ViewFile Gallery displays no slides for older version of XWiki with Libreoffice >= 24.2

[abrassat]

Describe the bug
On older versions of XWiki (14.10, 15.10), when using LibreOffice >= 24.2 as an office server, the ppt display in ViewFile macro shows no slides.
This is because LibreOffice removed support for exporting slides as png, see https://jira.xwiki.org/browse/XWIKI-22335 .

A workaround for this is to downgrade your LibreOffice version to something older, like libreoffice7.6.7.2 .

Steps to reproduce
Steps to reproduce the problematic behavior:

1. Ensure you have LibreOffice >= 24.2 installed
2. Try to include a viewfile macro with a ppt file

Expected behavior
The slides of the presentation are displayed in the gallery.

Actual behavior
No slides are shown in the gallery (like an empty presentation)

Screenshots
If applicable, add screenshots to help explain your problem.

Environment (please complete the following information):

• OS: linux mint
• Browser firefox
• XWiki version 14.10, 15.10
• App version Changes from View-File macro displays empty div for pptx files in full mode #703 #714

[michitux]

Note that XWiki itself exports the slides to PDF and then renders the PDF to images: https://github.com/xwiki/xwiki-platform/blob/4b3f196e29bcf7a63b777546dba0e0a9ff5ffed4/xwiki-platform-core/xwiki-platform-office/xwiki-platform-office-importer/src/main/java/org/xwiki/officeimporter/internal/builder/DefaultPresentationBuilder.java#L190-L236

You don't use org.xwiki.officeimporter.builder.PresentationBuilder to convert the office file in the extension? Or does this only affect old XWiki versions?

[abrassat]

This only affects XWiki 14.10, 15.10 . On XWiki 16.10.15, 18.1.0 it works fine

[michitux]

Should also be fine on 15.10.13 based on https://jira.xwiki.org/browse/XWIKI-22335. Might be good to indicate this a bit more prominently in the issue as at first glance this currently reads as if this affected all XWiki versions while in reality it only affects old versions.