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State Property

AccessibleObject::State Property

Gets the state of this accessible object.

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

public:
virtual property AccessibleStates State {
	AccessibleStates get ();
}

Property Value

Type: System.Windows.Forms::AccessibleStates
One of the AccessibleStates values, or AccessibleStates::None, if no state has been set.

Notes to Inheritors

All objects should support this property.

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 have 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 overriding 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 .
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


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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