1931814 - [a11y] Touch exploration with TalkBack stops working when scrolling

Status: RESOLVED FIXED

(Core :: Disability Access APIs, defect)

Description

[imjs2024]

Attachment: firefox134-nightly-talkback.mp4

I created this bug as a clone of https://bugzilla.mozilla.org/show_bug.cgi?id=1907247. It mentions the fix reached Firefox Nightly. Based on the revision: https://hg.mozilla.org/mozilla-central/rev/718887ce7d31, I understand that it reached Nightly on 10/31. However, I am still able to reproduce the bug reported on a Tablet using the Desktop view of the websites using Nightly with a build from November.

Steps to reproduce

1. On a tablet, open Firefox with TalkBack enabled.
2. Search for something, I chose wikipedia in the attached file.
3. Make sure to have the desktop version enabled.
4. Explore the page with Touch exploration. Do not scroll the view. Notice that everything works normally.
5. Scroll to the bottom of the page and try touch exploration again. Notice that TalkBack doesn't focus any element in the web view.
6. Use TalkBack navigation gestures to explore the page. Notice that elements which aren't focusable with Touch exploration can be reached when using navigation gestures.

Expected behavior

Touch exploration doesn't work for content that needs scroll to be reached.

Actual behavior

Touch exploration should work always.

Device information

• Firefox version:Firefox Nightly 134.0a1 from 2024-11-09T12:24:13.910618560. Build #2016055143
• Tablet Android device model: Samsung Galaxy Tab A9+, model SM-X210
• Android OS version: Android 14.

Any additional information?

• TalkBack version 13.5.00.9

Comment 1

[James Teh [:Jamie]]

NI eeejay to take a look at this when he gets back from leave.

Comment 2

[Diego Ramírez [:BlindMoon38]]

Can confirm it happens also in sites without mobile design, no Desktop version needed. Firefox Translations Models is a good example, since it shows that the content accessible through touch exploration scrolls a little, but doesn't follow the visible content when scrolled to the bottom of the page.

Comment 3

[James Teh [:Jamie]]

S2 for now given that this breaks explore by touch.

Comment 4

[Eitan Isaacson [:eeejay]]

After fixing bug 1934489 I can verify that this is a separate issue. Morgan, I think this one is related to the resolution/zoom change one you were dealing with. From what I can tell ScrollPosition pixels are in a different coordinate space from the zoom/resolution. Does that make sense?

If you think you know where to start looking feel free to assign this to yourself. Otherwise I can dig deeper.

Comment 5

[Morgan Reschenberg [:morgan]]

back from vacation ! looks like this is an issue with the viewport cache / an intersection with APZ, I'll take it. I've managed to repro on desktop. here's my STR:

1. Open the firefox translations page linked above
2. APZ "in" such that the visual viewport is smaller than the layout viewport
3. Scroll both the visual viewport and the page (document is a scroll container here)
4. Attempt to hit test the scrolled region, it won't hittest

Note if you scroll 1/2 of the original content off the page, the regions that previously contained the content will continue to hittest correctly. It only becomes an issue when the content is fully off screen. I think we're either:

• not updating the viewport cache
• not correctly filling the viewport cache with content from the visual viewport
• not correctly computing bounds for items that should have both a scroll offset from the page's scroll container and a "pan" offset from scrolling or moving the visual viewport

Comment 6

[Morgan Reschenberg [:morgan]]

Attachment: Bug 1931814: Always send the viewport cache, even if it is empty r?eeejay

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/9c843ad3136e
Always send the viewport cache, even if it is empty r=eeejay

Comment 8

[Atila Butkovits]

https://hg.mozilla.org/mozilla-central/rev/9c843ad3136e