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AccessibleObject.Bounds Property

.NET Framework 1.1

Gets the location and size of the accessible object.

[Visual Basic]
Public Overridable ReadOnly Property Bounds As Rectangle
[C#]
public virtual Rectangle Bounds {get;}
[C++]
public: __property virtual Rectangle get_Bounds();
[JScript]
public function get Bounds() : Rectangle;

Property Value

A Rectangle that represents the bounds of the accessible object.

Exceptions

Exception Type	Condition
COMException	The bounds of control cannot be retrieved.

Remarks

The Bounds property retrieves the object's bounding rectangle in screen coordinates. If the object has a nonrectangular shape, then this property represents the smallest rectangle that completely encompasses the entire object region. Therefore, for nonrectangular objects such as list view items, the coordinates of the object's bounding rectangle can fail, if tested, by calling the HitTest method, because HitTest determines the object's boundaries on a pixel-by-pixel basis.

Notes to Inheritors: The default implementation returns the accessible object's bounding rectangle if the object wraps a system control; otherwise, it returns Rectangle.Empty. All visible accessible objects must support this method. Sound objects do not support this method.

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 overriding the Bounds property. See the AccessibleObject class overview for the complete code example.

[Visual Basic] 
' Inner class CurveLegendAccessibleObject represents accessible information 
' associated with the CurveLegend object.
Public Class CurveLegendAccessibleObject
    Inherits AccessibleObject

    Private curveLegend As CurveLegend
    
    Public Sub New(curveLegend As CurveLegend)
        Me.curveLegend = curveLegend
    End Sub 'New
    
    ' Private property that helps get the reference to the parent ChartControl.                
    Private ReadOnly Property ChartControl() As ChartControlAccessibleObject
        Get
            Return CType(Parent, ChartControlAccessibleObject)
        End Get
    End Property

    ' Friend helper function that returns the ID for this CurveLegend.                
    Friend ReadOnly Property ID() As Integer
        Get
            Dim i As Integer
            For i = 0 To (ChartControl.GetChildCount()) - 1
                If ChartControl.GetChild(i) Is Me Then
                    Return i
                End If
            Next i
            Return - 1
        End Get
    End Property
    
    ' Gets the Bounds for the CurveLegend. This is used by accessibility programs.
    Public Overrides ReadOnly Property Bounds() As Rectangle
        Get
            ' The bounds is in screen coordinates.
            Dim loc As Point = curveLegend.Location
            Return New Rectangle(curveLegend.chart.PointToScreen(loc), curveLegend.Size)
        End Get
    End Property

    ' Gets or sets the Name for the CurveLegend. This is used by accessibility programs.                
    Public Overrides Property Name() As String
        Get
            Return curveLegend.Name
        End Get
        Set
            curveLegend.Name = value
        End Set
    End Property
    
    ' Gets the Curve Legend Parent's Accessible object.
    ' This is used by accessibility programs.                
    Public Overrides ReadOnly Property Parent() As AccessibleObject
        Get
            Return curveLegend.chart.AccessibilityObject
        End Get
    End Property
    
    ' Gets the role for the CurveLegend. This is used by accessibility programs.                
    Public Overrides ReadOnly Property Role() As AccessibleRole
        Get
            Return System.Windows.Forms.AccessibleRole.StaticText
        End Get
    End Property

    ' Gets the state based on the selection for the CurveLegend. 
    ' This is used by accessibility programs.                
    Public Overrides ReadOnly Property State() As AccessibleStates
        Get
            Dim stateTemp As AccessibleStates = AccessibleStates.Selectable
            If curveLegend.Selected Then
                stateTemp = stateTemp Or AccessibleStates.Selected
            End If
            Return stateTemp
        End Get
    End Property
    
    ' Navigates through siblings of this CurveLegend. This is used by accessibility programs.                
    Public Overrides Function Navigate(navdir As AccessibleNavigation) As AccessibleObject
        ' Use the Friend NavigateFromChild helper function that exists
        ' on ChartControlAccessibleObject.
        Return ChartControl.NavigateFromChild(Me, navdir)
    End Function
    
    ' Selects or unselects this CurveLegend. This is used by accessibility programs.
    Public Overrides Sub [Select](selection As AccessibleSelection)

        ' Use the internal SelectChild helper function that exists
        ' on ChartControlAccessibleObject.
        ChartControl.SelectChild(Me, selection)
    End Sub

End Class 'CurveLegendAccessibleObject

[C#] 
// Inner class CurveLegendAccessibleObject represents accessible information 
// associated with the CurveLegend object.
public class CurveLegendAccessibleObject : AccessibleObject
{
    private CurveLegend curveLegend;

    public CurveLegendAccessibleObject(CurveLegend curveLegend) : base() 
    {
        this.curveLegend = curveLegend;                    
    }                

    // Private property that helps get the reference to the parent ChartControl.
    private ChartControlAccessibleObject ChartControl
    {   
        get {
            return Parent as ChartControlAccessibleObject;
        }
    }

    // Internal helper function that returns the ID for this CurveLegend.
    internal int ID
    {
        get {
            for(int i = 0; i < ChartControl.GetChildCount(); i++) {
                if (ChartControl.GetChild(i) == this) {
                    return i;
                }
            }
            return -1;
        }
    }

    // Gets the Bounds for the CurveLegend. This is used by accessibility programs.
    public override Rectangle Bounds
    {
        get {                        
            // The bounds is in screen coordinates.
            Point loc = curveLegend.Location;
            return new Rectangle(curveLegend.chart.PointToScreen(loc), curveLegend.Size);
        }
    }

    // Gets or sets the Name for the CurveLegend. This is used by accessibility programs.
    public override string Name
    {
        get {
            return curveLegend.Name;
        }
        set {
            curveLegend.Name = value;                        
        }
    }

    // Gets the Curve Legend Parent's Accessible object.
    // This is used by accessibility programs.
    public override AccessibleObject Parent
    {
        get {
            return curveLegend.chart.AccessibilityObject;
        }
    }

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

    // Gets the state based on the selection for the CurveLegend. 
    // This is used by accessibility programs.
    public override AccessibleStates State 
    {
        get {
            AccessibleStates state = AccessibleStates.Selectable;
            if (curveLegend.Selected) 
            {
                state |= AccessibleStates.Selected;
            }
            return state;
        }
    }

    // Navigates through siblings of this CurveLegend. This is used by accessibility programs.
    public override AccessibleObject Navigate(AccessibleNavigation navdir) 
    {
        // Uses the internal NavigateFromChild helper function that exists
        // on ChartControlAccessibleObject.
        return ChartControl.NavigateFromChild(this, navdir);
    }

    // Selects or unselects this CurveLegend. This is used by accessibility programs.
    public override void Select(AccessibleSelection selection) 
    {
        // Uses the internal SelectChild helper function that exists
        // on ChartControlAccessibleObject.
        ChartControl.SelectChild(this, selection);
    }
}

[C++] 
// Inner class CurveLegendAccessibleObject represents accessible information
// associated with the CurveLegend object.
   public:
__gc class CurveLegendAccessibleObject : public AccessibleObject {
private:
   CurveLegend*  curveLegend;

public:
   CurveLegendAccessibleObject(CurveLegend* curveLegend) : AccessibleObject() {
      this->curveLegend = curveLegend;
   }

   // Private property that helps get the reference to the parent ChartControl.
private:
   __property ChartControlAccessibleObject* get_ChartControl() {
      return dynamic_cast<ChartControlAccessibleObject*>(Parent);
   }


   // Internal helper function that returns the ID for this CurveLegend.
public private:
   __property int get_ID() {
      for (int i = 0; i < ChartControl->GetChildCount(); i++) {
         if (ChartControl->GetChild(i) == this) {
            return i;
         }
      }
      return -1;
   }

   // Gets the Bounds for the CurveLegend. This is used by accessibility programs.
public:
   __property Rectangle get_Bounds() {
      // The bounds is in screen coordinates.
      Point loc = curveLegend->Location;
      return Rectangle(curveLegend->chart->PointToScreen(loc), curveLegend->Size);
   }

   // Gets or sets the Name for the CurveLegend. This is used by accessibility programs.
   __property String* get_Name() {
      return curveLegend->Name;
   }
   __property void set_Name(String* value) {
      curveLegend->Name = value;
   }

   // Gets the Curve Legend Parent's Accessible object.
   // This is used by accessibility programs.
   __property AccessibleObject* get_Parent() {
      return curveLegend->chart->AccessibilityObject;
   }

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

   // Gets the state based on the selection for the CurveLegend.
   // This is used by accessibility programs.
   __property AccessibleStates get_State() {
      AccessibleStates state = AccessibleStates::Selectable;
      if (curveLegend->Selected) {
         state = static_cast<AccessibleStates>( state | AccessibleStates::Selected );
      }
      return state;
   }

   // Navigates through siblings of this CurveLegend. This is used by accessibility programs.
   AccessibleObject* Navigate(AccessibleNavigation navdir) {
      // Uses the internal NavigateFromChild helper function that exists
      // on ChartControlAccessibleObject.
      return ChartControl->NavigateFromChild(this, navdir);
   }

   // Selects or unselects this CurveLegend. This is used by accessibility programs.
   void Select(AccessibleSelection selection) {
      // Uses the internal SelectChild helper function that exists
      // on ChartControlAccessibleObject.
      ChartControl->SelectChild(this, selection);
   }
}; // class CurveLgendAccessibleObject

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

Requirements