AccessibleNavigation Enum

Definition

public enum class AccessibleNavigation

public enum AccessibleNavigation

type AccessibleNavigation = 

Public Enum AccessibleNavigation

Arv

Object

ValueType

Enum

AccessibleNavigation

Fält

Exempel

I följande kodexempel visas hur du skapar en tillgänglighetsmedveten diagramkontroll med hjälp AccessibleObject av klasserna och Control.ControlAccessibleObject för att exponera tillgänglig information. Kontrollen ritar två kurvor tillsammans med en förklaring. Klassen ChartControlAccessibleObject , som härleds från ControlAccessibleObject, används i CreateAccessibilityInstance metoden för att tillhandahålla anpassad tillgänglig information för diagramkontrollen. Eftersom diagramförklaringen inte är en faktisk Control -based kontroll, utan i stället ritas av diagramkontrollen, finns det ingen inbyggd tillgänglig information. ChartControlAccessibleObject Därför åsidosätter GetChild klassen metoden för att returnera den CurveLegendAccessibleObject som representerar tillgänglig information för varje del av förklaringen. När ett tillgängligt program använder den här kontrollen kan kontrollen tillhandahålla nödvändig tillgänglig information.

Det här exemplet visar hur du använder AccessibleNavigation uppräkningen med Navigate -metoden. Se klassöversikten AccessibleObject för det fullständiga kodexemplet.

// Inner class ChartControlAccessibleObject represents accessible information associated with the ChartControl.
// The ChartControlAccessibleObject is returned in the ChartControl::CreateAccessibilityInstance .
ref class ChartControlAccessibleObject: public ControlAccessibleObject
{
private:
   ChartControl^ chartControl;

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


   property System::Windows::Forms::AccessibleRole Role 
   {

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

   }

   property AccessibleStates State 
   {

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

   }

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


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

      return nullptr;
   }


internal:

   // 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.
   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 nullptr;
   }


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

};

// class ChartControlAccessibleObject

// 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;                        
            }
        }            
    }
}

' 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
    
    ' 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
End Class

Kommentarer

Tillgängliga navigeringsriktningar är antingen rumsliga (uppåt, nedåt, vänster och höger) eller logiska (första underordnade, sista underordnade, nästa och föregående). Logiska riktningar används när klienter navigerar från ett användargränssnittselement till ett annat i samma container.

AccessibleObject använder den här uppräkningen.

Mer information finns i Microsoft Active Accessibility.

Se även

• AccessibleEvents
• AccessibleObject
• AccessibleRole
• AccessibleSelection
• AccessibleStates