Re: Drop longdesc, get aria-describedat?

To look blindly at 'calculation' is also to miss a point: You have 
defined what an 'img' role is. You could have said that 'img' element 
might also have 'description links', but that you have not defined what 
a 'description links' precisely is and precisely how it is handled, in 
the current version of ARIA.

Leif Halvard Silli

Janina Sajka, Tue, 13 Mar 2012 18:47:12 -0400:
> You're missing my point.
> 
> There's no calculation relating to longdesc because there's no need for
> it. As I keep reminding everyone, ARIA-DescribedAT does not exist.
> There's no need to define rules for what to use, because there's no
> competing ARIA markup that serves the use case of HTML's longdesc.
> 
> In the future, when we have an ARIA-DescribedAT, we will undoubtedly
> need to say something here. But, that day has not dawned.
> 
> Meanwhile, ARIA-LabeledBy, -DescribedBy, etc., etc., all figure in alt
> text. For this there is indeed the need to consider precedence, which
> our doc attempts to do at great detail--because this calculation is
> important.
> 
> PS: This should actually serve as further evidence that ARIA-DescribedBy
> isn't about long text alternatives but rather about short text
> alternatives, about that attribute known as "alt text" in html.
> 
> Janina
> 
> Leif Halvard Silli writes:
>> Janina Sajka, Tue, 13 Mar 2012 15:15:24 -0400:
>> 
>>>> ARIA defines where @title and @alt fits in in ARIA: In the accessible 
>>>> name. But ARIA does not explain where the longdesc link - or if you 
>>>> wish: an image with a longdesc - fits in.
>>>> 
>>> So?
>>    [ snip ]
>>>> However, while, ARIA expects AT to say 'image' if the element has 
>>>> role=img, and expects the accessible name to be presented as the 
>>>> content of the image, it  does not explain when and where the mere 
>>>> presence of a longdesc should be conveyed to the user. ARIA is silent. 
>>>> And makes no implicit expectations.
>>>> 
>>> No reason we should. You still haven't made the case that we are
>>> obligated to do this, or that we have a reason to do it.
>> 
>> That compelling reason, is found in the description of the img role: [1]
>> 
>>    "An img can contain captions and descriptive text, as well as 
>> multiple image files that when viewed together give the impression of a 
>> single image." 
>> 
>> Further more the characteristics section links to IMG in HTML4 and 
>> IMGGROUP in DTB. The later consist of one or more IMG, and each IMG may 
>> contain longdesc.]
>> 
>> Hence, many in the readership of ARIA 1.0, will assume that 'img' here 
>> is linked to HTML, whose image element is named <img>. And thus, that 
>> 'img' is formulated after the model of <img>. And so I ask: Where is 
>> HTML4's @longdesc in that description?  And where is it said that one 
>> might actually also find a description link inside an 'img'? The 'img' 
>> model of ARIA simply looks incomplete. [I had similar input during your 
>> last call too, but ...]
>> 
>>> From the accessible name calculation section and from other places in 
>> ARIA 1.0, it is further clear that an role 'img' element, from an AT 
>> perspective, only contains 'author' provided content. Thus: No 
>> 'contents' content. [For other readers: 'Author' content refers to 
>> contend specified via attributes: alt, title, aria-label, 
>> aria-labbelledby, aria-describedby. The clue is that AT only presents 
>> to the user such content that is explicitly referred to - or contained 
>> - in the designated attributes. ]
>> 
>> And so I ask: Is @longdesc 'author' provided content or 'contents'? It 
>> is clearly author provided - it contains a 'human inserted' URL. And 
>> so, from that perspective, it fits right into ARIA's model of 'img'. 
>> The only - somewhat dull - issue, is that @longdesc does not contain an 
>> author provided 'link text'. Only an author provided URL. It is an 
>> on/off thing: It is the author who adds it, or not. And then there is a 
>> standard presentation of that link.
>> 
>> The description of the 'img' role, also says: 
>> 
>>    "In order for elements with a role of img be perceivable, authors 
>> SHOULD provide alternative text or a label determined by the accessible 
>> name calculation." 
>> 
>> Which makes me ask: What about a link to a longer description for the 
>> image? SHOULD or MAY authors provide that? Do some images need - or not 
>> - a long, independent description in order to be perceivable?
>> 
>> Apparently, the ARIA task force *did* think that one description links 
>> are sometimes needed, because one or two ARIA specs/guides tell/told 
>> how one can use @aria-describedBY plus an anchor element to do that ... 
>> However the very description of the 'img' role, does not mention it ...
>> 
>>>> An image with longdesc indicates 'complex data image'. Hence, it seems 
>>>> logical with an early announcement about the presence the longdesc.
>>>> 
>>> Complex data? Maybe. Maybe not. Maybe it's a painting by Raphael. I
>>> would not characterize a long description of a painting as data
>>> structure.
>> 
>> Right. I should have skipped 'data' and only said 'complex' - or said 
>> 'complex or data filled'.
>> 
>> My main point here, was *early announcement*, so the user can choose to 
>> go for the long description instead of having to listen to the short - 
>> but possibly still long - alternative text. Longdesc is binary thing: 
>> Either it exist, or it doesn't. And so, its presence says something 
>> about the 'nature' of the element. That is why I likened to a sort of 
>> role. And something to be announced early.
>> 
>> Also, I think it is correct to say that *the author* [remember: 
>> 'author' provided content] consider the 'img' to be complex. The author 
>> decides what the 'img' needs. May be the 'img' doesn't contain so much 
>> 'data'. But the author still considers that an independent description 
>> is warranted, in order to go deep enough into its complexity.
>> 
>> [1] http://www.w3.org/TR/wai-aria/complete#img
>> -- 
>> leif halvard silli
> 
> -- 
> 
> Janina Sajka,	Phone:	+1.443.300.2200
> 		sip:janina@asterisk.rednote.net
> 
> Chair, Open Accessibility	janina@a11y.org	
> Linux Foundation		http://a11y.org
> 
> Chair, Protocols & Formats
> Web Accessibility Initiative	http://www.w3.org/wai/pf
> World Wide Web Consortium (W3C)
> 
>

Received on Tuesday, 13 March 2012 23:28:37 UTC