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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.
>>      

http://www.filamentgroup.com/lab/creating_accessible_charts_using_canvas_and_jquery/

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

http://www.andrewwooldridge.com/canvas/canvasquest/canvasquest.html

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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