Keys Enumeração

Definição

public enum class Keys

[System.ComponentModel.TypeConverter(typeof(System.Windows.Forms.KeysConverter))]
[System.Flags]
[System.Runtime.InteropServices.ComVisible(true)]
public enum Keys

[System.ComponentModel.TypeConverter(typeof(System.Windows.Forms.KeysConverter))]
[System.Flags]
public enum Keys

[<System.ComponentModel.TypeConverter(typeof(System.Windows.Forms.KeysConverter))>]
[<System.Flags>]
[<System.Runtime.InteropServices.ComVisible(true)>]
type Keys = 

[<System.ComponentModel.TypeConverter(typeof(System.Windows.Forms.KeysConverter))>]
[<System.Flags>]
type Keys = 

Public Enum Keys

Herança

Object

ValueType

Enum

Keys

Atributos

TypeConverterAttribute FlagsAttribute ComVisibleAttribute

Campos

Exemplos

O exemplo de código seguinte utiliza o KeyDown evento para determinar o tipo de carácter introduzido no controlo.

   // 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

Observações

A Keys classe contém constantes para processar a entrada do teclado. Os membros da enumeração de Chaves consistem num código de chave e num conjunto de modificadores combinados num único valor inteiro. Na interface de programação de aplicações (API) Win32, um valor de chave tem duas metades, com os bits de ordem superior a contendo o código de chave (que é o mesmo que um código de chave virtual do Windows), e os bits de ordem baixa a representarem modificadores de chave como as teclas SHIFT, CONTROL e ALT.

• Chama o IsKeyLocked método da Control aula.

• Para um controlo mais fino, use as funções Windows API GetKeyState, GetAsyncKeyState ou GetKeyboardState definidas em user32.dll, para isso. Para mais informações sobre como chamar funções nativas, veja Consuming Unmanaged DLL Functions.

A tabela seguinte mostra os valores dos códigos de teclas representados por dois valores enumerados, representando tanto as teclas originais gerais do fabricante do equipamento (OEM) como as associações mais específicas EUA-teclado.

Ver também

• KeysConverter
• SendKeys
• ConsoleKey
• Shortcut
• ModifierKeys
• IsKeyLocked(Keys)
• KeyEventArgs