I've made an initial stab at trying to get the baseline offset for rasterized math images; patch attached on: https://bugzilla.wikimedia.org/show_bug.cgi?id=32694

this is a feature from Blahtex that was much requested here for helping image renderings to match up with the surrounding text, and is done by getting the --depth option offset from dvipng (which itself needs the 'preview' latex package to be present to get reliable results).

Unfortunately in my offhand tests this isn't giving good results; I'm getting 0 or 1px baseline depth offsets despite having descender letters (like "q") or using "tall" constructs like a square root or fraction. The result is images that are higher up than they ought to be, whereas in the default centering positioning they are often slightly lower than they ought to be.

I'm not sure whether I'm doing something wrong, or whether the baseline depth that is retrieved is actually bogus to begin with. Need to compare in more detail against blahtex maybe...

... if we can't get this working, it's less of a big deal assuming MathJax can be set up to load fairly transparently, as that'll fix things up nice.

-- brion