MediaViewer displays images with associated metadata on top of wiki pages. When the user clicks on a thumbnail, that thumbnail is displayed in large, along with various information extracted from the HTML markup around the thumbnail and on the file's description page.

The alt text is currently not extracted. When the thumbnail has an alt text, set it in the image displayed by MediaViewer as well, and also on the embeddable HTML code generated in the download and share menus. The relevant modules for this are mmv.bootstrap (data extraction from thumbnails), mmv.ui.canvas (displaying the image) and mmv.EmbedFileFormatter (generating the embeddable HTML).

This is T75923/T66519 in Wikimedia's issue tracker.

Students are required to read Wikimedia's general instructions first.