[Accessibility] IAccessibleEx equivalent

Pete Brunet pete at a11ysoft.com
Wed Feb 17 10:13:15 PST 2010

Hi Alex, This is needed because you can't QI/QS a simple element.  A use
case would be if the accessible is a simple element backed by an object
implementing IA2.  As you most likely know, simple elements are only
accessible via a reference to the parent IAccessible plus a non-zero
child ID identifying a particular child simple element.  If you had the
IAccessible, child ID pair and wanted a reference to the associated
child IA2 object then you could use objectForChild.

Does that make sense?

Alexander Surkov wrote:
> Hi, Pete.
> I don't completely understand the idea of new interface. I'm looking
> at examples at https://lists.linux-foundation.org/pipermail/accessibility-ia2/2008-June/000512.html
> and it sounds this interface is intended to do the same we do by
> QueryInterface and QueryService methods (the conversion from
> IAccessible to IAccessible2 and vise versa). Could you please more
> details?
> Thanks.
> Alex.
> On Wed, Feb 17, 2010 at 1:32 PM, Pete Brunet <pete at a11ysoft.com> wrote:
>> Here is some background one of today's topics:
>> About two years ago Microsoft asked for the addition of two methods to IA2
>> which would be equivalent to UIA's IAccessibleEx::GetObjectForChild and
>> GetIAccessilbePair which translate back and forth between MSAA objects
>> (including simple elements) and UIA objects.  The proposed IA2 equivalent
>> is:
>> IAccessibleSimple (or some other name like IAccessible2Ex)
>> // For this parent accessible, fetch a full accessible representing the
>> specified
>> // child simple element where the accessible has implemented IAccessible2
>> [propget] HRESULT objectForChild( [in] long childID, [out, retval]
>> IAccessible2 *accessible2 );
>> // For this accessible, fetch the parent accessible, childID pair
>> representing an equivalent simple element
>> [propget] HRESULT accessiblePair( [out] IAccessible * accessible, [out,
>> retval] long childID );
>> For background follow this link:
>> http://bugs.freestandards.org/show_bug.cgi?id=114
>> --
>> 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

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