Longdesc file & link is lost in cnxml --> html transform

[brittweinstein]

Scenario

Description
This collection - https://cnx.org/contents/pkNZr_pp - includes a longdesc description for all three images. Per Phil S., the longdesc is lost in the cnxml --> html transformation. We need this to be preserved in the transformation. It must be accessible by screenreaders.

Steps to Reproduce

• Product: [ ] Tutor [ ] Concept Coach [ ] OS Web [ ] Content Production Toolkit [x] CNX

• How many times were you able to reproduce the issue? Phil S. produced the issue in the content linked above.

• Images or Screenshots Included: [ ] Yes [x] No (attach below)

Environment:

• Instance: [x] production [ ] qa [ ] staging [ ] dev [ ] content
• OS: [x] Mac OSX [ ] Windows [ ] iOS [ ] Android
• Browser: [x] Chrome [ ] Firefox [ ] Safari [ ] Opera [ ] IE [ ] Edge

Impact

• Severity: [ ] High [x] Medium [ ] Low
• Frequency of Occurrence: [x] High [ ] Medium [ ] Low

Phil's comment:
The gist is that we need to:

pass the longdesc="filename.txt" attribute from cnxml into XHTML
treat the longdesc attribute the same way we treat elements and translate it throughout the epub process

[reedstrm]

Work path: this will need two changes: one in rhaptos.cnxmlutils (in cnxml-to-html5.xsl, probably) to pass through the longdesc attribute, just like the src attribute (or other image attrs that we copy through). This is XSLT work.

The other change will be in cnx-epub, were we convert the filename that was passed through to a /resources/<sha1> path served by archive. Again, go looking for what we do for src attr. Pretty sure there's a list somewhere of attribute-names-that-are-actually-file-references that get converted at 'storage into the DB time'. This is python work.

[reedstrm]

Hmm, slightly more - seems we put longdesc on the wrapper media element, as well as/instead of on the image, so needs a little more XSLT work to move it to the img tag - we do the same thing for alt so copying that approach would work.

[openstaxalina]

Issue moved to openstax/webview #2191 via ZenHub

[openstaxalina]

Didn't mean to close this, only making a copy in webview so we can remember to track/discuss in Books sprint planning next week.

[Bkblodget]

Who will code this - possibly Marvin

Who will test this and how?