Re: Where does the accessibility hierarchy "start"?
Re: Where does the accessibility hierarchy "start"?
- Subject: Re: Where does the accessibility hierarchy "start"?
- From: Bill Cheeseman <email@hidden>
- Date: Fri, 02 Jun 2006 04:05:44 -0400
- Thread-topic: Where does the accessibility hierarchy "start"?
on 2006-06-01 5:52 AM, Håkan Waara at email@hidden wrote:
> How does the OS, or a third-party application such as VoiceOver get
> the first accessible object (from which it starts its traversal of
> the accessibility object hierarchy, I assume)?
A so-called "assistive" application creates a top-level or root application
UI element object by calling one of two functions in the accessibility API,
AXUIElementCreateApplication or AXUIElementCreateSystemWide. Everything else
in the hierarchy flows from those, either by traversing the hierarchy from
the top-level element, or by traversing the hierarchy from a "leaf" node by
reading the screen at a point under the mouse using
AXUIElementCopyElementAtPosition. You can also use accessibility functions
to get attributes of UI elements, perform actions on them, or register to
received notifications from them, or to "type" characters to a target
application.
For details, read the "Accessibility Reference for Assistive Applications
Release Notes." It's on your computer if you installed Xcode Tools with
documentation.
Also, look at the header files, on your computer at
/System/Library/Frameworks/ApplicationServices.framework/Frameworks/HIServic
es.framework/Headers. All the headers for accessibility begin with "AX".
Finally, study Apple's sample code for UI Element Inspector 1.0.
--
Bill Cheeseman - email@hidden
Quechee Software, Quechee, Vermont, USA
http://www.quecheesoftware.com
PreFab Software - http://www.prefab.com/scripting.html
The AppleScript Sourcebook - http://www.AppleScriptSourcebook.com
Vermont Recipes - http://www.stepwise.com/Articles/VermontRecipes
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