…16067)

Fixes nvaccess#12715

Summary of the issue:
Authors of PDFs can provide alternative text on formular nodes via the 'alt' attribute. However, NvDA ignores this and replaces it with a single space, with the assumption that the formula will contain an inner mathml tree structure.
The idea of embedding a full mathml tree structure with in formula nodes was never standardized, and only a few experimental PDFs actually exist. However, it is becoming common for authors to place alt text (perhaps a simple english representation of math) on formula nodes.

Description of user facing changes
In Adobe Reader, alternative text for formulas will be reported if provided by the author.

Description of development approach
Adobe Acrobat vbuf backend: Don't replace content in formula tags with a space, rather only do this for math nodes. this ensures NvDA still exposes alt text on formulas. this approach still allows for supporting embedded mathml trees if they exist as a direct child of the formula.

…16067)

Fixes nvaccess#12715

Summary of the issue:
Authors of PDFs can provide alternative text on formular nodes via the 'alt' attribute. However, NvDA ignores this and replaces it with a single space, with the assumption that the formula will contain an inner mathml tree structure.
The idea of embedding a full mathml tree structure with in formula nodes was never standardized, and only a few experimental PDFs actually exist. However, it is becoming common for authors to place alt text (perhaps a simple english representation of math) on formula nodes.

Description of user facing changes
In Adobe Reader, alternative text for formulas will be reported if provided by the author.

Description of development approach
Adobe Acrobat vbuf backend: Don't replace content in formula tags with a space, rather only do this for math nodes. this ensures NvDA still exposes alt text on formulas. this approach still allows for supporting embedded mathml trees if they exist as a direct child of the formula.

…16067)

Fixes nvaccess#12715

Summary of the issue:
Authors of PDFs can provide alternative text on formular nodes via the 'alt' attribute. However, NvDA ignores this and replaces it with a single space, with the assumption that the formula will contain an inner mathml tree structure.
The idea of embedding a full mathml tree structure with in formula nodes was never standardized, and only a few experimental PDFs actually exist. However, it is becoming common for authors to place alt text (perhaps a simple english representation of math) on formula nodes.

Description of user facing changes
In Adobe Reader, alternative text for formulas will be reported if provided by the author.

Description of development approach
Adobe Acrobat vbuf backend: Don't replace content in formula tags with a space, rather only do this for math nodes. this ensures NvDA still exposes alt text on formulas. this approach still allows for supporting embedded mathml trees if they exist as a direct child of the formula.

…vaccess#16067)"

This partially reverts commit fbfcd14. That commit broke getting MathML from the document. While there were almost no MathML PDFs available in the past, pdftex can now generate MathML in Associated Files which are then exposed as the contents when a formula tag has role=math.

New code in NVDAObjects\IAccessible\adobeAcrobat.py handles any alternative text that gets exposed by the PDF processor.

…e Reader: support alternative text on formulas in PDFs (nvaccess#16067)")

This change doesn't allow MathML in formula tags. That was ok before, but now pdftex puts out MathML in an associated file and FoxIt reader makes it the content of a formula tag.

Adobe is generally on board with this idea but hasn't implemented handling of associated files yet. Currently Adobe Reader does not know about Associated Files. So the contents are the alternative text. This is handled by making it an `mtext` element.

Note: if the alt text is LaTeX, then it has lots of "punctuation" such as `{` and `\`. This typically would _not_ be read by NVDA. MathCAT currently passes this along unchanged to NVDA, but I have marked this as a bug and will have MathCAT produce speech that won't be discarded, so the experience will be an improved one over just speaking the alt text.

…e Reader: support alternative text on formulas in PDFs (nvaccess#16067)")

This change doesn't allow MathML in formula tags. That was ok before, but now pdftex puts out MathML in an associated file and FoxIt reader makes it the content of a formula tag.

Adobe is generally on board with this idea but hasn't implemented handling of associated files yet. Currently Adobe Reader does not know about Associated Files. So the contents are the alternative text. This is handled by making it an `mtext` element.

Note: if the alt text is LaTeX, then it has lots of "punctuation" such as `{` and `\`. This typically would _not_ be read by NVDA. MathCAT currently passes this along unchanged to NVDA, but I have marked this as a bug and will have MathCAT produce speech that won't be discarded, so the experience will be an improved one over just speaking the alt text.