鼠标挂钩断开

Question

我正在尝试实现一个颜色选择器，它从屏幕上各处的像素中获取颜色。为此，我计划使用全局鼠标挂钩来监听 WM_MOUSEMOVE，以便在鼠标四处移动时更新颜色，并监听鼠标点击以确认（WM_LBUTTONDOWN）或取消（ WM_RBUTTONDOWN) 操作。

我遵循了众多教程中的一个，并想出了这个（在控制台应用程序中，只是为了测试该过程是否有效）：

static IntPtr hook;
static bool click;
static NativeMethods.LowLevelHookStruct llhs;

static void Main(string[] args)
{
  hook = NativeMethods.SetWindowsHookEx(NativeMethods.WH_MOUSE_LL, MouseHookCallback, (IntPtr)null, 0);
  if (hook != IntPtr.Zero)
  {
    Console.WriteLine("Hook Set");
    while (!Console.KeyAvailable) {
      Console.WriteLine("{0} {1} {2}", hook, llhs.pt.x, llhs.pt.y);

      if(click) Console.WriteLine("click!");
      click = false;

      System.Threading.Thread.Sleep(250); 
    }
  }
}

和

public static IntPtr MouseHookCallback(int nCode, IntPtr wParam, IntPtr lParam)
{
  if (nCode >= 0)
  {
    NativeMethods.LowLevelHookStruct hookStruct = (NativeMethods.LowLevelHookStruct)Marshal.PtrToStructure(lParam, typeof(NativeMethods.LowLevelHookStruct));

    if (NativeMethods.MouseMessages.WM_MOUSEMOVE == (NativeMethods.MouseMessages)wParam)
    {
      llhs = hookStruct;
    }

    if (NativeMethods.MouseMessages.WM_LBUTTONDOWN == (NativeMethods.MouseMessages)wParam)
    {
      click = true;
    }
    else if (NativeMethods.MouseMessages.WM_RBUTTONDOWN == (NativeMethods.MouseMessages)wParam)
    {
    }
  }

  return NativeMethods.CallNextHookEx(hook, nCode, wParam, lParam);
}

NativeMethods 只是一个 class 我保留所有 DllImport 相关内容的地方。

一旦我运行控制台应用程序，鼠标光标就会卡住几秒钟，并且在控制台中我得到这个 - 即使光标是卡住了

Hook Set
3945554872 0 0
3945554872 0 0
3945554872 0 0
3945554872 0 0
...

在调试中，似乎我的钩子从未被调用过，一次也没有。知道哪里出了问题吗？

Answer 1

根据@Hans Passant 的评论，我将测试代码移至 WinForms 应用程序，回调开始出现。

然后发现回调正在被垃圾收集只是一个问题，所以我所要做的就是改变

hook = NativeMethods.SetWindowsHookEx(NativeMethods.WH_MOUSE_LL, MouseHookCallback, (IntPtr)null, 0);

至

private NativeMethods.LowLevelHookProc _hookCallback;

...

_hookCallback = new NativeMethods.LowLevelHookProc(MouseHookCallback);
hook = NativeMethods.SetWindowsHookEx(NativeMethods.WH_MOUSE_LL, _hookCallback, (IntPtr)null, 0);

为了保留对回调的引用，这样它就不会被 GC。

鼠标挂钩断开

Mouse hook getting disconnected

.net

c#

mouse