Re: Proposal: Canvas accessibility and a media querries approach for alternative content (Action Item 6 in the HTML Accessibility Task Force)

Rich Schwerdtfeger
Distinguished Engineer, SWG Accessibility Architect/Strategist

public-canvas-api-request@w3.org wrote on 01/20/2010 06:40:50 AM:

> Ian Hickson <ian@hixie.ch> 
> Sent by: public-canvas-api-request@w3.org
> 
> 01/20/2010 06:40 AM
> 
> To
> 
> Steven Faulkner <faulkner.steve@gmail.com>
> 
> cc
> 
> public-canvas-api@w3.org, HTML WG <public-html@w3.org>
> 
> Subject
> 
> Re: Proposal: Canvas accessibility and a media querries approach 
> for  alternative content (Action Item 6 in the HTML Accessibility Task 
Force)
> 
> On Wed, 20 Jan 2010, Steven Faulkner wrote:
> > 
> > >The click fires on the <canvas>, and the script is responsible for 
> > >propagating the click to the link to cause the navigation (the UA has 

> > >no idea that it corresponds to the <a>, so it can't happen 
> > >automatically).
> > 
> > so if the script propagates the click to the link element, it would 
seem 
> > that the content of the canvas element should no longer be considered 
> > 'fallback' as interaction and resulting actions are routed through the 
a 
> > element in the canavas element for all users not only those with 
> > disabilites.
> > 
> > >On the other hand, if the user hits enter while the link is focused, 
> > >the event goes to the link and the UA does the navigation 
> > >automatically.
> > 
> > so if the link is focused and the user clicks on the region within the 

> > focus rectangle then the click will pass to the link without the need 
> > for the script?
> 
> That is not what I said, no.
> 
> I'm not sure how to phrase what I said more clearly. To clarify, if I 
may: 
> "click" is a mouse gesture, "hit enter" is a keyboard gesture. These are 

> different input devices with different resulting DOM events. Click 
events 
> are targetted based on the coordinates of the mouse cursor. Keyboard 
> events are targetted based on the current focus.
> 
Absolutely. All click events to the canvas must be processed by a mouse 
handler and manipulate the shadow DOM. The code simply needs to know the 
association between the drawing objects in the canvas area and the shadow 
DOM. The software will, in fact, know what defines a clickable area and 
should be able to make the association. It is more work but it can be 
done.

> HTH,
> -- 
> Ian Hickson               U+1047E                )\._.,--....,'``.    fL
> http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
> Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
>