KeyPressEventArgs Clase

Definición

Proporciona datos para el evento KeyPress.Provides data for the KeyPress event.

public ref class KeyPressEventArgs : EventArgs
[System.Runtime.InteropServices.ComVisible(true)]
public class KeyPressEventArgs : EventArgs
type KeyPressEventArgs = class
    inherit EventArgs
Public Class KeyPressEventArgs
Inherits EventArgs
Herencia
KeyPressEventArgs
Atributos

Ejemplos

En el ejemplo siguiente se muestra el KeyPressEventArgs uso de las teclas para contar a medida que se presionan y para mostrar los resultados después de cada pulsación de tecla.The following example illustrates using the KeyPressEventArgs to count keys as they are pressed and to display the results after each key press. Handleda continuación, se establece en true para evitar que el sistema operativo procese aún más la clave.Handled is then set to true to keep the operating system from further processing the key. En el ejemplo se supone que hay TextBox un formulario con un colocado en él.The example assumes a form with a TextBox placed on it.

public ref class myKeyPressClass
{
private:
   static long keyPressCount = 0;
   static long backspacePressed = 0;
   static long returnPressed = 0;
   static long escPressed = 0;
   TextBox^ textBox1;
   void myKeyCounter( Object^ sender, KeyPressEventArgs^ ex )
   {
      switch ( ex->KeyChar )
      {
            // Counts the backspaces.
         case '\b':
         backspacePressed = backspacePressed + 1;
         break;

            // Counts the ENTER keys.
         case '\r':
         returnPressed = returnPressed + 1;
         break;

            // Counts the ESC keys.  
         case (char)27:
         escPressed = escPressed + 1;
         break;
            
            // Counts all other keys.
         default:
         keyPressCount = keyPressCount + 1;
         break;
      }
      textBox1->Text = String::Concat( 
         backspacePressed, " backspaces pressed\r\n",
         escPressed, " escapes pressed\r\n",
         returnPressed, " returns pressed\r\n",
         keyPressCount, " other keys pressed\r\n" );
      ex->Handled = true;
   }
};
public class myKeyPressClass 
 {
     static long keyPressCount = 0 ;
     static long backspacePressed =  0;
     static long returnPressed = 0 ;
     static long escPressed = 0 ;
     private TextBox textBox1 = new TextBox();
     private void myKeyCounter(object sender, KeyPressEventArgs ex)
     {
     switch(ex.KeyChar)
     {
             // Counts the backspaces.
         case '\b':
         backspacePressed = backspacePressed + 1;
         break ;
             // Counts the ENTER keys.
         case '\r':
         returnPressed = returnPressed + 1 ;
         break ;
             // Counts the ESC keys.  
         case (char)27:
         escPressed = escPressed + 1 ;
         break ;
             // Counts all other keys.
         default:
         keyPressCount = keyPressCount + 1 ;
         break;
     }
     
     textBox1.Text = 
         backspacePressed + " backspaces pressed\r\n" + 
         escPressed + " escapes pressed\r\n" +
         returnPressed + " returns pressed\r\n" +
         keyPressCount + " other keys pressed\r\n" ;
     ex.Handled = true ;
     }
 }
Public Class myKeyPressClass
    Private Shared keyPressCount As Long = 0
    Private Shared backspacePressed As Long = 0
    Private Shared returnPressed As Long = 0
    Private Shared escPressed As Long = 0
    Private textBox1 As TextBox
    
    Private Sub myKeyCounter(sender As Object, ex As KeyPressEventArgs)
        Select Case ex.KeyChar
            ' Counts the backspaces.
            Case ControlChars.Back
                backspacePressed = backspacePressed + 1
            ' Counts the ENTER keys.
            Case ControlChars.Lf
                returnPressed = returnPressed + 1
            ' Counts the ESC keys.  
            Case Convert.ToChar(27)
                escPressed = escPressed + 1
            ' Counts all other keys.
            Case Else
                keyPressCount = keyPressCount + 1
        End Select
        
        textBox1.Text = backspacePressed & " backspaces pressed" & _
            ControlChars.Lf & ControlChars.Cr & escPressed & _
            " escapes pressed" & ControlChars.CrLf & returnPressed & _
            " returns pressed" & ControlChars.CrLf & keyPressCount & _
            " other keys pressed" & ControlChars.CrLf
        ex.Handled = True
    End Sub
End Class

Debe crear una nueva instancia de esta clase.You must create a new instance of this class. También debe establecer el controlador de eventos.You must also set the event handler. Puede hacerlo en el constructor de la clase.You can do this in the constructor for your class.

public:
   myKeyPressClass^ myKeyPressHandler;

   Form1()
   {
      myKeyPressHandler = gcnew myKeyPressClass;

      InitializeComponent();

      textBox1->KeyPress += gcnew KeyPressEventHandler(
         myKeyPressHandler, &myKeyPressClass::myKeyCounter );
   }
myKeyPressClass myKeyPressHandler = new myKeyPressClass();
public Form1()
{
     InitializeComponent();
 
     textBox1.KeyPress += new KeyPressEventHandler(myKeyPressHandler.myKeyCounter);
}
Private myKeyPressHandler As New myKeyPressClass()

Public Sub New()
    InitializeComponent()
    
    AddHandler textBox1.KeyPress, AddressOf myKeyPressHandler.myKeyCounter
End Sub

Cuando se genera el evento especificado en el control, se llama al método adjunto y la aplicación puede ejecutar código en respuesta al evento.When the specified event is raised in the control, the attached method is called and the application can execute code in response to the event.

Comentarios

KeyPressEventArgs Especifica el carácter que se crea cuando el usuario presiona una tecla.A KeyPressEventArgs specifies the character that is composed when the user presses a key. Por ejemplo, cuando el usuario presiona Mayús + K, la KeyChar propiedad devuelve una K mayúscula.For example, when the user presses SHIFT + K, the KeyChar property returns an uppercase K.

Un KeyPress evento se produce cuando el usuario presiona una tecla.A KeyPress event occurs when the user presses a key. Dos eventos que están estrechamente relacionados con el KeyPress evento son KeyUp y KeyDown.Two events that are closely related to the KeyPress event are KeyUp and KeyDown. El KeyDown evento precede cada KeyPress evento cuando el usuario presiona una tecla y se produce KeyUp un evento cuando el usuario suelta una tecla.The KeyDown event precedes each KeyPress event when the user presses a key, and a KeyUp event occurs when the user releases a key. Cuando el usuario mantiene presionada una tecla, KeyDown se KeyPress producen duplicados y eventos cada vez que se repite el carácter.When the user holds down a key, duplicate KeyDown and KeyPress events occur each time the character repeats. Al KeyUp liberarse, se genera un evento.One KeyUp event is generated upon release.

Con cada KeyPress evento, se KeyPressEventArgs pasa un.With each KeyPress event, a KeyPressEventArgs is passed. Se pasa con cada KeyDown evento y KeyUp. KeyEventArgsA KeyEventArgs is passed with each KeyDown and KeyUp event. Un KeyEventArgs especifica si se presionaron teclas modificadoras (Ctrl, Mayús o Alt) junto con otra clave.A KeyEventArgs specifies whether any modifier keys (CTRL, SHIFT, or ALT) were pressed along with another key. (Esta información del modificador también se puede obtener a ModifierKeys través de la Control propiedad de la clase).(This modifier information can also be obtained through the ModifierKeys property of the Control class.)

Establezca Handled KeyPress en true para cancelar el evento.Set Handled to true to cancel the KeyPress event. Esto evita que el control procese la pulsación de tecla.This keeps the control from processing the key press.

Nota

Algunos controles procesarán determinados trazos de KeyDowntecla.Some controls will process certain key strokes on KeyDown. Por ejemplo, RichTextBox procesa la tecla entrar antes KeyPress de llamar a.For example, RichTextBox processes the Enter key before KeyPress is called. En tales casos, no se puede cancelar KeyPress el evento y se debe cancelar el trazo de KeyDown clave de en su lugar.In such cases, you cannot cancel the KeyPress event, and must cancel the key stroke from KeyDown instead.

Para obtener información sobre el modelo de eventos, vea controlar y provocar eventos.For information about the event model, see Handling and Raising Events.

Constructores

KeyPressEventArgs(Char)

Inicializa una nueva instancia de la clase KeyPressEventArgs.Initializes a new instance of the KeyPressEventArgs class.

Propiedades

Handled

Obtiene o establece un valor que indica si se controló el evento KeyPress.Gets or sets a value indicating whether the KeyPress event was handled.

KeyChar

Obtiene o establece el carácter correspondiente a la tecla presionada.Gets or sets the character corresponding to the key pressed.

Métodos

Equals(Object)

Determina si el objeto especificado es igual al objeto actual.Determines whether the specified object is equal to the current object.

(Heredado de Object)
GetHashCode()

Sirve como la función hash predeterminada.Serves as the default hash function.

(Heredado de Object)
GetType()

Obtiene el Type de la instancia actual.Gets the Type of the current instance.

(Heredado de Object)
MemberwiseClone()

Crea una copia superficial del objeto Object actual.Creates a shallow copy of the current Object.

(Heredado de Object)
ToString()

Devuelve una cadena que representa el objeto actual.Returns a string that represents the current object.

(Heredado de Object)

Se aplica a

Consulte también: