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Re: Helping Canvas Tag Be Accessible

From: Steven Faulkner <faulkner.steve@gmail.com>
Date: Thu, 30 Jul 2009 14:23:20 +0100
Message-ID: <55687cf80907300623o3d050dffg111b95cd887719d5@mail.gmail.com>
To: Anne van Kesteren <annevk@opera.com>
Cc: Richard Schwerdtfeger <schwer@us.ibm.com>, HTML WG <public-html@w3.org>, W3C WAI-XTECH <wai-xtech@w3.org>
Hi Anne,
>>    A provision for equivalent alternative references that allow a canvas
>>    author to specify an alternative resource for drawing that cannot be
> >   made accessible through traditional API.

>This is already possible. Just include content between the two tags of the
element.

problem with this approach is its an extreme example of bolt-on
accessibility, and unikely to happen in many cases. What is required for
these cases is methods provided through the canvas API that automate the
production of the alternative content.

regards
steve


2009/7/30 Anne van Kesteren <annevk@opera.com>

> On Thu, 30 Jul 2009 14:50:45 +0200, Richard Schwerdtfeger <
> schwer@us.ibm.com> wrote:
> > In order to make canvas accessible we will need:
> >
> >    An object model to which authors can apply an accessibility API.
>
> Doesn't this defeat the whole idea of <canvas>? If you want an object model
> you could use SVG.
>
>
> >    A collection of callback interfaces that can be applied to objects to
> >    support an accessibility API mapping on each browser and platform and
> >    potentially a vehicle to fire events to ATs.
>
> I'm not quite I follow this point.
>
>
> >    A provision for equivalent alternative references that allow a canvas
> >    author to specify an alternative resource for drawing that cannot be
> >    made accessible through traditional API.
>
> This is already possible. Just include content between the two tags of the
> element.
>
>
> > [...] For those who do not know this WCAG 1 required that you be
> > accessible with Script and CSS turned off in the browser.
>
> <canvas> is still compatible with that model as fallback must be shown if
> JavaScript is disabled. Having said that, since JavaScript is part of the
> semantics of a page that seems like an odd restriction to make, though
> probably in line with best practices of its time.
>
>
> --
> Anne van Kesteren
> http://annevankesteren.nl/
>



-- 
with regards

Steve Faulkner
Technical Director - TPG Europe
Director - Web Accessibility Tools Consortium

www.paciellogroup.com | www.wat-c.org
Web Accessibility Toolbar -
http://www.paciellogroup.com/resources/wat-ie-about.html
Received on Thursday, 30 July 2009 13:24:04 UTC

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