Pete and all: > Andres, So far I have been told by two AT developers that using WM_GETOBJECT > is how to do it. I guess there is no downside to them though :-)
We use WM_GETOBJECT, SPI_GETSCREENREADER flag, and additional low level system info. It is mostly an app development problem, not an AT problem, although to find a solution we would definitely need both sides implementing the handshake mechanism. So that's why a forum like this would be the appropriate place to come to an agreement. > The downside is to app users not using AT but experiencing a performance > degradation, however minor. Not so minor in some cases. And it can involved extra GUI as well. > Have you collected any data on the occurrence of these false positives to > know how rare or non-rare they are? We have, and definitely occurs more often than we'd like. > An AT present flag would be helpful. Please start a new thread on this list > for that. Will do ASAP. Thanks, --Andres. ________________________________ From: Pete Brunet [mailto:[email protected]] Sent: Tuesday, May 25, 2010 7:11 AM To: Andres Gonzalez Cc: James Teh; IAccessible2 mailing list Subject: Re: [Accessibility-ia2] screen reader present flag Andres, So far I have been told by two AT developers that using WM_GETOBJECT is how to do it. I guess there is no downside to them though :-) The downside is to app users not using AT but experiencing a performance degradation, however minor. Have you collected any data on the occurrence of these false positives to know how rare or non-rare they are? An AT present flag would be helpful. Please start a new thread on this list for that. Thanks, Pete === Andres Gonzalez wrote: WM_GETOBJECT is NOT a reliable way of detecting AT either, since it may be triggered by apps and even device drivers that don't have anything to do with AT, so you are guarantied false positives even with the best heuristics. I'm very interested in developing a reliable handshake mechanism with AT, and would love to hear from others with ideas/proposals on this respect. Perhaps we can take this task for the next edition of IA2 in this list, or by a subgroup of interested parties, and bring back a concrete proposal to the general group. Thanks, --Andres. ________________________________ From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of Pete Brunet Sent: Monday, May 24, 2010 4:18 PM To: James Teh Cc: IAccessible2 mailing list Subject: Re: [Accessibility-ia2] screen reader present flag Thanks Jamie, I'll have to check with the architects to see if they would have any issues with blocking. If I can block then I might also be able to lazily call into the secondary thread to build the tree as needed. -Pete === James Teh wrote: On 25/05/2010 8:37 AM, Pete Brunet wrote: Thanks Jamie, [using WM_GETOBJECT to dynamically enable accessibility] may be a problem for the case where the app has multiple threads and a secondary thread needs to be called by the window proc to participate in the building of the accessibility tree. Is it acceptable to block the UI thread? I don't see why this is any different to creating the tree in the same thread. Either way, it will block the UI thread, as the WM_GETOBJECT message needs to return the requested accessible object. Can you shorten the setup time by creating parts of the tree lazily only when requested? Jamie
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