MFC对话框菜单控制问题

[atm008]

菜单属于对话框，如何Disable菜单
简单用EnableMenuItem不行
应该怎么处理？

[Kudeet]

http://blog.csdn.net/laiyiling/archive/2004/08/27/87027.aspx

[ywood]

建立一个控件变量,用该控件变量的Enabled来控制

[atm008]

http://blog.csdn.net/laiyiling/archive/2004/08/27/87027.aspx
看不到内容

[superroboy]

//设定可用性（当你打开下拉菜单时便会激发UPDATE _COMMAND_UI消息，映射如下函数：
void C***Dlg::OnUpdateMenuLogin(CCmdUI* pCmdUI)
{
// TODO: Add your command update UI handler code here
pCmdUI->Enable(mMenuActive & 0x01);
}
//手动添加下面函数到你的主DIALOG里
void C***Dlg::OnInitMenuPopup(CMenu* pPopupMenu, UINT nIndex, BOOL bSysMenu)
{
if (!bSysMenu)
{
ASSERT(pPopupMenu != NULL);

// check the enabled state of various menu items
CCmdUI state;
state.m_pMenu = pPopupMenu;
ASSERT(state.m_pOther == NULL);

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, FALSE); // popups are never auto disabled
}
else
{
// normal menu item
// Auto enable/disable if command is _not_ a system command
state.m_pSubMenu = NULL;
state.DoUpdate(this, state.m_nID < 0xF000);
}
}
}
}
//还得添加消息映射：
BEGIN_MESSAGE_MAP(CcontrolDlg, CDialog)
ON_WM_INITMENUPOPUP()
END_MESSAGE_MAP()

//现在便会按照你要打开菜单时它的可用性而显示是否变灰：）

[Kudeet]

看不到内容，把右边的滚动条拖到底！BS CSDN's blog

你不是还没有等待网页显示完吧？

[Kudeet]

问题：一般情况下我们用UPDATE_COMMAND_UI来修改菜单的状态(enable/disable, check/uncheck, change text)，但这个方法在一个基于对话框上的菜单却没有效果。
void CTestDlg::OnUpdateFileExit(CCmdUI* pCmdUI)
{
pCmdUI->Enable(FALSE);
pCmdUI->SetCheck(TRUE);
pCmdUI->SetRadio(TRUE);
pCmdUI->SetText("Close");
//以上方法在MDI、SDI程序中都能起作用，在对话框中却没有效果,根本没有调用这个函数。
}

原因分析：当显示一个下拉的菜单的时候，在显示菜单前会发送WM_INITMENUPOPUP消息。而CFrameWnd:: OnInitMenuPopup函数会刷新这个菜单项，同时如果有UPDATE_COMMAND_UI响应函数，则调用它。通过它来更新反应每个菜单的外观效果(enabled/disabled, checked/unchecked).
在一个基于对话框的程序中，因为没有OnInitMenuPopup函数，所以不会调用UPDATE_COMMAND_UI响应函数，而是使用了CWnd类的默认处理, 这种处理没有调用UPDATE_COMMAND_UI响应函数。

解决方法如下：
第一步：
在对话框类的.cpp文件，添加一个ON_WM_INITMENUPOPUP入口到消息映射里面
BEGIN_MESSAGE_MAP(CTestDlg, CDialog)
//}}AFX_MSG_MAP
ON_WM_INITMENUPOPUP()
END_MESSAGE_MAP()
第二步：
在对话框类的.h文件添加消息函数声明。
// Generated message map functions
//{{AFX_MSG(CDisableDlgMenuDlg)
afx_msg void OnInitMenuPopup(CMenu *pPopupMenu, UINT nIndex,BOOL bSysMenu);
//}}AFX_MSG
DECLARE_MESSAGE_MAP()
第三步：
在对话框类的.cpp文件添加如下函数代码(大部分代码取自WinFrm.cpp文件的函数CFrameWnd::OnInitMenuPopup):
void C******Dlg::OnInitMenuPopup(CMenu *pPopupMenu, UINT nIndex,BOOL bSysMenu)
{
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;
}
}

更详细的信息可参考
http://support.microsoft.com/default.aspx?scid=kb;en-us;242577

[wlwlxj]

OnCommandUI

[Kudeet]

FT