KeyEventArgs.Handled Eigenschaft

Definition

Ruft einen Wert ab, der angibt, ob das Ereignis behandelt wurde, oder legt diesen fest.Gets or sets a value indicating whether the event was handled.

public:
 property bool Handled { bool get(); void set(bool value); };
public bool Handled { get; set; }
member this.Handled : bool with get, set
Public Property Handled As Boolean

Eigenschaftswert

true, um die Standardbehandlung des Steuerelements zu umgehen, andernfalls false, um auch das Ereignis an den Standardsteuerelementhandler zu übergeben.true to bypass the control's default handling; otherwise, false to also pass the event along to the default control handler.

Beispiele

Im folgenden Beispiel wird ermittelt, ob der Benutzer einen nicht numerischen Schlüssel gedrückt hat, und wenn dies der Fall KeyPress ist, wird das Handled Ereignis mit der-Eigenschaft abgebrochen.The following example determines whether the user pressed a non-numeric key, and if so, cancels the KeyPress event by using the Handled property.

   // Boolean flag used to determine when a character other than a number is entered.
private:
   bool nonNumberEntered;

   // Handle the KeyDown event to determine the type of character entered into the control.
   void textBox1_KeyDown( Object^ /*sender*/, System::Windows::Forms::KeyEventArgs^ e )
   {
      // Initialize the flag to false.
      nonNumberEntered = false;

      // Determine whether the keystroke is a number from the top of the keyboard.
      if ( e->KeyCode < Keys::D0 || e->KeyCode > Keys::D9 )
      {
         // Determine whether the keystroke is a number from the keypad.
         if ( e->KeyCode < Keys::NumPad0 || e->KeyCode > Keys::NumPad9 )
         {
            // Determine whether the keystroke is a backspace.
            if ( e->KeyCode != Keys::Back )
            {
               // A non-numerical keystroke was pressed.
               // Set the flag to true and evaluate in KeyPress event.
               nonNumberEntered = true;
            }
         }
      }
      //If shift key was pressed, it's not a number.
      if (Control::ModifierKeys == Keys::Shift) {
         nonNumberEntered = true;
      }
   }

   // This event occurs after the KeyDown event and can be used to prevent
   // characters from entering the control.
   void textBox1_KeyPress( Object^ /*sender*/, System::Windows::Forms::KeyPressEventArgs^ e )
   {
      // Check for the flag being set in the KeyDown event.
      if ( nonNumberEntered == true )
      {         // Stop the character from being entered into the control since it is non-numerical.
         e->Handled = true;
      }
   }
// Boolean flag used to determine when a character other than a number is entered.
private bool nonNumberEntered = false;

// Handle the KeyDown event to determine the type of character entered into the control.
private void textBox1_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)
{
    // Initialize the flag to false.
    nonNumberEntered = false;

    // Determine whether the keystroke is a number from the top of the keyboard.
    if (e.KeyCode < Keys.D0 || e.KeyCode > Keys.D9)
    {
        // Determine whether the keystroke is a number from the keypad.
        if (e.KeyCode < Keys.NumPad0 || e.KeyCode > Keys.NumPad9)
        {
            // Determine whether the keystroke is a backspace.
            if(e.KeyCode != Keys.Back)
            {
                // A non-numerical keystroke was pressed.
                // Set the flag to true and evaluate in KeyPress event.
                nonNumberEntered = true;
            }
        }
    }
    //If shift key was pressed, it's not a number.
    if (Control.ModifierKeys == Keys.Shift) {
        nonNumberEntered = true;
    }
}

// This event occurs after the KeyDown event and can be used to prevent
// characters from entering the control.
private void textBox1_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
{
    // Check for the flag being set in the KeyDown event.
    if (nonNumberEntered == true)
    {
        // Stop the character from being entered into the control since it is non-numerical.
        e.Handled = true;
    }
}

 ' Boolean flag used to determine when a character other than a number is entered.
 Private nonNumberEntered As Boolean = False


 ' Handle the KeyDown event to determine the type of character entered into the control.
 Private Sub textBox1_KeyDown(sender As Object, e As System.Windows.Forms.KeyEventArgs) _
      Handles textBox1.KeyDown
     ' Initialize the flag to false.
     nonNumberEntered = False
   
     ' Determine whether the keystroke is a number from the top of the keyboard.
     If e.KeyCode < Keys.D0 OrElse e.KeyCode > Keys.D9 Then
         ' Determine whether the keystroke is a number from the keypad.
         If e.KeyCode < Keys.NumPad0 OrElse e.KeyCode > Keys.NumPad9 Then
             ' Determine whether the keystroke is a backspace.
             If e.KeyCode <> Keys.Back Then
                 ' A non-numerical keystroke was pressed. 
                 ' Set the flag to true and evaluate in KeyPress event.
                 nonNumberEntered = True
             End If
         End If
     End If
     'If shift key was pressed, it's not a number.
     If Control.ModifierKeys = Keys.Shift Then
         nonNumberEntered = true
     End If
 End Sub


 ' This event occurs after the KeyDown event and can be used 
 ' to prevent characters from entering the control.
 Private Sub textBox1_KeyPress(sender As Object, e As System.Windows.Forms.KeyPressEventArgs) _
     Handles textBox1.KeyPress
     ' Check for the flag being set in the KeyDown event.
     If nonNumberEntered = True Then
         ' Stop the character from being entered into the control since it is non-numerical.
         e.Handled = True
     End If
 End Sub

Hinweise

Handledwird von verschiedenen Steuerelementen in Windows Forms unterschiedlich implementiert.Handled is implemented differently by different controls within Windows Forms. Für Steuerelemente TextBox , die eine Unterklasse systemeigene Win32-Steuerelemente aufweisen, wird Sie so interpretiert, dass die Schlüssel Nachricht nicht an das zugrunde liegende Native Steuerelement übermittelt werden soll.For controls like TextBox which subclass native Win32 controls, it is interpreted to mean that the key message should not be passed to the underlying native control. Wenn Sie für Handled einen TextBoxauf true festgelegt haben, übergibt dieses Steuerelement den Tasten events Druck nicht an das zugrunde liegende Win32-Textfeld-Steuerelement, sondern zeigt dennoch die Zeichen an, die der Benutzer eingegeben hat.If you set Handled to true on a TextBox, that control will not pass the key press events to the underlying Win32 text box control, but it will still display the characters that the user typed.

Wenn Sie verhindern möchten, dass das aktuelle Steuerelement einen Tastendruck empfängt, verwenden SuppressKeyPress Sie die-Eigenschaft.If you want to prevent the current control from receiving a key press, use the SuppressKeyPress property.

Gilt für:

Siehe auch