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Re: Drop longdesc, get aria-describedat?

From: Janina Sajka <janina@rednote.net>
Date: Tue, 13 Mar 2012 19:35:51 -0400
To: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Cc: Charles McCathieNevile <chaals@opera.com>, Richard Schwerdtfeger <schwer@us.ibm.com>, W3C WAI-XTECH <wai-xtech@w3.org>, HTML Accessibility Task Force <public-html-a11y@w3.org>
Message-ID: <20120313233551.GD4810@sonata.rednote.net>
Well, there's certainly no reason you need to accept my word on any of
this. File a bug if you think it's a bug. That's the responsible thing
to do, no?

Janina

Leif Halvard Silli writes:
> 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)
> > 
> > 

-- 

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 23:36:41 UTC

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