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AccessibleObject.Bounds Property

Gets the location and size of the accessible object.

Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in system.windows.forms.dll)

public virtual Rectangle Bounds { get; }
/** @property */
public Rectangle get_Bounds ()

public function get Bounds () : Rectangle

Not applicable.

Property Value

A Rectangle that represents the bounds of the accessible object.

Exception typeCondition

COMException

The bounds of control cannot be retrieved.

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.

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

// 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);
    }
}

// Inner class CurveLegendAccessibleObject represents accessible 
// information associated with the CurveLegend object.
public static class CurveLegendAccessibleObject extends AccessibleObject
{
    private CurveLegend curveLegend;

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

    // Private property that helps get the reference to the parent 
    // ChartControl.
    /** @property 
     */
    private ChartControlAccessibleObject get_ChartControl()
    {
        return (ChartControlAccessibleObject)get_Parent();
    } //get_ChartControl

    // Internal helper function that returns the ID for this CurveLegend.
    /** @property 
     */
    int get_ID()
    {
        for (int i = 0; i < get_ChartControl().GetChildCount(); i++) {
            if (get_ChartControl().GetChild(i).Equals(this)) {
                return i;
            }
        }
        return -1;
    } //get_ID

    // Gets the Bounds for the CurveLegend. 
    // This is used by accessibility programs.
    /** @property 
     */
    public Rectangle get_Bounds()
    {
        // The bounds is in screen coordinates.
        Point loc = curveLegend.get_Location();
        return new Rectangle(curveLegend.chart.PointToScreen(loc),
            curveLegend.get_Size());
    } //get_Bounds

    // Gets or sets the Name for the CurveLegend. 
    // This is used by accessibility programs.
    /** @property 
     */
    public String get_Name()
    {
        return curveLegend.get_Name();
    } //get_Name

    /** @property 
     */
    public void set_Name(String value)
    {
        curveLegend.set_Name(value);
    } //set_Name

    // Gets the Curve Legend Parent's Accessible object.
    // This is used by accessibility programs.
    /** @property 
     */
    public AccessibleObject get_Parent()
    {
        return curveLegend.chart.get_AccessibilityObject();
    } //get_Parent

    // Gets the role for the CurveLegend. 
    // This is used by accessibility programs.
    /** @property 
     */
    public AccessibleRole get_Role()
    {
        return AccessibleRole.StaticText;
    } //get_Role

    // Gets the state based on the selection for the CurveLegend. 
    // This is used by accessibility programs.
    /** @property 
     */
    public AccessibleStates get_State()
    {
        AccessibleStates state = AccessibleStates.Selectable;
        if (curveLegend.get_Selected()) {
            state = state | AccessibleStates.Selected;
        }
        return state;
    } //get_State

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

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

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

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