MenuStrip.WndProc(Message) Método
Definición
Importante
Parte de la información hace referencia a la versión preliminar del producto, que puede haberse modificado sustancialmente antes de lanzar la versión definitiva. Microsoft no otorga ninguna garantía, explícita o implícita, con respecto a la información proporcionada aquí.
Procesa los mensajes de Windows.
protected:
override void WndProc(System::Windows::Forms::Message % m);protected override void WndProc (ref System.Windows.Forms.Message m);override this.WndProc : Message -> unitProtected Overrides Sub WndProc (ByRef m As Message)Parámetros
Ejemplos
En el ejemplo de código siguiente se muestra cómo invalidar el WndProc método para controlar los mensajes del sistema operativo identificados en la Message estructura . El mensaje del sistema operativo WM_ACTIVATEAPP se controla en este ejemplo para saber cuándo otra aplicación se está activa. Consulte la referencia de documentación del SDK de plataforma que se encuentra en https://learn.microsoft.com para comprender los valores disponibles Message.Msg, Message.LParamy Message.WParam . Los valores constantes reales se pueden encontrar en el archivo de encabezado windows.h incluido en la descarga del SDK de plataforma (SDK principal), que también está disponible en Docs.
using namespace System;
using namespace System::Drawing;
using namespace System::Windows::Forms;
using namespace System::Security::Permissions;
namespace csTempWindowsApplication1
{
public ref class Form1: public System::Windows::Forms::Form
{
private:
// Constant value was found in the "windows.h" header file.
static const Int32 WM_ACTIVATEAPP = 0x001C;
Boolean appActive;
public:
Form1()
{
appActive = true;
this->Size = System::Drawing::Size( 300, 300 );
this->Text = "Form1";
this->Font = gcnew System::Drawing::Font( "Microsoft Sans Serif",18.0F,System::Drawing::FontStyle::Bold,System::Drawing::GraphicsUnit::Point,((System::Byte)(0)) );
}
protected:
virtual void OnPaint( PaintEventArgs^ e ) override
{
// Paint a string in different styles depending on whether the
// application is active.
if ( appActive )
{
e->Graphics->FillRectangle( SystemBrushes::ActiveCaption, 20, 20, 260, 50 );
e->Graphics->DrawString( "Application is active", this->Font, SystemBrushes::ActiveCaptionText, 20, 20 );
}
else
{
e->Graphics->FillRectangle( SystemBrushes::InactiveCaption, 20, 20, 260, 50 );
e->Graphics->DrawString( "Application is Inactive", this->Font, SystemBrushes::ActiveCaptionText, 20, 20 );
}
}
[SecurityPermission(SecurityAction::Demand, Flags=SecurityPermissionFlag::UnmanagedCode)]
virtual void WndProc( Message% m ) override
{
// Listen for operating system messages.
switch ( m.Msg )
{
case WM_ACTIVATEAPP:
// The WParam value identifies what is occurring.
appActive = (int)m.WParam != 0;
// Invalidate to get new text painted.
this->Invalidate();
break;
}
Form::WndProc( m );
}
};
}
[STAThread]
int main()
{
Application::Run( gcnew csTempWindowsApplication1::Form1 );
}
using System;
using System.Drawing;
using System.Windows.Forms;
namespace csTempWindowsApplication1
{
public class Form1 : System.Windows.Forms.Form
{
// Constant value was found in the "windows.h" header file.
private const int WM_ACTIVATEAPP = 0x001C;
private bool appActive = true;
[STAThread]
static void Main()
{
Application.Run(new Form1());
}
public Form1()
{
this.Size = new System.Drawing.Size(300,300);
this.Text = "Form1";
this.Font = new System.Drawing.Font("Microsoft Sans Serif", 18F, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, ((System.Byte)(0)));
}
protected override void OnPaint(PaintEventArgs e)
{
// Paint a string in different styles depending on whether the
// application is active.
if (appActive)
{
e.Graphics.FillRectangle(SystemBrushes.ActiveCaption,20,20,260,50);
e.Graphics.DrawString("Application is active", this.Font, SystemBrushes.ActiveCaptionText, 20,20);
}
else
{
e.Graphics.FillRectangle(SystemBrushes.InactiveCaption,20,20,260,50);
e.Graphics.DrawString("Application is Inactive", this.Font, SystemBrushes.ActiveCaptionText, 20,20);
}
}
protected override void WndProc(ref Message m)
{
// Listen for operating system messages.
switch (m.Msg)
{
// The WM_ACTIVATEAPP message occurs when the application
// becomes the active application or becomes inactive.
case WM_ACTIVATEAPP:
// The WParam value identifies what is occurring.
appActive = (((int)m.WParam != 0));
// Invalidate to get new text painted.
this.Invalidate();
break;
}
base.WndProc(ref m);
}
}
}
Imports System.Drawing
Imports System.Windows.Forms
Namespace csTempWindowsApplication1
Public Class Form1
Inherits System.Windows.Forms.Form
' Constant value was found in the "windows.h" header file.
Private Const WM_ACTIVATEAPP As Integer = &H1C
Private appActive As Boolean = True
<STAThread()> _
Shared Sub Main()
Application.Run(New Form1())
End Sub
Public Sub New()
MyBase.New()
Me.Size = New System.Drawing.Size(300, 300)
Me.Text = "Form1"
Me.Font = New System.Drawing.Font("Microsoft Sans Serif", 18.0!, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
End Sub
Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs)
' Paint a string in different styles depending on whether the
' application is active.
If (appActive) Then
e.Graphics.FillRectangle(SystemBrushes.ActiveCaption, 20, 20, 260, 50)
e.Graphics.DrawString("Application is active", Me.Font, SystemBrushes.ActiveCaptionText, 20, 20)
Else
e.Graphics.FillRectangle(SystemBrushes.InactiveCaption, 20, 20, 260, 50)
e.Graphics.DrawString("Application is Inactive", Me.Font, SystemBrushes.ActiveCaptionText, 20, 20)
End If
End Sub
<System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _
Protected Overrides Sub WndProc(ByRef m As Message)
' Listen for operating system messages
Select Case (m.Msg)
' The WM_ACTIVATEAPP message occurs when the application
' becomes the active application or becomes inactive.
Case WM_ACTIVATEAPP
' The WParam value identifies what is occurring.
appActive = (m.WParam.ToInt32() <> 0)
' Invalidate to get new text painted.
Me.Invalidate()
End Select
MyBase.WndProc(m)
End Sub
End Class
End Namespace
Comentarios
Todos los mensajes se envían al WndProc método después de filtrarse a través del PreProcessMessage método .
El método WndProc corresponde exactamente a la función WindowProc de Windows. Para obtener más información sobre el procesamiento de mensajes de Windows, vea Función de devolución de llamada WindowProc.
Notas a los desarrolladores de herederos
Los controles heredados deben llamar al método de WndProc(Message) la clase base para procesar los mensajes que no controlan.
