什麼會導致Windows發送ID_HELP命令兩次

Question

在我的應用程序中，我忽略了CFrameWnd::OnHelp以打開word文檔而不是我們的舊.hlp文件。但是，當我按F1時，我發現該功能正在執行兩次。我檢查了堆棧，發現AfxWndProcBase正在接收命令0x1E146，然後當調用CFrameWnd::OnCmdMsg時CWnd::OnCommand截斷爲0xE146，並且0xE146是ID_HELP命令。然後緊接着，AfxWndProcBase正在接收命令0xE146，並再次運行幫助命令。經過一些實驗後，我發現正在處理第一條消息時，正在接收並處理內部對AfxMessageBox的呼叫。

處理程序是在這裏：（？，什麼是第一個）

void CMainFrame::OnHelp() { 
    BOOL bWorked; 
    STARTUPINFO suInfo = {}; 
    suInfo.cb = sizeof(suInfo); 
    PROCESS_INFORMATION procInfo = {}; 
    CString m_Process = _T("Start"); 
    CString vipx = /*_T("\"") +*/ CString(AfxGetApp()->m_pszHelpFilePath) /*+ _T("\"")*/; 

    bWorked = ::CreateProcess(m_Process, 
      vipx.GetBuffer(),  // requires non-const :(
      NULL, 
      NULL, 
      FALSE, 
      NORMAL_PRIORITY_CLASS, 
      NULL, 
      NULL, 
      &suInfo, 
      &procInfo); 
    vipx.ReleaseBuffer(); 

    if (procInfo.dwThreadId==NULL || bWorked==false) 
     AfxMessageBox(_T("Failed to launch help: " + GetErrNoText(GetLastError()))); 
    //AfxMessageBox causes my app to receive the message again? 

    CloseHandle(procInfo.hProcess); 
    CloseHandle(procInfo.hThread); 
} 

爲什麼都0x1E146和0xE146被髮送到我的應用程序，當我按下F1

重寫後，我發現，調用ShellExecute也會導致「1深度遞歸」。

我不知道，如果它是培訓相關，但這裏是我的表格的消息映射：

BEGIN_MESSAGE_MAP(CMainFrame, CFrameWnd) 
//{{AFX_MSG_MAP(CMainFrame) 
    ON_WM_CREATE() 
//}}AFX_MSG_MAP 
    // Global help commands 
    ON_COMMAND(ID_HELP, OnHelp) //F1 <--- both messages are this one? 
END_MESSAGE_MAP() 

在我的資源文件中，我發現這些，一個是F1，一個用於Shift + F1鍵：

VK_F1,   ID_CONTEXT_HELP,  VIRTKEY, SHIFT, NOINVERT 
VK_F1,   ID_HELP,    VIRTKEY, NOINVERT 

可能沒用，但這裏的兩個調用堆棧：

MyApp.exe!CMainFrame::OnHelp() Line 66 C++ 
mfc90ud.dll!_AfxDispatchCmdMsg(CCmdTarget * pTarget=0x01fea410, unsigned int nID=57670, int nCode=0, void (void)* pfn=0x0040b720, void * pExtra=0x00000000, unsigned int nSig=57, AFX_CMDHANDLERINFO * pHandlerInfo=0x00000000) Line 82 C++ 
mfc90ud.dll!CCmdTarget::OnCmdMsg(unsigned int nID=57670, int nCode=0, void * pExtra=0x00000000, AFX_CMDHANDLERINFO * pHandlerInfo=0x00000000) Line 381 + 0x27 bytes C++ 
mfc90ud.dll!CFrameWnd::OnCmdMsg(unsigned int nID=57670, int nCode=0, void * pExtra=0x00000000, AFX_CMDHANDLERINFO * pHandlerInfo=0x00000000) Line 946 + 0x18 bytes C++ 
mfc90ud.dll!CWnd::OnCommand(unsigned int wParam=123206, long lParam=0) Line 2364 C++ 
mfc90ud.dll!CFrameWnd::OnCommand(unsigned int wParam=123206, long lParam=0) Line 366 C++ 
mfc90ud.dll!CWnd::OnWndMsg(unsigned int message=273, unsigned int wParam=123206, long lParam=0, long * pResult=0x0018fba4) Line 1769 + 0x1e bytes C++ 
mfc90ud.dll!CWnd::WindowProc(unsigned int message=273, unsigned int wParam=123206, long lParam=0) Line 1755 + 0x20 bytes C++ 
mfc90ud.dll!AfxCallWndProc(CWnd * pWnd=0x01fea410, HWND__ * hWnd=0x001703da, unsigned int nMsg=273, unsigned int wParam=123206, long lParam=0) Line 240 + 0x1c bytes C++ 
mfc90ud.dll!AfxWndProc(HWND__ * hWnd=0x001703da, unsigned int nMsg=273, unsigned int wParam=123206, long lParam=0) Line 403 C++ 
mfc90ud.dll!AfxWndProcBase(HWND__ * hWnd=0x001703da, unsigned int nMsg=273, unsigned int wParam=123206, long lParam=0) Line 441 + 0x15 bytes C++ 
    ... 
mfc90ud.dll!CFrameWnd::PreTranslateMessage(tagMSG * pMsg=0x00712740) Line 249 + 0x1b bytes C++ 
mfc90ud.dll!CWnd::WalkPreTranslateTree(HWND__ * hWndStop=0x00160bb4, tagMSG * pMsg=0x00712740) Line 2946 + 0x14 bytes C++ 
mfc90ud.dll!AfxInternalPreTranslateMessage(tagMSG * pMsg=0x00712740) Line 233 + 0x12 bytes C++ 
mfc90ud.dll!CWinThread::PreTranslateMessage(tagMSG * pMsg=0x00712740) Line 777 + 0x9 bytes C++ 
MyApp.exe!CCXMyAppApp::PreTranslateMessage(tagMSG * pMsg=0x00712740) Line 749 C++ 
mfc90ud.dll!AfxPreTranslateMessage(tagMSG * pMsg=0x00712740) Line 252 + 0x11 bytes C++ 
mfc90ud.dll!AfxInternalPumpMessage() Line 178 + 0x18 bytes C++ 

二消息：

MyApp.exe!CMainFrame::OnHelp() Line 66 C++ 
mfc90ud.dll!_AfxDispatchCmdMsg(CCmdTarget * pTarget=0x01fea410, unsigned int nID=57670, int nCode=0, void (void)* pfn=0x0040b720, void * pExtra=0x00000000, unsigned int nSig=57, AFX_CMDHANDLERINFO * pHandlerInfo=0x00000000) Line 82 C++ 
mfc90ud.dll!CCmdTarget::OnCmdMsg(unsigned int nID=57670, int nCode=0, void * pExtra=0x00000000, AFX_CMDHANDLERINFO * pHandlerInfo=0x00000000) Line 381 + 0x27 bytes C++ 
mfc90ud.dll!CFrameWnd::OnCmdMsg(unsigned int nID=57670, int nCode=0, void * pExtra=0x00000000, AFX_CMDHANDLERINFO * pHandlerInfo=0x00000000) Line 946 + 0x18 bytes C++ 
mfc90ud.dll!CWnd::OnCommand(unsigned int wParam=57670, long lParam=0) Line 2364 C++ 
mfc90ud.dll!CFrameWnd::OnCommand(unsigned int wParam=57670, long lParam=0) Line 366 C++ 
mfc90ud.dll!CWnd::OnWndMsg(unsigned int message=273, unsigned int wParam=57670, long lParam=0, long * pResult=0x0018e264) Line 1769 + 0x1e bytes C++ 
mfc90ud.dll!CWnd::WindowProc(unsigned int message=273, unsigned int wParam=57670, long lParam=0) Line 1755 + 0x20 bytes C++ 
mfc90ud.dll!AfxCallWndProc(CWnd * pWnd=0x01fea410, HWND__ * hWnd=0x001703da, unsigned int nMsg=273, unsigned int wParam=57670, long lParam=0) Line 240 + 0x1c bytes C++ 
mfc90ud.dll!AfxWndProc(HWND__ * hWnd=0x001703da, unsigned int nMsg=273, unsigned int wParam=57670, long lParam=0) Line 403 C++ 
mfc90ud.dll!AfxWndProcBase(HWND__ * hWnd=0x001703da, unsigned int nMsg=273, unsigned int wParam=57670, long lParam=0) Line 441 + 0x15 bytes C++ 
... 
mfc90ud.dll!CWnd::SendMessageW(unsigned int message=273, unsigned int wParam=57670, long lParam=0) Line 42 + 0x44 bytes C++ 
mfc90ud.dll!CWnd::OnHelpInfo(tagHELPINFO * __formal=0x0008c890) Line 3195 C++ 
mfc90ud.dll!CWnd::OnWndMsg(unsigned int message=83, unsigned int wParam=0, long lParam=575632, long * pResult=0x0018e5ec) Line 1948 + 0xd bytes C++ 
mfc90ud.dll!CWnd::WindowProc(unsigned int message=83, unsigned int wParam=0, long lParam=575632) Line 1755 + 0x20 bytes C++ 
mfc90ud.dll!AfxCallWndProc(CWnd * pWnd=0x0253a410, HWND__ * hWnd=0x00160bb4, unsigned int nMsg=83, unsigned int wParam=0, long lParam=575632) Line 240 + 0x1c bytes C++ 
mfc90ud.dll!AfxWndProc(HWND__ * hWnd=0x00160bb4, unsigned int nMsg=83, unsigned int wParam=0, long lParam=575632) Line 403 C++ 
mfc90ud.dll!AfxWndProcBase(HWND__ * hWnd=0x00160bb4, unsigned int nMsg=83, unsigned int wParam=0, long lParam=575632) Line 441 + 0x15 bytes C++ 
    ... 
mfc90ud.dll!CWnd::DefWindowProcW(unsigned int nMsg=83, unsigned int wParam=0, long lParam=575632) Line 1043 + 0x20 bytes C++ 
mfc90ud.dll!CWnd::Default() Line 274 C++ 
mfc90ud.dll!CWnd::OnHelpInfo(tagHELPINFO * __formal=0x0008c890) Line 3198 + 0x8 bytes C++ 
mfc90ud.dll!CWnd::OnWndMsg(unsigned int message=83, unsigned int wParam=0, long lParam=575632, long * pResult=0x0018eb70) Line 1948 + 0xd bytes C++ 
mfc90ud.dll!CWnd::WindowProc(unsigned int message=83, unsigned int wParam=0, long lParam=575632) Line 1755 + 0x20 bytes C++ 
mfc90ud.dll!AfxCallWndProc(CWnd * pWnd=0x0253aa28, HWND__ * hWnd=0x000b08c6, unsigned int nMsg=83, unsigned int wParam=0, long lParam=575632) Line 240 + 0x1c bytes C++ 
mfc90ud.dll!AfxWndProc(HWND__ * hWnd=0x000b08c6, unsigned int nMsg=83, unsigned int wParam=0, long lParam=575632) Line 403 C++ 
mfc90ud.dll!AfxWndProcBase(HWND__ * hWnd=0x000b08c6, unsigned int nMsg=83, unsigned int wParam=0, long lParam=575632) Line 441 + 0x15 bytes C++ 
    ... 
mfc90ud.dll!CWnd::DefWindowProcW(unsigned int nMsg=77, unsigned int wParam=0, long lParam=0) Line 1043 + 0x20 bytes C++ 
mfc90ud.dll!CWnd::WindowProc(unsigned int message=77, unsigned int wParam=0, long lParam=0) Line 1756 + 0x1c bytes C++ 
mfc90ud.dll!AfxCallWndProc(CWnd * pWnd=0x0253aa28, HWND__ * hWnd=0x000b08c6, unsigned int nMsg=77, unsigned int wParam=0, long lParam=0) Line 240 + 0x1c bytes C++ 
mfc90ud.dll!AfxWndProc(HWND__ * hWnd=0x000b08c6, unsigned int nMsg=77, unsigned int wParam=0, long lParam=0) Line 403 C++ 
mfc90ud.dll!AfxWndProcBase(HWND__ * hWnd=0x000b08c6, unsigned int nMsg=77, unsigned int wParam=0, long lParam=0) Line 441 + 0x15 bytes C++ 
    ... 
mfc90ud.dll!CWnd::WindowProc(unsigned int message=7423648, unsigned int wParam=7423712, long lParam=2016221872) Line 1755 + 0x20 bytes C++ 
    ... 
mfc90ud.dll!AfxDeactivateActCtx(unsigned long dwFlags=0, unsigned long ulCookie=353633777) Line 260 + 0x17 bytes C++ 
mfc90ud.dll!AFX_MAINTAIN_STATE2::~AFX_MAINTAIN_STATE2() Line 63 + 0xe bytes C++ 

Answer 1

它看起來像ID_HELP是一個預先定義的MFC #define，如果你想繼續使用這個ID，你需要有處理程序在你的CWinApp派生類（見this MSDN article），而不是框架類。

或者，您可以用您自己的ID（例如IDM_HELP）代替ID_HELP，這與預先定義的MFC ID不衝突，這樣您就不會爲同一個ID獲得兩個單獨的處理程序。

Answer 2

Apperently this person found the same issue並談論原因和結果。

此雙重事件處理是由於一些遺留代碼。

自Windows 95（Viorel_提到的支持文章）以來，Windows自動將F1密鑰轉換爲WM_HELP消息。您注意到的與0x4d消息的處理完全相同;這是一些Windows代碼。然後，當應用程序收到WM_HELP消息時，它可以通過調用WinHelp來處理它。

在Windows 95之前，WM_HELP消息不存在。處理F1的唯一方法是創建一個VK_F1快捷方式，併爲其添加一個處理程序。 Windows 95通過添加WM_HELP消息，使幫助管理更加容易。由於Win95，您不必爲ID_HELP創建VK_F1快捷方式。

但是，如果選擇「上下文相關幫助」選項，MFC應用程序嚮導仍會添加此快捷方式。MFC比Windows 95舊！如果使用上下文相關幫助創建MFC Appwizard應用程序，則會爲與CFrameWnd :: OnHelp（）相關聯的VK_F1創建快捷方式，該快捷方式將WM_HELP消息路由到應用程序的窗口窗口。 「到現在爲止還挺好」。

但Windows也自動將F1按鍵轉換爲WM_HELP消息。所以再次調用CFrameWnd :: OnHelp（），因爲MFC處理WM_HELP事件。

如果您不想被調用兩次，請刪除資源文件中的鍵盤快捷方式，然後處理WM_HELP。然後，你將有以下過程：

• 的Windows捕獲F1鍵，生成WM_HELP

• 對於WM_HELP（ON_WM_HELPINFO）消息處理程序在你的代碼捕獲WM_HELP消息。 WM_HELP的MFC默認消息處理是發送WM_COMMAND（ID_HELP）消息（這是另一個有趣的部分！）

• 代碼中WM_COMMAND（ID_HELP）的消息處理程序調用默認的MFC處理。這運行winhelp。

以下的CMainFrame代碼不處理兩次幫助信息：

ON_WM_HELPINFO() 
ON_COMMAND(ID_HELP, &CMDIFrameWndEx::OnHelp) 

.. 


BOOL CMainFrame::OnHelpInfo(HELPINFO* pHelpInfo) 
{ 
    return CMDIFrameWndEx::OnHelpInfo(pHelpInfo); 
} 

而且不要忘記刪除快捷方式VK_F1資源文件！

不要給予好評這個帖子，follow the link and upvote the origional post