W3C home > Mailing lists > Public > public-html@w3.org > October 2009

Re: ISSUE-30 (Longdesc) Change Proposal

From: Lachlan Hunt <lachlan.hunt@lachy.id.au>
Date: Tue, 27 Oct 2009 13:10:23 +0100
Message-ID: <4AE6E32F.3000206@lachy.id.au>
To: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Cc: "public-html@w3.org" <public-html@w3.org>
Leif Halvard Silli wrote:
>> On Mon, Oct 26, 2009 at 11:26 AM, Leif Halvard Silli
>>> Another argument for this feature is, I think (as have been mentioned
>>> earlier) that aria-describedby="" can be used for the same thing.
>
> I found Lachlan's comment in September: [1]
>
>> That would just be reinventing longdesc with a different name without
>> solving any of the problems that longdesc has.
>
> However, upon rereading, it seems like Lachlan was actually expressing
> satisfaction that describedby and longdesc has not been defined the same
> way. There are other comments in that same thread expressing similar
> things.

My take on longdesc is that it's badly designed for the problem it's 
trying to solve, and even aria-describedby is not ideal for addressing 
the cases where the description is in an external document.

I would rather see the problem of how to provide access to a long 
description in an external document addressed in a way that can utilise 
ordinary links, without introducing too much complexity.  There are 
several ways this could be achieved.

1. Making the image itself a link to its description:

<a href="desc.html" rel="longdesc"><img src="image" alt="..."></a>

The rel=longdesc attribute should be enough for ATs to identify the link 
as being a long description, and the fact that the image is inside the 
link should be enough to make the association.

It's also significantly easier than having to add an id and matching 
aria-describedby attributes, and is far more resistant to things like 
copy/paste errors, commonly seen with, e.g., the label/for attribute, 
and which is likely to occur with aria-describedby too.  (In fact, it's 
likely to occur more often with aria-describedby since, unlike 
label/for, there's no easy way to detect mismatched IDs/IDREFs).

2. If the image has a caption, including the link within that:

<figure>
   <img src="image" alt="...">
   <legend>Some caption here.  <a href="desc.html" rel="longdesc">More 
information</a>.</legend>
</figure>

(Using <legend> for now cause the dt/dd idea needs to be dropped and we 
don't have another alternative in the spec yet)

3. Using an adjacent link that shares the same parent as the image 
itself, and implying the association:

<p><img src="image" alt="..."> <a href="desc.html" rel="longdesc">More 
information</a></p>

This would need to have an implicit association algorithm defined to 
handle cases where there are more than one image and/or description links.

-- 
Lachlan Hunt - Opera Software
http://lachy.id.au/
http://www.opera.com/
Received on Tuesday, 27 October 2009 12:10:56 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Wednesday, 9 May 2012 00:16:51 GMT