AccessibleEvents AccessibleEvents AccessibleEvents AccessibleEvents Enum

Definition

Specifies events that are reported by accessible applications.

public enum class AccessibleEvents
public enum AccessibleEvents
type AccessibleEvents = 
Public Enum AccessibleEvents
Inheritance
AccessibleEventsAccessibleEventsAccessibleEventsAccessibleEvents

Fields

AcceleratorChange AcceleratorChange AcceleratorChange AcceleratorChange 32786

An object's KeyboardShortcut property changed. Server applications send the event for their accessible objects.

Create Create Create Create 32768

An object was created. The operating system sends the event for the following user interface elements: caret, header control, list view control, tab control, toolbar control, tree view control, and window object. Server applications send this event for their accessible objects. Servers must send this event for all an object's child objects before sending the event for the parent object. Servers must ensure that all child objects are fully created and ready to accept calls from clients when the parent object sends the event.

DefaultActionChange DefaultActionChange DefaultActionChange DefaultActionChange 32785

An object's DefaultAction property changed. The system sends this event for dialog boxes. Server applications send this event for their accessible objects. Therefore, server applications do not need to send this event for the child objects. Hidden objects have a state of Invisible, and shown objects do not. Events of type AccessibleEvents.Hide indicate that a state of Invisible has been set. Therefore, servers do not need to send the AccessibleEvents.StateChange event in this case.

DescriptionChange DescriptionChange DescriptionChange DescriptionChange 32781

An object's Description property changed. Server applications send this event for their accessible objects.

Destroy Destroy Destroy Destroy 32769

An object was destroyed. The system sends this event for the following user interface elements: caret, header control, list view control, tab control, toolbar control, tree view control, and window object. Server applications send this event for their accessible objects. This event may or may not be sent for child objects. However, clients can conclude that all the children of an object have been destroyed when the parent object sends this event.

Focus Focus Focus Focus 32773

An object has received the keyboard focus. The system sends this event for the following user interface elements: list view control, menu bar, shortcut menu, switch window, tab control, tree view control, and window object. Server applications send this event for their accessible objects.

HelpChange HelpChange HelpChange HelpChange 32784

An object's Help property changed. Server applications send this event for their accessible objects.

Hide Hide Hide Hide 32771

An object is hidden. The system sends the event for the following user interface elements: caret and cursor. Server applications send the event for their accessible objects. When the event is generated for a parent object, all child objects have already been hidden. Therefore, server applications do not need to send the event for the child objects. The system does not send the event consistently.

LocationChange LocationChange LocationChange LocationChange 32779

An object has changed location, shape, or size. The system sends this event for the following user interface elements: caret and window object. Server applications send this event for their accessible objects. This event is generated in response to the top-level object within the object hierarchy that has changed, not for any children it might contain. For example, if the user resizes a window, the system sends this notification for the window, but not for the menu bar, title bar, scroll bars, or other objects that have also changed. The system does not send this event for every non-floating child window when the parent moves. However, if an application explicitly resizes child windows as a result of being resized, the system sends multiple events for the resized children. If an object's State property is set to Floating, servers should send a location change event whenever the object changes location. If an object does not have this state, servers should raise this event when the object moves relative to its parent.

NameChange NameChange NameChange NameChange 32780

An object's Name property changed. The system sends this event for the following user interface elements: check box, cursor, list view control, push button, radio button, status bar control, tree view control, and window object. Server applications send this event for their accessible objects.

ParentChange ParentChange ParentChange ParentChange 32783

An object has a new parent object. Server applications send this event for their accessible objects.

Reorder Reorder Reorder Reorder 32772

A container object has added, removed, or reordered its children. The system sends this event for the following user interface elements: header control, list view control, toolbar control, and window object. Server applications send this event as appropriate for their accessible objects. This event is also sent by a parent window when the z order for the child windows changes.

Selection Selection Selection Selection 32774

An accessible object within a container object has been selected. This event signals a single selection. Either a child has been selected in a container that previously did not contain any selected children, or the selection has changed from one child to another.

SelectionAdd SelectionAdd SelectionAdd SelectionAdd 32775

An item within a container object was added to the selection. The system sends this event for the following user interface elements: list box, list view control, and tree view control. Server applications send this event for their accessible objects. This event signals that a child has been added to an existing selection.

SelectionRemove SelectionRemove SelectionRemove SelectionRemove 32776

An item within a container object was removed from the selection. The system sends this event for the following user interface elements: list box, list view control, and tree view control. Server applications send this event for their accessible objects. This event signals that a child has been removed from an existing selection.

SelectionWithin SelectionWithin SelectionWithin SelectionWithin 32777

Numerous selection changes occurred within a container object. The system sends this event for list boxes. Server applications send this event for their accessible objects. This event can be sent when the selected items within a control have changed substantially. This event informs the client that many selection changes have occurred. This is preferable to sending several SelectionAdd or SelectionRemove events.

Show Show Show Show 32770

A hidden object is being shown. The system sends this event for the following user interface elements: caret, cursor, and window object. Server applications send this event for their accessible objects. Clients can conclude that, when this event is sent by a parent object, all child objects have already been displayed. Therefore, server applications do not need to send this event for the child objects.

StateChange StateChange StateChange StateChange 32778

An object's state has changed. The system sends the event for the following user interface elements: check box, combo box, header control, push button, radio button, scroll bar, toolbar control, tree view control, up-down control, and window object. Server applications send the event for their accessible objects. For example, a state change can occur when a button object has been pressed or released, or when an object is being enabled or disabled. The system does not send the event consistently.

SystemAlert SystemAlert SystemAlert SystemAlert 2

An alert was generated. Server applications send this event whenever an important user interface change has occurred that a user might need to know about. The system does not send the event consistently for dialog box objects.

SystemCaptureEnd SystemCaptureEnd SystemCaptureEnd SystemCaptureEnd 9

A window has lost mouse capture. The system sends the event; servers never send this event.

SystemCaptureStart SystemCaptureStart SystemCaptureStart SystemCaptureStart 8

A window is being moved or resized. The system sends the event; servers never send this event.

SystemContextHelpEnd SystemContextHelpEnd SystemContextHelpEnd SystemContextHelpEnd 13

A window exited context-sensitive Help mode. The system does not send the event consistently.

SystemContextHelpStart SystemContextHelpStart SystemContextHelpStart SystemContextHelpStart 12

A window entered context-sensitive Help mode. The system does not send the event consistently.

SystemDialogEnd SystemDialogEnd SystemDialogEnd SystemDialogEnd 17

A dialog box was closed. The system does not send the event for standard dialog boxes. Servers send this event for custom dialog boxes. The system does not send the event consistently.

SystemDialogStart SystemDialogStart SystemDialogStart SystemDialogStart 16

A dialog box was displayed. The system sends the event for standard dialog boxes. Servers send this event for custom dialog boxes. The system does not send the event consistently.

SystemDragDropEnd SystemDragDropEnd SystemDragDropEnd SystemDragDropEnd 15

An application is about to exit drag-and-drop mode. Applications that support drag-and-drop operations must send this event; the system does not.

SystemDragDropStart SystemDragDropStart SystemDragDropStart SystemDragDropStart 14

An application is about to enter drag-and-drop mode. Applications that support drag-and-drop operations must send this event; the system does not.

SystemForeground SystemForeground SystemForeground SystemForeground 3

The foreground window changed. The system sends this event even if the foreground window is changed to another window in the same thread. Server applications never send this event.

SystemMenuEnd SystemMenuEnd SystemMenuEnd SystemMenuEnd 5

A menu from the menu bar was closed. The system sends this event for standard menus. Servers send this event for custom menus.

SystemMenuPopupEnd SystemMenuPopupEnd SystemMenuPopupEnd SystemMenuPopupEnd 7

A shortcut menu was closed. The system sends this event for standard menus. Servers send this event for custom menus. When a shortcut menu is closed, the client receives this message followed almost immediately by the SystemMenuEnd event. The system does not send the event consistently.

SystemMenuPopupStart SystemMenuPopupStart SystemMenuPopupStart SystemMenuPopupStart 6

A shortcut menu was displayed. The system sends this event for standard menus. Servers send this event for custom menus. The system does not send the event consistently.

SystemMenuStart SystemMenuStart SystemMenuStart SystemMenuStart 4

A menu item on the menu bar was selected. The system sends this event for standard menus. Servers send this event for custom menus. The system might raise more than one MenuStart event that might or might not have a corresponding MenuEnd event.

SystemMinimizeEnd SystemMinimizeEnd SystemMinimizeEnd SystemMinimizeEnd 23

A window object was minimized or maximized. The system sends the event; servers never send this event.

SystemMinimizeStart SystemMinimizeStart SystemMinimizeStart SystemMinimizeStart 22

A window object is about to be minimized or maximized. The system sends the event; servers never send this event.

SystemMoveSizeEnd SystemMoveSizeEnd SystemMoveSizeEnd SystemMoveSizeEnd 11

The movement or resizing of a window is finished. The system sends the event; servers never send this event.

SystemMoveSizeStart SystemMoveSizeStart SystemMoveSizeStart SystemMoveSizeStart 10

A window is being moved or resized. The system sends the event; servers never send this event.

SystemScrollingEnd SystemScrollingEnd SystemScrollingEnd SystemScrollingEnd 19

Scrolling has ended on a scroll bar. The system sends this event for scroll bars attached to a window and for standard scroll bar controls. Servers send this event for custom scroll bars.

SystemScrollingStart SystemScrollingStart SystemScrollingStart SystemScrollingStart 18

Scrolling has started on a scroll bar. The system sends the event for scroll bars attached to a window and for standard scroll bar controls. Servers send this event for custom scroll bars.

SystemSound SystemSound SystemSound SystemSound 1

A sound was played. The system sends this event when a system sound, such as for menus, is played, even if no sound is audible. This might be caused by lack of a sound file or sound card. Servers send this event if a custom user interface element generates a sound.

SystemSwitchEnd SystemSwitchEnd SystemSwitchEnd SystemSwitchEnd 21

The user released ALT+TAB. The system sends the SwitchEnd event; servers never send this event. If only one application is running when the user presses ALT+TAB, the system sends the SwitchEnd event without a corresponding SwitchStart event.

SystemSwitchStart SystemSwitchStart SystemSwitchStart SystemSwitchStart 20

The user pressed ALT+TAB, which activates the switch window. If only one application is running when the user presses ALT+TAB, the system raises the SwitchEnd event without a corresponding SwitchStart event.

ValueChange ValueChange ValueChange ValueChange 32782

An object's Value property changed. The system raises the ValueChange event for the following user interface elements: edit control, header control, hot key control, progress bar control, scroll bar, slider control, and up-down control. Server applications send this event for their accessible objects.

Examples

The following code example demonstrates the creation of an accessibility-aware chart control, using the AccessibleObject and Control.ControlAccessibleObject classes to expose accessible information. The control plots two curves along with a legend. The ChartControlAccessibleObject class, which derives from ControlAccessibleObject, is used in the CreateAccessibilityInstance method to provide custom accessible information for the chart control. Because the chart legend is not an actual Control -based control, but instead is drawn by the chart control, it does not any built-in accessible information. Because of this, the ChartControlAccessibleObject class overrides the GetChild method to return the CurveLegendAccessibleObject that represents accessible information for each part of the legend. When an accessible-aware application uses this control, the control can provide the necessary accessible information.

This example demonstrates using the AccessibleEvents enumeration with the AccessibilityNotifyClients method. See the AccessibleObject class overview for the complete code example.

   // Gets or sets the location for the curve legend.
   Point get()
   {
      return location;
   }

   void set( Point value )
   {
      location = value;
      chart->Invalidate();
      
      // Notifies the chart of the location change. This is used for
      // the accessibility information. AccessibleEvents::LocationChange
      // tells the chart the reason for the notification.
      chart->AccessibilityNotifyClients( AccessibleEvents::LocationChange, (dynamic_cast<CurveLegendAccessibleObject^>(AccessibilityObject))->ID );
   }

}

property String^ Name 
{

   // Gets or sets the Name for the curve legend.
   String^ get()
   {
      return name;
   }

   void set( String^ value )
   {
      if ( name != value )
      {
         name = value;
         chart->Invalidate();
         
         // Notifies the chart of the name change. This is used for
         // the accessibility information. AccessibleEvents::NameChange
         // tells the chart the reason for the notification.
         chart->AccessibilityNotifyClients( AccessibleEvents::NameChange, (dynamic_cast<CurveLegendAccessibleObject^>(AccessibilityObject))->ID );
      }
   }

}

property bool Selected 
{

   // Gets or sets the Selected state for the curve legend.
   bool get()
   {
      return selected;
   }

   void set( bool value )
   {
      if ( selected != value )
      {
         selected = value;
         chart->Invalidate();
         
         // Notifies the chart of the selection value change. This is used for
         // the accessibility information. The AccessibleEvents value depends upon
         // if the selection is true (AccessibleEvents::SelectionAdd) or
         // false (AccessibleEvents::SelectionRemove).
         chart->AccessibilityNotifyClients( selected ? AccessibleEvents::SelectionAdd : AccessibleEvents::SelectionRemove, (dynamic_cast<CurveLegendAccessibleObject^>(AccessibilityObject))->ID );
      }
   }
    // Gets or sets the location for the curve legend.
    public Point Location
    {   
        get {
            return location;
        }
        set {
            location = value;
            chart.Invalidate();

            // Notifies the chart of the location change. This is used for
            // the accessibility information. AccessibleEvents.LocationChange
            // tells the chart the reason for the notification.

            chart.AccessibilityNotifyClients(AccessibleEvents.LocationChange, 
                ((CurveLegendAccessibleObject)AccessibilityObject).ID);
        }
    }            

    // Gets or sets the Name for the curve legend.
    public string Name
    {   
        get {
            return name;
        }
        set {
            if (name != value) 
            {
                name = value;
                chart.Invalidate();

                // Notifies the chart of the name change. This is used for
                // the accessibility information. AccessibleEvents.NameChange
                // tells the chart the reason for the notification.

                chart.AccessibilityNotifyClients(AccessibleEvents.NameChange, 
                    ((CurveLegendAccessibleObject)AccessibilityObject).ID);
            }
        }
    }

    // Gets or sets the Selected state for the curve legend.
    public bool Selected
    {   
        get {
            return selected;
        }
        set {
            if (selected != value) 
            {
                selected = value;
                chart.Invalidate();

                // Notifies the chart of the selection value change. This is used for
                // the accessibility information. The AccessibleEvents value depends upon
                // if the selection is true (AccessibleEvents.SelectionAdd) or 
                // false (AccessibleEvents.SelectionRemove).
                chart.AccessibilityNotifyClients(
                    selected ? AccessibleEvents.SelectionAdd : AccessibleEvents.SelectionRemove, 
                    ((CurveLegendAccessibleObject)AccessibilityObject).ID);
            }
        }
    }
' Gets or sets the location for the curve legend.            
Public Property Location() As Point
    Get
        Return m_location
    End Get
    Set
        m_location = value
        chart.Invalidate()

        ' Notifies the chart of the location change. This is used for
        ' the accessibility information. AccessibleEvents.LocationChange
        ' tells the chart the reason for the notification.
        chart.ExposeAccessibilityNotifyClients(AccessibleEvents.LocationChange, _
                CType(AccessibilityObject, CurveLegendAccessibleObject).ID)
    End Set
End Property

' Gets or sets the Name for the curve legend.            
Public Property Name() As String
    Get
        Return m_name
    End Get
    Set
        If m_name <> value Then
            m_name = value
            chart.Invalidate()

            ' Notifies the chart of the name change. This is used for
            ' the accessibility information. AccessibleEvents.NameChange
            ' tells the chart the reason for the notification. 
            chart.ExposeAccessibilityNotifyClients(AccessibleEvents.NameChange, _
                    CType(AccessibilityObject, CurveLegendAccessibleObject).ID)
        End If
    End Set
End Property

' Gets or sets the Selected state for the curve legend.            
Public Property Selected() As Boolean
    Get
        Return m_selected
    End Get
    Set
        If m_selected <> value Then
            m_selected = value
            chart.Invalidate()

            ' Notifies the chart of the selection value change. This is used for
            ' the accessibility information. The AccessibleEvents value varies
            ' on whether the selection is true (AccessibleEvents.SelectionAdd) or 
            ' false (AccessibleEvents.SelectionRemove). 
            If m_selected Then
                chart.ExposeAccessibilityNotifyClients(AccessibleEvents.SelectionAdd, _
                        CType(AccessibilityObject, CurveLegendAccessibleObject).ID) 
            Else
                chart.ExposeAccessibilityNotifyClients(AccessibleEvents.SelectionRemove, _
                        CType(AccessibilityObject, CurveLegendAccessibleObject).ID) 
            End If
        End If
    End Set
End Property

Remarks

The operating system and accessibility server applications generate accessibility events in response to changes in the user interface.

This enumeration is used by AccessibleObject and Control.

For more information about the accessibility application, search for "Microsoft Active Accessibility" in the MSDN Library.

Applies to

See also