[Accessibility-ia2] a11y support registry API

Pete Brunet pete at a11ysoft.com
Fri Jul 30 09:43:58 PDT 2010


David and I chatted on the mozilla irc yesterday.  Here is a summary:

David listed these points as drivers for needing this function:
- There is a performance problem.
- There are some commonly installed tools, like anti-spyware that
invokes the gecko a11y engine which degrades performance for people who
don't need full a11y
- It is suspected that not all msaa/ia2 is actually used by AT resulting
in a lot of needless cpu cycles, i.e. it's a waste to internally handle
an event and fire it if no AT is listening.

David believes it would be helpful if some a11y features could be turned
off, e.g.
- some tools might only care about focus events and roles
- some, like GOK, don't care about relations, especially reverse
relations which are costly to compute

What questions are needed in order to make the right decisions?  Below
are some possible candidates.  These questions would have to be asked
across a range of applications and ATs.
- What features if disabled in a server would significantly improve
performance in the server?
- What would the user experience be in an AT if those features were not
available?
- If the AT experience would be acceptable with a feature disabled is
adding an enablement switch needed to provide an improved UI experience?

In a system with more than one AT the application would have to
configure itself based on the highest combined set of demands.

There would need to be coordination in the community so that when, for
example, Gecko turns off its switchable features all ATs will be
prepared to turn on the ones that are needed.

Pete

David Bolter wrote:
> Are we ready to define the API? Have we resolved concerns? If so, I just 
> want to say that the kind of granularity I am looking for is something like:
>
> "focus show hide"
> or
> FOCUS | SHOW | HIDE
>
> Not to suggest events are all we care about.
>
> Note:I am also thinking that repeated calls to the API do not unset and 
> support features, but are cumulative.
>
> cheers,
> David
>
> Richard Schwerdtfeger wrote:
>   
>> suggestion below.
>>
>>
>> Rich Schwerdtfeger
>> CTO Accessibility Software Group
>>
>> accessibility-ia2-bounces at lists.linuxfoundation.org wrote on 
>> 06/21/2010 01:00:38 PM:
>>
>>     
>>> From: James Teh <jamie at nvaccess.org>
>>> To: accessibility-ia2 at lists.linuxfoundation.org
>>> Date: 06/21/2010 01:13 PM
>>> Subject: Re: [Accessibility-ia2] a11y support registry API
>>> Sent by: accessibility-ia2-bounces at lists.linuxfoundation.org
>>>
>>> On 22/06/2010 2:14 AM, David Bolter wrote:
>>>       
>>>> IApplicationAccessible
>>>>    - setRequestedSupport([in] long supportBitflag, [out] long
>>>> supportedBitflag);
>>>> This API suggestion is just illustrative. Something like this would
>>>> allow applications to provide needed support without wasting 
>>>>         
>> performance
>>     
>>>> by also providing unused support. Thoughts?
>>>>         
>>> This sounds okay. The problem is that in order to preserve backwards
>>> compatibility with older ATs which don't know about this new API, apps
>>> will have to enable everything by default anyway, which rather defeats
>>> the purpose.
>>>
>>>       
>> Would it be better to have a generic function like this to pass a 
>> string representing the feature we are asking for?
>>
>> RequestFeature([in] String feature, [out] long feature);
>>
>> The string could be a set of features. If it were not supported in the 
>> current implementation return a -1.
>> otherwise you return a value.
>>
>> Some strings:
>>
>> "EnableIA2"
>>
>> future (and I am just making things up)
>>
>> "filter object tree"
>> "limittovisiblearea"
>>
>>
>>
>> Rich
>>
>>
>> It may be less performant but it is more flexible and gets rid of 
>> versioning problems down the road.
>>
>>     
>>> Jamie
>>>
>>> --
>>> James Teh
>>> Vice President
>>> NV Access Inc, ABN 61773362390
>>> Email: jamie at nvaccess.org
>>> Web site: http://www.nvaccess.org/
>>> ___________
>>>       
>
> _______________________________________________
> Accessibility-ia2 mailing list
> Accessibility-ia2 at lists.linuxfoundation.org
> https://lists.linux-foundation.org/mailman/listinfo/accessibility-ia2
>
>
>   

-- 
*Pete Brunet*
                                                                
a11ysoft - Accessibility Architecture and Development
(512) 238-6967 (work), (512) 689-4155 (cell)
Skype: pete.brunet
IM: ptbrunet (AOL, Google), ptbrunet at live.com (MSN)
http://www.a11ysoft.com/about/
Ionosphere: WS4G
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.linux-foundation.org/pipermail/accessibility-ia2/attachments/20100730/fea7c05e/attachment.htm 


More information about the Accessibility-ia2 mailing list