NativeWindow.ReleaseHandle Metodo
Definizione
Importante
Alcune informazioni sono relative alla release non definitiva del prodotto, che potrebbe subire modifiche significative prima della release definitiva. Microsoft non riconosce alcuna garanzia, espressa o implicita, in merito alle informazioni qui fornite.
Rilascia l'handle associato a questa finestra.
public:
virtual void ReleaseHandle();public virtual void ReleaseHandle ();abstract member ReleaseHandle : unit -> unit
override this.ReleaseHandle : unit -> unitPublic Overridable Sub ReleaseHandle ()Esempio
Nell'esempio di codice seguente viene illustrata l'intercettazione dei messaggi della finestra del sistema operativo in una routine finestra. Nell'esempio viene creata una classe che eredita da NativeWindow per eseguire questa operazione.
La MyNativeWindowListener classe esegue l'hook nella routine finestra del modulo passato al costruttore ed esegue l'override del WndProc metodo per intercettare il messaggio della WM_ACTIVATEAPP finestra. La classe illustra l'uso dei AssignHandle metodi e ReleaseHandle per identificare l'handle NativeWindow della finestra utilizzato da . L'handle viene assegnato in base agli Control.HandleCreated eventi e Control.HandleDestroyed . Quando viene ricevuto il messaggio della WM_ACTIVATEAPP finestra, la classe chiama il form1.ApplicationActivated metodo .
Questo codice è un estratto dell'esempio illustrato nella panoramica della NativeWindow classe. Alcuni codici non vengono visualizzati allo scopo di brevità. Vedere NativeWindow per l'intero elenco di codice.
// 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
Commenti
Questo metodo non elimina definitivamente l'handle della finestra. Imposta invece la routine della finestra dell'handle sulla routine della finestra predefinita. Imposta la Handle proprietà su 0 e chiama OnHandleChange per riflettere la modifica.
Una finestra chiama automaticamente questo metodo se riceve un messaggio win32 nativo WM_NCDESTROY, a indicare che Windows ha eliminato definitivamente l'handle.
