X-reader should support reading PDF/UA (PDF/Universal Accessibility) documents and slides

[goebbe]

 * Xreader version (xreader --version)
 * Distribution - (Mint 21)

Issue Currently, Xreader does not support pdf/ua standard that has been developed for accessibility. A pdf reader should enable e.g. blind people to navigate through a pdf/ua document via standard keyboard bindings (e.g. by fully supporting Orca screen reader). This includes screen reader support (orca) that support usage of the UI of Xreader AND reading the content of pdf/ua files, structural navigation, navigation by tags, showing/ reading invisible content (like image descriptions) if required.

Major office applications (LibreOffice/ MS-Office) are able to generate, verify and export pdf/ua documents or slides. Xreader should have full support for accessibility features.

Steps to reproduce Open pdf/ua file with Xreader. Enable orca (screen) reader via Preferences > Accessibility > Visual Aids > Screen reader

Result: UI-elements of X-reader are supported by the screen reader with mouse over.

On a laptop one can start the screen reader (orca) to read the entire contents of a document by pressing CapsLock+; (hold long enough): Result:

• First some rubbish is read (not content of the document)
• Then the title and part of the current page is read

Issues:

• The command should read the whole document - not just the current page/ slide
• Language of the document seems to be ignored
• structural navigation did not work
• lists did not work (completely ignored)
• figure descriptions and alternative text did not work

Summary: Currently, blind people cannot use Xreader to get access to the accessibility features of pdf/ua files on Linux Mint.

Expected behaviour Text to speech for pdf-content, structural navigation, tables, navigation by tags and access to invisible (pdf/ua) content should be supported out of the box.

Other information pdf/ua is an ISO and ANSI standard: https://en.wikipedia.org/wiki/PDF/UA

In EU-European countries, public bodies/ schools/ Universities are legally required to publish all electronic documents in pdf/ua standard format. It seems that currently there is no free pdf-reader on linux that provides pdf/ua support. :-/

[goebbe]

Poppler seems to know about the standard: https://poppler.freedesktop.org/api/glib/PopplerDocument.html:

PDF Subtype POPPLER_PDF_SUBTYPE_PDF_UA ISO 14289 - Document management applications -- Electronic document file format enhancement for accessibility (PDF/UA)

Not sure if the standard is fully supported, though.

Orca screen reader seems to support most of what is required:
https://help.gnome.org/users/orca/stable/ See also the comments on structural navigation/ supported applications: https://help.gnome.org/users/orca/stable/howto_structural_navigation.html.en

pdf/ua reference suite 1.1: The pdf/ua reference suite is freely available. This might be useful for testing.
https://www.pdfa.org/resource/pdfua-reference-suite/

Note, this issue is not about generating or editing pdf/ua files, but to support navigation (invisible tags, tables) and screen readers (invisible picture name and description of the pictures).