钩子和线程，鼠标阻塞

Posted 2023-02-22

【中文标题】钩子和线程，鼠标阻塞

【英文标题】：hooks and threads, mouse blocking

【发布时间】：2012-01-24 09:36:51

【问题描述】：

#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);

我用_beginthread 创建线程。该线程模拟鼠标的移动并调用Sleep(2000)。模拟线程中的移动后我无法移动鼠标。但如果我在void thread(void *param) 中评论这行代码

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”。大家能解释一下原因吗。

【参考方案1】：

调用 SetWindowsHookEx() 来设置低级鼠标钩子的线程必须泵送消息循环。必需，以便 Windows 可以调用您注册的回调，以便通知您鼠标消息。哪个是你的问题，你启动的线程设置了一个钩子，但没有发送消息循环。

Windows 可以防止此类行为不端的程序，当它必须等待太长时间才能进行回调时，它会自动销毁挂钩。但是您的线程休眠了 2 秒，不足以触发超时。然后调用 UnhookWindowsHookEx() 来解除对 Windows 的阻塞。但马上又挂了。

在该线程中调用 SetWindowsHookEx() 毫无意义。只需将其删除，您在主线程中设置的钩子就会正常运行。顺便说一句，很难看出该线程的意义。