At UCL we've been working with pdf.js (Apache 2 license, maintained by Mozilla) to both display and provide annotation tools for mod_coursework. You can see our initial implementation here:
https://github.com/ucl-isd/moodle-mod_coursework/commit/3d85e6f29e46cfe5e5d135971b77603fc7e3deeb
And read about pdf.js here:
https://mozilla.github.io/pdf.js/
We would like to create an assign_feedback plugin that uses it.
Stretch goals would be:
- Extend it to support stamps
- Extend it to support a comments library
- Create a migration path from Davo's excellent (but YUI dependent) feedback_editpdf
- Create similar functionality within the quiz module
- Persuade HQ this is a worthy inclusion in core