c# - 全局鼠标事件处理程序

Question

我有以下从某处获取的代码，用于捕获鼠标事件。我修改了它并制作了一个事件处理程序，以便我可以订阅它。鼠标事件被正确捕获。但它从不触发事件处理程序。任何人都可以找出代码有什么问题吗？

public static class MouseHook
{
    public static event EventHandler MouseAction = delegate { };

    public static void Start() => _hookID = SetHook(_proc);
    public static void stop() => UnhookWindowsHookEx(_hookID);

    private static LowLevelMouseProc _proc = HookCallback;
    private static IntPtr _hookID = IntPtr.Zero;

    private static IntPtr SetHook(LowLevelMouseProc proc)
    {
        using (Process curProcess = Process.GetCurrentProcess())
        using (ProcessModule curModule = curProcess.MainModule)
        {
            return SetWindowsHookEx(WH_MOUSE_LL, proc,
              GetModuleHandle(curModule.ModuleName), 0);
        }
    }

    private delegate IntPtr LowLevelMouseProc(int nCode, IntPtr wParam, IntPtr lParam);

    private static IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
    {
        if (nCode >= 0 && MouseMessages.WM_LBUTTONDOWN == (MouseMessages)wParam)
        {
           MSLLHOOKSTRUCT hookStruct = (MSLLHOOKSTRUCT)Marshal.PtrToStructure(lParam, typeof(MSLLHOOKSTRUCT));  
           MouseAction(null,new EventArgs());
        }
        return CallNextHookEx(_hookID, nCode, wParam, lParam);
    }

    private const int WH_MOUSE_LL = 14;

    private enum MouseMessages
    {
        WM_LBUTTONDOWN = 0x0201,
        WM_LBUTTONUP   = 0x0202,
        WM_MOUSEMOVE   = 0x0200,
        WM_MOUSEWHEEL  = 0x020A,
        WM_RBUTTONDOWN = 0x0204,
        WM_RBUTTONUP   = 0x0205
    }

    [StructLayout(LayoutKind.Sequential)]
    private struct POINT
    {
        public int x;
        public int y;
    }

    [StructLayout(LayoutKind.Sequential)]
    private struct MSLLHOOKSTRUCT
    {
        public POINT pt;
        public uint mouseData, flags, time;
        public IntPtr dwExtraInfo;
    }

    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern IntPtr SetWindowsHookEx(int idHook,
      LowLevelMouseProc lpfn, IntPtr hMod, uint dwThreadId);

    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool UnhookWindowsHookEx(IntPtr hhk);

    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern IntPtr CallNextHookEx(IntPtr hhk, int nCode,
      IntPtr wParam, IntPtr lParam);

    [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern IntPtr GetModuleHandle(string lpModuleName);
}

我是这样订阅的

MouseHook.Start();  
MouseHook.MouseAction += new EventHandler(Event);

接收事件的函数。

private void Event(object sender, EventArgs e) => Console.WriteLine("Left mouse click!"); 

更新: 我将工作代码放在一起 open source nuget package for user action hooks.

Answer 1

return SetWindowsHookEx(WH_MOUSE_LL, proc, GetModuleHandle(curModule.ModuleName), 0);

当您在早于 Windows 8 的 Windows 版本上的 .NET 4 上运行此代码时，此代码将失败。CLR 不再模拟托管程序集的非托管模块句柄。您无法在代码中检测到此故障，因为它缺少所需的错误检查。在 GetModuleHandle 和 SetWindowsHookEx 上。 pinvoke 时切勿跳过错误检查，winapi 不会抛出异常。检查它们是否返回 IntPtr.Zero 并在返回时简单地抛出 Win32Exception。

修复很简单，SetWindowsHookEx() 需要一个有效的模块句柄，但在设置低级鼠标 Hook 时实际上并不使用它。所以任何句柄都可以，您可以传递 user32.dll 的句柄，它始终加载在 .NET 应用程序中。修复:

IntPtr hook = SetWindowsHookEx(WH_MOUSE_LL, proc, GetModuleHandle("user32"), 0);
if (hook == IntPtr.Zero) 
{
    throw new System.ComponentModel.Win32Exception();
}
return hook;