windows钩子的奇怪行为(Strange behaviour of windows hooks)

我一直在寻找一种可能性，在.NET Windows应用程序时，在操作系统（Windows XP 32位）被激活的任何窗口通知。在CodeProject我发现通过使用全球系统钩子的解决方案。

http://www.codeproject.com/Articles/18638/Using-Window-Messages-to-Implement-Global-System-H 。

下面是这个过程的一个简短的摘要：

在非托管组件（用C ++编写）的方法被实现，其安装WH_CBT钩。

bool InitializeCbtHook(int threadID, HWND destination) 
{ 
    if (g_appInstance == NULL) 
    { 
       return false; 
    }  

    if (GetProp(GetDesktopWindow(), " HOOK_HWND_CBT") != NULL) 
    { 
        SendNotifyMessage((HWND)GetProp(GetDesktopWindow(), "HOOK_HWND_CBT"), 
            RegisterWindowMessage("HOOK_CBT_REPLACED"),  0, 0); 
    } 

    SetProp(GetDesktopWindow(), " HOOK_HWND_CBT", destination); 


    hookCbt = SetWindowsHookEx(WH_CBT, (HOOKPROC)CbtHookCallback,     g_appInstance, threadID); 

    return hookCbt != NULL; 

}

在取决于钩型回调方法（过滤功能）的窗口消息被发送到的目的地的窗口。

static LRESULT CALLBACK CbtHookCallback(int code, WPARAM wparam, LPARAM lparam) 
{ 
    if (code >= 0) 
    { 
        UINT msg = 0; 

        if (code == HCBT_ACTIVATE) 
            msg = RegisterWindowMessage("HOOK_HCBT_ACTIVATE"); 
        else if (code == HCBT_CREATEWND) 
            msg = RegisterWindowMessage("HOOK_HCBT_CREATEWND"); 
        else if (code == HCBT_DESTROYWND) 
            msg = RegisterWindowMessage("HOOK_HCBT_DESTROYWND"); 
        else if (code == HCBT_MINMAX) 
            msg = RegisterWindowMessage("HOOK_HCBT_MINMAX"); 
        else if (code == HCBT_MOVESIZE) 
            msg = RegisterWindowMessage("HOOK_HCBT_MOVESIZE"); 
        else if (code == HCBT_SETFOCUS) 
            msg = RegisterWindowMessage("HOOK_HCBT_SETFOCUS"); 
        else if (code == HCBT_SYSCOMMAND) 
            msg = RegisterWindowMessage("HOOK_HCBT_SYSCOMMAND"); 

        HWND dstWnd = (HWND)GetProp(GetDesktopWindow(), HOOK_HWND_CBT"); 

        if (msg != 0) 
            SendNotifyMessage(dstWnd, msg, wparam, lparam); 
    } 

    return CallNextHookEx(hookCbt, code, wparam, lparam); 
}

要在.NET Windows应用程序使用该程序集下面的方法需要进口：

[DllImport("GlobalCbtHook.dll", CallingConvention = CallingConvention.Cdecl)] 
public static extern bool InitializeCbtHook (int threadID, IntPtr DestWindow);

[DllImport("GlobalCbtHook.dll", CallingConvention = CallingConvention.Cdecl)]
public static extern void UninitializeCbtHook(int hookType);

调用后InitializeCbtHook从接收的消息GlobalCbtHook.dll可以进行处理：

protected override void WndProc(ref Message msg)

该消息具有在组装，并通过调用应用程序既要注册RegisterWindowMessage 。

[DllImport("user32.dll")]
private static extern int RegisterWindowMessage(string lpString);

此实现正常工作。但在大多数情况下，当我激活Microsoft Office Outlook中我的.NET应用程序接收激活事件后，我尽量减少Outlook或激活其他窗口。起初我还以为我的.NET包装是问题的原因。但我用从上面的链接的来源后，我可以确认的相同的行为。我其实解决方法是使用WH_SHELL钩。我知道之间的一个差WH_CBT和WH_SHELL当使用钩是WH_CBT钩有可能通过不调用中断滤波器函数链CallNextHookEx方法。难道这发挥我的问题的作用？请提供帮助。

显然挂钩不起作用在Outlook的情况下- 那其他 Microsoft产品（文字，电源点......）？

但是，为什么挂钩？如果Outlook启动这个小班会甚至工作

using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;

namespace WindowsMonitor
{
    public class ActiveWindowChangedEventArgs : EventArgs
    {
        public IntPtr CurrentActiveWindow { get; private set; }
        public IntPtr LastActiveWindow { get; private set; }

        public ActiveWindowChangedEventArgs(IntPtr lastActiveWindow, IntPtr currentActiveWindow)
        {
            this.LastActiveWindow = lastActiveWindow;
            this.CurrentActiveWindow = currentActiveWindow;
        }
    }

    public delegate void ActiveWindowChangedEventHandler(object sender, ActiveWindowChangedEventArgs e);

    public class ActiveWindowMonitor
    {
        [DllImport("user32.dll")]
        private static extern IntPtr GetForegroundWindow();

        private Timer monitorTimer;

        public IntPtr ActiveWindow { get; private set; }
        public event ActiveWindowChangedEventHandler ActiveWindowChanged;

        public ActiveWindowMonitor()
        {
            this.monitorTimer = new Timer();
            this.monitorTimer.Tick += new EventHandler(monitorTimer_Tick);
            this.monitorTimer.Interval = 10;
            this.monitorTimer.Start();
        }

        private void monitorTimer_Tick(object sender, EventArgs e)
        {
            CheckActiveWindow();
        }

        private void CheckActiveWindow()
        {
            IntPtr currentActiveWindow = GetForegroundWindow();
            if (this.ActiveWindow != currentActiveWindow)
            {
                IntPtr lastActiveWindow = this.ActiveWindow;
                this.ActiveWindow = currentActiveWindow;

                OnActiveWindowChanged(lastActiveWindow, this.ActiveWindow);
            }
        }

        protected virtual void OnActiveWindowChanged(IntPtr lastActiveWindow, IntPtr currentActiveWindow)
        {
            ActiveWindowChangedEventHandler temp = ActiveWindowChanged;
            if (temp != null)
            {
                temp.Invoke(this, new ActiveWindowChangedEventArgs(lastActiveWindow, currentActiveWindow));
            }
        }
    }
}

用法

    public void InitActiveWindowMonitor()
    {
        WindowsMonitor.ActiveWindowMonitor monitor = new WindowsMonitor.ActiveWindowMonitor();
        monitor.ActiveWindowChanged += new WindowsMonitor.ActiveWindowChangedEventHandler(monitor_ActiveWindowChanged);
    }

    private void monitor_ActiveWindowChanged(object sender, WindowsMonitor.ActiveWindowChangedEventArgs e)
    {
        //ouh a window got activated
    }