KeyEventArgs.Handled Propriedade

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

Valor da propriedade

true para fazer bypass do tratamento padrão do controle; caso contrário, false também passa o evento para o manipulador de controle padrão.

Exemplos

O exemplo a seguir determina se o usuário pressionou uma tecla não numérica e, em caso afirmativo, cancela o KeyPress evento usando a Handled propriedade .

   // 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)
      {         // 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)
    {
        // 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

Comentários

Handledé implementado de forma diferente por controles diferentes dentro de Windows Forms. Para controles como TextBox quais controles Win32 nativos de subclasse, é interpretado como significando que a mensagem de chave não deve ser passada para o controle nativo subjacente. Se você definir Handled como true em um TextBox, esse controle não passará a tecla pressionar events para o controle de caixa de texto subjacente do Win32, mas ainda exibirá os caracteres que o usuário digitou.

Se você quiser impedir que o controle atual receba um pressionamento de tecla, use a SuppressKeyPress propriedade .

Aplica-se a

Confira também

• SuppressKeyPress