[q] the difference between ON_COMMAND_EX and ON_UPDATE_COMMAND_UI

to the mfc gurus,

except for the obvious prototypes and function declaration difference
between the two:

// UPDATE_COMMAND_UI
void CMainFrame::OnMyUpdateCommandUI(CCmdUI* pCmdUI)
{
// some code
}
//ON_COMMAND_EX
void CMainFrame::OnMyCommandEX(UINT nID)
{
// some code
}




why can't the pointer to CCmdUI* pCmdUI be easly got inside of the
ON_COMMAND_EX handler (if so how)? I want to be able to enable or
disable a toolbar button from the ON_COMMAND_EX handler but no one
seems to know the ON_COMMAND_EX handler but I'm quite sure it can be
done (can it)? there is very little verbiage on ON_COMMAND_EX! and I
would like to know the proper usage of both of them.

all help will be greatly appreciated
michael b. williams

ON_COMMAND_EX essentially allows you to completely take over what MFC is doing -- you can return TRUE to indicate that the command has been handled, otherwise routing will continue to other command target objects.

The OnMyUpdateCommandUI(CCmdUI* pCmdUI) on the other hand is a quick way to enable controls (the documentation shows that it can do buttons, check boxes...) in control bars during idle (CWindApp::OnIdle) processing.

mbw4359 wrote

why can't the pointer to CCmdUI* pCmdUI be easly got inside of the
ON_COMMAND_EX handler (if so how)? I want to be able to enable or
disable a toolbar button from the ON_COMMAND_EX handler but no one
seems to know the ON_COMMAND_EX handler but I'm quite sure it can be
done (can it)? there is very little verbiage on ON_COMMAND_EX! and I
would like to know the proper usage of both of them.


but what about the question about the CmdUI* pCmdUI? How do I initialize it so that I can call


// ON_COMMAND_EX handler
void CMainFrame::OnMyCommandEX(UINT UID)
{
CmdUI* pCmdUI = ???????????????????; // to intialize it pointing to the button on my toolbar
pCmdU->Enable(TRUE);
// or
pCmdU->Enable(FALSE);
}

If you do a search through the MFC src code for ON_COMMAND_EX there are quite a few examples where you can see how MS use this function... One instance which appears to be close to what you want to do is in Winfrm.cpp:

BEGIN_MESSAGE_MAP(CFrameWnd, CWnd)
//{{AFX_MSG_MAP(CFrameWnd)
:
ON_COMMAND_EX(ID_VIEW_STATUS_BAR, OnBarCheck)
:
//}}AFX_MSG_MAP

BOOL CFrameWnd::OnBarCheck(UINT nID)
{
ASSERT(ID_VIEW_STATUS_BAR == AFX_IDW_STATUS_BAR);
ASSERT(ID_VIEW_TOOLBAR == AFX_IDW_TOOLBAR);

CControlBar* pBar = GetControlBar(nID);
if (pBar != NULL)
{
ShowControlBar(pBar, (pBar->GetStyle() & WS_VISIBLE) == 0, FALSE);
return TRUE;
}
return FALSE;
}


Rail

------------
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Rail Jon Rogut Software
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