MediaViewer doesn't open when clicking magnify button on pages rendered by Parsoid
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Description

Background

Parsoid uses a different HTML structure for images than the legacy Parser originally did. This new Parsoid format generally uses pure CSS approach to display a "magnify" button (via an ::after pseudo-element), whereas in the legacy HTML there is a dedicated <div class=magnify> element in the caption.

MediaViewer supports both variants in mmv.bootstrap.js via the processThumb() function and just below it, the processParsoidThumb() function.

As part of debugging T422586, I noticed that 1) we process thumbnails for the "Parsoid" path even when using the legacy parser, and 2) the magnify button does not work when using a custom link.

Problem

As part of T394054, $wgParserEnableLegacyMediaDOM was removed and now Parsoid and the legacy Parser both use this new format.

In T329413, the new format was changed to bring back the dedicated <div class=magnify> element for cases where the thumbnail has a custom link.

[[File:Example.jpg|thumb|link=https://wikipedia.org]]

MediaViewer does not recognize the magnify link anymore as a result of this, because this was not part of Parsoid originally.

https://www.mediawiki.org/w/index.php?title=Project:Sandbox&oldid=8349168

MediaViewer does not open when clicking "Magnify" in the image caption.

Details

Related Changes in Gerrit:

Subject	Repo	Branch	Lines +/-
Add a test for recognizing thumbs with mw-file-magnify links	mediawiki/extensions/MultimediaViewer	master	+30 -2
Rename variables to reflect new reality	mediawiki/extensions/MultimediaViewer	master	+14 -10
Open MediaViewer with mw-file-magnify links	mediawiki/extensions/MultimediaViewer	master	+11 -3

Customize query in gerrit

Related Objects

Mentioned Here: T422586: MediaViewer downloads high-res image twice if original is a medium-size JPEG
T329413: Magnify links don't point to the file description page when |link= media option is used
T394054: Remove $wgParserEnableLegacyMediaDOM option to disable new media HTML

Event Timeline

Krinkle created this task.Apr 21 2026, 7:32 PM

Restricted Application added a project: Parsoid. · View Herald TranscriptApr 21 2026, 7:33 PM

Restricted Application added a subscriber: Aklapper. · View Herald Transcript

The MediaViewer source makes reference to https://www.mediawiki.org/wiki/Specs/HTML#Media, where, as of writing (version 2.8.0) there is no mention of "magnify".

Should the spec be updated to include this?

Krinkle updated the task description. (Show Details)Apr 21 2026, 7:35 PM

Change #1276050 had a related patch set uploaded (by Arlolra; author: Arlolra):

[mediawiki/extensions/MultimediaViewer@master] Open MediaViewer with mw-file-magnify links

https://gerrit.wikimedia.org/r/1276050

gerritbot added a project: Patch-For-Review.Apr 21 2026, 9:05 PM

we process thumbnails for the "Parsoid" path even when using the legacy parser

The naming there is historic and just refers to the new media structure, nothing Parsoid specific. Now that $wgParserEnableLegacyMediaDOM is removed, the legacy parser always emits that for thumbs.

Would processThumb and processLegacyThumb be preferable? It's a bit confusing between legacy parser and legacy media dom

The MediaViewer source makes reference to https://www.mediawiki.org/wiki/Specs/HTML#Media, where, as of writing (version 2.8.0) there is no mention of "magnify".

The spec currently says,

Note 3: The PHP parser adds a <a href="./File:Foo.jpg" class="internal sprite details magnify" title="View photo details"></a> element inside the <figure>. Parsoid adds this with css (see T329413 where, in some cases, the css implementation is insufficient and further development is needed).

That should be updated, yes

ABreault-WMF moved this task from Backlog to Code Review on the Content-Transform-Team (Work In Progress) board.Apr 21 2026, 9:21 PM

ABreault-WMF moved this task from Needs Triage to Media Structure on the Parsoid board.Apr 24 2026, 1:19 AM

Change #1276050 merged by jenkins-bot:

[mediawiki/extensions/MultimediaViewer@master] Open MediaViewer with mw-file-magnify links

https://gerrit.wikimedia.org/r/1276050

ReleaseTaggerBot added a project: MW-1.46-notes (1.46.0-wmf.26; 2026-04-28).Apr 27 2026, 10:00 PM

Maintenance_bot removed a project: Patch-For-Review.Apr 27 2026, 10:31 PM

ABreault-WMF moved this task from Code Review to To Deploy on the Content-Transform-Team (Work In Progress) board.Apr 27 2026, 10:33 PM

Jdlrobson-WMF added a project: Reader Growth Team.Apr 30 2026, 7:13 PM

Post-deploy, the magnify link opens MediaViewer on https://www.mediawiki.org/w/index.php?title=Project:Sandbox&oldid=8349168

Change #1287003 had a related patch set uploaded (by Arlolra; author: Arlolra):

[mediawiki/extensions/MultimediaViewer@master] Rename variables to reflect new reality

https://gerrit.wikimedia.org/r/1287003

gerritbot added a project: Patch-For-Review.Wed, May 13, 6:46 PM

Change #1287040 had a related patch set uploaded (by Arlolra; author: Arlolra):

[mediawiki/extensions/MultimediaViewer@master] Add a test for recognizing thumbs with mw-file-magnify links

https://gerrit.wikimedia.org/r/1287040

Change #1287003 merged by jenkins-bot: