CancelEventArgs CancelEventArgs CancelEventArgs CancelEventArgs Class

Definizione

public ref class CancelEventArgs : EventArgs

public class CancelEventArgs : EventArgs

type CancelEventArgs = class
    inherit EventArgs

Public Class CancelEventArgs
Inherits EventArgs

Ereditarietà

ObjectObjectObjectObject

EventArgsEventArgsEventArgsEventArgs

CancelEventArgsCancelEventArgsCancelEventArgsCancelEventArgs

Derivato

StartupEventArgsStartupEventArgsStartupEventArgsStartupEventArgs

DoWorkEventArgsDoWorkEventArgsDoWorkEventArgsDoWorkEventArgs

SettingChangingEventArgsSettingChangingEventArgsSettingChangingEventArgsSettingChangingEventArgs

PrintEventArgsPrintEventArgsPrintEventArgsPrintEventArgs

ErrorEventArgsErrorEventArgsErrorEventArgsErrorEventArgs

Altro…

Esempi

L'esempio seguente usa CancelEventArgs e una CancelEventHandler per gestire le Closing eventi di un Form.The following example uses CancelEventArgs and a CancelEventHandler to handle the Closing event of a Form. Questo codice presuppone che sia stato creato un Form con un livello di classe Boolean variabile denominata isDataSaved.This code assumes that you have created a Form with a class-level Boolean variable named isDataSaved. Presuppone anche che è stata aggiunta un'istruzione per richiamare il OtherInitialize metodo del form Load metodo o costruttore (dopo la chiamata a InitializeComponent).It also assumes that you have added a statement to invoke the OtherInitialize method from the form's Load method or the constructor (after the call to InitializeComponent).

private:
   // Call this method from the InitializeComponent() method of your form
   void OtherInitialize()
   {
      this->Closing += gcnew CancelEventHandler( this, &Form1::Form1_Cancel );
      this->myDataIsSaved = true;
   }

   void Form1_Cancel( Object^ /*sender*/, CancelEventArgs^ e )
   {
      if ( !myDataIsSaved )
      {
         e->Cancel = true;
         MessageBox::Show( "You must save first." );
      }
      else
      {
         e->Cancel = false;
         MessageBox::Show( "Goodbye." );
      }
   }

// Call this method from the constructor of your form
    private void OtherInitialize() {
       this.Closing += new CancelEventHandler(this.Form1_Closing);
       // Exchange commented line and note the difference.
       this.isDataSaved = true;
       //this.isDataSaved = false;
    }

    private void Form1_Closing(Object sender, CancelEventArgs e) {
       if (!isDataSaved) {
          e.Cancel = true;
          MessageBox.Show("You must save first.");
       }
       else {
          e.Cancel = false;
          MessageBox.Show("Goodbye.");
       }
    }
 

' Call this method from the Load method of your form.
Private Sub OtherInitialize()
    ' Exchange commented line and note the difference.
    Me.isDataSaved = True
    'Me.isDataSaved = False
End Sub 'OtherInitialize

Private Sub Form1_Closing(sender As Object, e As _
   System.ComponentModel.CancelEventArgs) Handles MyBase.Closing
    If Not isDataSaved Then
        e.Cancel = True
        MessageBox.Show("You must save first.")
    Else
        e.Cancel = False
        MessageBox.Show("Goodbye.")
    End If
End Sub 'Form1_Closing

Commenti

Viene generato un evento annullabile da un componente quando sta per eseguire un'azione che può essere annullata, ad esempio la Closing eventi di un Form.A cancelable event is raised by a component when it is about to perform an action that can be canceled, such as the Closing event of a Form.

CancelEventArgs fornisce il Cancel proprietà che indica se l'evento deve essere annullata.CancelEventArgs provides the Cancel property to indicate whether the event should be canceled.

Costruttori

Proprietà

Metodi

Si applica a

Vedi anche

• CancelEventHandler