https://bugs.documentfoundation.org/show_bug.cgi?id=138504

Christophe Strobbe <[email protected]> changed:

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--- Comment #4 from Christophe Strobbe <[email protected]> ---
Note that marking an image or other non-text object as decorative requires a
new attribute in the ODF specification; ODF currently does not have a feature
that allows authors to mark objects as decorative.

I have submitted a feature request for this to the OASIS ODF committee. I
reproduce the entire text of my request below, because it contains important
information for implementers:


This is a request to add an attribute to ODF that marks an image or other type
of (non-text) object as decorative or presentational. A decorative or
presentational object would not have a text alternative (for example, neither
<svg:title> nor <svg:desc> in a <draw:frame> with
presentation:class="graphic").

Details:
1. Such an object would not be mapped to the accessibility API when the
document is viewed in a read mode, such as the Slide Show mode in LibreOffice
Impress or the Read Mode in Microsoft Word. (LibreOffice Writer doesn't have
anything like a Read Mode.) However, the presence of decorative object should
still be exposed to the accessibility API in all editing modes, since screen
reader users need to be made aware of its presence when editing a document.
2. When an object is marked as decorative, editors should disable fields that
allow authors to edit text alternatives (so <svg:title> and <svg:desc> are not
output at all).
3. When an image or object has a caption, editors should not allow it to be
marked as decorative. (The presence of a caption signals that the object
conveys meaning.)
4. The new attribute seems relevant to <draw:frame> elements with a
presentation:class attribute with the value 'graphic' or 'object', and to
<draw:custom-shape>. However, whether an object or shape is decorative or not
depends on the author's intent. I am not aware of a mechanism to determine this
automatically.
5. When a document containing a decorative object is exported as tagged PDF,
the object should also be marked as decorative in the PDF file. (In Adobe
Acrobat DC, the checkbox "Decorative figure" in the "Set Altenate Text" would
be checked and the "Alternate text" field would be grayed out.)
6. When a document containing a decorative object is exported as HTML or XHTML,
the alt attribute on the img element would simply be empty. (This is HTML's
convention for signalling that the img element is decorative). If the object is
output using an element other than img, the ARIA attribute role="presentation"
would be added to the element (see also
https://www.w3.org/TR/wai-aria-1.1/#presentation ). (This is relevant to
Appendix D.1.)

Note that Microsoft Office introduced the ability to mark images and other
objects in Word documents and PowerPoint presentations in version 2019 of the
office suite. (Support in assistive technologies seems to be lagging.) The
above request would eventually enable something similar in LibreOffice and
Apache OpenOffice.

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