A thread-safe timed message box

#include <stdafx.h>
#include "afximpl.h"	// to be found in .\MFC\Src
#include "timedmsgbox.h"

//
// copyright Markus Loibl
// markus.loibl@epost.de
// 
// Feel free to use this code
//
// History
//
//  5.11.2000  Initial release
// 14.11.2000  fixed a problem unter NT4
//             Problem was the missing CALLBACK in the TIMERPROC
// 05.02.2001  Bug: if generated with MB_OK the button has NOT IDOK, but IDCANCEL
// 05.02.2001  global function -> into the scope of the class
//


/////////////////////////////////////////////////////////////////////////
//
// CDlgTimedMessageBox
//
/////////////////////////////////////////////////////////////////////////

CMapPtrToPtr		CDlgTimedMessageBox::m_mapTimerIdToClassMe;
CCriticalSection	CDlgTimedMessageBox::m_sectMap;

// the static one to call the messagebox with one line
UINT CDlgTimedMessageBox::TimedMessageBox(UINT flags, LPCTSTR ptszMessage, LPCTSTR ptszTitle, 
						DWORD dwTimeout, UINT dDefaultReturn,
						LPCTSTR ptszMessageTimer, HWND hwndParent, BOOL *pbStoppedByUser)
{
	CDlgTimedMessageBox		msgBox(flags, ptszMessage, ptszTitle, 
									dwTimeout, dDefaultReturn, 
									ptszMessageTimer, hwndParent);

	return msgBox.ShowMessageBox(pbStoppedByUser);
}

CDlgTimedMessageBox::CDlgTimedMessageBox(UINT flags, 
								LPCTSTR ptszMessage, LPCTSTR ptszTitle, 
								DWORD dwTimeout, UINT dDefaultReturn,
								LPCTSTR ptszMessageTimer, 
								HWND hwndParent)
{
	m_hParent			= hwndParent;
	m_Message			= ptszMessage;
	m_Title				= ptszTitle;
	m_flags				= flags;
	m_dwTimeout			= dwTimeout-1;
	m_MessageTimer		= ptszMessageTimer;
	m_DefaultReturn		= dDefaultReturn;
	
	m_hMsgBox			= NULL;
	m_hStaticText		= NULL;
	m_hDefaultButton	= NULL;
	m_bRunning			= FALSE;
	m_bStoppedByTimer	= FALSE;

	if( !m_hParent )
	{
		CWnd *m_pParent = AfxGetApp()->GetMainWnd();
		m_hParent = m_pParent->m_hWnd;
	}
}

CDlgTimedMessageBox::~CDlgTimedMessageBox()
{
}

UINT CDlgTimedMessageBox::ShowMessageBox(BOOL *pbStoppedByUser)
{
	// start timer 
	CDlgTimedMessageBox::m_sectMap.Lock();
	{
		m_idTimer = ::SetTimer(NULL, 0, 1000, (TIMERPROC) CDlgTimedMessageBox::GlobalTimerProc);
		CDlgTimedMessageBox::m_mapTimerIdToClassMe.SetAt((void*)m_idTimer, this);
	}
	CDlgTimedMessageBox::m_sectMap.Unlock();
	
	// show MessageBox
	m_bRunning = TRUE;
	m_dwStarted = ::GetTickCount();
	
	m_CurrentMessage = m_Message;
	if( !m_MessageTimer.IsEmpty() )
	{
		CString	second;
		second.Format(m_MessageTimer, (m_dwTimeout+1)/1000);
		m_CurrentMessage.Format("%s%s", m_Message, second);
	}
	UINT erg = ::MessageBox(m_hParent, m_CurrentMessage, m_Title, m_flags);
	m_bRunning = FALSE;

	CDlgTimedMessageBox::m_sectMap.Lock();
	{
		::KillTimer(NULL, m_idTimer);
		m_idTimer = 0;
		CDlgTimedMessageBox::m_mapTimerIdToClassMe.RemoveKey((void*)m_idTimer);
	}
	CDlgTimedMessageBox::m_sectMap.Unlock();

	if( pbStoppedByUser )
		*pbStoppedByUser = !m_bStoppedByTimer;
	
	return erg;
}

void CALLBACK CDlgTimedMessageBox::GlobalTimerProc(HWND hwnd, UINT uiMsg, UINT_PTR idEvent, DWORD dwTime)
{
	//TRACE("Global timer with id=%u\n", idEvent);
	
	CDlgTimedMessageBox	*pMe = NULL;
	
	// Find the corresponding class by the timer-id
	CDlgTimedMessageBox::m_sectMap.Lock();
	{
		CDlgTimedMessageBox::m_mapTimerIdToClassMe.Lookup((void*)idEvent, (void *&) pMe);
	}	
	CDlgTimedMessageBox::m_sectMap.Unlock();
	
	if( pMe!=NULL )
		pMe->LocalTimerProc();
}

void CDlgTimedMessageBox::LocalTimerProc(void)
{
	//TRACE("Local timer with id=%u (%s)\n", m_idTimer, m_Title);

	if( !m_bRunning )
		return;

	// lookup the handles 
	GetWindowHandles();


	if( !m_hStaticText || !m_hMsgBox )
		return;

	DWORD now = GetTickCount()-m_dwStarted;
	
	if( now >= (m_dwTimeout) )
	{
		// done with the box
		m_bStoppedByTimer = TRUE;
		::PostMessage(m_hMsgBox, WM_COMMAND, (WPARAM) m_DefaultReturn, (LPARAM) m_hDefaultButton);
	}
	else
	{
		m_CurrentMessage = m_Message;
	
		// not done: set text again
		if( !m_MessageTimer.IsEmpty() )
		{
			CString	second;
			second.Format(m_MessageTimer, (100+m_dwTimeout-now)/1000);
			m_CurrentMessage.Format("%s%s", m_Message, second);
		}
		::SetWindowText(m_hStaticText, m_CurrentMessage);
	}	
}

void CDlgTimedMessageBox::GetWindowHandles(void)
{
	HWND		hWnd;
	CWnd		*pWnd;
	CString		title;
	CPtrList	allButtons;

	//
	// Handle of the messageBox
	//
	if( !m_hMsgBox )
	{
		hWnd = ::GetWindow(::GetDesktopWindow(), GW_CHILD);
		while( (hWnd!=NULL) && (m_hMsgBox==NULL) )
		{
			pWnd = CWnd::FromHandle(hWnd);
			pWnd->GetWindowText(title);

			if( AfxIsDescendant(m_hParent, hWnd) && ::IsWindowVisible(hWnd) && (m_Title.CompareNoCase(title)==0) )
			{
				m_hMsgBox = hWnd;
				break;
			}
			
			hWnd = ::GetWindow(hWnd, GW_HWNDNEXT);
		}
	}

	//
	// Handle of the static text
	// TODO only if text-replace is needed
	//
	if( m_hMsgBox && !m_hStaticText )
	{
		// not sure if this will work always
		// under Win2000 it did
		//m_hStaticText = ::GetDlgItem(m_hMsgBox, 0xFFFF);

		// not sure, so lets find it dynamically!

		char		className[_MAX_PATH];
		CString		classNameOk("STATIC");
		LONG		id;

		hWnd = ::GetWindow(m_hMsgBox, GW_CHILD);
		while( (hWnd!=NULL) && (m_hStaticText==NULL) )
		{
			id = ::GetWindowLong(hWnd, GWL_ID);
			
			// small ids only for buttons
			if( id > IDHELP )
			{
				if( ::GetClassName(hWnd, className, _MAX_PATH) )
				{

					// looking only for a static 
					if( classNameOk.CompareNoCase(className) == 0 )
					{
						// not check the text
						pWnd = CWnd::FromHandle(hWnd);
						pWnd->GetWindowText(title);
						
						if( m_CurrentMessage.CompareNoCase(title) == 0 )
						{
							m_hStaticText = hWnd;
							break;
						}

					}
				}
			}
			else
			{
				allButtons.AddTail(hWnd);
			}

			hWnd = ::GetWindow(hWnd, GW_HWNDNEXT);
		}

	}

	//
	// Handle of the default button
	//
	if( m_hMsgBox && !m_hDefaultButton )
	{
		m_hDefaultButton = ::GetDlgItem(m_hMsgBox, m_DefaultReturn);
		
		// Problem: (reported from Keith Brown)
		// if generated with MB_OK the button has NOT IDOK, but IDCANCEL !!
		// then lets take the first button we find !
		// (with and IDCANCEL this works, because it is the only button
		// if this problem encounters also with 2 buttons, I have no chance 
		// to find out which one is the better one!)
		while( allButtons.GetCount()>0 && !m_hDefaultButton )
		{
			m_hDefaultButton = (HWND) allButtons.GetHead();
			allButtons.RemoveHead();
			
			if( m_hDefaultButton )
				m_DefaultReturn = ::GetWindowLong(m_hDefaultButton, GWL_ID);
		}
	}
}