Re: CP, ISSUE-30: Link longdesc to role of img [Was: hypothetical question on longdesc]

On Wed, Mar 21, 2012 at 7:55 AM, Charles Pritchard <chuck@jumis.com> wrote:
> On 3/20/2012 11:18 PM, John Foliot wrote:
>>
>> This is the very same reason why aria-describedby cannot point to "hidden"
>> text, as it too will be flattened to the same string text, using the same
>> computational rules.
>
>
> Can we get by with aria-describedby pointing to an embedded image tag?
>
> <video poster="poster.jpg" aria-describedby="poster"
> longdesc="videolongdesc.html" aria-label="My video">
> <a href="videolongdesc.html" title="My Video"><img id="poster"
> src="poster.jpg" longdesc="posterlongdesc.html" alt="My Poster" /></a>
> </video>
>
> We're pointing aria-describedby at an element with special semantics: img
> @longdesc, and it's not a display: none/@hidden element,
> so we're not violating any laws there... though I would have no expectation
> that the img could gain focus as fallback for video.

I think that is not going to work since:

1. Image descriptions need to accessible via mainstream browser UI and
ARIA is being implemented as an AT-only access mechanism.

2. Under the recent edits PFWG has been making, non-rendered fallback
for <video> would arguably fall under "Elements, including their
descendents, that have host language semantics specifying that the
element is hidden, such as CSS display:none or visibility:hidden or
HTML 5 hidden attribute". ("hidden" is not properly defined here ...
I've provided some feedback requesting it be defined.) Consequently
the @longdesc link would not be accessible even to AT.

    http://www.w3.org/WAI/PF/aria-implementation/#exclude-elements

--
Benjamin Hawkes-Lewis