MenuStrip.WndProc(Message) 方法

参考

定义

命名空间:: System.Windows.Forms

程序集:: System.Windows.Forms.dll

重要

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处理 Windows 消息。

protected:
 override void WndProc(System::Windows::Forms::Message % m);

protected override void WndProc (ref System.Windows.Forms.Message m);

override this.WndProc : Message -> unit

Protected Overrides Sub WndProc (ByRef m As Message)

参数

m: Message

要处理的 Windows Message。

示例

下面的代码示例演示如何重写 WndProc 方法以处理结构中 Message 标识的操作系统消息。在此示例中处理WM_ACTIVATEAPP操作系统消息，以了解另一个应用程序何时变为活动状态。请参阅中的平台 SDK 文档参考 https://learn.microsoft.com ，了解可用的 Message.Msg、 Message.LParam和 Message.WParam 值。可以在平台 SDK (Core SDK 部分中包含的 windows.h 头文件中找到实际常量值，) 下载，该部分也可在 Docs 上获取。

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

注解

通过 PreProcessMessage 方法进行筛选后，WndProc所有消息都发送到方法。

WndProc 方法与 Windows WindowProc 函数完全对应。有关处理 Windows 消息的详细信息，请参阅 WindowProc 回调函数。

继承者说明

继承控件应调用基类 WndProc(Message) 的方法来处理它们不处理的任何消息。

适用于

通过

MenuStrip.WndProc(Message) 方法

定义

参数

示例

注解

继承者说明

适用于

其他资源