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AccessibleStates Enumeration

Specifies values representing possible states for an accessible object.

This enumeration has a FlagsAttribute attribute that allows a bitwise combination of its member values.

[Visual Basic]
<Flags>
<Serializable>
Public Enum AccessibleStates
[C#]
[Flags]
[Serializable]
public enum AccessibleStates
[C++]
[Flags]
[Serializable]
__value public enum AccessibleStates
[JScript]
public
   Flags
 Serializable
enum AccessibleStates

Remarks

An accessible object can be associated with one or more of these states.

For additional information on the accessibility application, search for "Microsoft Active Accessibility" in the Microsoft Developer Network (MSDN) library.

Members

Member name Description Value
AlertHigh The important information that should be conveyed to the user immediately. For example, a battery level indicator reaching a critical low level would transition to this state, in which case, a blind access utility would announce this information immediately to the user, and a screen magnification program would scroll the screen so that the battery indicator is in view. This state is also appropriate for any prompt or operation that must be completed before the user can continue. 268435456
AlertLow The low-priority information that might not be important to the user. 67108864
AlertMedium The important information that does not need to be conveyed to the user immediately. For example, when a battery level indicator is starting to reach a low level, it could generate a medium-level alert. Blind access utilities could then generate a sound to let the user know that important information is available, without actually interrupting the user's work. Users can then query the alert information at their leisure. 134217728
Animated The object that rapidly or constantly changes appearance. Graphics that are occasionally animated, but not always, should be defined as Graphic OR Animated. This state should not be used to indicate that the object's location is changing. 16384
Busy A control that cannot accept input in its current condition. 2048
Checked An object with a selected check box. 16
Collapsed The hidden children of the object that are items in an outline or tree structure. 1024
Default The default button or menu item. 256
Expanded The displayed children of the object that are items in an outline or tree structure. 512
ExtSelectable The altered selection such that all objects between the selection anchor, which is the object with the keyboard focus, and this object take on the anchor object's selection state. If the anchor object is not selected, the objects are removed from the selection. If the anchor object is selected, the selection is extended to include this object and all objects in between. You can set the selection state by combining this with AccessibleSelection.AddSelection or AccessibleSelection.RemoveSelection. This state does not change the focus or the selection anchor unless it is combined with AccessibleSelection.TakeFocus. 33554432
Floating The object that is not fixed to the boundary of its parent object and that does not move automatically along with the parent. 4096
Focusable The object on the active window that can receive keyboard focus. 1048576
Focused An object with the keyboard focus. 4
HotTracked The object hot-tracked by the mouse, meaning its appearance is highlighted to indicate the mouse pointer is located over it. 128
Indeterminate A three-state check box or toolbar button whose state is indeterminate. The check box is neither checked nor unchecked, and it is in the third or mixed state. 32
Invisible An object without a visible user interface. 32768
Linked A linked object that has not been previously selected. 4194304
Marqueed An object with scrolling or moving text or graphics. 8192
Mixed A three-state check box or toolbar button whose state is indeterminate. The check box is neither checked nor unchecked, and it is in the third or mixed state. 32
Moveable A movable object. 262144
MultiSelectable An object that accepts multiple selected items. 16777216
None No state. 0
Offscreen No on-screen representation. A sound or alert object would have this state, or a hidden window that is never made visible. 65536
Pressed A pressed object. 8
Protected A password-protected edit control. 536870912
ReadOnly A read-only object. 64
Selectable An object that can accept selection. 2097152
Selected A selected object. 2
SelfVoicing The object or child can use text-to-speech (TTS) to describe itself. A speech-based accessibility aid should not announce information when an object with this state has the focus, because the object automatically announces information about itself. 524288
Sizeable A sizable object. 131072
Traversed A linked object that has previously been selected. 8388608
Unavailable An unavailable object. 1
Valid A valid object. 1073741823

Example

[Visual Basic, C#, C++] The following 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. Since 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.

[Visual Basic, C#, C++] This code excerpt demonstrates using the AccessibleStates enumeration with the State property. See the AccessibleObject class overview for the complete code example.

[Visual Basic] 
' Inner Class ChartControlAccessibleObject represents accessible information 
' associated with the ChartControl.
' The ChartControlAccessibleObject is returned in the         ' ChartControl.CreateAccessibilityInstance override.
Public Class ChartControlAccessibleObject
    Inherits Control.ControlAccessibleObject

    Private chartControl As ChartControl
    
    Public Sub New(ctrl As ChartControl)
        MyBase.New(ctrl)
        chartControl = ctrl
    End Sub 'New
    
    ' Get the role for the Chart. This is used by accessibility programs.            
    Public Overrides ReadOnly Property Role() As AccessibleRole
        Get
            Return System.Windows.Forms.AccessibleRole.Chart
        End Get
    End Property
    
    ' Get the state for the Chart. This is used by accessibility programs.            
    Public Overrides ReadOnly Property State() As AccessibleStates
        Get
            Return AccessibleStates.ReadOnly
        End Get
    End Property                        
    
    ' The CurveLegend objects are "child" controls in terms of accessibility so 
    ' return the number of ChartLengend objects.            
    Public Overrides Function GetChildCount() As Integer
        Return chartControl.Legends.Length
    End Function 
    
    ' Get the Accessibility object of the child CurveLegend idetified by index.
    Public Overrides Function GetChild(index As Integer) As AccessibleObject
        If index >= 0 And index < chartControl.Legends.Length Then
            Return chartControl.Legends(index).AccessibilityObject
        End If
        Return Nothing
    End Function 
    
    ' Helper function that is used by the CurveLegend's accessibility object
    ' to navigate between sibiling controls. Specifically, this function is used in
    ' the CurveLegend.CurveLegendAccessibleObject.Navigate function.
    Friend Function NavigateFromChild(child As CurveLegend.CurveLegendAccessibleObject, _
                                    navdir As AccessibleNavigation) As AccessibleObject
        Select Case navdir
            Case AccessibleNavigation.Down, AccessibleNavigation.Next
                    Return GetChild(child.ID + 1)
            
            Case AccessibleNavigation.Up, AccessibleNavigation.Previous
                    Return GetChild(child.ID - 1)
        End Select
        Return Nothing
    End Function            

    ' Helper function that is used by the CurveLegend's accessibility object
    ' to select a specific CurveLegend control. Specifically, this function is used 
    ' in the CurveLegend.CurveLegendAccessibleObject.Select function.            
    Friend Sub SelectChild(child As CurveLegend.CurveLegendAccessibleObject, selection As AccessibleSelection)
        Dim childID As Integer = child.ID
        
        ' Determine which selection action should occur, based on the
        ' AccessibleSelection value.
        If (selection And AccessibleSelection.TakeSelection) <> 0 Then
            Dim i As Integer
            For i = 0 To chartControl.Legends.Length - 1
                If i = childID Then
                    chartControl.Legends(i).Selected = True
                Else
                    chartControl.Legends(i).Selected = False
                End If
            Next i
            
            ' AccessibleSelection.AddSelection means that the CurveLegend will be selected.
            If (selection And AccessibleSelection.AddSelection) <> 0 Then
                chartControl.Legends(childID).Selected = True
            End If

            ' AccessibleSelection.AddSelection means that the CurveLegend will be unselected.                    
            If (selection And AccessibleSelection.RemoveSelection) <> 0 Then
                chartControl.Legends(childID).Selected = False
            End If
        End If
    End Sub 'SelectChild
End Class 'ChartControlAccessibleObject

[C#] 
// Inner class ChartControlAccessibleObject represents accessible information associated with the ChartControl.
// The ChartControlAccessibleObject is returned in the ChartControl.CreateAccessibilityInstance override.
public class ChartControlAccessibleObject : ControlAccessibleObject
{
    ChartControl chartControl;

    public ChartControlAccessibleObject(ChartControl ctrl) : base(ctrl) 
    {
        chartControl = ctrl;
    }

    // Gets the role for the Chart. This is used by accessibility programs.
    public override AccessibleRole Role
    {  
        get {
            return AccessibleRole.Chart;
        }
    }

    // Gets the state for the Chart. This is used by accessibility programs.
    public override AccessibleStates State
    {  
        get {                    
            return AccessibleStates.ReadOnly;
        }
    }

    // The CurveLegend objects are "child" controls in terms of accessibility so 
    // return the number of ChartLengend objects.
    public override int GetChildCount()
    {  
        return chartControl.Legends.Length;
    }

    // Gets the Accessibility object of the child CurveLegend idetified by index.
    public override AccessibleObject GetChild(int index)
    {  
        if (index >= 0 && index < chartControl.Legends.Length) {
            return chartControl.Legends[index].AccessibilityObject;
        }                
        return null;
    }

    // Helper function that is used by the CurveLegend's accessibility object
    // to navigate between sibiling controls. Specifically, this function is used in
    // the CurveLegend.CurveLegendAccessibleObject.Navigate function.
    internal AccessibleObject NavigateFromChild(CurveLegend.CurveLegendAccessibleObject child, 
                                                AccessibleNavigation navdir) 
    {  
        switch(navdir) {
            case AccessibleNavigation.Down:
            case AccessibleNavigation.Next:
                return GetChild(child.ID + 1);
                
            case AccessibleNavigation.Up:
            case AccessibleNavigation.Previous:
                return GetChild(child.ID - 1);                        
        }
        return null;
    }

    // Helper function that is used by the CurveLegend's accessibility object
    // to select a specific CurveLegend control. Specifically, this function is used
    // in the CurveLegend.CurveLegendAccessibleObject.Select function.
    internal void SelectChild(CurveLegend.CurveLegendAccessibleObject child, AccessibleSelection selection) 
    {   
        int childID = child.ID;

        // Determine which selection action should occur, based on the
        // AccessibleSelection value.
        if ((selection & AccessibleSelection.TakeSelection) != 0) {
            for(int i = 0; i < chartControl.Legends.Length; i++) {
                if (i == childID) {
                    chartControl.Legends[i].Selected = true;                        
                } else {
                    chartControl.Legends[i].Selected = false;
                }
            }

            // AccessibleSelection.AddSelection means that the CurveLegend will be selected.
            if ((selection & AccessibleSelection.AddSelection) != 0) {
                chartControl.Legends[childID].Selected = true;                        
            }

            // AccessibleSelection.AddSelection means that the CurveLegend will be unselected.
            if ((selection & AccessibleSelection.RemoveSelection) != 0) {
                chartControl.Legends[childID].Selected = false;                        
            }
        }            
    }
}

[C++] 
// Inner class ChartControlAccessibleObject represents accessible information associated with the ChartControl.
// The ChartControlAccessibleObject is returned in the ChartControl::CreateAccessibilityInstance .
__gc class ChartControlAccessibleObject : public ControlAccessibleObject {
   ChartControl* chartControl;

public:
   ChartControlAccessibleObject(ChartControl* ctrl) : ControlAccessibleObject (ctrl) {
      chartControl = ctrl;
   }

   // Gets the role for the Chart. This is used by accessibility programs.
   __property System::Windows::Forms::AccessibleRole get_Role() {
      return AccessibleRole::Chart;
   }

   // Gets the state for the Chart. This is used by accessibility programs.
   __property AccessibleStates get_State() {
      return AccessibleStates::ReadOnly;
   }

   // The CurveLegend objects are "child" controls in terms of accessibility so
   // return the number of ChartLengend objects.
   int GetChildCount() {
      return chartControl->Legends->Length;
   }

   // Gets the Accessibility object of the child CurveLegend idetified by index.
   AccessibleObject* GetChild(int index) {
      if (index >= 0 && index < chartControl->Legends->Length) {
         return chartControl->Legends[index]->AccessibilityObject;
      }
      return 0;
   }

   // Helper function that is used by the CurveLegend's accessibility object
   // to navigate between sibiling controls. Specifically, this function is used in
   // the CurveLegend::CurveLegendAccessibleObject.Navigate function.
public private:
   AccessibleObject* NavigateFromChild(CurveLegend::CurveLegendAccessibleObject* child,
      AccessibleNavigation navdir) {
         switch(navdir) {
                 case AccessibleNavigation::Down:
                 case AccessibleNavigation::Next:
                    return GetChild(child->ID + 1);

                 case AccessibleNavigation::Up:
                 case AccessibleNavigation::Previous:
                    return GetChild(child->ID - 1);
         }
         return 0;
      }

      // Helper function that is used by the CurveLegend's accessibility object
      // to select a specific CurveLegend control. Specifically, this function is used
      // in the CurveLegend::CurveLegendAccessibleObject.Select function.
      void SelectChild(CurveLegend::CurveLegendAccessibleObject* child, AccessibleSelection selection) {
         int childID = child->ID;

         // Determine which selection action should occur, based on the
         // AccessibleSelection value.
         if ((selection & AccessibleSelection::TakeSelection) != 0) {
            for (int i = 0; i < chartControl->Legends->Length; i++) {
               if (i == childID) {
                  chartControl->Legends[i]->Selected = true;
               } else {
                  chartControl->Legends[i]->Selected = false;
               }
            }

            // AccessibleSelection->AddSelection means that the CurveLegend will be selected.
            if ((selection & AccessibleSelection::AddSelection) != 0) {
               chartControl->Legends[childID]->Selected = true;
            }

            // AccessibleSelection->AddSelection means that the CurveLegend will be unselected.
            if ((selection & AccessibleSelection::RemoveSelection) != 0) {
               chartControl->Legends[childID]->Selected = false;
            }
         }
      }
}; // class ChartControlAccessibleObject

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Namespace: System.Windows.Forms

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

Assembly: System.Windows.Forms (in System.Windows.Forms.dll)

See Also

System.Windows.Forms Namespace | AccessibleEvents | AccessibleObject | AccessibleNavigation | AccessibleRole | AccessibleSelection

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