天行健 君子当自强而不息

很简单,就是在WinProc函数里增加一个WM_ACTIVATE消息处理,然后调用ClipCursor来限制鼠标的可移动范围.
好像WIN32没有直接将RECT从client坐标转换成screen坐标的,所以我自己写了这么个函数.
当然这里给出的代码并不是高效的,GetSystemMetrics不应该在WinProc里调用,但这里只是给出了一种解决方案,暂不考虑代码执行效率的问题.

//-------------------------------------------------------------------------
// Translates rect from client coordinate to screen coordinate.
//-------------------------------------------------------------------------
void RectFromClientToScreen(LPRECT rect)
{
    POINT tmp;
 
    tmp.x = rect->left;
    tmp.y = rect->top;

    ClientToScreen(g_mainWindowHandle, &tmp);

    rect->left = tmp.x;
    rect->top  = tmp.y;

    tmp.x = rect->right;
    tmp.y = rect->bottom;

    ClientToScreen(g_mainWindowHandle, &tmp);

    rect->right  = tmp.x;
    rect->bottom = tmp.y;
}

//-------------------------------------------------------------------------
// Main windows event procedure.
//-------------------------------------------------------------------------
LRESULT CALLBACK WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    PAINTSTRUCT ps;     // used in WM_APINT
    HDC hdc;            // handle to a device context

    int screenWidth  = GetSystemMetrics(SM_CXSCREEN);
    int screenHeight = GetSystemMetrics(SM_CYSCREEN);
 
    RECT screenRect = {0, 0, screenWidth, screenHeight};
    RECT clientRect; 
 
    // what is the message
    switch (msg)
    {
    case WM_CREATE:
        // do initialization stuff here
        return 0;
    case WM_PAINT:
        // start painting
        hdc = BeginPaint(hwnd, &ps);
        // end painting
        EndPaint(hwnd, &ps);
        return 0;
    case WM_ACTIVATE:
       if(LOWORD(wParam) == WA_ACTIVE)
       {
          GetClientRect(g_mainWindowHandle, &clientRect);   
          RectFromClientToScreen(&clientRect);   
          ClipCursor(&clientRect);
       }
    else if(LOWORD(wParam) == WA_INACTIVE)
       ClipCursor(&screenRect);
       break;
    case WM_DESTROY:
        // kill the application
        PostQuitMessage(0);
        return 0;
    }

    // process any messages that we did not take care of
    return DefWindowProc(hwnd, msg, wParam, lParam);
}