While working on the issue, I noticed that the current implementation of
the method filter_mathjaxloader::map_language_code() is suboptimal and
does not work well for many Moodle language packs such as pt_br or de_du
and other variants. It did not give particularly wrong results. It just
fell back to the default English too early without trying more hard.
This patch improves the mapping logic and adds a unit test for the
method.
This is to solve a tricky edge case, when a page has no equations, and then an AJAX
action loads filtered content which contains an equation. (The glossary filter can do this).
To fix this I split the loading into configuration and typesetting. The config always happens,
but does not load the external mathjax libraries. The typesetting happens when an equation is
found - and is what triggers the load of MathJax. This can happen in response to an AJAX event.
* Remove all traces of mathjax from the atto equation editor - it is filter agnostic
* Add a M.core.event module for core events that can be published/subscribed to by plugins (loose coupling)
* Add a FILTER_CONTENT_UPDATED event so plugins can tell the filter system when nodes are added to the page
* Implement a listener for this event in the MathJax filter
* Fire this event from the equation editor and from the glossary filter
* Add a nolink tag to the mathjax filter, so equations will not be processed by the other filters
* Add a smarter throttle function to the equation editor preview updates (Y.throttle is dumb)
Tim Hunt