How do screen readers handle nested aria-live with aria-atomic?

StackOverflow https://stackoverflow.com/questions/22179824

Frage

How would a screen reader handle the case where you have an element with aria-live and aria-atomic inside another element with aria-live and aria-atomic and content changes inside the nested element?

Would it read both sections, reading the nested section twice?

HTML:

<div aria-live="polite" aria-atomic="true">
    Here is some text, <span>this itself may change</span>.  It is a large section of the page
    <div aria-live="polite" aria-atomic="true">
        This is another part of the page that may change, it is also large. <span>This part may change too</span>
    </div>
</div>

The reason I ask is because I am using AngularJS to make a SPA that needs to be ADA-compliant. The site has a nested layout scheme where inner sections of the page would be changed without changing outer sections, but the outer sections may change a one point. Ideally, I would want only the inner section to be read when it changes. When the outer section changes, it would read all of it, once.

War es hilfreich?

Lösung

Sorry, it's API specific:

Table of document change scenarios and events to be fired in each API

Scenario                MSAA + UIA Express event        MSAA + IAccessible2 event               ATK/AT-SPI event        Mac OS X Notification
When text is removed    EVENT_OBJECT_LIVEREGIONCHANGED  IAccessible2: IA2_EVENT_TEXT_REMOVED    text_changed::delete    If in a live region, AXLiveRegionChanged
When text is inserted   EVENT_OBJECT_LIVEREGIONCHANGED  IAccessible2: IA2_EVENT_TEXT_INSERTED   text_changed::insert    If in a live region, AXLiveRegionChanged
When text is changed    EVENT_OBJECT_LIVEREGIONCHANGED  IAccessible2: IA2_EVENT_TEXT_REMOVE     text_changed::delete    If in a live region, AXLiveRegionChanged
                                                        and IA2_EVENT_TEXT_INSERTED             and text_changed::insert

aria-atomic behavior is suggested:

User agents SHOULD check the chain of ancestor elements for aria-atomic="true". If found, user agents SHOULD set the RELATION_MEMBER_OF relation to point to the ancestor that sets aria-atomic="true".

aria-live behavior is as well:

User agents SHOULD ensure that an assistive technology, running in process can receive notification of a node being removed prior to removal. This allows an assistive technology, such as a screen reader, to refer back to the corresponding DOM node being deleted. This is important for live regions where removals are important. For example, a screen reader would want to notify a user that another user has left a chat room. The event in MSAA would be EVENT_OBJECT_HIDE. For ATK/AT-SPI this would be children_changed::remove. And in Mac OS X, the event is AXLiveRegionChanged. This also requires the user agent to provide a unique ID in the accessibility API notification identifying the unique node being removed.

References

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