493683 - Fire name/description change event when aria-labelledby/describedby content changes

Status: RESOLVED FIXED

(Core :: Disability Access APIs, defect, P3)

Description

[alexander :surkov (:asurkov)]

Our AT's want to get name change event when name change is changed with one exception they don't need name change event if it's calculated from subtree.

Comment 1

[alexander :surkov (:asurkov)]

there is sub bug 507559 to fire name change events for window title changes.

Comment 3

[Xiao Yong Li]

Hi, can this issue be fixed recently?

Comment 4

[alexander :surkov (:asurkov)]

(In reply to Xiao Yong Li from comment #3)
> Hi, can this issue be fixed recently?

what do you mean?

Comment 5

[Xiao Yong Li]

Our product is under accessibility certification process, Firefox doesn't fire a name change event and thus JAWS doesn't read the changed name on the button of our widget. If this issue can be fixed before release date (July 30th) we can declare our widget accessibility compliant, otherwise we need to file a deviation which means our widget is not completely accessible.

Comment 6

[alexander :surkov (:asurkov)]

this bug is kind of generic and making a complete fix should regress our performance. Do you have use case?

Comment 7

[Xiao Yong Li]

We use dojo titlePane, this use case and problem are similar with bug#470082: https://bugzilla.mozilla.org/show_bug.cgi?id=470082.

Comment 8

[alexander :surkov (:asurkov)]

(In reply to Xiao Yong Li from comment #7)
> We use dojo titlePane, this use case and problem are similar with
> bug#470082: https://bugzilla.mozilla.org/show_bug.cgi?id=470082.

can you provide URL or attach a test case?

Comment 9

[Xiao Yong Li]

This is reference guide of dijit.TitlePane of dojo 1.8:http://dojotoolkit.org/reference-guide/1.8/dijit/TitlePane.html#programmatic-example
Run any example and click the header of TitlePane. When a TitlePane is activated to open or close the associated panel the accessible name is changed, i.e. the prefix of title is a '+' if the pane is closed and '-' if the pane is open. However Firefox doesn't fire a name change event and thus JAWS doesn't read the new name on the button.

Comment 10

[alexander :surkov (:asurkov)]

I can see accessible name like "I'm a TitlePanel too" and it's not changed at all. So the problem seems to be not about eventing. Does it what you see too?

Comment 11

[Xiao Yong Li]

The expand and collapse status marks ("+" and "-") changes alternately whenever the title being pressed. And these marks are inside a WAI-ARIA "button" role, so the accessible name of this "button" changes too.But Firefox doesn't fire a name change event and thus JAWS doesn't read the new name on the button.

Comment 12

[James Teh [:Jamie]]

This is affecting people in the real world. See NVDA issues https://github.com/nvaccess/nvda/issues/9387 https://github.com/nvaccess/nvda/issues/1626. This is a problem for the Facebook Notifications button (and the fact that this misbehaves was one reason for an NVDA performance improvement being backed out); see https://github.com/nvaccess/nvda/pull/9114#issuecomment-467665494. A similar problem applies to aria-describedby; see https://github.com/nvaccess/nvda/issues/9400.

Both of these test cases demonstrate the problem and work in Chrome, but fail in Firefox:

Label change (pressing the button should fire a name change event):
data:text/html,<div id="label">a</div><button aria-labelledby="label" onClick="label.textContent = 'b';">foo</button>

Description change (pressing the button should fire a description change event):
data:text/html,<div id="desc">a</div><button aria-describedby="desc" onClick="desc.textContent = 'b';">label</button>

In both cases, NVDA's virtual buffer does not update with the correct info because the appropriate events aren't fired.

Comment 13

[alexander :surkov (:asurkov)]

Bug title feels too generic, because it's difficult to implement name change events whenever name is changed, but supporting aria-labelledby/described_by is doable. So I would change bug summary to reflect that. Regarding to implementation itself, it seems HasNameDependentParent logic should be extended to handle ID-referencing attributes.

Comment 14

[James Teh [:Jamie]]

Agreed. Thanks heaps for the implementation hint, Alex!

Comment 15

[James Teh [:Jamie]]

Attachment: Bug 493683 part 1: Rename HasNameDependentParent to HasNameDependent due to upcoming broader usage.

Comment 16

[James Teh [:Jamie]]

Attachment: Bug 493683 part 2: When an Accessible mutates, fire name change events on an Accessible labelled by it (or an ancestor thereof) via a relation.

HasNameDependent is now set on an Accessible (and thus its descendants) which has A LABEL_FOR relation.
When text mutations occur on such an Accessible, EventQueue::PushNameChange now queues a name change for the Accessible being labelled.

Comment 17

[James Teh [:Jamie]]

Attachment: Bug 493683 part 3: When an Accessible mutates, fire description change events on an Accessible described by it (or an ancestor thereof) via a relation.

This uses a similar approach to HasNameDependent, introducing a new HasDescriptionDependent.
However, we don't fire events on ancestors, since a description is never computed from an Accessible's own subtree without an explicit described by relation.

Comment 18

[James Teh [:Jamie]]

Attachment: Bug 493683 part 4: Add a PivotRule to match any local Accessible in the same document.

Comment 19

[James Teh [:Jamie]]

Attachment: Bug 493683 part 5: When aria-labell/describedby is set, set HasName/DescriptionDependent on the target subtree.

Comment 20

[James Teh [:Jamie]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=a0bfeb695d5c11df69dc42e761e05fd04d1431cd

Comment 21

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/12e73301de8f
part 1: Rename HasNameDependentParent to HasNameDependent due to upcoming broader usage. r=eeejay
https://hg.mozilla.org/integration/autoland/rev/24847760402f
part 2: When an Accessible mutates, fire name change events on an Accessible labelled by it (or an ancestor thereof) via a relation. r=eeejay
https://hg.mozilla.org/integration/autoland/rev/cefb1c1d3f5e
part 3: When an Accessible mutates, fire description change events on an Accessible described by it (or an ancestor thereof) via a relation. r=eeejay
https://hg.mozilla.org/integration/autoland/rev/2a3f24bdb8e2
part 4: Add a PivotRule to match any local Accessible in the same document. r=eeejay
https://hg.mozilla.org/integration/autoland/rev/2c9004c95a7a
part 5: When aria-labell/describedby is set, set HasName/DescriptionDependent on the target subtree. r=eeejay

Comment 22

[Sandor Molnar]

https://hg.mozilla.org/mozilla-central/rev/12e73301de8f
https://hg.mozilla.org/mozilla-central/rev/24847760402f
https://hg.mozilla.org/mozilla-central/rev/cefb1c1d3f5e
https://hg.mozilla.org/mozilla-central/rev/2a3f24bdb8e2
https://hg.mozilla.org/mozilla-central/rev/2c9004c95a7a