1754680 - Bullets treated as embedded objects by RemoteAccessible (AKA li elements broken with NVDA + CTW)

Status: RESOLVED FIXED

(Core :: Disability Access APIs, defect)

Description

[James Teh [:Jamie]]

STR (with the NVDA screen reader):

1. Load this test case:
   data:text/html,<ul><li><a href="https://example.com/">test
2. Read the content of the document with the cursor keys.
   • Expected: There should be a list item containing a bullet and a "test" link.
   • Actual: There is only a bullet; the link is missing.

This occurs because IAccessibleHyperlink::get_hyperlink(0) fails with E_NOINTERFACE instead of returning the link. That happens because RemoteAccessibleBase::EmbeddedChildAt returns the bullet, which it shouldn't do; the bullet is part of the text, not an embedded object. That in turn occurs because RemoteAccessibleBase::IsEmbeddedObject returns true for bullets. That should be a pretty straightforward fix.

Comment 1

[James Teh [:Jamie]]

Attachment: Bug 1754680: Don't treat a list item bullet as an embedded object.

This was causing LinkAt to return a bullet instead of the first embedded object in a list item, breaking rendering with NVDA when the cache was enabled.
Rather than adding another role to RemoteAccessibleBase::IsEmbeddedObject, I changed it to use IsText().
This is consistent with how embedded objects are determined for LocalAccessible in EmbeddedObjCollector.
I think the reason this previously used roles is that when this was originally implemented, AccTypes weren't remoted, so IsText() couldn't be used.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/1ae02b556de8
Don't treat a list item bullet as an embedded object. r=eeejay

Comment 3

[Norisz Fay [:noriszfay]]

https://hg.mozilla.org/mozilla-central/rev/1ae02b556de8

Comment 4

[Alex Finder|PTO, back on Nov 25th]

== Change summary for alert #33285 (as of Wed, 16 Feb 2022 17:00:13 GMT) ==

Improvements:

Ratio	Test	Platform	Options	Absolute values (old vs new)
7%	a11yr dhtml.html	linux1804-64-shippable-qr	e10s fission stylo webrender-sw	570.65 -> 530.37
7%	a11yr dhtml.html	linux1804-64-shippable-qr	e10s fission stylo webrender	580.24 -> 539.46

For up to date results, see: https://treeherder.mozilla.org/perfherder/alerts?id=33285