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Re: A presentational img?

From: Steve Faulkner <faulkner.steve@gmail.com>
Date: Tue, 10 May 2011 19:20:22 +0100
Message-ID: <BANLkTin8War5rZEM4OA3CrnU-5WefSe=pA@mail.gmail.com>
To: James Craig <jcraig@apple.com>, Richard Schwerdtfeger <schwer@us.ibm.com>
Cc: W3C WAI-XTECH <wai-xtech@w3.org>
hi james, just a point of clarification:

an <img> without alt is not mapped to role=presentation in HTML5

only <img alt="">

regards
stevef

On 10 May 2011 18:54, James Craig <jcraig@apple.com> wrote:

> On May 10, 2011, at 7:16 AM, Leif Halvard Silli wrote:
>
> > as VoiceOver developer and as WAI-ARIA editor,
>
> Well, since you asked it like that: The following opinions are my own and
> do not necessary represent the views of my employer, nor do they represent
> group consensus within the ARIA subteam of the PFWG.
>
> > is it in your view
> > correct to treat the following image as non-presentational?
> >
> > <img alt="" title="Advicory text" src="i" />
> >
> > VoiceOver currently does treat it as non-presentational and reads the
> > @title to the user. Ahis seems correct to do, from my POV. The
> > background for my question is found int Bug 12587 against HTML5. [1]
> >
> > [1] http://www.w3.org/Bugs/Public/show_bug.cgi?id=12587
>
> In my opinion, the presentation state would only apply if one of the
> following were true:
>
>  the author explicitly provided a role of presentation on the img tag,
> <img role="presentation">
>  the host language labeling mechanism (in this case @alt) equaled an empty
> string, *AND* the ARIA text alternative computation [1] equaled an empty
> string.
>
> The ARIA spec does *NOT* limit the ability of assistive technologies to use
> heuristic to determine the text alternative of an image with missing
> alternative text. Sometimes these heuristics fall back to image file name
> substrings on standalone images, or link path substring on linked images.
> For example, some assistive technologies will determine the following
> alternative text from the following markup (that is invalid in HTML4 b/c of
> the missing @alt)
>
> "contact": <img src="contact.png">
> "about us": <a href="/path/about_us.html"><img src="contact.png"></a>
>
> Perhaps if the HTML editors were to standardize the heuristic mechanism
> above, the accessibility advocates in the HTML group would be appeased. As
> is, it's unacceptable to state that these images are presentational, because
> it is in the best interest of the spec editors, browser vendors, AT users,
> and AT vendors to make sure rendering engines provide the most accessible
> output, even with the worst possible markup:
>
> <img src="asdfhjklafds_gibberish_12347612394786.png">
>
> W3C process requires that, in order for HTML 5 to reach Candidate
> Recommendation phase, the Working Group will have to prove on each part of
> the spec, that two rendering engines have implemented the requirement.
> Despite what is currently in the HTML 5 spec, I don't believe any of the
> major browser vendors will decrease the accessibility of their rendering
> engines in order to make <img src="contact.png"> presentational, because it
> would be a user interface regression.
>
> And again, these opinions are my own and do not necessary represent the
> views of my employer, nor do they represent group consensus within the ARIA
> subteam of the PFWG.
>
> Cheers,
> James
>
> 1. ARIA text alternative computation:
> http://www.w3.org/TR/wai-aria/complete#textalternativecomputation
>
>
>


-- 
with regards

Steve Faulkner
Technical Director - TPG

www.paciellogroup.com | www.HTML5accessibility.com |
www.twitter.com/stevefaulkner
HTML5: Techniques for providing useful text alternatives -
dev.w3.org/html5/alt-techniques/
Web Accessibility Toolbar - www.paciellogroup.com/resources/wat-ie-about.html
Received on Tuesday, 10 May 2011 18:27:34 UTC

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