NativeWindow.Handle Proprietà

public:
 property IntPtr Handle { IntPtr get(); };

public IntPtr Handle { get; }

member this.Handle : nativeint

Public ReadOnly Property Handle As IntPtr

Valore della proprietà

In caso di esito positivo, oggetto IntPtr che rappresenta l'handle associato alla finestra Win32 nativa; in caso contrario, 0 se non esistono handle associati alla finestra.

Implementazioni

Esempio

Nell'esempio di codice seguente viene illustrata la creazione di una finestra con un nome specifico della classe della finestra del sistema operativo. Nell'esempio viene creata una classe che eredita da NativeWindow per eseguire questa operazione. L'esempio illustra anche l'override del OnHandleChange metodo da ricevere una notifica quando le Handle modifiche vengono modificate.

La MyNativeWindow classe crea una nuova finestra con il ClassName set su BUTTON. In questo modo viene creata una finestra del pulsante Win32. La posizione e le dimensioni del pulsante sono impostate, insieme alla specifica di stili di finestra aggiuntivi. La classe illustra come usare il metodo e eseguire l'override del CreateHandleWndProc metodo per intercettare i messaggi della finestra ricevuti. Anche se l'esempio cerca il messaggio WM_ACTIVATEAPP, questo potrebbe essere sostituito in un programma reale con messaggi di finestra specifici del tipo creato.

// MyNativeWindow class to create a window given a class name.
ref class MyNativeWindow: public NativeWindow
{
private:

   // Constant values were found in the S"windows.h" header file.
   literal int WS_CHILD = 0x40000000,WS_VISIBLE = 0x10000000,WM_ACTIVATEAPP = 0x001C;
   int windowHandle;

public:
   MyNativeWindow( Form^ parent )
   {
      CreateParams^ cp = gcnew CreateParams;

      // Fill in the CreateParams details.
      cp->Caption = "Click here";
      cp->ClassName = "Button";

      // Set the position on the form
      cp->X = 100;
      cp->Y = 100;
      cp->Height = 100;
      cp->Width = 100;

      // Specify the form as the parent.
      cp->Parent = parent->Handle;

      // Create as a child of the specified parent
      cp->Style = WS_CHILD | WS_VISIBLE;

      // Create the actual window
      this->CreateHandle( cp );
   }

protected:

   // Listen to when the handle changes to keep the variable in sync

   virtual void OnHandleChange() override
   {
      windowHandle = (int)this->Handle;
   }

   virtual void WndProc( Message % m ) override
   {
      // Listen for messages that are sent to the button window. Some messages are sent
      // to the parent window instead of the button's window.
      switch ( m.Msg )
      {
         case WM_ACTIVATEAPP:
            
            // Do something here in response to messages
            break;
      }
      NativeWindow::WndProc( m );
   }
};

// MyNativeWindow class to create a window given a class name.
internal class MyNativeWindow : NativeWindow
{

    // Constant values were found in the "windows.h" header file.
    private const int WS_CHILD = 0x40000000,
                      WS_VISIBLE = 0x10000000,
                      WM_ACTIVATEAPP = 0x001C;

    private int windowHandle;

    public MyNativeWindow(Form parent)
    {

        CreateParams cp = new CreateParams();

        // Fill in the CreateParams details.
        cp.Caption = "Click here";
        cp.ClassName = "Button";

        // Set the position on the form
        cp.X = 100;
        cp.Y = 100;
        cp.Height = 100;
        cp.Width = 100;

        // Specify the form as the parent.
        cp.Parent = parent.Handle;

        // Create as a child of the specified parent
        cp.Style = WS_CHILD | WS_VISIBLE;

        // Create the actual window
        this.CreateHandle(cp);
    }

    // Listen to when the handle changes to keep the variable in sync
    protected override void OnHandleChange()
    {
        windowHandle = (int)this.Handle;
    }

    protected override void WndProc(ref Message m)
    {
        // Listen for messages that are sent to the button window. Some messages are sent
        // to the parent window instead of the button's window.

        switch (m.Msg)
        {
            case WM_ACTIVATEAPP:
                // Do something here in response to messages
                break;
        }
        base.WndProc(ref m);
    }
}

' MyNativeWindow class to create a window given a class name.
<System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _
Friend Class MyNativeWindow
    Inherits NativeWindow

    ' Constant values were found in the "windows.h" header file.
    Private Const WS_CHILD As Integer = &H40000000, _
                  WS_VISIBLE As Integer = &H10000000, _
                  WM_ACTIVATEAPP As Integer = &H1C

    Private windowHandle As Integer

    Public Sub New(ByVal parent As Form)

        Dim cp As CreateParams = New CreateParams()

        ' Fill in the CreateParams details.
        cp.Caption = "Click here"
        cp.ClassName = "Button"

        ' Set the position on the form
        cp.X = 100
        cp.Y = 100
        cp.Height = 100
        cp.Width = 100

        ' Specify the form as the parent.
        cp.Parent = parent.Handle

        ' Create as a child of the specified parent
        cp.Style = WS_CHILD Or WS_VISIBLE

        ' Create the actual window
        Me.CreateHandle(cp)
    End Sub

    ' Listen to when the handle changes to keep the variable in sync
    <System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _
    Protected Overrides Sub OnHandleChange()
        windowHandle = Me.Handle.ToInt32()
    End Sub

    <System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _
        Protected Overrides Sub WndProc(ByRef m As Message)
        ' Listen for messages that are sent to the button window. Some messages are sent
        ' to the parent window instead of the button's window.

        Select Case (m.Msg)
            Case WM_ACTIVATEAPP
                ' Do something here in response to messages
        End Select

        MyBase.WndProc(m)
    End Sub

End Class

Commenti

Usare questo metodo quando si chiamano i metodi API di Windows che richiedono un handle per una finestra o un controllo.

Si applica a

Vedi anche

• AssignHandle(IntPtr)
• CreateHandle(CreateParams)
• DestroyHandle()
• ReleaseHandle()
• OnHandleChange()