// 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:)
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
看不到内容
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:)
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