NativeWindow.AssignHandle(IntPtr) Metoda

Definicja

Przestrzeń nazw:

System.Windows.Forms

Zestaw:

System.Windows.Forms.dll

Przypisuje do tego okna uchwyt.

public:
 void AssignHandle(IntPtr handle);

public void AssignHandle (IntPtr handle);

member this.AssignHandle : nativeint -> unit

Public Sub AssignHandle (handle As IntPtr)

Parametry

handle

IntPtr

nativeint

Uchwyt do przypisania do tego okna.

Wyjątki

Exception

To okno ma już dojście.

Win32Exception

Nie można pobrać procedury systemu Windows dla skojarzonego okna natywnego.

Przykłady

Poniższy przykład kodu przedstawia przechwytywanie komunikatów okien systemu operacyjnego w procedurze okna. W przykładzie jest tworzona klasa dziedziczona z NativeWindow w celu osiągnięcia tego celu.

Klasa MyNativeWindowListener łączy się z procedurą okna formularza przekazaną do konstruktora i przesłania WndProc metodę w celu przechwycenia komunikatu WM_ACTIVATEAPP okna. Klasa demonstruje użycie AssignHandle metod i ReleaseHandle w celu zidentyfikowania, które okno będzie używane NativeWindow . Dojście jest przypisywane na podstawie zdarzeń Control.HandleCreated i Control.HandleDestroyed . Po odebraniu komunikatu WM_ACTIVATEAPP okna klasa wywołuje metodę form1.ApplicationActivated .

Ten kod jest fragmentem przykładu pokazanego w omówieniu NativeWindow klasy. Niektóre kody nie są wyświetlane w celu zwięzłości. Zobacz NativeWindow , aby zapoznać się z całą listą kodu.

// NativeWindow class to listen to operating system messages.
ref class MyNativeWindowListener: public NativeWindow
{
private:

   // Constant value was found in the S"windows.h" header file.
   literal int WM_ACTIVATEAPP = 0x001C;
   Form1^ parent;

public:
   MyNativeWindowListener( Form1^ parent )
   {
      parent->HandleCreated += gcnew EventHandler( this, &MyNativeWindowListener::OnHandleCreated );
      parent->HandleDestroyed += gcnew EventHandler( this, &MyNativeWindowListener::OnHandleDestroyed );
      this->parent = parent;
   }

internal:

   // Listen for the control's window creation and then hook into it.
   void OnHandleCreated( Object^ sender, EventArgs^ /*e*/ )
   {
      // Window is now created, assign handle to NativeWindow.
      AssignHandle( (dynamic_cast<Form1^>(sender))->Handle );
   }

   void OnHandleDestroyed( Object^ /*sender*/, EventArgs^ /*e*/ )
   {
      // Window was destroyed, release hook.
      ReleaseHandle();
   }

protected:

   virtual void WndProc( Message %m ) override
   {
      // Listen for operating system messages
      switch ( m.Msg )
      {
         case WM_ACTIVATEAPP:

            // Notify the form that this message was received.
            // Application is activated or deactivated,
            // based upon the WParam parameter.
            parent->ApplicationActived( ((int)m.WParam != 0) );
            break;
      }
      NativeWindow::WndProc( m );
   }

};

// NativeWindow class to listen to operating system messages.
internal class MyNativeWindowListener : NativeWindow
{
    // Constant value was found in the "windows.h" header file.
    private const int WM_ACTIVATEAPP = 0x001C;

    private Form1 parent;

    public MyNativeWindowListener(Form1 parent)
    {

        parent.HandleCreated += new EventHandler(this.OnHandleCreated);
        parent.HandleDestroyed += new EventHandler(this.OnHandleDestroyed);
        this.parent = parent;
    }

    // Listen for the control's window creation and then hook into it.
    internal void OnHandleCreated(object sender, EventArgs e)
    {
        // Window is now created, assign handle to NativeWindow.
        AssignHandle(((Form1)sender).Handle);
    }
    internal void OnHandleDestroyed(object sender, EventArgs e)
    {
        // Window was destroyed, release hook.
        ReleaseHandle();
    }

    protected override void WndProc(ref Message m)
    {
        // Listen for operating system messages

        switch (m.Msg)
        {
            case WM_ACTIVATEAPP:

                // Notify the form that this message was received.
                // Application is activated or deactivated, 
                // based upon the WParam parameter.
                parent.ApplicationActivated(((int)m.WParam != 0));

                break;
        }
        base.WndProc(ref m);
    }
}

' NativeWindow class to listen to operating system messages.
Friend Class MyNativeWindowListener
    Inherits NativeWindow

    ' Constant value was found in the "windows.h" header file.
    Private Const WM_ACTIVATEAPP As Integer = &H1C

    Private parent As Form1

    Public Sub New(ByVal parent As Form1)

        AddHandler parent.HandleCreated, AddressOf Me.OnHandleCreated
        AddHandler parent.HandleDestroyed, AddressOf Me.OnHandleDestroyed
        Me.parent = parent
    End Sub

    ' Listen for the control's window creation and hook into it.    
    Private Sub OnHandleCreated(ByVal sender As Object, ByVal e As EventArgs)
        ' Window is now created, assign handle to NativeWindow.
        AssignHandle(CType(sender, Form).Handle)
    End Sub

    Private Sub OnHandleDestroyed(ByVal sender As Object, ByVal e As EventArgs)
        ' Window was destroyed, release hook.
        ReleaseHandle()
    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)
            Case WM_ACTIVATEAPP

                ' Notify the form that this message was received.
                ' Application is activated or deactivated, 
                ' based upon the WParam parameter.
                parent.ApplicationActivated(m.WParam.ToInt32() <> 0)

        End Select

        MyBase.WndProc(m)
    End Sub
End Class

Uwagi

WndProc przechwytuje komunikaty okien wysyłane do parametru handle . Użyj polecenia ReleaseHandle , aby zresetować procedurę okna dojścia do domyślnej procedury okna.

Metoda AssignHandle wywołuje metodę OnHandleChange , aby wskazać, że wartość Handle właściwości uległa zmianie.

Uwaga

Dojście do przypisania nie może być w innym procesie aplikacji.

Zobacz też

• Handle
• CreateHandle(CreateParams)
• DestroyHandle()
• ReleaseHandle()
• Finalize()
• OnHandleChange()