Control.ControlAccessibleObject(Control) Constructor
Definition
Important
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Initializes a new instance of the Control.ControlAccessibleObject class.
public:
ControlAccessibleObject(System::Windows::Forms::Control ^ ownerControl);
public ControlAccessibleObject (System.Windows.Forms.Control ownerControl);
new System.Windows.Forms.Control.ControlAccessibleObject : System.Windows.Forms.Control -> System.Windows.Forms.Control.ControlAccessibleObject
Public Sub New (ownerControl As Control)
Parameters
- ownerControl
- Control
The Control that owns the Control.ControlAccessibleObject.
Exceptions
The ownerControl
parameter value is null
.
Examples
The following code example creates a check box control that derives from the CheckBox class and creates a custom Control.ControlAccessibleObject for the derived class to use. The derived class, MyCheckBox
, has an Appearance of Button by default so it appears as a toggle button. The derived Control.ControlAccessibleObject class, MyCheckBoxControlAccessibleObject
, overrides three properties to account for the difference in appearance.
#using <Accessibility.dll>
#using <System.Drawing.dll>
#using <System.dll>
#using <System.Windows.Forms.dll>
using namespace System;
using namespace System::Windows::Forms;
using namespace System::Drawing;
namespace MyCustomControls
{
public ref class MyCheckBox: public CheckBox
{
public:
MyCheckBox()
{
// Make the check box appear like a toggle button.
this->Appearance = ::Appearance::Button;
// Center the text on the button.
this->TextAlign = ContentAlignment::MiddleCenter;
// Set the AccessibleDescription text.
this->AccessibleDescription = "A toggle style button.";
}
protected:
// Create an instance of the AccessibleObject
// defined for the 'MyCheckBox' control
virtual AccessibleObject^ CreateAccessibilityInstance() override;
};
// Accessible Object* for use with the 'MyCheckBox' control.
private ref class MyCheckBoxAccessibleObject: public Control::ControlAccessibleObject
{
public:
MyCheckBoxAccessibleObject( MyCheckBox^ owner )
: ControlAccessibleObject( owner )
{}
property String^ DefaultAction
{
virtual String^ get() override
{
// Return the DefaultAction based upon
// the state of the control.
if ( (dynamic_cast<MyCheckBox^>(Owner))->Checked )
{
return "Toggle button up";
}
else
{
return "Toggle button down";
}
}
}
property String^ Name
{
virtual String^ get() override
{
// Return the Text property of the control
// if the AccessibleName is 0.
String^ name = Owner->AccessibleName;
if ( name != nullptr )
{
return name;
}
return (dynamic_cast<MyCheckBox^>(Owner))->Text;
}
virtual void set( String^ value ) override
{
ControlAccessibleObject::Name = value;
}
}
property AccessibleRole Role
{
virtual AccessibleRole get() override
{
// Since the check box appears like a button,
// make the Role the same as a button.
return AccessibleRole::PushButton;
}
}
};
AccessibleObject^ MyCheckBox::CreateAccessibilityInstance()
{
return gcnew MyCheckBoxAccessibleObject( this );
}
}
using System;
using System.Windows.Forms;
using Accessibility;
using System.Drawing;
namespace MyCustomControls
{
public class MyCheckBox : CheckBox
{
public MyCheckBox()
{
// Make the check box appear like a toggle button.
this.Appearance = Appearance.Button;
// Center the text on the button.
this.TextAlign = ContentAlignment.MiddleCenter;
// Set the AccessibleDescription text.
this.AccessibleDescription = "A toggle style button.";
}
// Create an instance of the AccessibleObject
// defined for the 'MyCheckBox' control
protected override AccessibleObject CreateAccessibilityInstance()
{
return new MyCheckBoxAccessibleObject(this);
}
}
// Accessible object for use with the 'MyCheckBox' control.
internal class MyCheckBoxAccessibleObject : Control.ControlAccessibleObject
{
public MyCheckBoxAccessibleObject(MyCheckBox owner) : base(owner)
{
}
public override string DefaultAction
{
get
{
// Return the DefaultAction based upon
// the state of the control.
if( ((MyCheckBox)Owner).Checked )
{
return "Toggle button up";
}
else
{
return "Toggle button down";
}
}
}
public override string Name
{
get
{
// Return the Text property of the control
// if the AccessibleName is null.
string name = Owner.AccessibleName;
if (name != null)
{
return name;
}
return ((MyCheckBox)Owner).Text;
}
set
{
base.Name = value;
}
}
public override AccessibleRole Role
{
get
{
// Since the check box appears like a button,
// make the Role the same as a button.
return AccessibleRole.PushButton;
}
}
}
}
Imports System.Windows.Forms
Imports Accessibility
Imports System.Drawing
Namespace MyCustomControls
Public Class MyCheckBox
Inherits CheckBox
Public Sub New()
' Make the check box appear like a toggle button.
Me.Appearance = Appearance.Button
' Center the text on the button.
Me.TextAlign = ContentAlignment.MiddleCenter
End Sub
' Create an instance of the AccessibleObject
' defined for the 'MyCheckBox' control
Protected Overrides Function CreateAccessibilityInstance() _
As AccessibleObject
Return New MyCheckBoxAccessibleObject(Me)
End Function
End Class
' Accessible object for use with the 'MyCheckBox' control.
Friend Class MyCheckBoxAccessibleObject
Inherits Control.ControlAccessibleObject
Public Sub New(owner As MyCheckBox)
MyBase.New(owner)
End Sub
Public Overrides ReadOnly Property DefaultAction() As String
Get
' Return the DefaultAction based upon
' the state of the control.
If CType(Owner, MyCheckBox).Checked Then
Return "Toggle button up"
Else
Return "Toggle button down"
End If
End Get
End Property
Public Overrides Property Name() As String
Get
' Return the Text property of the control
' if the AccessibleName is null.
Dim accessibleName As String = Owner.AccessibleName
If (accessibleName IsNot Nothing) Then
Return accessibleName
End If
Return CType(Owner, MyCheckBox).Text
End Get
Set
MyBase.Name = value
End Set
End Property
Public Overrides ReadOnly Property Role() As AccessibleRole
Get
' Since the check box appears like a button,
' make the Role the same as a button.
Return AccessibleRole.PushButton
End Get
End Property
End Class
End Namespace