[jooyoungseo]

Description

Fixes #15033.

Backport image announcements to the bundled reveal.js 5.1.0 without upgrading the presentation framework:

• Skip style and script contents, including Mermaid's inline SVG stylesheet.
• Announce native image/video alternative text, so fig-alt is included alongside the caption.
• Announce role="img" elements by their name rather than their presentational descendants, using the fix proposed in Fix screen reader image names and exclude SVG styles hakimel/reveal.js#3949.
• Keep the existing hidden-content filtering, 5.1.0 whitespace behavior, and SVG titles outside named images.

The readable source patch is included with an updater step that reapplies it and rebuilds the UMD/ESM bundles and source maps. The updater notes that the upstream PR is not yet merged and that both fixes must be present in a future reveal.js release before removing the backport.

This does not include the separate slide/fragment announcement changes in #15020 or change Graphviz's per-node title/label duplication.

Validation

• Rendered the new fixture with Quarto 1.10.19 and the regenerated reveal.js 5.1.0 bundles.
• Playwright: 27/27 tests pass across Chromium, Firefox, and WebKit (revealjs-image-announcements.spec.ts --workers=1).
• Before the fix, 8 of the 9 Chromium cases fail. WebKit's existing SVG-title filtering was also checked against the original bundle and is preserved.
• Applied the source patch to pristine 5.1.0 and verified that the result matches the build source after normalizing Windows line endings.
• Both bundle formats and maps were rebuilt using the upstream lockfile. The source-map source list is unchanged; only js/reveal.js differs.
• The full Quarto test suite was not run.

Checklist

I have (if applicable):

• referenced the GitHub issue this PR closes
• updated the appropriate changelog in the PR
• ensured the present test suite passes (focused browser tests pass; full suite not run)
• added new tests
• created a separate documentation PR in Quarto's website repo and linked it to this PR (not applicable to this bug fix)

AI-assisted PR

• AI tool used: Aside
• Codebase grounding: Local clones of Quarto main and reveal.js, the issue reproductions, repository contribution and test documentation, and the existing backport workflow.
• Human review: I reviewed the changes and test results and approved this submission.

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[cderv]

As I have merge previous PR, the assets needs to be rebuild.

[jooyoungseo]

Thanks @cderv, addressed in 7f93ab2.

I merged current main and rebuilt the reveal.js 5.1.0 UMD/ESM bundles and both source maps with the fragment announcement fix from #15020 and this PR's image announcement fix applied together. The updater now applies the existing screen-reader patch first, followed by revealjs-0002-image-announcements.patch.

Validation:

• Both patches apply in order to pristine reveal.js 5.1.0, and the resulting sources match the build sources.
• The source-map source list is unchanged from main; only js/reveal.js differs, so the fragments.js and location.js fixes are preserved.
• Re-rendered all three fixtures with Quarto 1.10.19 and the rebuilt bundles. revealjs-announcements.spec.ts and revealjs-image-announcements.spec.ts pass 54/54 tests across Chromium, Firefox, and WebKit (--workers=1). This includes a new combined regression test for image names inside nested fragments, moving forward and backward.

The full Quarto test suite was not run.

[cderv]

Thanks for the rebuild on top of #15020.

I checked this locally and it looks good to me.

One thing I wanted to check is if the caption would be read twice for a figure without fig-alt. It is not, Quarto does not set alt in that case (Markdown image or knitr fig-cap), so only the caption is announced.

Two small edge cases in getImageName(), both also in the upstream PR, so I think they belong there first so the backport stays the same as upstream:

• <div role="img" title="Rated 4 stars">★★★★☆</div> is now announced as nothing, as the contents are skipped and the title attribute is not used as a last fallback for the name.
• aria-labelledby pointing to an <img alt="..."> gives an empty name, because textContent of an image is empty.

Quarto itself does not produce role="img" in revealjs output, so this only matters for raw HTML or extensions, and I don't think it should block this PR. Would you mind raising them on hakimel/reveal.js#3949 maybe ?

I'll merge this PR as is for now.

[jooyoungseo]

Thanks @cderv for the review and merge, and for checking the caption behavior. I raised both naming edge cases on the upstream PR, with examples and expected announcements: hakimel/reveal.js#3949 (comment). Agreed that they should be addressed upstream first so the backport stays aligned.