c++ - 钩子(Hook)和线，鼠标阻塞

Question

#include <windows.h>
#include <process.h>

HWND MainHwnd;
HHOOK MouseHook;
LRESULT CALLBACK WndProc(HWND hwnd,UINT iMsg,WPARAM wParam,LPARAM lParam);
int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,PSTR szCmdLine,int iCmdShow)
{
    static wchar_t szAppName[]=L"hooks";
    HWND hwnd;
    MSG msg;
    WNDCLASSEX wndclass;

    wndclass.cbSize=sizeof(wndclass);
    wndclass.style=CS_HREDRAW|CS_VREDRAW;
    wndclass.lpfnWndProc=WndProc;
    wndclass.cbClsExtra=0;
    wndclass.cbWndExtra=0;
    wndclass.hInstance=hInstance;
    wndclass.hIcon=LoadIcon(NULL,IDI_APPLICATION);
    wndclass.hCursor=LoadCursor(NULL,IDC_ARROW);
    wndclass.hbrBackground=(HBRUSH)GetStockObject(WHITE_BRUSH);
    wndclass.lpszMenuName=NULL;
    wndclass.lpszClassName=szAppName;
    wndclass.hIconSm=LoadIcon(NULL,IDI_APPLICATION);

    RegisterClassEx(&wndclass);

    MainHwnd=hwnd=CreateWindow(szAppName,L"hooks",WS_OVERLAPPEDWINDOW,CW_USEDEFAULT,
        CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,NULL,NULL,hInstance,NULL);
    ShowWindow(hwnd,SW_MAXIMIZE);
    UpdateWindow(hwnd);

    while(GetMessage(&msg,NULL,0,0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return msg.wParam;
}
LRESULT CALLBACK LowLevelMouseProc(int nCode,WPARAM wParam,LPARAM lParam) 
{
    if (nCode==HC_ACTION) 
        ((LPMSLLHOOKSTRUCT)lParam)->flags=0;
  return CallNextHookEx(NULL,nCode,wParam,lParam);
}
 void thread(void *param)
 {
    for (int i=0;i<3;i++)
    {
        UnhookWindowsHookEx(MouseHook);
        MouseHook=SetWindowsHookEx(WH_MOUSE_LL,reinterpret_cast<HOOKPROC>(LowLevelMouseProc),(HINSTANCE)GetWindowLong(MainHwnd,GWL_HINSTANCE),NULL);
        for (int j=0;j<100;j++)
        {
                mouse_event(MOUSEEVENTF_ABSOLUTE|MOUSEEVENTF_MOVE, (j)*(65535.0/500),(j)*(65535.0/500),0,0);
                Sleep(10);
        }
        Sleep(2000);
    }
 }
LRESULT CALLBACK WndProc(HWND hwnd,UINT iMsg,WPARAM wParam,LPARAM lParam)
{
    HDC hdc;
    PAINTSTRUCT ps;
    switch(iMsg)
    {
    case WM_CREATE:
        {
            MouseHook=SetWindowsHookEx(WH_MOUSE_LL,reinterpret_cast<HOOKPROC>(LowLevelMouseProc),(HINSTANCE)GetWindowLong(hwnd,GWL_HINSTANCE),NULL);
            _beginthread(thread,0,0);
            return 0;
        }
    case WM_PAINT:
        {
            hdc=BeginPaint(hwnd,&ps);
            EndPaint(hwnd,&ps);
            return 0;
        }
    case WM_DESTROY:
        UnhookWindowsHookEx(MouseHook);
        PostQuitMessage(0);
        return 0;
    }
    return DefWindowProc(hwnd,iMsg,wParam,lParam);
}

我使用 _beginthread 创建线程。该线程模拟鼠标移动并调用Sleep(2000)。在线程中模拟移动后我无法移动鼠标。但是如果我在 void thread(void *param)

中评论这一行

UnhookWindowsHookEx(MouseHook);
MouseHook=SetWindowsHookEx(WH_MOUSE_LL,reinterpret_cast<HOOKPROC>(LowLevelMouseProc),(HINSTANCE)GetWindowLong(MainHwnd,GWL_HINSTANCE),NULL);`

程序将正常运行，没有鼠标“阻塞”。大家能说说原因吗。

Answer 1

调用 SetWindowsHookEx() 以设置低级鼠标 Hook 的线程必须抽取消息循环。必需，以便 Windows 可以调用您注册的回调，以便它可以通知您鼠标消息。这是你的问题，你启动的线程设置了一个钩子(Hook)但没有发送消息循环。

Windows 可以防止此类行为不当的程序，当它必须等待太长时间才能进行回调时，它会自动销毁 Hook 。但是您的线程休眠了 2 秒，不足以触发超时。然后您调用 UnhookWindowsHookEx() 来取消阻止 Windows。但立即再次 Hook 。

在该线程中调用 SetWindowsHookEx() 毫无意义。只需删除它，您在主线程中设置的钩子(Hook)就会正常运行。顺便说一下，很难看出该线程的意义。