MFC 如何启用/禁用菜单（返灰/不可点击状态）

1、为页面（窗口）添加一个菜单栏和子菜单

2、在XXDlg.h文件中定义一个菜单栏变量和bool变量

CMenu m_Menu;	//菜单变量
bool m_EnableMenu;//菜单栏中某个子菜单禁用/启用（变灰）的控制变量

3、在OnInitDialog函数中进行初始化：（即将菜单栏植入主界面）

m_Menu.LoadMenu(IDR_MENU_MAIN);//菜单栏的ID
SetMenu(&m_Menu);//添加入到界面
m_EnableMenu =false;//初始化为禁用子菜单

4、添加菜单ID的ON_UPDATE_COMMAND_UI消息，点击菜单，在子菜单上右键点击，添加事件处理程序，选择你的对话框类，在左边的消息类型中选择UPDATE_COMMAND_UI添加如下代码：
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void CXXDlg::OnUpdateDisconnectAll(CCmdUI *pCmdUI)
{pCmdUI->Enable(m_EnableMenu); //m_EnableMenu的值对应禁用和启用，1是启用，0是禁用
}

根据网上资料，对于视图文档类MFC程序，在主框架类CMainFrame的构造函数中把成员变量m_bAutoMenuEnable=FALSE就可以解决问题了。但是基于对话框的MFC应用程序没有m_bAutoMenuEnable变量。解决方法：

5、在对话框类的消息中加入OnInitMenuPopup（）消息：
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消息函数内重载如下：

void CXXXDlg::OnInitMenuPopup(CMenu* pPopupMenu, UINT nIndex, BOOL bSysMenu)
{CDialog::OnInitMenuPopup(pPopupMenu, nIndex, bSysMenu);// TODO: 在此处添加消息处理程序代码ASSERT(pPopupMenu != NULL);// Check the enabled state of various menu items.CCmdUI state;state.m_pMenu = pPopupMenu;ASSERT(state.m_pOther == NULL);ASSERT(state.m_pParentMenu == NULL);// Determine if menu is popup in top-level menu and set m_pOther to// it if so (m_pParentMenu == NULL indicates that it is secondary popup).HMENU hParentMenu;if (AfxGetThreadState()->m_hTrackingMenu == pPopupMenu->m_hMenu)state.m_pParentMenu = pPopupMenu;    // Parent == child for tracking popup.else if ((hParentMenu = ::GetMenu(m_hWnd)) != NULL){CWnd* pParent = this;// Child windows don't have menus--need to go to the top!if (pParent != NULL &&(hParentMenu = ::GetMenu(pParent->m_hWnd)) != NULL){int nIndexMax = ::GetMenuItemCount(hParentMenu);for (int nIndex = 0; nIndex < nIndexMax; nIndex++){if (::GetSubMenu(hParentMenu, nIndex) == pPopupMenu->m_hMenu){// When popup is found, m_pParentMenu is containing menu.state.m_pParentMenu = CMenu::FromHandle(hParentMenu);break;}}}}state.m_nIndexMax = pPopupMenu->GetMenuItemCount();for (state.m_nIndex = 0; state.m_nIndex < state.m_nIndexMax;state.m_nIndex++){state.m_nID = pPopupMenu->GetMenuItemID(state.m_nIndex);if (state.m_nID == 0)continue; // Menu separator or invalid cmd - ignore it.ASSERT(state.m_pOther == NULL);ASSERT(state.m_pMenu != NULL);if (state.m_nID == (UINT)-1){// Possibly a popup menu, route to first item of that popup.state.m_pSubMenu = pPopupMenu->GetSubMenu(state.m_nIndex);if (state.m_pSubMenu == NULL ||(state.m_nID = state.m_pSubMenu->GetMenuItemID(0)) == 0 ||state.m_nID == (UINT)-1){continue;       // First item of popup can't be routed to.}state.DoUpdate(this, TRUE);   // Popups are never auto disabled.}else{// Normal menu item.// Auto enable/disable if frame window has m_bAutoMenuEnable// set and command is _not_ a system command.state.m_pSubMenu = NULL;state.DoUpdate(this, FALSE);}// Adjust for menu deletions and additions.UINT nCount = pPopupMenu->GetMenuItemCount();if (nCount < state.m_nIndexMax){state.m_nIndex -= (state.m_nIndexMax - nCount);while (state.m_nIndex < nCount &&pPopupMenu->GetMenuItemID(state.m_nIndex) == state.m_nID){state.m_nIndex++;}}state.m_nIndexMax = nCount;}
}