Re: hit testing and retained graphics

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



From:	paniz alipour <alipourpaniz@gmail.com>
To:	Richard Schwerdtfeger/Austin/IBM@IBMUS
Cc:	chuck@jumis.com, cyns@exchange.microsoft.com,
            david.bolter@gmail.com, franko@microsoft.com, Mike@w3.org,
            public-canvas-api@w3.org, public-html@w3.org,
            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



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>
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>
  To: Richard Schwerdtfeger/Austin/IBM@IBMUS
  Cc: chuck@jumis.com, franko@microsoft.com, Mike@w3.org,
  david.bolter@gmail.com, cyns@exchange.microsoft.com,
  public-canvas-api@w3.org, public-html-a11y@w3.org, 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> 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