IContainerControl Interface


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Provides the functionality for a control to act as a parent for other controls.

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

Public Interface IContainerControl


Gets or sets the control that is active on the container control.


Activates a specified control.

Notes to Implementers:

Implement this interface in classes that you want to parent a collection of controls. The members of this interface allow you to activate a child control, or determine which control is currently active. When implemented in a class, ActivateControl takes a Control as a parameter and activates the specified control. The ActiveControl property activates or retrieves the control that is active.

In most common scenarios, you do not need to directly implement this interface. For example, if you create a Windows Control Library project, Visual Studio generates an initial class for you. That class inherits from the UserControl class, and UserControl implements IContainerControl for you.

The following example inherits from the ScrollableControl class and implements the IContainerControl interface. Implementation is added to the ActiveControl property and the ActivateControl method.

Imports System
Imports System.Windows.Forms
Imports System.Drawing

   Public Class MyContainerControl
      Inherits ScrollableControl
      Implements IContainerControl 

      Private myActiveControl As Control

      Public Sub New()
         ' Make the container control Blue so it can be distinguished on the form.
         Me.BackColor = Color.Blue

         ' Make the container scrollable.
         Me.AutoScroll = True
      End Sub 

      ' Add implementation to the IContainerControl.ActiveControl property.
      Public Property ActiveControl() As Control Implements IContainerControl.ActiveControl
            Return Me.myActiveControl
         End Get

            ' Make sure the control is a member of the ControlCollection.
            If Me.Controls.Contains(value) Then
               Me.myActiveControl = value
            End If
         End Set
      End Property

      ' Add implementation to the IContainerControl.ActivateControl(Control) method.
      public Function ActivateControl(active As Control) As Boolean Implements IContainerControl.ActivateControl
         If Me.Controls.Contains(active) Then
            ' Select the control and scroll the control into view if needed.
            Me.myActiveControl = active
            Return True
         End If
         Return False
      End Function 

   End Class  

.NET Framework
Available since 1.1
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