Keys Výčet

Definice

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

Dědičnost

Object

ValueType

Enum

Keys

Atributy

TypeConverterAttribute FlagsAttribute ComVisibleAttribute

Pole

Příklady

Následující příklad kódu používá KeyDown událost k určení typu znaku zadaného do ovládacího prvku.

   // 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

Poznámky

Třída Keys obsahuje konstanty pro zpracování vstupu z klávesnice. Členy výčtu Klíče se skládají z kódu klíče a sady modifikátorů sloučených do jedné celočíselné hodnoty. V aplikačním programovacím rozhraní (API) Win32 má hodnota klíče dvě poloviny, přičemž bity ve vysokém pořadí obsahují kód klíče (který je stejný jako kód virtuálního klíče Windows) a bity nízkého pořadí představující modifikátory klíčů, jako jsou klávesy SHIFT, CONTROL a ALT.

• IsKeyLocked Zavolejte metodu Control třídy .

• K tomu použijte funkce GetKeyStaterozhraní API systému Windows , GetAsyncKeyStatenebo GetKeyboardState definované v user32.dll. Další informace o volání nativních funkcí naleznete v tématu Používání nespravovaných funkcí knihovny DLL.

Následující tabulka uvádí hodnoty kódu klíčů představované dvěma výčtovými hodnotami, které představují jak obecné klíče výrobce OEM (Original Equipment Manufacturer), tak konkrétnější přidružení klávesnice pro USA.

Platí pro

Viz také

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