's pretty much
where I am now. I really, really want to hook in to MW's [[Image:]]
handling code, so displaying the dynamically generated images is no
different to any other uploaded image!
That Scribunto extension looks promising though. It seems to implement
a FileRepo, allowing all the existing [[Image:]] code to work as-is. I
will definitely look at that, because as far as I could work out before,
providing a custom FileRepo would probably do the trick. Thanks!
Cheers,
Adam.