是什么原因导致Windows发送ID_HELP命令两次
What can cause Windows to send the ID_HELP command twice
在我的应用程序中，我重写了CFrameWnd::OnHelp以打开word文档，而不是旧的.hlp文件。然而，当我按下F1时，我注意到该功能被执行了两次。我检查了堆栈，发现AfxWndProcBase正在接收命令0x1E146，然后CWnd::OnCommand在调用CFrameWnd::OnCmdMsg时将其截断为0xE146，0xE146是ID_HELP命令。然后紧接着，AfxWndProcBase正在接收命令0xE146，并再次运行帮助命令。经过一些实验，我发现当第一条消息被处理时，第二条消息正在对AfxMessageBox的调用中被接收和处理。
处理程序在这里：
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);
}
为什么当我按F1时0x1E146和0xE146都被发送到我的应用程序（第一个是什么？）
重写后，我发现调用ShellExecute也会导致"1深度递归"。
我不知道它是否是相关的，但这是我表格的消息图：
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()
在我的资源文件中，我发现了这些，一个用于F1，另一个用于Shift+F1:
VK_F1, ID_CONTEXT_HELP, VIRTKEY, SHIFT, NOINVERT
VK_F1, ID_HELP, VIRTKEY, NOINVERT
可能没用，但这里有两个调用堆栈：
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++
第二条消息：
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++
看起来ID_HELP是一个预定义的MFC #define，如果您想继续使用此ID，您需要在CWinApp派生类（请参阅MSDN的这篇文章）中设置处理程序，而不是Frame类。
或者，您可以用自己的ID（比如IDM_HELP）替换ID_HELP，这与预定义的MFC ID不冲突，这样就不会为同一ID获得两个单独的处理程序。
这个人发现了同样的问题，并谈到了因果关系。
这种双重事件处理是由于一些遗留代码造成的。
自Windows95（Viorel_提到的支持文章）以来，Windows自动将F1键转换为WM_HELP消息。您注意到的0x4d消息的处理正是这样做的；这是一些Windows代码。然后，当应用程序接收到WM_HELP消息时，它（可以）通过调用WinHelp来处理它。
在Windows 95之前，WM_HELP消息不存在。处理F1的唯一方法是创建一个VK_F1快捷方式，并为其添加一个处理程序。Windows 95通过添加WM_HELP消息，使帮助管理变得更容易。自Win95以来，您不再需要为ID_HELP创建VK_F1快捷方式。
如果您选择"上下文相关帮助"选项，MFC应用程序向导仍然会添加此快捷方式。MFC比Windows 95旧！如果使用上下文相关帮助创建MFC应用程序向导应用程序，则会为VK_F1创建一个与CFrameWnd:：OnHelp（）关联的快捷方式，该快捷方式将WM_help消息路由到应用程序的框架窗口。"到目前为止还不错"。
但Windows也会自动将F1击键转换为WM_HELP消息。因此再次调用CFrameWnd:：OnHelp（），因为WM_HELP事件由MFC处理。
如果不想被调用两次，请删除资源文件中的键盘快捷键，改为处理WM_HELP。然后你将有以下过程：
Windows捕获F1键，生成WM_HELP
代码中WM_HELP的消息处理程序（ON_WM_HELPINFO）捕获WM_HELP消息。MFC对WM_HELP的默认消息处理是发送WM_COMMAND（ID_HELP）消息（这是另一个有趣的部分！）
代码中WM_COMMAND（ID_HELP）的消息处理程序调用默认的MFC处理。这将运行winhelp。
以下CMainFrame代码无法处理两次帮助消息：
ON_WM_HELPINFO() ON_COMMAND(ID_HELP, &CMDIFrameWndEx::OnHelp) .. BOOL CMainFrame::OnHelpInfo(HELPINFO* pHelpInfo) { return CMDIFrameWndEx::OnHelpInfo(pHelpInfo); }不要忘记删除资源文件中VK_F1的快捷方式！
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