挂钩 WH_GETMESSAGE 消息

Question

我正在尝试从我的班级挂钩WH_GETMESSAGE 以确定特定窗口调整大小的时刻。但是，似乎没有设置钩子。

我尝试挂钩的类：

class WindowDisplayHelper : // public ...
{    
public:
    // some other public methods here
    void SetMsgHook();
protected:
    LRESULT CALLBACK GetMsgProcHook(int code, WPARAM wParam, LPARAM lParam);
    static LRESULT CALLBACK MsgPoc(int code, WPARAM wParam, LPARAM lParam);
private:
    // some other private members there
    HWND m_windowHandle;
    bool m_isWindowResizing = false;
    static HHOOK m_msgHook;
    static WindowsDisplayHelperMasterWindow* m_pThis;
};

.cpp 文件：

WindowDisplayHelper* WindowDisplayHelper ::m_pThis = nullptr;
HHOOK WindowDisplayHelper ::m_msgHook = NULL;

void WindowDisplayHelper ::SetMsgHook()
{
    m_pThis = this;
    m_msgHook = SetWindowsHookEx(WH_GETMESSAGE, MsgPoc, NULL, 0);
}

LRESULT CALLBACK WindowDisplayHelper::MsgPoc(int code, WPARAM wParam, LPARAM lParam)
{
    if (m_pThis != nullptr)
    {
        return m_pThis->GetMsgProcHook(code, wParam, lParam);
    }
    return CallNextHookEx(0, code, wParam, lParam);
}

LRESULT CALLBACK WindowDisplayHelper::GetMsgProcHook(int code, WPARAM wParam, LPARAM lParam)
{
    DUMPER_INFO("Hooked");
    if (code < 0)
    {
        return CallNextHookEx(0, code, wParam, lParam);
    }
    MSG* lpmsg = (MSG*)lParam;
    DUMPER_INFO("Hooked for HWND: %p. Current window %p", lpmsg->hwnd, m_windowHandle);
    if (lpmsg->hwnd != m_windowHandle)
    {
        return CallNextHookEx(0, code, wParam, lParam);
    }
    if (lpmsg->message == WM_ENTERSIZEMOVE && !m_isWindowResizing)
    {
        DUMPER_INFO("Start window resizing");
        m_isWindowResizing = true;
    }
    else if (lpmsg->message == WM_EXITSIZEMOVE && m_isWindowResizing)
    {
        DUMPER_INFO("Stop window resizing");
        m_isWindowResizing = false;
    }

    return CallNextHookEx(0, code, wParam, lParam);
}

这是我创建 WindowDisplayHelper 对象的方法：

bool DisplayManager::CreateWindowDisplay(TDisplayId displayId, void * windowHandle)
{
    auto helper = boost::make_shared<WindowDisplayHelper>(windowHandle);
    helper->SetMsgHook();
    AddDisplayHelper(displayId, helper);

    return true;
}

虽然我在创建对象后调用了 SetMsgHook()，但似乎没有设置钩子，因为我在日志文件中看不到任何调试输出，并且 m_isWindowResizing 变量始终 == false。所以问题是为什么我的钩子不起作用？ 谢谢。

Answer 1

m_msgHook = SetWindowsHookEx(WH_GETMESSAGE, MsgPoc, NULL, 0);

这一行产生一个 ERROR_HOOK_NEEDS_HMOD (1428) system error。这意味着不能在没有模块句柄的情况下设置非本地挂钩。如果将dwThreadId 参数设置为零，则挂钩过程与在与调用线程相同的桌面上运行的所有现有线程相关联。这是一个非加载挂钩，您需要指定一个有效的hmod 参数。正如@Remy Lebeau 指出的那样，您需要将钩子代码放在DLL中。

或者正如@rudolfninja 指出的那样，使用GetCurrentThreadId() 设置一个有效的dwThreadId 参数。

我使用以下代码基于 Windows 桌面应用程序模板进行测试。有用。你可以试一试。

int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
                     _In_opt_ HINSTANCE hPrevInstance,
                     _In_ LPWSTR    lpCmdLine,
                     _In_ int       nCmdShow)
{
    // ...

    HHOOK m_msgHook = SetWindowsHookEx(WH_GETMESSAGE, MsgPoc, NULL, GetCurrentThreadId());
    DWORD errCode = GetLastError();

    MSG msg;

    // Main message loop:
    while (GetMessage(&msg, nullptr, 0, 0))
    {
        if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
    }

    return (int) msg.wParam;
}

LRESULT CALLBACK MsgPoc(int code, WPARAM wParam, LPARAM lParam)
{
    OutputDebugString(L"Hooked");
    if (code < 0)
    {
        return CallNextHookEx(0, code, wParam, lParam);
    }
    MSG* lpmsg = (MSG*)lParam;
    //OutputDebugString("Hooked for HWND: %p. Current window %p", lpmsg->hwnd, m_windowHandle);
    if (lpmsg->hwnd != m_windowHandle)
    {
        return CallNextHookEx(0, code, wParam, lParam);
    }
    if (lpmsg->message == WM_ENTERSIZEMOVE && !m_isWindowResizing)
    {
        OutputDebugString(L"Start window resizing");
        m_isWindowResizing = true;
    }
    else if (lpmsg->message == WM_EXITSIZEMOVE && m_isWindowResizing)
    {
        OutputDebugString(L"Stop window resizing");
        m_isWindowResizing = false;
    }

    return CallNextHookEx(0, code, wParam, lParam);
}