AccessibleStates Enumeration

 
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Specifies values representing possible states for an accessible object.

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

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

<FlagsAttribute>
Public Enumeration AccessibleStates

Member nameDescription
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.

AlertLow

The low-priority information that might not be important to the user.

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 any time they choose.

Animated

The object that rapidly or constantly changes appearance. Graphics that are occasionally animated, but not always, should be defined as GraphicORAnimated. This state should not be used to indicate that the object's location is changing.

Busy

A control that cannot accept input in its current condition.

Checked

An object with a selected check box.

Collapsed

The hidden children of the object that are items in an outline or tree structure.

Default

The default button or menu item.

Expanded

The displayed children of the object that are items in an outline or tree structure.

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.

Floating

The object that is not fixed to the boundary of its parent object and that does not move automatically along with the parent.

Focusable

The object on the active window that can receive keyboard focus.

Focused

An object with the keyboard focus.

HasPopup

The object displays a pop-up menu or window when invoked.

HotTracked

The object hot-tracked by the mouse, meaning its appearance is highlighted to indicate the mouse pointer is located over it.

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.

Invisible

An object without a visible user interface.

Linked

A linked object that has not been previously selected.

Marqueed

An object with scrolling or moving text or graphics.

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.

Moveable

A movable object.

MultiSelectable

An object that accepts multiple selected items.

None

No state.

Offscreen

No on-screen representation. A sound or alert object would have this state, or a hidden window that is never made visible.

Pressed

A pressed object.

Protected

A password-protected edit control.

ReadOnly

A read-only object.

Selectable

An object that can accept selection.

Selected

A selected object.

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.

Sizeable

A sizable object.

Traversed

A linked object that has previously been selected.

Unavailable

An unavailable object.

Valid

Obsolete. A valid object. This property is deprecated in .NET Framework 2.0.

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

For more information about the accessibility application, see "Microsoft Active Accessibility" in the Microsoft Developer Network (MSDN) library at http://msdn.microsoft.com/library.

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 on Control, but instead is drawn by the chart control, it does not contain 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 code excerpt demonstrates using the AccessibleStates enumeration with the State property. See the AccessibleObject class overview for the complete code example.

' 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 'NewNew

    ' 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

.NET Framework
Available since 1.1
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