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Re: hit testing and retained graphics

From: Charles Pritchard <chuck@jumis.com>
Date: Thu, 07 Jul 2011 07:07:05 -0700
Message-ID: <4E15BD89.1040506@jumis.com>
To: paniz alipour <alipourpaniz@gmail.com>
CC: Richard Schwerdtfeger <schwer@us.ibm.com>, cyns@exchange.microsoft.com, david.bolter@gmail.com, franko@microsoft.com, Mike@w3.org, public-canvas-api@w3.org, public-canvas-api-request@w3.org, public-html@w3.org, public-html-a11y@w3.org
If the developer does not use the Shadow DOM to include the checkbox element
then the Canvas app will not be accessible to ATs; the user will not be 
able to
use their keyboard to set focus to the checkbox element, though the app
can still be used with a keyboard, the UA and OS will not know
that the user has focused on a checkbox element.

There are some special cases, for instance:
[canvas role="checkbox"][/checkbox]
does not require the author to use the subdom, as the entire canvas element
is a checkbox.

With the following, users will see the fallback content if canvas is not 
supported,
and will otherwise be able to focus on the checkbox if canvas and shadow 
dom are supported.

[canvas][input type=checkbox /][/canvas],

-Charles

On 7/7/2011 7:03 AM, paniz alipour wrote:
> Hi Richard,
>
> Yes I get your purpose,except one part :
>
> _ You control the drawing _ ?!
>
>
> in this sentence:
> If you wanted to create a canvas rendering of a checkbox in the 
> fallback content, on the canvas that was 70X70 you can do it. You 
> control the drawing
>
> and some thing else if a developer doesn't use sub-tree in shadow DOM? 
> what does happen?
>
>
> Thanks
>
>
> On Thu, Jul 7, 2011 at 6:25 PM, Richard Schwerdtfeger 
> <schwer@us.ibm.com <mailto:schwer@us.ibm.com>> wrote:
>
>     Hi Paniz,
>
>     I am not sure if I am answering your question but you could create
>     these objects on canvas and create equivalents in the canvas
>     subtree whereby the canvas is a rendering of the HTML element in
>     the canvas subtree and you can give it any size and dimension you
>     want. All the elements in canvas subtree could be placed in the
>     keyboard navigation order. If you wanted to create a canvas
>     rendering of a checkbox in the fallback content, on the canvas
>     that was 70X70 you can do it. You control the drawing.
>     Accessibility wise I don't yet have a way to communicate those
>     bounds to the accessibility API. This is what we have been
>     discussing. We have been discussing creating a drawing path on
>     canvas that represents the bounds of the object, binding it to the
>     canvas subtree element (which is in the keyboard navigation
>     order). In doing so we would have the user agent to do hit testing
>     on the drawing objects in canvas and pass the pointing event to
>     the corresponding object in the accessibility subtree. The bounds
>     of the object used for hit testing would be passed to the
>     corresponding accessible object (corresponding the to the DOM
>     element in the subtree). Now a magnifier would know how to zoom to
>     the corresponding 70x70 checkbox on the canvas.
>
>     To be honest, this is not new. This is how desktops like Windows
>     work. You have a graphic on the screen bound to a COM object which
>     supports MSAA. The MSAA bounding rectangle is retrieved from the
>     retained mode graphic.
>     We are arguing for putting this capability into canvas.
>
>
>     Rich
>
>
>     Rich Schwerdtfeger
>     CTO Accessibility Software Group
>
>     Inactive hide details for paniz alipour ---07/07/2011 08:42:16
>     AM---Hi Richard, I mean for example I have an interaction UI on
>     paniz alipour ---07/07/2011 08:42:16 AM---Hi Richard, I mean for
>     example I have an interaction UI on canvas as like web pages,
>
>
>     From: paniz alipour <alipourpaniz@gmail.com
>     <mailto:alipourpaniz@gmail.com>>
>     To: Richard Schwerdtfeger/Austin/IBM@IBMUS
>     Cc: chuck@jumis.com <mailto:chuck@jumis.com>,
>     cyns@exchange.microsoft.com <mailto:cyns@exchange.microsoft.com>,
>     david.bolter@gmail.com <mailto:david.bolter@gmail.com>,
>     franko@microsoft.com <mailto:franko@microsoft.com>, Mike@w3.org
>     <mailto:Mike@w3.org>, public-canvas-api@w3.org
>     <mailto:public-canvas-api@w3.org>, public-html@w3.org
>     <mailto:public-html@w3.org>, public-html-a11y@w3.org
>     <mailto:public-html-a11y@w3.org>
>     Date: 07/07/2011 08:42 AM
>
>     Subject: Re: hit testing and retained graphics
>     Sent by: public-canvas-api-request@w3.org
>     <mailto:public-canvas-api-request@w3.org>
>     ------------------------------------------------------------------------
>
>
>
>     Hi Richard,
>
>     I mean for example I have an interaction UI on canvas as like web
>     pages,
>
>     textbox,radiobutton ,checkbox,.... .I want to know these elements
>     that are drawn or are images on canvas
>
>     could be incredible,Of course they can but in your opinion how
>     many percent it is possible(forexample checkbox with height 70 and
>     width 70)
>
>     Best Regards
>
>     On Thu, Jul 7, 2011 at 6:02 PM, Richard Schwerdtfeger
>     <_schwer@us.ibm.com_ <mailto:schwer@us.ibm.com>> wrote:
>
>           Hi Paniz,
>
>           I am not quite following you. Could you please provide more
>           detail?
>
>           Thanks,
>
>
>           Rich
>
>
>           Rich Schwerdtfeger
>           CTO Accessibility Software Group
>
>           Inactive hide details for paniz alipour ---07/07/2011
>           06:32:18 AM---Hello to all, Maybe you think that this
>           question is not relpaniz alipour ---07/07/2011 06:32:18
>           AM---Hello to all, Maybe you think that this question is not
>           related to this discussion,
>
>           From: paniz alipour <_alipourpaniz@gmail.com_
>           <mailto:alipourpaniz@gmail.com>>
>           To: Richard Schwerdtfeger/Austin/IBM@IBMUS
>           Cc: _chuck@jumis.com_ <mailto:chuck@jumis.com>,
>           _franko@microsoft.com_ <mailto:franko@microsoft.com>,
>           _Mike@w3.org_ <mailto:Mike@w3.org>, _david.bolter@gmail.com_
>           <mailto:david.bolter@gmail.com>,
>           _cyns@exchange.microsoft.com_
>           <mailto:cyns@exchange.microsoft.com>,
>           _public-canvas-api@w3.org_
>           <mailto:public-canvas-api@w3.org>, _public-html-a11y@w3.org_
>           <mailto:public-html-a11y@w3.org>, _public-html@w3.org_
>           <mailto:public-html@w3.org>
>           Date: 07/07/2011 06:32 AM
>
>           Subject: Re: hit testing and retained graphics
>
>           ------------------------------------------------------------------------
>
>
>
>
>           Hello to all,
>
>           Maybe you think that this question is not related to this
>           discussion,
>
>           But I want to know whether the web widget that are located
>           on canvas,
>
>           are they incredible .I mean a check box with height
>           70,weight 70,
>
>           or no it will design as the common web widget on websites?
>
>           Thanks
>
>           On Fri, Jun 17, 2011 at 11:11 PM, Richard Schwerdtfeger
>           <_schwer@us.ibm.com_ <mailto:schwer@us.ibm.com>> wrote:
>                 Charles, Frank, Mike,
>
>                 I am back from vacation. How far do we need to go with
>                 hit testing? Right now I am looking at associating a
>                 closed draw path with a DOM object in the canvas
>                 subtree. We would then need to address the routing of
>                 pointing device input events to the DOM object. The
>                 drawing path can be used to provide bound information
>                 to platform accessibility API.
>
>                 Do we need to bind any other drawing properties to the
>                 canvas object - similar to the way device context's
>                 are handled on graphic subsystems like Windows?
>
>                 Mike, I am including you as before I went on vacation
>                 you indicated that a number of developers desired this
>                 feature and wanted to be involved.
>
>                 Rich
>
>
>                 Rich Schwerdtfeger
>                 CTO Accessibility Software Group 
>
>
>
>           -- 
>           Paniz Alipour
>
>
>
>
>
>     -- 
>     Paniz Alipour
>
>
>
>
> -- 
> Paniz Alipour
Received on Thursday, 7 July 2011 14:07:30 UTC

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