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RE: Image description extension review

From: David MacDonald <david100@sympatico.ca>
Date: Sat, 17 Nov 2012 07:03:59 -0500
Message-ID: <BLU0-SMTP29227A1E0C27C2A207A4A7FE500@phx.gbl>
To: "'Charles McCathie Nevile'" <chaals@yandex-team.ru>, <public-html-a11y@w3.org>, 'Léonie Watson' <tink@tink.co.uk>
Hi Chaals

 

I put up a test page:

http://www.davidmacd.com/test/longdesc.html

 

-JAWS 13 doesn’t support longdesc on the same page in IE9,

- JAWS 13 and FF14, neither example opens. 

-JAWS 13 in Chrome 23.0.1271.64m: Neither example opens.

 

> I think there is a lot of advice to use null alt text for decorative images. But there is reason such images should not have a longdesc.

 

I think we have our wires crossed. I was commenting on your first example:

 

<!-- pointing to something internal to the page -->
<img src="http://example.com/image" alt="" title="photo" longdesc="#photo1">

 

My concern is that the example is using null alt text on a non-decorative image. There is currently no precedence for that, I would suggest. Current practice is to provide a short description AND a long description for images requiring long description. This is what is done in example H45 in WCAG.

 

Cheers

David MacDonald

 

CanAdapt Solutions Inc.

  "Enabling the Web"

 <http://www.can-adapt.com/> www.Can-Adapt.com

 

From: Charles McCathie Nevile [mailto:chaals@yandex-team.ru] 
Sent: November-17-12 3:12 AM
To: public-html-a11y@w3.org; 'Léonie Watson'; David MacDonald
Subject: Re: Image description extension review

 

On Fri, 16 Nov 2012 22:38:57 +0100, David MacDonald <david100@sympatico.ca> wrote:

Hi Chaals

 

On the call you had mentioned that longdesc pointing to an anchor on the same page is included in the HTML4 spec. I’m sorry but I’m unable to find any reference or example in HTML 4 of Longdesc referring to information (an anchor id) on the same page.

 

It's a URI - a link. That can be relative or absolute, including pointing to something else in the same page. It's common practice to have links to somewhere else in a page. There is very little in the HTML 4 spec about the precise mechanics of the link. But my testing showed that browsers which implemented longdesc assumed it should work for all URIs including links within the page.

 

 Nor can I find any recommended advice to use null alt text (alt=“”) on an image that has a longdesc...

 

I think there is a lot of advice to use null alt text for decorative images. But there is reason such images should not have a longdesc.

 

Nor are there any example techniques in WCAG showing this use of longdesc or of null alt text.

http://www.w3.org/TR/2012/NOTE-WCAG20-TECHS-20120103/H45

 

If I get time I can offer some.

 

In 10 years on the WCAG team and weekly calls, I’ve never heard this use case of Longdesc discussed, nor in 14 years in the field have I ever seen it done.

 

OK. I've done it, but I can't think of any examples I have available in public.

 

I’m fine with the longdesc extension... but I think we either need to demonstrate that this use case exists in the real world and is in HTML4,

 

The use case of longdesc within a page? There have been arguments raised many times that longdesc is deficient because it doesn't allow for this use case (which is simply untrue). If the people who are opposed to longdesc think this use case is important, that's good enough for me.

 

As for the use case of long description fora  purely decorative image, I think that's easy to establish. And it is already accepted that such images should have null alt. The interesting point that perhaps we should make in the spec is to consider this case when ensuring discoverability.

 

cheers

 

Chaals

 

or we have to acknowledge that it’s a new behaviour for Longdesc.  I also don’t think we should introduce null alt text for anything but decorative images... so far automated checkers rightly flag null alt text to ensure it’s purely decorative... in the future we may need to expand the use of null alt text for cases when there is another type of text alternative such as figcaption, aria-describedby, longdesc, etc.. but I don’t think such a precedence currently exists.

 

HTML4 references

http://www.w3.org/TR/REC-html40/struct/objects.html#adef-longdesc-IMG

http://www.w3.org/TR/REC-html40/struct/objects.html#adef-alt

http://www.w3.org/TR/REC-html40/appendix/notes.html#accessibility

 

 

 

Cheers

David MacDonald

 

CanAdapt Solutions Inc.

  "Enabling the Web"

www.Can-Adapt.com <http://www.can-adapt.com/> 

 

From: Charles McCathie Nevile [mailto:chaals@yandex-team.ru] 
Sent: November-15-12 9:08 PM
To: public-html-a11y@w3.org; Léonie Watson
Subject: Re: Image description extension review

 

On Fri, 09 Nov 2012 21:41:55 +0100, Léonie Watson <tink@tink.co.uk> wrote:

Hello,

 

A few thoughts, mostly editorial.

 

Mostly I've adopted or adapted your suggestions.  

 

Introduction...

 

The code examples all have null alt attributes. Could they be more practical examples?

 

Actually only one had a null value, the others had something but in parentheses so I removed them and cleaned them a tiny bit. I'd be happy for people to propose better examples...

 

Also wonder whether some best practice examples of longer descriptions would be helpful? The extension may not be the right place for them, but a separate note might do the trick.

 

Steve also suggested this. For now I put it in a note as out of scope, with a question about whether it would make sense to link to some other document...

 

Thanks for the review. I updated the document: http://dvcs.w3.org/hg/html-proposals/raw-file/default/longdesc1/longdesc.html

 

cheers

 

Chaals

 

-- 

Charles McCathie Nevile - Consultant (web standards) CTO Office, Yandex
chaals@yandex-team.ru Find more at http://yandex.com





-- 

Charles McCathie Nevile - Consultant (web standards) CTO Office, Yandex
chaals@yandex-team.ru Find more at http://yandex.com
Received on Saturday, 17 November 2012 12:04:43 UTC

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