IContainerControl Interface


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 class 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.

using namespace System;
using namespace System::Windows::Forms;
using namespace System::Drawing;

public ref class MyContainer: public ScrollableControl, public IContainerControl
   Control^ activeControl;

      // Make the container control Blue so it can be distinguished on the form.
      this->BackColor = Color::Blue;

      // Make the container scrollable.
      this->AutoScroll = true;

   property Control^ ActiveControl 
      // Add implementation to the IContainerControl.ActiveControl property.
      virtual Control^ get()
         return activeControl;

      virtual void set( Control^ value )

         // Make sure the control is a member of the ControlCollection.
         if ( this->Controls->Contains( value ) )
            activeControl = value;

   // Add implementations to the IContainerControl.ActivateControl(Control) method.
   virtual bool ActivateControl( Control^ active )
      if ( this->Controls->Contains( active ) )
         // Select the control and scroll the control into view if needed.
         active->Select(  );
         this->ScrollControlIntoView( active );
         this->activeControl = active;
         return true;

      return false;

.NET Framework
Available since 1.1
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