Appendix G: Active Accessibility Bridge to UI Automation

This appendix contains information about the Microsoft Active Accessibility Bridge. The Active Accessibility Bridge enables applications that implement Microsoft Active Accessibility to access applications that implement Microsoft UI Automation. By bridging Microsoft Active Accessibility and UI Automation together, Microsoft Active Accessibility-based clients, such as a screenreader on Windows XP, can programmatically interact with UI Automation-based providers of UI Automation, such as a Windows Presentation Foundation (WPF) application. It is part of the UI Automation Native Core API (UIAutomationCore.dll).

The Active Accessibility Bridge maps UI Automation properties and events to those of Microsoft Active Accessibility. The following tables map the Microsoft Active Accessibility IAccessible interface methods and properties to UI Automation. Use these tables to determine appropriate coding practices for developing your Microsoft Active Accessibility-based client.

Navigation and Hierarchy Properties

IAccessible property	UI Automation property
get_accChild	Not implemented
get_accChildCount	Derived from UI Automation tree
get_accParent	Derived from UI Automation tree
accNavigate	Not implemented

 

Descriptive Properties and Methods

IAccessible	UI Automation
accDoDefaultAction	See the Control Types and accRole table for details.
get_accDefaultAction	See the Control Types and accRole table for details.
get_accKeyboardShortcut	AccessKeyPropertyor AcceleratorKeyProperty; if both present, AccessKeyProperty takes precedence.
get_accName	NameProperty
get_accRole	ControlTypeProperty. See the Control Types and accRole table for details.
get_accState	See the Control Types and accRole table for details.
get_accValue	ValueProperty; supported on control types that support the Value control pattern or RangeValue control pattern control pattern. RangeValue values are consistent with Microsoft Active Accessibility behavior (0 to 100). Value items use a string.
put_accValue	ValueProperty; supported on control types that support the Value control pattern or RangeValue control pattern
get_accHelp	HelpTextProperty
get_accDescription	Not implemented
get_accHelpTopic	Not implemented

 

Control Types and accRole

The Microsoft Active Accessibility default role is ROLE_SYSTEM_CLIENT. If no default action is found for a control type, the Active Accessibility Bridge will also use the following available control patterns: Invoke, ExpandCollapse, and Toggle. For example, a groupbox control has no default action. If it supports ExpandCollapse, then the Active Accessibility Bridge will use that for the default action.

UI Automation control type	accRole	Default action
Button	ROLE_SYSTEM_PUSHBUTTON	Press
Calendar	ROLE_SYSTEM_CLIENT	None
CheckBox	ROLE_SYSTEM_CHECKBUTTON	Check/Uncheck (toggle)
ComboBox	ROLE_SYSTEM_COMBOBOX	None
Custom	ROLE_SYSTEM_CLIENT	None
DataGrid	ROLE_SYSTEM_LIST	None
DataItem	ROLE_SYSTEM_LISTITEM	None
Document	ROLE_SYSTEM_DOCUMENT	None
Edit	ROLE_SYSTEM_TEXT	None
Group	ROLE_SYSTEM_GROUPING	None
Header	ROLE_SYSTEM_LIST	None
HeaderItem	ROLE_SYSTEM_COLUMNHEADER	Click
Hyperlink	ROLE_SYSTEM_LINK	Jump (maps to Invoke)
Image	ROLE_SYSTEM_GRAPHIC	None
List	ROLE_SYSTEM_LIST	None
ListItem	ROLE_SYSTEM_LISTITEM	Double click
Menu	ROLE_SYSTEM_MENUPOPUP	None
MenuBar	ROLE_SYSTEM_MENUBAR	None
MenuItem	ROLE_SYSTEM_MENUITEM	Execute or Open/Close for menu items that have children.
Pane	ROLE_SYSTEM_PANE	None
ProgressBar	ROLE_SYSTEM_PROGRESSBAR	None
RadioButton	ROLE_SYSTEM_RADIOBUTTON	Check
ScrollBar	ROLE_SYSTEM_SCROLLBAR	None
Slider	ROLE_SYSTEM_SLIDER	None
Spinner	ROLE_SYSTEM_SPINBUTTON	None
SplitButton	ROLE_SYSTEM_SPLITBUTTON	None
StatusBar	ROLE_SYSTEM_STATUSBAR	None
Tab	ROLE_SYSTEM_PAGETABLIST	None
TabItem	ROLE_SYSTEM_PAGETAB	Switch
Table	ROLE_SYSTEM_TABLE	None
Text	ROLE_SYSTEM_STATICTEXT	None
Thumb	ROLE_SYSTEM_INDICATOR	None
TitleBar	ROLE_SYSTEM_TITLEBAR	None
ToolBar	ROLE_SYSTEM_TOOLBAR	None
ToolTip	ROLE_SYSTEM_TOOLTIP	None
Tree	ROLE_SYSTEM_OUTLINE	None
TreeItem	ROLE_SYSTEM_OUTLINEITEM	Expand or Collapse
Window	ROLE_SYSTEM_WINDOW	None

 

UI Automation Properties and accState

accState	UI Automation property	Triggers state change
STATE_SYSTEM_CHECKED	For ControlType = "checkbox" use ToggleState.On. For "radiobutton" use SelectionItemPattern::IsSelected	Yes
STATE_SYSTEM_FOCUSABLE	IsKeyboardFocusableProperty	No
STATE_SYSTEM_FOCUSED	HasKeyboardFocusProperty	No
STATE_SYSTEM_PROTECTED	IsPasswordProperty	No
STATE_SYSTEM_READONLY	IsReadOnlyProperty (Value control pattern and RangeValue control pattern)	No
STATE_SYSTEM_UNAVAILABLE	IsEnabledProperty	Yes
STATE_SYSTEM_LINKED	ControlTypeProperty = "hyperlink"	No
STATE_SYSTEM_SELECTABLE	SelectionItemPattern is supported	No
STATE_SYSTEM_SELECTED	IsSelectedProperty (SelectionItem control pattern)	No
STATE_SYSTEM_COLLAPSED	ExpandCollapseState = Collapsed	Yes
STATE_SYSTEM_EXPANDED	ExpandCollapseState = Expanded or PartiallyExpanded	Yes
STATE_SYSTEM_HASPOPUP	Menu items that support Expand/Collapse	No
STATE_SYSTEM_MIXED	ToggleState = Indeterminate	No
STATE_SYSTEM_SIZEABLE	IUIAutomationTransformPattern::CanResize	No
STATE_SYSTEM_MOVEABLE	IUIAutomationTransformPattern::CanMove	No
STATE_SYSTEM_MULTISELECTABLE	IUIAutomationSelectionPattern::CanSelectMultiple	No

 

Selection and Focus

IAccessible	UI Automation
get_accFocus	IUIAutomation::FocusedElement
accSelect	See the UI Automation Properties and accSelect SELFLAGs table for details.
get_accSelection	SelectionPattern::GetSelection

 

UI Automation Properties and accSelect SELFLAGs

accSelect SELFLAGs	UI Automation property
SELFLAG_NONE	Not available
SELFLAG_TAKFOCUS	IUIAutomationElement::SetFocus
SELFLAG_TAKESELECTION	IUIAutomationSelectionItemPattern::Select
SELFLAG_ADDSELECTION	IUIAutomationSelectionItemPattern::AddToSelection
SELFLAG_TAKEREMOVESELECTION	IUIAutomationSelectionItemPattern::RemoveFromSelection
SELFLAG_EXTENDSELECTION	Not available

 

Spatial Mapping

IAccessible	UI Automation
accLocation	BoundingRectangleProperty
accHitTest	IRawElementProviderFragmentRoot::ElementProviderFromPoint

 

Events

System-Level Event Constants	UI Automation
EVENT_SYSTEM_MENUPOPUPSTART	UIA_MenuOpenedEventId (Note: Must check if this is a pop-up window.)
EVENT_SYSTEM_MENUPOPUPEND	UIA_MenuClosedEventId
EVENT_SYSTEM_MENUSTART	UIA_MenuModeStartEventId
EVENT_SYSTEM_MENUEND	UIA_MenuModeEndEventId
EVENT_SYSTEM_SOUND
EVENT_SYSTEM_ALERT
EVENT_SYSTEM_CAPTURESTART
EVENT_SYSTEM_CAPTUREEND
EVENT_SYSTEM_DIALOGSTART
EVENT_SYSTEM_DIALOGEND
EVENT_SYSTEM_MOVESIZESTART
EVENT_SYSTEM_MOVESIZEEND
EVENT_SYSTEM_CONTEXTHELPSTART
EVENT_SYSTEM_CONTEXTHELPEND	Not relevant
EVENT_SYSTEM_DRAGDROPSTART
EVENT_SYSTEM_DRAGDROPEND
EVENT_SYSTEM_SWITCHSTART	Not relevant
EVENT_SYSTEM_SWITCHEND	Not relevant
EVENT_SYSTEM_MINIMIZESTART
EVENT_SYSTEM_MINIMIZEEND
EVENT_SYSTEM_FOREGROUND
EVENT_SYSTEM_SCROLLINGSTART	Not available
EVENT_SYSTEM_SCROLLINGEND	Not available

 

Object-Level Event Constants	UI Automation
EVENT_OBJECT_FOCUS	AutomationFocusChangedEvent
EVENT_OBJECT_VALUECHANGE	ValueProperty (Value control pattern and RangeValue control pattern)
EVENT_OBJECT_SELECTION	ElementSelectedEvent (SelectionItem control pattern)
EVENT_OBJECT_SELECTIONADD	ElementAddedToSelectionEvent (SelectionItem control pattern)
EVENT_OBJECT_SELECTIONREMOVE	ElementRemovedFromSelectionEvent
EVENT_OBJECT_SELECTIONWITHIN	EventsSelectionInvalidatedEvent
EVENT_OBJECT_STATECHANGE	See UI Automation Properties and accState table for states that trigger a state change