ISO/IEC TR 13066-2:2012

Information technology — Interoperability with Assistive Technology (AT) — Part 2: Windows accessibility application programming interface (API)

ISO/IEC TR 13066-2:2012 provides information about the Microsoft® Windows® Automation Frameworks, including Microsoft Active Accessibility, User Interface (UI) Automation, and the common interfaces of these accessibility frameworks including the IAccessibleEx interface specification. It provides information on application programming interfaces (APIs) needed to use these frameworks. A primary goal of ISO/IEC TR 13066-2:2012 is to ensure that accessible software applications can be written in such a way that they are fully compatible with the Microsoft Accessibility APIs available on the Microsoft Windows operating system.

Technologies de l'information — Interopérabilité avec les technologies d'assistance — Partie 2: Interface de programmation d'applications (API) d'accessibilité Windows

General Information

• Status: Withdrawn
• Publication Date: 16-Oct-2012
• Withdrawal Date: 16-Oct-2012
• ICS: 11.180.99 - Other standards related to aids for disabled and handicapped people
• ICS: 35.180 - IT Terminal and other peripheral equipment
• Technical Committee: ISO/IEC JTC 1/SC 35 - User interfaces
• Drafting Committee: ISO/IEC JTC 1/SC 35 - User interfaces
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 26-Jan-2016

Relations

• Revised: ISO/IEC TR 13066-2:2016 - Information technology — Interoperability with assistive technology (AT) — Part 2: Windows accessibility application programming interface (API)
• Effective Date: 04-Jan-2014

Standards Content (Sample)

TECHNICAL ISO/IEC
REPORT TR
13066-2
First edition
2012-10-15


Information technology — Interoperability
with Assistive Technology (AT) —
Part 2:
Windows accessibility application
programming interface (API)
Technologies de l'information — Interopérabilité avec les technologies
d'assistance —
Partie 2: Interface de programmation d'applications (API) d'accessibilité
Windows




Reference number
ISO/IEC TR 13066-2:2012(E)
©
ISO/IEC 2012

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ISO/IEC TR 13066-2:2012(E)

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©  ISO/IEC 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
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ISO/IEC TR 13066-2:2012(E)
Contents Page
Foreword . iv
Introduction . v
1  Scope . 1
2  Terms and definitions . 1
3  General Description and Architecture of the Microsoft Windows Automation API . 7
3.1  General Description . 7
3.2  Architecture . 10
4  Using the API . 12
4.1  Using the Microsoft Active Accessibility API . 12
4.2  Using the UI Automation API . 15
4.3  Using the IAccessibleEx Interface . 20
5  Exposing User Interface Element Information . 24
5.1  Exposing UI Elements with Microsoft Active Accessibility . 25
5.2  Exposing UI Elements with UI Automation . 28
6  Exposing User Interface Element Actions . 33
6.1  Exposing User Interface Element Actions in MSAA . 33
6.2  Exposing User Interface Element Actions in UI Automation . 33
7  Keyboard Focus . 36
7.1  MSAA Keyboard Focus and Selection . 36
7.2  UI Automation Keyboard Focus and Selection . 38
8  Events . 45
8.1  WinEvents . 45
8.2  UI Automation Events . 47
9  Programmatic Modifications of States, Properties, Values and Text . 49
9.1  UI Automation Design Considerations . 49
10  Design Considerations . 52
10.1  UI Automation Design Considerations . 52
10.2  IAccessibleEx Design Considerations . 60
11  Further Information . 66
11.1  Microsoft Active Accessibility and Extensibility . 66
11.2  UI Automation Extensibility Features . 66
Annex A (informative) Microsoft Active Accessibility to Automation Proxy . 69
Annex B (informative) UI Automation to Microsoft Active Accessibility Bridge . 78
Annex C (informative) UI Automation for W3C Accessible Rich Internet Applications (ARIA)
Specification . 83
Annex D (informative) Other Useful APIs for Development and Support of Assistive Technologies . 87
Bibliography . 94

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ISO/IEC TR 13066-2:2012(E)
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees
established by the respective organization to deal with particular fields of technical activity. ISO and IEC
technical committees collaborate in fields of mutual interest. Other international organizations, governmental
and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information
technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International
Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as
an International Standard requires approval by at least 75 % of the national bodies casting a vote.
In exceptional circumstances, when the joint technical committee has collected data of a different kind from
that which is normally published as an International Standard (“state of the art”, for example), it may decide to
publish a Technical Report. A Technical Report is entirely informative in nature and shall be subject to review
every five years in the same manner as an International Standard.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
ISO/IEC TR 13066-2 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 35, User interfaces.
ISO/IEC TR 13066 consists of the following parts, under the general title Information technology —
Interoperability with Assistive Technology (AT):
 Part 1: Requirements and recommendations for interoperability
 Part 2: Windows accessibility application programming interface (API) [Technical Report]
 Part 3: IAccessible2 accessibility application programming interface (API) [Technical Report]
1
 Part 4: Linux/UNIX graphical environments accessibility API [Technical Report]
 Part 6: Java accessibility API [Technical Report]

1
To be published.
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ISO/IEC TR 13066-2:2012(E)
Introduction
Individuals with a wide range of functional disabilities, impairments, and difficulties require specific technology
to enable computers and software to be accessible to them. This part of ISO/IEC TR 13066 provides
information about the Microsoft® Windows® Automation Frameworks, including Microsoft Active Accessibility,
User Interface (UI) Automation, and the common interfaces of these accessibility frameworks including the
IAccessibleEx interface specification.
The intent of this part of ISO/IEC TR 13066 is to provide information and application programming interfaces
(APIs) needed to use these frameworks. A primary goal of this part of ISO/IEC TR 13066 is to ensure that
accessible software applications can be written in such a way that they are fully compatible with the Microsoft
Accessibility APIs available on the Microsoft Windows operating system.
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TECHNICAL REPORT ISO/IEC TR 13066-2:2012(E)

Information technology — Interoperability with Assistive
Technology (AT) —
Part 2:
Windows accessibility application programming interface (API)
1 Scope
This part of ISO/IEC TR 13066 specifies services provided in the Microsoft Windows platform to enable
assistive technologies (AT) to interact with other software. One goal of this part of ISO/IEC TR 13066 is to
define a set of application programming interfaces (APIs) for allowing software applications to enable
accessible technologies on the Microsoft Windows platform. Another goal of this part of ISO/IEC TR 13066 is
to facilitate extensibility and interoperability by enabling implementations by multiple vendors on multiple
platforms.
This part of ISO/IEC TR 13066 is applicable to the broad range of ergonomics and how ergonomics apply to
human interaction with software systems.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
application programming interface
API
standard set of documented and supported routines that expose operating system programming interfaces
and services to applications
NOTE An API is usually a source code interface that an operating system, library, or service provides to support
requests made by computer programs.
EXAMPLE Examples of operating system services that are exposed by APIs include administration and
management, diagnostics, graphics and multimedia, networking, security, system services, user interfaces, and
accessibility.
2.2
accessibility
degree to which a computer system is easy to use by all people, including those with disabilities
2.3
accessible object
part of user interface object that is accessible by Microsoft Active Accessibility
NOTE An accessible object is represented by an IAccessible interface and a ChildId identifier.
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ISO/IEC TR 13066-2:2012(E)
2.4
Accessible Rich Internet Applications
ARIA
accessibility framework from W3C that exposes web content to assistive technologies such as screen readers
and speech commanding programs
2.5
Assistive Technology
AT
technology designed to provide accessibility support to individuals with physical or cognitive impairments or
disabilities
NOTE Assistive Technology can be manifested through both hardware and software.
2.6
Accessibility Toolkit (Linux)
ATK
programming support accessibility features in their applications
2.7
automation
replacement of manual operations by computerized methods
NOTE With respect to this part of ISO/IEC 13066, automation is a way to manipulate an application's user interface
from outside the application.
2.8
automation element
object or element that is accessible by the UI Automation object model
NOTE Similar to accessible objects in Microsoft Active Accessibility, an automation element in UI Automation
represents a piece or a part of the user interface, such as button, window, or desktop.
2.9
Audio Video Interleaved
AVI
format that enables both audio and video data in a file container
2.10
C#
a programming language designed for building applications that run on the .NET Framework
NOTE 1 C#, which is an evolution of C and C++, is type safe and object oriented.
NOTE 2 Because it is compiled as managed code, it benefits from the services of the common language runtime, such
as language interoperability, security, and garbage collection.
2.11
callback function
function or procedure that third party or client code supplies to a component, often by passing a function
pointer through the component’s API
NOTE The component may then call this code at specific times. This technique is often used by components to
signal client code that some event has taken place, or to request client code to perform some specific task.
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ISO/IEC TR 13066-2:2012(E)
2.12
clients
component that uses the services of another component
NOTE In this part of ISO/IEC 13066, client refers more specifically to a component that uses the services of Microsoft
Active Accessibility or UI Automation, or both, to access, identify, or manipulate the user interface (UI) elements of an
application.
2.13
Common Language Runtime
CLR
Microsoft’s commercial implementation of the Common Language Infrastructure (CLI) specification
NOTE 1 The CLI provides a specification for executable code and the execution environment in which it runs
NOTE 2 At the center of the CLI is a unified type system, a virtual execution system, and a specification for multiple
programming languages to share the type system and compile into a common intermediate language.
2.14
Component Object Model
COM
object-oriented programming model that defines how objects interact within a single process or between
processes
NOTE In COM, clients have access to an object through interfaces implemented on the object.
2.15
content view
subset of the control view of the UI Automation tree
NOTE The content view contains UI items that convey the actual information in a user interface, including UI items
that can receive keyboard focus and some text that is not a label on a UI item.
2.16
control pattern
design implementation that describes a discrete piece of functionality for a control
NOTE This functionality can include the visual appearance of a control and the actions it can perform.
2.17
control view
subset of the raw view of the UI Automation tree
NOTE The control view includes the UI items that provide information to the user or enable the user to perform an
action.
2.18
enumerator
object that iterates through its associated collection
NOTE An enumerator can be thought of as a movable pointer to any element in the collection.
2.19
Global Unique Identifier
GUID
unique reference number used as an identifier in computer software
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ISO/IEC TR 13066-2:2012(E)
2.20
HWND
unique long integer value that is assigned by Microsoft Windows to the current window, where a window is a
primitive of Windows’ UI management
2.21
in-process
Microsoft Accessibility code that is executed in a target application’s process
2.22
Java Accessibility Application Programming Interface
JAAPI
accessibility framework for the Java SE platform that exposes Java applications to assistive technologies such
as screen readers and speech commanding programs
2.23
Java Development Kit
JDK
collection of programming tools
2.24
Java Virtual Machine
JVM
environment in which Java bytecode can be executed
2.25
managed API
API that, when compiled and run, is under the control of an intermediary runtime infrastructure, like a virtual
machine
EXAMPLE Microsoft’s Common Language Runtime (CLR) and the Java Virtual Machine (JVM) are examples of
runtime infrastructures.
NOTE Managed code is compiled into an intermediate language construct (for example, byte code) and the runtime
infrastructure handles the compilation into machine code. The runtime infrastructure handles programming constructs like
memory management.
2.26
Microsoft Active Accessibility
COM-based technology that improves the way accessibility aids work with applications running on Microsoft
Windows
NOTE Microsoft Active Accessibility provides dynamic-link libraries (DLLs) that are incorporated into the operating
system, as well as a COM interface and application programming elements that provide reliable methods for exposing
information about user interface elements.
2.27
MSDN
Microsoft Developer Network, which is a technical information resource for developers who are using
Microsoft technologies
2.28
Multiple Document Interface
MDI
document interface that allows a window to reside under a parent window
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ISO/IEC TR 13066-2:2012(E)
2.29
native API
API that, when compiled and run, is not under the control of an intermediary runtime infrastructure such as a
virtual machine or CLR
NOTE Native code compiles directly to machine code, and the developer is responsible for most aspects of
programming constructs (for example, pointers, freeing memory, and so on). Also known as a native API.
2.30
out-of-process
Microsoft Accessibility code that is executed in a different process from the target
application’s process
2.31
providers
components that expose information about UI elements
EXAMPLE Such components can be applications, DLLs, and so on
NOTE These include any control, module, or application which implements UI Automation provider interfaces.
2.32
raw view
full tree of UI Automation element objects in the UI Automation tree for which the desktop is the root
NOTE The raw view closely follows the native programmatic structure of an application and, therefore, is the most
accurate view of the UI structure. It is also the base on which the other views of the tree are built
2.33
root element
element of the UI Automation tree that represents the current desktop and whose child elements represent
application windows
NOTE Each of these child elements can contain elements representing pieces of UI such as menus, buttons,
toolbars, and list boxes.
2.34
servers
components of Microsoft Active Accessibility that have UI elements and expose information about the UI
elements and/or allow them to be manipulated
EXAMPLE Such components can be applications, DLLs, and so on.
NOTE A Microsoft Active Accessibility server has the same role as a UI Automation provider.
2.35
simple element
element that shares an IAccessible object with other peer elements
NOTE A simple element relies on the shared IAccessible object (typically its parent in the object hierarchy) to
expose its properties.
2.36
Services Control Manager
SCM
system process that maintains a database of installed services and driver services, and provides a unified and
secure means of controlling them
NOTE The database includes information on how each service or driver service should be started. It also enables
system administrators to customize security requirements for each service and thereby control access to the service.
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ISO/IEC TR 13066-2:2012(E)
2.37
system service
application conforming to the interface rules of the Service Control Manager (SCM)
NOTE 1 It can be started automatically at system boot, by a user through the Services control panel applet, or by an
application that uses the service functions
NOTE 2 Services can execute even when no user is logged on to the system. File services, indexing service, memory
management, power management, and remote desktop services are examples of services.
2.38
Text Services Framework
TSF
simple and scalable framework for the delivery of advanced text input and natural language technologies
NOTE 1 TSF can be enabled in applications, or as a TSF text service
NOTE 2 A TSF text service provides multilingual support and delivers text services such as keyboard processors,
handwriting recognition, and speech recognition.
2.39
user interface
UI
mechanisms by which a person interacts with a computer system
NOTE 1 The user interface provides input mechanisms, allowing users to manipulate a system
NOTE 2 It also provides output mechanisms, allowing the system to produce the effects of the users’ manipulation.
2.40
User Interface Automation
UI Automation
UIA
accessibility framework that exposes applications to software automation or to assistive technologies such as
screen readers and speech commanding programs
2.41
virtual machine
VM
computer within a computer, implemented in software
NOTE 1 A virtual machine emulates a complete hardware system, from processor to network card, in a self-contained,
isolated software environment, enabling the simultaneous operation of otherwise incompatible operating systems.
NOTE 2 Each operating system runs in its own isolated software partition.
2.42
Visual Basic
VB
generally visual programming environment from Microsoft based on the BASIC programming language
2.43
Web Accessibility Initiative
WAI
an effort to improve the accessibility of the World Wide Web
2.44
WinEvents
mechanism that allows servers and the Windows operating system to notify clients when an accessible object
changes
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ISO/IEC TR 13066-2:2012(E)
2.45
World Wide Web Consortium
W3C
standards organization for the World Wide Web
3 General Description and Architecture of the Microsoft Windows Automation API
3.1 General Description
The Microsoft® Windows® Automation API consists of two accessibility frameworks — Microsoft Active
Accessibility and User Interface Automation (UI Automation). The IAccessibleEx interface specification
integrates the two accessibility frameworks.
Although Microsoft Active Accessibility and UI Automation are two different frameworks, the basic design
principles are similar. The purpose of both is to expose rich information about the UI elements used in
Windows applications. Developers of accessibility tools can use this information to help make applications
more accessible to people with vision, hearing, or motion disabilities.
3.1.1 Microsoft Active Accessibility Overview
Microsoft Active Accessibility is based on the Component Object Model (COM), which defines a common way
for applications and operating systems to communicate. The goal of Microsoft Active Accessibility is to allow
custom controls to expose basic information, such as name, location on screen, or type of control, and state
information such as visibility, enabled, or selected.
The accessible object is the central object of Microsoft Active Accessibility and is represented by an
IAccessible COM interface and an integer ChildId. It allows applications to expose UI elements as a tree
structure that represents the structure of the UI. Each element of this tree exposes a set of properties and
methods that allow the corresponding UI element to be manipulated. Microsoft Active Accessibility clients can
access the programmatic UI information through a standard API. The following sections describe the main
parts of Microsoft Active Accessibility, including accessible objects, the WinEvents mechanism, the Microsoft
Active Accessibility runtime (Oleacc.dll), and Microsoft Active Accessibility clients and servers.
3.1.1.1 Microsoft Active Accessibility Components
Microsoft Active Accessibility contains the following main components:
 Accessible Object – A logical UI element (such as a button) that is represented by an IAccessible COM
interface and a ChildId value.
 The IAccessible interface has properties and methods for obtaining information about and
manipulating UI elements.
 ChildId is an identifier for an accessible object that is used together with an IAccessible instance
to refer to a specific UI element.
 WinEvents – An event system that allows servers to notify clients when an accessible object changes.
For more information, see Events.
 Oleacc.dll– A run-time dynamic-link library that provides the Microsoft Active Accessibility API and the
accessibility system framework. Oleacc.dll also provides proxy objects for the Windows operating
system standard controls.
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ISO/IEC TR 13066-2:2012(E)
3.1.1.2 Oleacc.dll
The following APIs and functions are included in Oleacc.dll:
 Client APIs – APIs that clients use to request an IAccessible interface pointer (for example,
AccessibleObjectFromX).
 Server APIs– APIs that servers use to return an IAccessible interface pointer to a client (for example,
LresultFromObject).
 APIs for getting localized text for the role and state codes (for example, GetRoleText and
GetStateText).
 Helper APIs (for example, AccessibleChildren).
 Proxies– Code that provides the default implementation of an IAccessible interface for standard USER
and COMCTL controls. Because these controls implement the IAccessible interface on behalf of the
system controls, they are known as proxies.
3.1.1.3 Microsoft Active Accessibility Clients
Microsoft Active Accessibility helps accessibility aids, called clients, interact with standard and custom UI
elements of other applications and the operating system. Clients can use Microsoft Active Accessibility to
access, identify, and manipulate an application's UI elements. Clients include accessibility aids, automated
testing tools, and computer-based training applications.
Clients must know when the server's UI changes so that information can be conveyed to the user. They are
notified about changes in the server UI by registering to receive notifications of specific changes through a
mechanism called Window Events, or WinEvents. For more information, see Events.
To learn about and manipulate a particular UI element, clients use a pair consisting of an IAccessible
interface and a ChildId.
3.1.1.4 Microsoft Active Accessibility Servers
Applications that interact with and provide information to clients are called servers. Servers include any
control, module, or application that implements Microsoft Active Accessibility. A server uses Microsoft Active
Accessibility to provide information about its UI elements to clients.
3.1.2 UI Automation Overview
UI Automation provides programmatic access to UI elements on the desktop, enabling assistive technology
products such as screen readers to provide information about the UI to end users and to manipulate the UI by
means other than standard input. UI Automation also allows automated test scripts to interact with the UI. The
UI Automation Specification is designed so that it can be supported across platforms other than Microsoft
Windows.
UI Automation is broader in scope than just an interface definition. UI Automation provides:
 A set of classes that make it easy for client applications to receive events, retrieve property values, and
manipulate UI elements.
 A core infrastructure for doing fetch, find, and similar operations efficiently across process boundaries.
 A set of interfaces for providers to express the UI as a tree structure, along with some general properties.
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ISO/IEC TR 13066-2:2012(E)
 A set of interfaces that providers use to express other properties and functionality specific to the control
type. These are the control pattern interfaces.
To improve on Microsoft Active Accessibility, UI Automation aims to address the following goals:
 Enable efficient out-of-process clients, while continuing to allow in-process access.
 Expose more information about the UI in a way that allows clients to be out-of-process.
 Co-exist with and use Microsoft Active Accessibility, but do not inherit problems that exist in Microsoft
Active Accessibility.
 Provide an alternative to IAccessible that is simple to implement.
The Microsoft Windows implementation of UI Automation features COM-based interfaces and managed
interfaces that are included with the Microsoft .NET Framework.
3.1.2.1 UI Automation Components
UI Automation h
...