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Appendix G: Active Accessibility Bridge to UI Automation

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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.

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