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RE: Request for advice on <canvas> accessibility

From: Steve Faulkner <sfaulkner@paciellogroup.com>
Date: Fri, 10 Jul 2009 10:43:45 +0100
To: "'Ian Hickson'" <ian@hixie.ch>, "'W3C WAI-XTECH'" <wai-xtech@w3.org>, "'HTMLWG WG'" <public-html@w3.org>
Cc: "'James Craig'" <jcraig@apple.com>, "'Steven Faulkner'" <faulkner.steve@gmail.com>, "'Joshue O Connor'" <joshue.oconnor@cfit.ie>, "'Catherine Roy'" <ecrire@catherine-roy.net>, "'Debi Orton'" <oradnio@gmail.com>, "'Gez Lemon'" <gez.lemon@gmail.com>, "'Jason White'" <jason@jasonjgw.net>, "'John Foliot'" <foliot@wats.ca>, "'Laura Carlson'" <laura.lee.carlson@gmail.com>, "'Leif Halvard Silli'" <lhs@malform.no>, "'Patrick H. Lauke'" <redux@splintered.co.uk>, "'Philip TAYLOR'" <p.taylor@rhul.ac.uk>, "'Robert J Burns'" <rob@robburns.com>, "'Roger Johansson'" <roger@456bereastreet.com>, "'Shelley Powers'" <shelleyp@burningbird.net>
Message-ID: <00db01ca0142$eb385f90$c1a91eb0$@com>
Hi Ian, 
>How can I help?

The discussion on IRC last night was useful
http://krijnhoetmer.nl/irc-logs/whatwg/20090710#l-8, in that it started to
grapple with the issues of providing methods to allow developers to provide
objects in canvas with built in interaction behaviours, something they could
use in their course of their development without having to think about how
to add accessibility.

> Is there 
>some way to follow the WAI's work on this? What is the process by which 
>the WAI can provide advice on such topics?

Discussion will occur on wai-xtech and public html lists
Though I think that the technical progress will come more from those such as
yourself who have the most expertise in engineering HTML.

>I'm certainly happy to look at other cases also. The main reason I 
>suggested the HTML5 issues list graph:
>http://www.whatwg.org/issues/data.html

Problem with this example as i previously pointed out is that it is not
interactive, it essentially an image of a graph. Frankly I am surprised that
you would need somebody to tell you how to make the graph more accessible.
The answer to making this accessible is to provide the data in html format
marked up as a data table. And yes this involves duplication, but in this
case it is probably the best option. I don't think that it will be possible
in every case to provide accessible canvas content without duplication. I
envisage the answer will in many circumstances involve a mix of built in and
bolt on. But the more built in that can be provided will make it more
probable that canvas content will be accessible.

>...is that it isn't a demo, so if there is anything that can be done to 
>make it accessible, I'd like to do that, so that the graph is actually 
>more accessible.

It is a demo of a UI control that is being considered for use in Bespin
implemented via canvas, I provided it as it a simple example of the issue.
That demonstrates important aspects of the issue that your example does not.

The example i posted yesterday http://tools.mozilla.com/ is not a demo and
provides another example of a canvas containing interactive elements.



>> 3. rephrase the question:  what would need to be added to the canvas API 
>> so that the UI controls in the example could have programmtic focus 
>> (like an area on an image map) and name, role and state information 
>> exposed to accessibility APIs, without expecting the author to 
>> completely recreate the UI controls in HTML.

>I think this is definitely one of the things that would need addressing, 
>yes.

I am pleased we have your agreement on this.

Regards
stevef

-----Original Message-----
From: Ian Hickson [mailto:ian@hixie.ch] 
Sent: 10 July 2009 00:10
To: W3C WAI-XTECH; HTMLWG WG
Cc: James Craig; Steven Faulkner; Joshue O Connor; Catherine Roy; Debi
Orton; Gez Lemon; Jason White; John Foliot; Laura Carlson; Leif Halvard
Silli; Patrick H. Lauke; Philip TAYLOR; Robert J Burns; Roger Johansson;
Shelley Powers; Steve Faulkner
Subject: Re: Request for advice on <canvas> accessibility

On Fri, 26 Jun 2009, James Craig wrote:
> 
> I, admittedly, haven't thought about this problem in depth, but it seems 
> that canvas (or any DOM element for that matter) could be special-cased 
> to allow a programmatic representation of the data displayed, along with 
> an any relevant accessibility information and interaction methods. I 
> have no ideas for how to make this "automatic" like you request, but I'm 
> sure we can come to a reasonable solution that would allow 
> accessibility-conscious authors to make their canvas-based applications 
> accessible.

On Sat, 27 Jun 2009, Joshue O Connor wrote:
> 
> Good stuff Ian. It will be great for us to get our heads together and 
> work this one out. It is a fantastic challenge and opportunity for 
> closer collaboration :-)

How can I help? I really don't know how to approach this problem, and I 
really would like the input of the WAI groups on this matter. Is there 
some way to follow the WAI's work on this? What is the process by which 
the WAI can provide advice on such topics?


On Sat, 27 Jun 2009, Steven Faulkner wrote:
> 
> I would suggest 3 things:
> 
> 1. For a problem that has stumped you we need as much technical 
> expertise as is possible, so have included the HTML WG in this email.

Oops; I intended to do so, my apologies.


> 2. we use an example that embodies the problem: 
> http://people.mozilla.com/~jdicarlo/piemenus.html contains 2 examples of 
> UI controls rendered using canvas.

I'm certainly happy to look at other cases also. The main reason I 
suggested the HTML5 issues list graph:

   http://www.whatwg.org/issues/data.html

...is that it isn't a demo, so if there is anything that can be done to 
make it accessible, I'd like to do that, so that the graph is actually 
more accessible.


> 3. rephrase the question:  what would need to be added to the canvas API 
> so that the UI controls in the example could have programmtic focus 
> (like an area on an image map) and name, role and state information 
> exposed to accessibility APIs, without expecting the author to 
> completely recreate the UI controls in HTML.

I think this is definitely one of the things that would need addressing, 
yes.

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Friday, 10 July 2009 09:44:49 UTC

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