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Re: feedback requested on WAI CG Consensus Resolutions on Text alternatives in HTML 5 document

From: Steven Faulkner <faulkner.steve@gmail.com>
Date: Mon, 17 Aug 2009 11:48:41 +0100
Message-ID: <55687cf80908170348w1fc70cfei7a61daf972c52009@mail.gmail.com>
To: Maciej Stachowiak <mjs@apple.com>
Cc: Benjamin Hawkes-Lewis <bhawkeslewis@googlemail.com>, Ian Hickson <ian@hixie.ch>, HTMLWG WG <public-html@w3.org>, W3C WAI-XTECH <wai-xtech@w3.org>
here are a few more examples

<p id="chart1">As you can see from the chart below, sales increased in
2008:</p>
<img src="chart.png" aria-labelledby="chart1" aria-describedby="chart2">
<a href="#chart" id="chart2">full description of chart</a>



<p id="chart1">As you can see from the chart below, sales increased in
2008:</p>
<img src="chart.png" aria-labelledby="chart1" aria-describedby="chart2">
<table id="chart2"><caption>chart data</caption>
.....</table>



<p>As you can see from the chart below, sales increased in 2008:</p>
<img src="chart.png" alt="sales chart" aria-describedby="chart2">

<table id="chart2"><caption>chart data</caption>
.....</table>


regards
stevef

2009/8/17 Steven Faulkner <faulkner.steve@gmail.com>

> hi benjamin,
>  <p>As you can see from the chart below, sales increased in 2008:</p>
> <img alt="" src="chart.png">
>
> from my understaning this does not conform to WCAG 2.0.
> here is an example from wcag 2.0 of what is required.
>
> *"A data chart*
>
> A bar chart compares how many widgets were sold in June, July, and August.
> The short label says, "Figure one - Sales in June, July and August." The
> longer description identifies the type of chart, provides a high-level
> summary of the data, trends and implications comparable to those available
> from the chart. Where possible and practical, the actual data is provided in
> a table. "
>
>
> http://www.w3.org/TR/UNDERSTANDING-WCAG20/text-equiv-all.html#text-equiv-all-examples-head
> if an image contains complex information it should have some form of text
> alternative and should  be mapped to the accessibility API.
>
> some possible examples of achieving this
> <figure><p>As you can see from the chart below, sales increased in
> 2008:</p>
> <img  src="chart.png">
> <legend><a href="chart.html">full description of chart</a></legend>
> </figure>
>
> <p id="chart1">As you can see from the chart below, sales increased in
> 2008:</p>
> <img src="chart.png" aria-labelledby="chart1" aria-describedby="chart2">
> <a href="chart.html" id="chart2">full description of chart</a>
>
> regards
> stevef
>
> 2009/8/17 Maciej Stachowiak <mjs@apple.com>
>
>
>> On Aug 17, 2009, at 2:00 AM, Benjamin Hawkes-Lewis wrote:
>>
>> On 17/08/2009 09:42, Maciej Stachowiak wrote:
>>>
>>>> Would it be appropriate, in light of this, to add a user agent
>>>> requirement that an img with empty alt should not be mapped to
>>>> accessibility APIs at all?
>>>>
>>>
>>> Given the variety of authoring practice around "alt", I don't think that
>>> would be safe.
>>>
>>> In situations like:
>>>
>>> <a href="#"><img src="delete.png" alt=""></a>
>>>
>>> It's useful to AT for the "img" to be exposed and to be able to access
>>> "src" attributes for the purpose of providing a substitute for proper
>>> alternative text.
>>>
>>
>> If that's so, then wouldn't it be better for authors to use alt="" instead
>> of role="presentation", so that AT can decide whether it needs to expose the
>> image anyway? In particular, if your example was marked up like this:
>>
>> <a href="#"><img src="delete.png" role="presentation"></a>
>>
>> Then isn't it equally necessary and appropriate for AT to expose that
>> image?
>>
>> It seems like, based on this example, images should always be exposed to
>> accessibility APIs, and AT should make the call on whether it needs to
>> override the author-provided semantics.
>>
>> http://www.w3.org/TR/WAI-USERAGENT/guidelines.html#tech-missing-alt
>>>
>>> More tendentiously, perhaps, in situations like:
>>>
>>> <p>As you can see from the chart below, sales increased in 2008:</p>
>>> <img alt="" src="chart.png">
>>>
>>> Even if users can't consume the chart themselves, it's useful to users to
>>> be able to download or hotlink that referenced chart in a collaborative
>>> environment (e.g. a corporate wiki).
>>>
>>> By contrast:
>>>
>>> <img alt="" src="bullet.png">
>>>
>>> really is purely decorative; in a collaborative environment that seems
>>> likely to be generated by authoring software.
>>>
>>
>> And likewise for these examples - it seems like AT should be left free to
>> apply heuristics.
>>
>> Regards,
>> Maciej
>>
>>
>>
>
>
> --
> with regards
>
> Steve Faulkner
> Technical Director - TPG Europe
> Director - Web Accessibility Tools Consortium
>
> www.paciellogroup.com | www.wat-c.org
> Web Accessibility Toolbar -
> http://www.paciellogroup.com/resources/wat-ie-about.html
>



-- 
with regards

Steve Faulkner
Technical Director - TPG Europe
Director - Web Accessibility Tools Consortium

www.paciellogroup.com | www.wat-c.org
Web Accessibility Toolbar -
http://www.paciellogroup.com/resources/wat-ie-about.html
Received on Monday, 17 August 2009 10:49:24 UTC

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