W3C home > Mailing lists > Public > public-html-a11y@w3.org > September 2010

RE: use of aria-hidden to provide a text description not visible on the page.

From: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Date: Wed, 15 Sep 2010 02:06:27 +0200
To: "Gunderson, Jon R" <jongund@illinois.edu>
Cc: 'W3C WAI-XTECH' <wai-xtech@w3.org>, 'HTML Accessibility Task Force' <public-html-a11y@w3.org>
Message-ID: <20100915020627632938.cc6e9b98@xn--mlform-iua.no>
Gunderson, Jon R, Tue, 14 Sep 2010 16:21:56 -0500:
> I believe the intent of aria-hidden was to hide information that IS 
> presented visually from the accessibility API.

If by "visually" you mean "not display:none", then yes. An element can 
appear hidden without having display:none. If you add aria-hidden=true 
to such an element, then to a user of ARIA supporting AT, the element 
will be hidden (but could, nevertheless and in the right context, be 
accessible, provided that you point to from the element in need of 
label/description with aria-labelledby/aria-describedby).

>  For example an image 
> that is used to indicate the state of a tree leaf does not need to be 
> part of the accessibility tree if aria-expanded state is being used.
> 
> This way any aria- enabled technology would ignore the ALT text of 
> the image, and assistive technology that is not ARIA aware could may 
> use the ALT content of the image to describe state.

Another way which ARIA allows you do this, is by making sure the <img> 
is considered presentational - then its @alt is hidden. You could do it 
this way:

<img role="presentation" src=img alt="State info for un-ARIA-aware">

Or, for example, this way - where ARIA supporting AT SHOULD make the 
child element(s) invisible, unless you point to them via 
aria-labelledby/aria-describedby:

<span role=img >
   <img src=img alt="State informatino for not ARIA aware">
</span>

The latter way allows both ARIA-compatible and not ARIA-compatible UAs 
to see it as an image.

If the feature is visual to all, then I believe ARIA suggests that yo 
dou not use aria-hidden.
-- 
leif halvard silli
Received on Wednesday, 15 September 2010 00:07:04 UTC

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