Re: hit testing and retained graphics

IE8 does not support canvas; it shows the fallback content.



On Jul 7, 2011, at 11:18 PM, paniz alipour <alipourpaniz@gmail.com> wrote:

> Hi Richard,
> 
> There was some thing marvelous! As I found out shadow Dom or fallback content was just supported in IE9 ,but I saw that it is run in IE8 too.
> 
> I mean your sample that you had sent it for me.
> 
> Am I right ? What has happened?
> 
> Thanks
> 
> On Thu, Jul 7, 2011 at 6:45 PM, Richard Schwerdtfeger <schwer@us.ibm.com> wrote:
> Yes, the author draws the widget on the canvas based on the information in the canvas subtree.
> 
> If you don't use the subtree it won't be in the keyboard navigation order and you can't provide the accessibility information 
> 
> From the HTML 5 spec on canvas: http://dev.w3.org/html5/spec/the-canvas-element.html#the-canvas-element
> 
> "When a canvas element represents embedded content, the user can still focus descendants of the canvas element (in the fallback content). When an element is focused, it is the target of keyboard interaction events (even though the element itself is not visible). This allows authors to make an interactive canvas keyboard-accessible: authors should have a one-to-one mapping of interactive regions to focusable elements in the fallback content. (Focus has no effect on mouse interaction events.) [DOMEVENTS]"
> 
> Attached is a basic example:
> 
> 
> (See attached file: CanvasEditor.html)
> 
> 
> Rich Schwerdtfeger
> CTO Accessibility Software Group
> 
> <graycol.gif>paniz alipour ---07/07/2011 09:04:12 AM---Hi Richard, Yes I get your purpose,except one part :
> 
> 
> 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-canvas-api-request@w3.org, public-html@w3.org, public-html-a11y@w3.org
> Date:	07/07/2011 09:04 AM
> 
> Subject:	Re: hit testing and retained graphics
> Sent by:	public-canvas-api-request@w3.org
> 
> 
> 
> 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> 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
> 
> <graycol.gif>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>
> 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
> 
> <graycol.gif>paniz 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
> 
> 
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> Paniz Alipour
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> Paniz Alipour
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> Paniz Alipour
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> Paniz Alipour