对话框程序菜单项可以禁用但不变灰问题的解决方法

来源：互联网发布：java 短信防刷编辑：程序博客网时间：2024/05/19 03:17

1、问题描述

今天在做基于对话框的MFC程序时，根据条件禁用了某一菜单项：

测试发现该菜单项确实功能无效，但是没有变灰的效果。

2、解决方法

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。

继续搜索网上资料，发现可行方法为：

首先，在消息中加入OnInitMenuPopup（）消息，

然后，在消息函数内重载如下：

void CXXXDlg::OnInitMenuPopup(CMenu* pPopupMenu, UINT nIndex, BOOL bSysMenu)
{
CDialog::OnInitMenuPopup(pPopupMenu, nIndex, bSysMenu);

// TODO: Add your message handler code here

    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;
    }
}

3、参考资料

http://summerrose1975.blog.sohu.com/159791848.html

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