SO WIRD'S GEMACHT: Verwenden einer Klasse für Windows-Prozeduren verknüpfen

Artikel
11/06/2009
Dieser Dokumentation für die Vorschau nur ist und in späteren Versionen geändert. Leere Themen wurden als Platzhalter eingefügt.]
Dieses Beispielprogramm weist eine Windows-Prozedur, WndProc zu ein Fenster, wenn es eine bestimmte Windows-Meldung empfängt. Diese Aktion tritt, wenn das Fensterhandle, hwnd, zu einer Auflistung zugeordnet ist Handles zu reagieren, wenn die Windows-Nachricht empfangen wird. Diese Klasse wird in den folgenden Gewusst-wie-Themen verwenden:
Dieses Beispielprogramm wird Bilden von Unterklassen von Steuerelementen mit einer verwalteten Windows-Prozedur detailliert beschrieben.
Beispiel

                        public
                        class WndProcHooker
{

    // The WndProcCallback method is used when a hooked// window's message map contains the hooked message.// Parameters:// hwnd - The handle to the window for which the message// was received.// wParam - The message's parameters (part 1).// lParam - The message's parameters (part 2).// handled - The invoked function sets this to true if it// handled the message. If the value is false when the callback// returns, the next window procedure in the wndproc chain is// called.//// Returns a value specified for the given message.publicdelegateint WndProcCallback(
        IntPtr hwnd, uint msg, uint wParam, int lParam, refbool handled);

    // This is the global list of all the window procedures we have// hooked. The key is an hwnd. The value is a HookedProcInformation// object which contains a pointer to the old wndproc and a map of// message's callbacks for the window specified. Controls whose handles// have been created go into this dictionary.privatestatic Dictionary<IntPtr, HookedProcInformation> hwndDict =
        new Dictionary<IntPtr, HookedProcInformation>();

    // The key for this dictionary is a control and the value is a// HookedProcInformation. Controls whose handles have not been created// go into this dictionary. When the HandleCreated event for the// control is fired the control is moved into hwndDict.privatestatic Dictionary<Control, HookedProcInformation> ctlDict =
        new Dictionary<Control, HookedProcInformation>();

    // Makes a connection between a message on a specified window handle// and the callback to be called when that message is received. If the// window was not previously hooked it is added to the global list of// all the window procedures hooked.// Parameters:// ctl - The control whose wndproc we are hooking.// callback - The method to call when the specified.// message is received for the specified window.// msg - The message being hooked.publicstaticvoid HookWndProc(
        Control ctl, WndProcCallback callback, uint msg)
    {
        HookedProcInformation hpi = null;
        if (ctlDict.ContainsKey(ctl))
            hpi = ctlDict[ctl];
        elseif (hwndDict.ContainsKey(ctl.Handle))
            hpi = hwndDict[ctl.Handle];
        if (hpi == null)
        {
            // If new control, create a new// HookedProcInformation for it.
            hpi = new HookedProcInformation(ctl,
                new Win32.WndProc(WndProcHooker.WindowProc));
            ctl.HandleCreated += new EventHandler(ctl_HandleCreated);
            ctl.HandleDestroyed += new EventHandler(ctl_HandleDestroyed);
            ctl.Disposed += new EventHandler(ctl_Disposed);

            // If the handle has already been created set the hook. If it// hasn't been created yet, the hook will get set in the// ctl_HandleCreated event handler.if (ctl.Handle != IntPtr.Zero)
                hpi.SetHook();
        }

        // Stick hpi into the correct dictionary.if (ctl.Handle == IntPtr.Zero)
            ctlDict[ctl] = hpi;
        else
            hwndDict[ctl.Handle] = hpi;

        // Add the message/callback into the message map.
        hpi.messageMap[msg] = callback;
    }

    // The event handler called when a control is disposed.staticvoid ctl_Disposed(object sender, EventArgs e)
    {
        Control ctl = sender as Control;
        if (ctlDict.ContainsKey(ctl))
            ctlDict.Remove(ctl);
        else
            System.Diagnostics.Debug.Assert(false);
    }

    // The event handler called when a control's handle is destroyed.// We remove the HookedProcInformation from hwndDict and// put it back into ctlDict in case the control get re-// created and we still want to hook its messages.staticvoid ctl_HandleDestroyed(object sender, EventArgs e)
    {
        // When the handle for a control is destroyed, we want to// unhook its wndproc and update our lists
        Control ctl = sender as Control;
        if (hwndDict.ContainsKey(ctl.Handle))
        {
            HookedProcInformation hpi = hwndDict[ctl.Handle];
            UnhookWndProc(ctl, false);
        }
        else
            System.Diagnostics.Debug.Assert(false);
    }

    // The event handler called when a control's handle is created. We// call SetHook() on the associated HookedProcInformation object and// move it from ctlDict to hwndDict.staticvoid ctl_HandleCreated(object sender, EventArgs e)
    {
        Control ctl = sender as Control;
        if (ctlDict.ContainsKey(ctl))
        {
            HookedProcInformation hpi = ctlDict[ctl];
            hwndDict[ctl.Handle] = hpi;
            ctlDict.Remove(ctl);
            hpi.SetHook();
        }
        else
            System.Diagnostics.Debug.Assert(false);
    }

    // This is a generic wndproc. It is the callback for all hooked// windows. If we get into this function, we look up the hwnd in the// global list of all hooked windows to get its message map. If the// message received is present in the message map, its callback is// invoked with the parameters listed here.// Parameters:// hwnd - The handle to the window that received the// message// msg - The message// wParam - The message's parameters (part 1)// lParam - The messages's parameters (part 2)// Returns the callback handled the message, the callback's return// value is returned form this function. If the callback didn't handle// the message, the message is forwarded on to the previous wndproc.privatestaticint WindowProc(
        IntPtr hwnd, uint msg, uint wParam, int lParam)
    {
        if (hwndDict.ContainsKey(hwnd))
        {
            HookedProcInformation hpi = hwndDict[hwnd];
            if (hpi.messageMap.ContainsKey(msg))
            {
                WndProcCallback callback = hpi.messageMap[msg];
                bool handled = false;
                int retval = callback(hwnd, msg, wParam, lParam, ref handled);
                if (handled)
                    return retval;
            }

            // If the callback didn't set the handled property to true,// call the original window procedure.return hpi.CallOldWindowProc(hwnd, msg, wParam, lParam);
        }
        System.Diagnostics.Debug.Assert(
            false, "WindowProc called for hwnd we don't know about");
        return Win32.DefWindowProc(hwnd, msg, wParam, lParam);
    }

    // This method removes the specified message from the message map for// the specified hwnd.publicstaticvoid UnhookWndProc(Control ctl, uint msg)
    {
        // Look for the HookedProcInformation in the// ctrDict and hwndDict dictionaries.
        HookedProcInformation hpi = null;
        if (ctlDict.ContainsKey(ctl))
            hpi = ctlDict[ctl];
        elseif (hwndDict.ContainsKey(ctl.Handle))
            hpi = hwndDict[ctl.Handle];
        // if we couldn't find a HookedProcInformation, throwif (hpi == null)
            thrownew ArgumentException("No hook exists for this control");

        // look for the message we are removing in the messageMapif (hpi.messageMap.ContainsKey(msg))
            hpi.messageMap.Remove(msg);
        else// if we couldn't find the message, throwthrownew ArgumentException(
                string.Format(
                "No hook exists for message ({0}) on this control",
                msg));
    }

    // Restores the previous wndproc for the specified window.// Parameters:// ctl - The control whose wndproc we no longer want to hook.// disposing - True if HookedProcInformation is not//   read back into ctlDict.publicstaticvoid UnhookWndProc(Control ctl, bool disposing)
    {
        HookedProcInformation hpi = null;
        if (ctlDict.ContainsKey(ctl))
            hpi = ctlDict[ctl];
        elseif (hwndDict.ContainsKey(ctl.Handle))
            hpi = hwndDict[ctl.Handle];
        if (hpi == null)
            thrownew ArgumentException("No hook exists for this control");

        // If we found our HookedProcInformation in ctlDict and we are// disposing remove it from ctlDict.if (ctlDict.ContainsKey(ctl) && disposing)
            ctlDict.Remove(ctl);

        // If we found our HookedProcInformation in hwndDict, remove it// and if we are not disposing stick it in ctlDict.if (hwndDict.ContainsKey(ctl.Handle))
        {
            hpi.Unhook();
            hwndDict.Remove(ctl.Handle);
            if (!disposing)
                ctlDict[ctl] = hpi;
        }
    }

    // This class remembers the old window procedure for the specified// window handle and also provides the message map for the messages// hooked on that window.class HookedProcInformation
    {

        // The message map for the window.public Dictionary<uint, WndProcCallback> messageMap;

        // The old window procedure for the window.private IntPtr oldWndProc;

        // The delegate that gets called in place of this window's// wndproc.private Win32.WndProc newWndProc;

        // Control whose wndproc is being hooked.private Control control;

        // Constructs a new HookedProcInformation object// Parameters:// ctl - The handle to the window being hooked// wndproc - The window procedure to replace the// original one for the control.public HookedProcInformation(Control ctl, Win32.WndProc wndproc)
        {
            control = ctl;
            newWndProc = wndproc;
            messageMap = new Dictionary<uint, WndProcCallback>();
        }

        // Replaces the windows procedure for control with the// one specified in the constructor.publicvoid SetHook()
        {
            IntPtr hwnd = control.Handle;
            if (hwnd == IntPtr.Zero)
                thrownew InvalidOperationException(
                    "Handle for control has not been created");

            oldWndProc = Win32.SetWindowLong(hwnd, Win32.GWL_WNDPROC,
                Marshal.GetFunctionPointerForDelegate(newWndProc));
        }

        // Restores the original window procedure for the control.publicvoid Unhook()
        {
            IntPtr hwnd = control.Handle;
            if (hwnd == IntPtr.Zero)
                thrownew InvalidOperationException(
                    "Handle for control has not been created");

            Win32.SetWindowLong(hwnd, Win32.GWL_WNDPROC, oldWndProc);
        }

        // Calls the original window procedure of the control with the// arguments provided.// Parameters:// hwnd - The handle of the window that received the// message// msg - The message// wParam - The message's arguments (part 1)// lParam - The message's arguments (part 2)// Returns the value returned by the control's original wndproc.publicint CallOldWindowProc(
            IntPtr hwnd, uint msg, uint wParam, int lParam)
        {
            return Win32.CallWindowProc(
                oldWndProc, hwnd, msg, wParam, lParam);
        }
    }
}
Siehe auch

SO WIRD'S GEMACHT: Verwenden einer Klasse für Windows-Prozeduren verknüpfen

Beispiel

Siehe auch

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