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Re: Adaptive Image Element Proposal

From: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Date: Tue, 4 Sep 2012 23:53:57 +0200
To: Kornel Lesiński <kornel@geekhood.net>
Cc: public-html@w3.org
Message-ID: <20120904235357928237.5962baa3@xn--mlform-iua.no>
Kornel Lesiński, Tue, 04 Sep 2012 22:06:35 +0100:
> On Tue, 04 Sep 2012 21:41:49 +0100, Leif Halvard Silli  wrote:
> 
>> If we say that <picture> should have img role, then we imply that
>> alternative text should be provided via an attribute.
> 
> Why?

Because that is what ARIA 1.0 says about the img role: "In order for 
elements with a role of img be perceivable, authors
SHOULD provide alternative text or a label determined by the accessible 
name calculation." 

Note that I, by "via an attribute", also had aria-labelledby="*" and 
aria-describedby="*". 

But, OK ARIA says "should not" with regard to rendering children that 
have NOT been pointed out via aria-labelledby/aria-descriedby. So one 
should not say that it is completely ruled out that <picture> could 
have 'img' role even if etc. But I think role img do imply that 
alternative text should be provided via attributes, but that there 
could be exceptions.

>> This means that
>> AT will pick the alternative text from the img element, as long as they
>> don't support picture. Fine. But it also means that at the moment when
>> picture support is enabled, they will suddenly start to take the
>> alternative text from another element - picture.
> 
> Why? Can't we require UAs to take alt from content (fallback <img>) 
> even in that case? Basically behave *as if* there was alt on the 
> picture, but don't actually use `alt` attribute to implement that?

You mean, treat <img>’s @alt like the <caption> of <table>, for 
instance? That is: Make it <img> a required part of the <picture> 
construct, for instance? I do think that integrating <img> into 
<picture> as a part of the picture compound element, sounds 
interesting. And it could be possible, I guess. But is there advantage, 
do you think, in saying that <picture> should have role 'img'? If so, 
then AT would announce every <picture> the same way they announce <img> 
today. One could further make the role of the <picture> depend on the 
role of the <img>. E.g. if the <img> has empty alt, then the entire 
<picture> is presentational.

I am open to these thing - and the idea of make <img> an integrated 
part of <picture>, sounds interesting. But it looks to me as if we need 
to clarify to which degree we are limiting the role of mark-up if we 
pick the img role as the default role for the <picture>.

One thing to think about is this: If we e.g. have a <table> which we 
declare as presentational, then we also, per the ARIA rules, declare 
the elements that are part of the <table> construct of that particular 
table (<td>, <tr> etc) as presentational. So, if <img> was seen as part 
of <picture>, then, to declare <picture> as presentational would also 
affect the <img>.

I may over-thinking things here - your idea was perhaps much simpler ...
-- 
leif halvard silli
Received on Tuesday, 4 September 2012 21:54:31 UTC

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