c++ - 当嵌入式 ActiveX 控件接收和失去键盘焦点时如何得到通知？

Question

我有一个基于 C++/MFC 对话框的小型应用程序，带有嵌入式 Internet Explorer ActiveX 控件。我想知道嵌入式控件何时接收和失去键盘焦点。我想这样做:

BOOL CWinAppDerivedClass::PreTranslateMessage(MSG* pMsg)
{
    if(pMsg->message == WM_SETFOCUS)
    {
        //if(checkIEWindow(pMsg->hwnd))
        {
            //Process it
        }
    }

    return CWinApp::PreTranslateMessage(pMsg);
}

但是不管我怎么做，WM_SETFOCUS好像根本就没有发出来。

知道怎么做吗？

Answer 1

一种方法是在进程范围内使用 window procedure hook .

首先，您需要在 GUI 应用程序主线程的某个位置安装 Hook 。如果是 MFC 对话窗口，最好的位置是 OnInitDialog 通知处理程序:

//hHook is "this" class member variable, declared as HHOOK. Set it to NULL initially.
hHook = ::SetWindowsHookEx(WH_CALLWNDPROC, CallWndProcHook, AfxGetInstanceHandle(), ::GetCurrentThreadId());

然后钩子(Hook)过程可以这样设置:

static LRESULT CALLBACK CallWndProcHook(int nCode, WPARAM wParam, LPARAM lParam)
{
    if (nCode == HC_ACTION) 
    {
        CWPSTRUCT* pCWS = (CWPSTRUCT*)lParam;

        //Check if this is the message we need
        if(pCWS->message == WM_SETFOCUS ||
            pCWS->message == WM_KILLFOCUS)
        {
            //Check if this is the window we need
            if(pCWS->hwnd == hRequiredWnd)
            {
                //Process your message here
            }
        }
    }

    return ::CallNextHookEx(NULL, nCode, wParam, lParam);
}

还记得解钩。它的一个好地方是 PostNcDestroy 处理程序:

if(hHook != NULL)
{
    ::UnhookWindowsHookEx(hHook);
    hHook = NULL;
}