W3C home > Mailing lists > Public > wai-xtech@w3.org > February 2009

Re: Example canvas element use - accessibility concerns

From: Robin Berjon <robin@berjon.com>
Date: Wed, 18 Feb 2009 16:16:12 +0100
Cc: Steven Faulkner <faulkner.steve@gmail.com>, HTML WG <public-html@w3.org>, W3C WAI-XTECH <wai-xtech@w3.org>, Janina Sajka <janina@rednote.net>
Message-Id: <6BCFD6B6-D6AC-4220-B941-0E7EBD9EB33C@berjon.com>
To: Philip Taylor <pjt47@cam.ac.uk>
On Feb 18, 2009, at 15:52 , Philip Taylor wrote:
> The main problem I see with adding built-in (as opposed to bolt-on)  
> accessibility to canvas is that I can't even begin to imagine any  
> way that could ever possibly work at all :-). That may be largely  
> because my imagination is limited - I'd be interested in concrete  
> suggestions of how it could be done. Otherwise I can't think of  
> anything the spec could say to help accessibility here.

Well the canvas text API gets text in, so it's possible that one could  
get text out. The problem is: in what order. There are various  
heuristics that could be used (the order in which it's drawn, its  
rendered distance from the origin, or other more elaborate  
approaches). I'm not saying it's ideal, or even the right thing to do,  
but there certainly is information being provided by the developer to  
the canvas API that could be exposed to AT.

There could, furthermore, be additional pushAnnotation(string)/ 
popAnnotation() calls added to the API that could provide alternative  
text information about what is being painted. Again, I'm not sure that  
that's a good idea, I'm just indicating that there /might/ be options.

Since Bespin is designed largely as an experiment (even if it is meant  
to continue) it might just be the right place/occasion to have such  

At first thought I would tend to consider that a good first step would  
be to write an authoring guide providing guidance as to when to use  
canvas and when to use something else.

Robin Berjon - http://berjon.com/
     Feel like hiring me? Go to http://robineko.com/
Received on Wednesday, 18 February 2009 15:16:50 UTC

This archive was generated by hypermail 2.3.1 : Tuesday, 6 January 2015 21:51:39 UTC