Control.OnControlRemoved(ControlEventArgs) Control.OnControlRemoved(ControlEventArgs) Control.OnControlRemoved(ControlEventArgs) Control.OnControlRemoved(ControlEventArgs) Method

Definizione

Genera l'evento ControlRemoved.Raises the ControlRemoved event.

protected:
 virtual void OnControlRemoved(System::Windows::Forms::ControlEventArgs ^ e);
protected virtual void OnControlRemoved (System.Windows.Forms.ControlEventArgs e);
abstract member OnControlRemoved : System.Windows.Forms.ControlEventArgs -> unit
override this.OnControlRemoved : System.Windows.Forms.ControlEventArgs -> unit
Protected Overridable Sub OnControlRemoved (e As ControlEventArgs)

Parametri

e
ControlEventArgs ControlEventArgs ControlEventArgs ControlEventArgs

Oggetto ControlEventArgs che contiene i dati dell'evento.A ControlEventArgs that contains the event data.

Esempi

Il codice seguente viene illustrato come utilizzare ControlRemoved per rimuovere un controllo da un form e visualizza il nome del controllo rimosso in una MessageBox.The following code example uses ControlRemoved to remove a control from a form and displays the name of the removed control in a MessageBox.

   // This example demonstrates the use of the ControlAdded and
   // ControlRemoved events. This example assumes that two Button controls
   // are added to the form and connected to the addControl_Click and
   // removeControl_Click event-handler methods.
private:
   void Form1_Load( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      // Connect the ControlRemoved and ControlAdded event handlers
      // to the event-handler methods.
      // ControlRemoved and ControlAdded are not available at design time.
      this->ControlRemoved += gcnew System::Windows::Forms::ControlEventHandler( this, &Form1::Control_Removed );
      this->ControlAdded += gcnew System::Windows::Forms::ControlEventHandler( this, &Form1::Control_Added );
   }

   void Control_Added( Object^ /*sender*/, System::Windows::Forms::ControlEventArgs^ e )
   {
      MessageBox::Show( String::Format( "The control named {0} has been added to the form.", e->Control->Name ) );
   }

   void Control_Removed( Object^ /*sender*/, System::Windows::Forms::ControlEventArgs^ e )
   {
      MessageBox::Show( String::Format( "The control named {0} has been removed from the form.", e->Control->Name ) );
   }

   // Click event handler for a Button control. Adds a TextBox to the form.
   void addControl_Click( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      // Create a new TextBox control and add it to the form.
      TextBox^ textBox1 = gcnew TextBox;
      textBox1->Size = System::Drawing::Size( 100, 10 );
      textBox1->Location = Point(10,10);

      // Name the control in order to remove it later. The name must be specified
      // if a control is added at run time.
      textBox1->Name = "textBox1";

      // Add the control to the form's control collection.
      this->Controls->Add( textBox1 );
   }

   // Click event handler for a Button control.
   // Removes the previously added TextBox from the form.
   void removeControl_Click( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      // Loop through all controls in the form's control collection.
      IEnumerator^ myEnum = this->Controls->GetEnumerator();
      while ( myEnum->MoveNext() )
      {
         Control^ tempCtrl = safe_cast<Control^>(myEnum->Current);
         
         // Determine whether the control is textBox1,
         // and if it is, remove it.
         if ( tempCtrl->Name->Equals( "textBox1" ) )
         {
            this->Controls->Remove( tempCtrl );
         }
      }
   }
// This example demonstrates the use of the ControlAdded and
// ControlRemoved events. This example assumes that two Button controls
// are added to the form and connected to the addControl_Click and
// removeControl_Click event-handler methods.
private void Form1_Load(object sender, System.EventArgs e)
{
    // Connect the ControlRemoved and ControlAdded event handlers
    // to the event-handler methods.
    // ControlRemoved and ControlAdded are not available at design time.
    this.ControlRemoved += new System.Windows.Forms.ControlEventHandler(this.Control_Removed);
    this.ControlAdded += new System.Windows.Forms.ControlEventHandler(this.Control_Added);
}

private void Control_Added(object sender, System.Windows.Forms.ControlEventArgs e)
{
    MessageBox.Show("The control named " + e.Control.Name + " has been added to the form.");
}

private void Control_Removed(object sender, System.Windows.Forms.ControlEventArgs e)
{
    MessageBox.Show("The control named " + e.Control.Name + " has been removed from the form.");
}

// Click event handler for a Button control. Adds a TextBox to the form.
private void addControl_Click(object sender, System.EventArgs e)
{
    // Create a new TextBox control and add it to the form.
    TextBox textBox1 = new TextBox();
    textBox1.Size = new Size(100,10);
    textBox1.Location = new Point(10,10);
    // Name the control in order to remove it later. The name must be specified
    // if a control is added at run time.
    textBox1.Name = "textBox1";

    // Add the control to the form's control collection.
    this.Controls.Add(textBox1);
}

// Click event handler for a Button control.
// Removes the previously added TextBox from the form.
private void removeControl_Click(object sender, System.EventArgs e)
{
    // Loop through all controls in the form's control collection.
    foreach (Control tempCtrl in this.Controls)
    {
        // Determine whether the control is textBox1,
        // and if it is, remove it.
        if (tempCtrl.Name == "textBox1")
        {
            this.Controls.Remove(tempCtrl);
        }
    }
}
' This example demonstrates the use of the ControlAdded and
' ControlRemoved events. This example assumes that two Button controls 
' are added to the form and connected to the addControl_Click and 
' removeControl_Click event-handler methods.
Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load
    ' Connect the ControlRemoved and ControlAdded event handlers to the event-handler methods.
    ' ControlRemoved and ControlAdded are not available at design time.
    AddHandler Me.ControlRemoved, AddressOf Me.Control_Removed
    AddHandler Me.ControlAdded, AddressOf Me.Control_Added
End Sub 'Form1_Load


Private Sub Control_Added(ByVal sender As Object, ByVal e As System.Windows.Forms.ControlEventArgs)
    MessageBox.Show(("The control named " + e.Control.Name + " has been added to the form."))
End Sub


Private Sub Control_Removed(ByVal sender As Object, ByVal e As System.Windows.Forms.ControlEventArgs)
    MessageBox.Show(("The control named " + e.Control.Name + " has been removed from the form."))
End Sub


' Click event handler for a Button control. Adds a TextBox to the form.
Private Sub addControl_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles button1.Click
    ' Create a new TextBox control and add it to the form.
    Dim textBox1 As New TextBox()
    textBox1.Size = New Size(100, 10)
    textBox1.Location = New Point(10, 10)
    ' Name the control in order to remove it later. 
    ' The name must be specified if a control is added at run time.
    textBox1.Name = "textBox1"

    ' Add the control to the form's control collection.
    Me.Controls.Add(textBox1)
End Sub


' Click event handler for a Button control.
' Removes the previously added TextBox from the form.
Private Sub removeControl_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles button2.Click
    ' Loop through all controls in the form's control collection.
    Dim tempCtrl As Control
    For Each tempCtrl In Me.Controls
        ' Determine whether the control is textBox1,
        ' and if it is, remove it.
        If tempCtrl.Name = "textBox1" Then
            Me.Controls.Remove(tempCtrl)
        End If
    Next tempCtrl
End Sub

Commenti

Chiamato quando un controllo figlio viene rimosso dal controllo.Called when a child control is removed from the control.

Quando viene generato un evento, il gestore dell'evento viene richiamato tramite un delegato.Raising an event invokes the event handler through a delegate. Per altre informazioni, vedere la gestione e generazione di eventi.For more information, see Handling and Raising Events.

Il metodo OnControlRemoved consente inoltre alle classi derivate di gestire l'evento senza associare un delegato.The OnControlRemoved method also allows derived classes to handle the event without attaching a delegate. È la tecnica consigliata per la gestione dell'evento in una classe derivata.This is the preferred technique for handling the event in a derived class.

Note per gli eredi

Quando si esegue l'override di OnControlRemoved(ControlEventArgs) in una classe derivata, verificare di chiamare il metodo OnControlRemoved(ControlEventArgs) della classe di base in modo che i delegati registrati ricevano l'evento.When overriding OnControlRemoved(ControlEventArgs) in a derived class, be sure to call the base class's OnControlRemoved(ControlEventArgs) method so that registered delegates receive the event.

Si applica a

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