Speed Grader view doesn't show any annotations at first

[seanh]

1. As a teacher, create an assignment
2. As a student, do the assignment, create some annotations and submit them
3. As a teacher, view the student's submission in Canvas's Speed Grader

Expected: You should seed the annotations that the student submitted.

Actual: You don't see anything, until you click on the link.

This is how the Speed Grader view looks when the teacher first opens it:

It says "Annotations by seanh" but there are never any annotations there.

If you click on the link, though, you will then see the student's annotations. Here's how it looks after clicking the link:

[seanh]

The Annotations by seanh with no annotations under it that first appears is actually an image file, a screenshot that Canvas takes of our LTI app's https://lti.hypothes.is/lti_export?... page. At the time when Canvas takes a screenshot of the page it is apparently a blank white page.

I suspect that the problem here is that our app's /lti_export page uses JavaScript to fetch and display the student's annotations, but that whatever Canvas uses to screenshot the page doesn't support JavaScript.

If so then a fix would be that our /lti_export page should be rewritten to render the student's annotations server-side instead, which is a better design anyway.

[seanh]

P.S. We should also remove the thing seen in the screenshot above where the teacher has to paste their Hypothesis developer key, that's also incompatible with Canvas's screenshotting, separate issue: https://github.com/hypothesis/lti/issues/106

[seanh]

Canvas Speed Grader docs: https://community.canvaslms.com/docs/DOC-10712 and https://www.youtube.com/watch?v=0rp5rT6M-xY