Link to issue number:

None
Blocked by #17984

Summary of the issue:

In #17276, NVDA now treats the value of formular nodes in Adobe Acrobat as mathml, with out any real validation.
In PDF 2.0 documents, this is no doubt an okay assumption, but for PDF 1.7 documents generated by Microsoft Word, this is now causing Microsoft word generated math speech alternative text to be processed by mathCAT, resulting in broken or junk navigation, as Microsoft Word is exposing its math speech text as the value of the node.
However, at the same time Microsoft has also introduced a new custom mathml attribute it is exposing on formula nodes in PDFs generated from Microsoft Word, that contains real mathMl which is suitable for MathCAT.
NVDA should make use of this new custom attribute if it exists.

Description of user facing changes

In Adobe Acrobat, NVDA can now read and interact with Math equations in PDF documents generated by Microsoft word.

Description of development approach

AcrobatNode NVDAObject's mathml property: first try and fetch Microsoft Office's custom mathMl custom attribute if it exists. Otherwise fallback to using the node's value or descendants.

Testing strategy:

Opened several PDF documents generated by icrosoft ord that contain math equations. Ensured that they could be read and interactive with using MathCAT.

Known issues with pull request:

None known.

Code Review Checklist:

• Documentation:
  • Change log entry
  • User Documentation
  • Developer / Technical Documentation
  • Context sensitive help for GUI changes
• Testing:
  • Unit tests
  • System (end to end) tests
  • Manual testing
• UX of all users considered:
  • Speech
  • Braille
  • Low Vision
  • Different web browsers
  • Localization in other languages / culture than English
• API is compatible with existing add-ons.
• Security precautions taken.

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