W3C home > Mailing lists > Public > public-html-a11y@w3.org > February 2010

Re: Please vote on the canvas accessibility proposal

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Wed, 24 Feb 2010 09:17:28 +1100
Message-ID: <2c0e02831002231417w65589c9dge8f6ce53003312b2@mail.gmail.com>
To: Steven Faulkner <faulkner.steve@gmail.com>
Cc: "public-html-a11y@w3.org" <public-html-a11y@w3.org>, public-canvas-api@w3.org
Hi Steven,

Thanks for your continuing patience in explaining. Sorry I have to
keep asking since it seems to me that if there is an issue with
canvas, the same issues apply to fallback in the video element, right?

On Wed, Feb 24, 2010 at 2:13 AM, Steven Faulkner
<faulkner.steve@gmail.com> wrote:
> if the content of the canvas sub tree is exposed to AT and focusable
> elements are included in the tab order, by default, then regardless of what
> browser an AT user has they will get get this content. Regardless of what
> relationship any interactive content has to the canvas content, keyboard
> only users will be able to tab into and interact with focusable elements.
> So for example if I am a keyboard only user and encounter  a canvas element
> that includes a link or 2 links or many that are not associated with the
> displayed canvas, because they are "fallback" then focus will be lost to the
> users,  end result= confusion

Is this because the AT doesn't support the canvas element yet? I would
think that it is expected of AT that supports HTML5 markup to ignore
"fallback" on an element that only applies to legacy browsers.

Or even stronger: the browser that supports the canvas element should
not make the fallback content available, or accessible through the tab
order. If it is I would regard that as a bug in the browser
implementation, no?

I actually just tested this in Firefox 3.7a2pre on a video element.
The fallback content - even if it has a link (a element) and a
tabindex on the link - doesn't become part of the tab order. I would
think that the canvas is working the same way, or should, if one of
the browsers hasn't implemented it this way yet.

> or  I am an AT user accessing the page *using* Firefox, I encounter the
> message "your browser does not support canvas get Firefox" end
> result=confusion.

This is what I don't understand. If it is a modern Firefox, then this
message should not ever be displayed, not on screen and not to AT. Can
you explain?

Thanks for helping me understand.

Best Regards,
Received on Tuesday, 23 February 2010 22:18:27 UTC

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