- From: Richard Schwerdtfeger <schwer@us.ibm.com>
- Date: Tue, 20 Mar 2012 16:27:31 -0500
- To: public-html-a11y@w3.org
- Cc: jbrewer@w3.org, chuck@jumis.com, "Frank Olivier" <Frank.Olivier@microsoft.com>, cyns@exchange.microsoft.com, janina@rednote.net, david.bolter@gmail.com, faulkner.steve@gmail.com
- Message-ID: <OFD08303E9.59FEA0D5-ON862579C7.006F6FD7-862579C7.0075E079@us.ibm.com>
I was asked to review Ian's changes to the canvas 2D Context API and its impact on the accessibility issue for magnifiers, hit testing, and Frank Olivier's proposal: 1. Ian's change was only to introduce SVG's path functionality to Canvas. Standing on its own it does not address Issue-201 (http://www.w3.org/html/wg/tracker/issues/201) for supporting canvas hit testing and providing location information to assistive technologies. I don't know if an issue was logged to provide SVG Path support but it was discussed on the list. 2. His proposal is part of a collection of changes that Ian is working on that would impact these accessibility defects: http://wiki.whatwg.org/wiki/Canvas As I may have mentioned Steve Faulkner and I have been providing use cases to Ian and feedback on work he is doing to address Issue-201. You can see some of that on this page. That said, Ian has not made a direct change to the W3C spec. to address our defects nor has he submitted a change proposal to the working group for a new function addHitRegion(). That said, the change does impact Frank's proposal (http://www.w3.org/wiki/Canvas_hit_testing) and the work being done on the link, if submitted, would introduce a new web MVC mechanism to the Web that either non-WebKit-based or non-Chrome browsers does not support today. That would have accessibility implications. I will elaborate: 1. Frank's proposal assumed the using the current canvas path. Ian has introduced an entirely new path mechanism, that is a bit heavy weight, that was not there before. Frank's proposal would need to change to accommodate it, yet Frank stated Microsoft would not support it. - a conundrum. 2. When I was at TPAC a Google developer showed me new work he was doing on a new MVC model for the Web, similar to XBL, with a new model that could be bound to different rendering engines: SVG, Canvas, etc. This object model is separate from the DOM and I was told that this recently went into a Chrome trunk. The addHitRegion() function would allow for access to a separate model in that the element parameter is not required (See Ian's comments). None of the ATs, including Google Chrome make use of it today so introducing this mechanism would require a comprehensive accessibility effort as it is a DOM circumvention. Please read my comments on addHitRegion. Rich Rich Schwerdtfeger
Received on Tuesday, 20 March 2012 21:28:55 UTC