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Re: Please vote on the canvas accessibility proposal

From: Ian Hickson <ian@hixie.ch>
Date: Thu, 25 Feb 2010 09:58:39 +0000 (UTC)
To: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Cc: public-canvas-api@w3.org, "public-html-a11y@w3.org" <public-html-a11y@w3.org>
Message-ID: <Pine.LNX.4.64.1002250935280.20980@ps20323.dreamhostps.com>
On Thu, 25 Feb 2010, Silvia Pfeiffer wrote:
> 
> So, are we also saying that fallback inside the <canvas> should always 
> function as accessibility markup? If that is the case, then it means 
> that as soon as there is markup inside the <canvas>, we have support for 
> accessibility. End of story. don't read any further. :-)

That's more or less what I'm saying, yes, though more specifically, when 
there is content in the DOM inside <canvas>, rather than markup on the 
wire. What's important for ATs is what the DOM contains, and that can be 
different from what's on the wire -- a hopefully common case in the future 
will be for the page to have markup with legacy fallback, then the script 
detects <canvas> support and replaces it with focusable/accessible 
content. (This isn't done today since no browser actually supports this.)

Hence why adom="" is redundant -- the element's contents always fall into 
one of these buckets, all of which should be read to the user by ATs:

 - content is empty (reading has no effect)
 - content is accessible augmentation of <canvas>
 - content is the only accessible alternative to the <canvas>
 - there is no accessible alternative and the content says so

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Thursday, 25 February 2010 09:59:12 GMT

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