- 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>
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