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Re: canvas API changes to drive magnification

From: David Bolter <david.bolter@gmail.com>
Date: Tue, 09 Mar 2010 14:50:24 -0500
Message-ID: <4B96A680.4080708@gmail.com>
To: Richard Schwerdtfeger <schwer@us.ibm.com>
CC: Charles McCathieNevile <chaals@opera.com>, cooper@w3.org, cyns@exchange.microsoft.com, Steven Faulkner <faulkner.steve@gmail.com>, Frank Olivier <franko@microsoft.com>, janina@rednote.net, jcraig@apple.com, "public-canvas-api@w3.org" <public-canvas-api@w3.org>, public-canvas-api-request@w3.org
Hi Rich,

On 09/03/10 2:01 PM, Richard Schwerdtfeger wrote:
> canDrawFocus is specific to<canvas>. The areamap would not be rendered if
> it were used as the shadow DOM for canvas.

Yeah. It isn't really rendered for image maps either (just the visual 
focus shapes). I guess it depends on what we mean by 'rendered'.

>   Are you thinking that the
> browser uses the area map coordinates to draw the rectangle on the canvas?
>    

The thought crossed my mind, but I don't know if this is best. Basically 
I want to know if the idea is that author is always responsible for 
visually indicating focus/caret. If they are, then "drawFocusRing" 
should maybe be something more like "setFocusRing" right? (Here I am 
assuming it is the author who calls the function -- but I'm not 100% 
sure if that is the intent).

What do others think?

cheers,
David
> Rich
>
> Rich Schwerdtfeger
> Distinguished Engineer, SWG Accessibility Architect/Strategist
>
>
>
>               David Bolter
>               <david.bolter@gma
>               il.com>                                                     To
>               Sent by:                  Richard
>               public-canvas-api         Schwerdtfeger/Austin/IBM@IBMUS
>               -request@w3.org                                            cc
>                                         Charles McCathieNevile
>                                         <chaals@opera.com>, cooper@w3.org,
>               03/09/2010 12:29          cyns@exchange.microsoft.com, Steven
>               PM                        Faulkner
>                                         <faulkner.steve@gmail.com>, Frank
>                                         Olivier<franko@microsoft.com>,
>                                         janina@rednote.net,
>                                         jcraig@apple.com,
>                                         "public-canvas-api@w3.org"
>                                         <public-canvas-api@w3.org>,
>                                         public-canvas-api-request@w3.org
>                                                                     Subject
>                                         Re: canvas API changes to drive
>                                         magnification
>
>
>
>
>
>
>
>
>
>
> The typical image map is an image element with the usemap attribute
> pointing to a map of elements that specify their shape and coordinates.
> With image maps the browser is responsible for drawing focus. I was
> thinking if we wanted to support this, the canDrawCustom might be
> relevant? But really I don't know what is intended.
>
> cheers,
> David
>
> On 09/03/10 12:29 PM, Richard Schwerdtfeger wrote:
>    
>> I am still confused. In the usemap appraoch we would have DOM elements in
>> the area map which would act as elements. This is no different than if we
>> created a navsubtree. So, now we have an element to reference in either
>> scenario.
>>
>> To draw a caret. the element has to either be focused or child descendant
>> of the focused element. The caret is drawn on the canvas itself.
>>
>> Steve, can you provide more clarification behind canDrawCustom? Hixie's
>> wording was unclear to David and me.
>>
>> BTW - I am trying to integrate areamap and navsubtree with Charles on a
>> single proposal.
>>
>> Rich
>>
>> Rich Schwerdtfeger
>> Distinguished Engineer, SWG Accessibility Architect/Strategist
>>
>>
>>
>>                David Bolter
>>                <david.bolter@gma
>>                il.com>
>>      
> To
>    
>>                Sent by:                  Richard
>>                public-canvas-api         Schwerdtfeger/Austin/IBM@IBMUS
>>                -request@w3.org
>>      
> cc
>    
>>                                          Charles McCathieNevile
>>                                          <chaals@opera.com>,
>>      
> cooper@w3.org,
>    
>>                03/09/2010 10:00          cyns@exchange.microsoft.com,
>>      
> Steven
>    
>>                AM                        Faulkner
>>                                          <faulkner.steve@gmail.com>, Frank
>>                                          Olivier<franko@microsoft.com>,
>>                                          janina@rednote.net,
>>                                          jcraig@apple.com,
>>                                          "public-canvas-api@w3.org"
>>                                          <public-canvas-api@w3.org>
>>
>>      
> Subject
>    
>>                                          Re: canvas API changes to drive
>>                                          magnification
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Hi Rich,
>>
>> I don't know if I am against the canDrawCustom attribute, I just want to
>> understand it better. Perhaps it is useful for interop with the usemap
>> approach?
>>
>> cheers,
>> David
>> On 09/03/10 9:56 AM, Richard Schwerdtfeger wrote:
>>
>>      
>>> David,
>>>
>>> Good pickup. I believe the author should be responsible for drawing the
>>> caret. The canDrawCustom argument is left over from Hixie's proposal and
>>>
>>>        
>> I
>>
>>      
>>> agree that is a bit confusing. I have not seen a convention whereby the
>>> system draws the caret - has anyone else? I left it in. Do you think it
>>>
>>>        
>> is
>>
>>      
>>> possible for the browser to draw a default caret?  I can see a focus
>>>        
> ring
>    
>>> being doable but for caret I have my doubts.
>>>
>>> Rich
>>>
>>> Rich Schwerdtfeger
>>> Distinguished Engineer, SWG Accessibility Architect/Strategist
>>>
>>>
>>>
>>>                 David Bolter
>>>                 <david.bolter@gma
>>>                 il.com>
>>>
>>>        
>> To
>>
>>      
>>>                                           Richard
>>>                 03/09/2010 08:34          Schwerdtfeger/Austin/IBM@IBMUS
>>>                 AM
>>>
>>>        
>> cc
>>
>>      
>>>                                           cooper@w3.org,
>>>
>>>        
>> janina@rednote.net,
>>
>>      
>>>                                           Charles McCathieNevile
>>>                                           <chaals@opera.com>,
>>>                                           cyns@exchange.microsoft.com,
>>>
>>>        
>> Steven
>>
>>      
>>>                                           Faulkner
>>>                                           <faulkner.steve@gmail.com>,
>>>        
> Frank
>    
>>>                                           Olivier<franko@microsoft.com>,
>>>                                           jcraig@apple.com,
>>>                                           "public-canvas-api@w3.org"
>>>                                           <public-canvas-api@w3.org>
>>>
>>>
>>>        
>> Subject
>>
>>      
>>>                                           Re: canvas API changes to drive
>>>                                           magnification
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> Hi Rich, all,
>>>
>>> I just read the proposal at
>>> http://www.w3.org/html/wg/wiki/ChangeProposals/canvasaccessibility,
>>>
>>> I don't feel like I fully understand the proposal. Take the case for
>>>
>>>        
>> canvas
>>
>>      
>>> drawn text. Each time the user presses the right arrow, does the author
>>> catch that event and call e.g. drawFocusRing(myTextBox, 10, 5, true,
>>>
>>>        
>> true)?
>>
>>      
>>> I want to understand who is responsible for drawing the caret or focus
>>>
>>>        
>> ring
>>
>>      
>>> in various examples.
>>>
>>> http://www.paciellogroup.com/blog/misc/canvas/2dcontext-caret.html is
>>> really hard to understand (maybe because of typos). For example I don't
>>> understand how to parse this sentence: " If the given element is focused
>>>
>>>        
>> or
>>
>>      
>>> is a descendant of the focus element, and isCaret is true, canDrawCustom
>>> argument is true draws a caret following the platform conventions for
>>> carets." -- Who draws?
>>>
>>> cheers,
>>> David
>>>
>>> On 08/03/10 7:17 PM, Richard Schwerdtfeger wrote:
>>>
>>>
>>>          I would like to have people review Steve and my proposal to the
>>>          canvas
>>>          accessibility API to address focus and caret tracking for the
>>>        
> next
>    
>>>          canvas
>>>          meeting on the 15th so that we can take this to the task force
>>>        
> for
>    
>>>          approval. David, Frank, Cynthia, James, and Charles I would very
>>>
>>>        
>> much
>>
>>      
>>>          like
>>>          your feedback by the next call.
>>>
>>>
>>>        
> http://www.w3.org/html/wg/wiki/ChangeProposals/canvasaccessibility
>    
>>>          Thanks,
>>>          Rich
>>>
>>>          Rich Schwerdtfeger
>>>          Distinguished Engineer, SWG Accessibility Architect/Strategist
>>>
>>>
>>>
>>>
>>>        
>>
>>
>>      
>
>
>    
Received on Tuesday, 9 March 2010 19:51:04 UTC

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