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Re: "Where's the Beef?" department (was RE: Example canvas element use - accessibility concerns)

From: Rob Sayre <rsayre@mozilla.com>
Date: Tue, 24 Feb 2009 20:29:45 -0500
Message-ID: <49A49F09.4090804@mozilla.com>
To: Jonas Sicking <jonas@sicking.cc>
CC: "John Foliot - WATS.ca" <foliot@wats.ca>, HTML WG <public-html@w3.org>, W3C WAI-XTECH <wai-xtech@w3.org>
On 2/24/09 7:40 PM, Jonas Sicking wrote:
> On Tue, Feb 24, 2009 at 4:15 PM, John Foliot - WATS.ca<foliot@wats.ca>  wrote:
>> I challenge you to show us *one* example of<canvas>  in the wild that
>> attempts to even consider accessibility, never-mind actually achieve any
>> modicum of accommodation or equivalency.


It doesn't use the children of the canvas element, though. More below.

>> In the grand tradition of WHAT WG
>> the burden of proof rests in your corner - show us that developers using
>> <canvas>  today have taken the "suggestion" of ensuring that accessible
>> fallback is present - I mean, after all, it *is* in the spec.
> Isn't the question at hand here: would saying MUST rather than SHOULD
> result in more sites being accessible?

Interestingly, most examples with fallback I could find use the children 
of the canvas element to send messages about browser support. One example is


That tells me that the HTML5 has mixed accessibility and browser support 
concerns in specifying the fallback content for <canvas>.

Beyond that, many of the <canvas> elements I did find were created with 
JavaScript after the page loaded. That tells me that a validator without 
JavaScript support isn't going to help much with this element.

I don't have a good way quantifying or searching for data on this. Sorry.

- Rob
Received on Wednesday, 25 February 2009 01:30:40 UTC

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