NVDA cannot navigate math content in Chromium

[cary-rowen]

This is most likely a Chromium regression, but it's unclear which version introduced it. I hope the community can provide more information. In the meantime, I will report this issue to the Chromium team.

Steps to reproduce:

1. Open the following Wikipedia page: https://en.wikipedia.org/wiki/Quadratic_equation
2. Use NVDA to locate the mathematical content on the page. You can use Single Letter Navigation commands.
3. Press the space key on the math content to try interacting with it.
4. Use the left/right arrow keys to navigate the math content.

Actual behavior:

• Step 3: Unable to enter interactive mode.
• Step 4: Unable to navigate or find the math object.

Note: Using object navigation (NVDA+numpad4/6), you can locate the mathematical content, but interaction is still not possible.

Expected behavior:

NVDA should be able to interact with math content in Chromium, just like it does in Firefox.

NVDA logs, crash dumps, and other attachments:

System configuration:

NVDA installed/portable/running from source:

Installed

NVDA version:

2024.4.1 (Alpha snapshot)

Windows version:

Windows 10 22H2 (AMD64) Build 19045.5131

Name and version of other software in use when reproducing the issue:

Chrome 131.0.6778.86

Other information about your system:

None

Other questions:

Does the issue still occur after restarting your computer?

Yes

Have you tried any other versions of NVDA? If so, please describe their behavior:

The issue can be reproduced in versions 2024.1, 2024.2, and 2024.3.

If NVDA add-ons are disabled, does the problem still occur?

Yes

Does the issue still occur after running the COM Registration Fixing Tool in NVDA's tools menu?

Yes

[cary-rowen]

Hi cc @NSoiffer
Can you take a look at this?

Many thanks

[NSoiffer]

It worked for me yesterday or the day before that on Chrome. I don't remember what the version was. Version 131.0.6778.71 and the just updated Version 131.0.6778.86 are not triggering the calls to MathCAT. Everything is working in Firefox. Edge Version 131.0.2903.51 has the same problem as Chrome (not surprisingly). The problem is also there in Chrome Canary Version 133.0.6849.0.

I suspect the stable build on Nov 12 (131.0.6778.70) was working. However, Google doesn't make it easy download old versions and I failed in my attempt to download that version.

Note 1: on my Windows 10 computer, there is no speech period, let alone the ability to navigate it.

Note 2: NVDA 2025.1 alpha builds fails for navigation of math with MathCAT due to a problem in NVDA's braille code. That's a separate issue that I hope to file a bug report on in the next few days. It is not a problem for 2024.4 (or 2024.4.1).

[Adriani90]

If you report this to Chromium as well, please post the link here so we can track it as well.

[SasnikOmega]

I have the same problem. Heres what I noticed.
Looking at detailed info about the current navigator object using NVDA f1, theres a property called "IAccessible2 attributes".
Usually its value looks like this:
IAccessible2 attributes: 'display:block;tag:p;text-align:left;'. Or, in case of math objects:
IAccessible2 attributes: 'display:block math;tag:math;text-align:left;'.
In last versions of Chromium-based browsers though, NVDA considers math content itself as the part of IAccessible2 attributes. It looks like this:
IAccessible2 attributes: 'display:block math;tag:math;text-align:left;math:\n<mrow>\n <mi>x</mi>\n <mo>\\=</mo>\n <mfrac>\n <mrow>\n <mrow>\n <mo>-</mo>\n <mi>b</mi>\n </mrow>\n <mo>±</mo>\n <msqrt>\n <mrow>\n <msup>\n <mi>b</mi>\n <mn>2</mn>\n </msup>\n <mo>-</mo>\n <mrow>\n <mn>4</mn>\n <mo>\u2062</mo>\n <mi>a</mi>\n <mo>\u2062</mo>\n <mi>c</mi>\n </mrow>\n </mrow>\n </msqrt>\n </mrow>\n <mrow>\n <mn>2</mn>\n <mo>\u2062</mo>\n <mi>a</mi>\n </mrow>\n </mfrac>\n</mrow>\n;'
(Source
Unfortunately, thats all I can say. Hope that helps though.

[NSoiffer]

FYI: here is the Chromium bug report: https://issues.chromium.org/issues/380161205.

[cary-rowen]

Thanks @NSoiffer

[cary-rowen]

Thanks @SasnikOmega

The information you provided may be useful and I will update the progress of the original bug here.

[aleventhal]

I'm guessing that Chrome needs to strip out the newlines so that it doesn't break parsing of the object attributes. It wouldn't have been an issue when NVDA retrieved the math through ISimpleDOMNode::get_innerHTML because it doesn't need to break that string up into multiple attributes.

[cary-rowen]

Yes, thanks to the Chromium engineers for working on this.

Let's keep an eye on the canary version.