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
>
>
> 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