void CInstanceChecker::QuitPreviousInstance(int nExitCode)
{
//Try to open the previous instances MMF
HANDLE hPrevInstance = OpenFileMapping(FILE_MAP_ALL_ACCESS, FALSE, GetMMFFilename());
if (hPrevInstance)
{
// Open up the MMF
int nMMFSize = sizeof(CWindowInstance);
CWindowInstance* pInstanceData = static_cast<CWindowInstance*>(MapViewOfFile(hPrevInstance, FILE_MAP_READ | FILE_MAP_WRITE, 0, 0, nMMFSize));
if (pInstanceData != NULL) //Opening the MMF should work
{
// Lock the data prior to reading from it
CSingleLock dataLock(&m_instanceDataMutex, TRUE);
//activate the old window
ASSERT(pInstanceData->hMainWnd); //Something gone wrong with the MMF?
HWND hWnd = pInstanceData->hMainWnd;
//Ask it to exit
HWND hChildWnd = GetLastActivePopup(hWnd);
PostMessage(hChildWnd, WM_QUIT, nExitCode, 0);
}
//Close the file handle now that we
CloseHandle(hPrevInstance);
}
}
// Returns TRUE if a previous instance of the App is running.
BOOL CInstanceChecker::PreviousInstanceRunning()
{
//Try to open the MMF first to see if we are the second instance
HANDLE hPrevInstance = OpenFileMapping(FILE_MAP_ALL_ACCESS, FALSE, GetMMFFilename());
BOOL bPreviousInstance = (hPrevInstance != NULL);
if (hPrevInstance)
CloseHandle(hPrevInstance);
return bPreviousInstance;
}
// Activate the Previous Instance of our Application.
HWND CInstanceChecker::ActivatePreviousInstance()
{
//Try to open the previous instances MMF
HANDLE hPrevInstance = ::OpenFileMapping(FILE_MAP_ALL_ACCESS, FALSE, GetMMFFilename());
if (hPrevInstance)
{
// Open up the MMF
int nMMFSize = sizeof(CWindowInstance);
CWindowInstance* pInstanceData = (CWindowInstance*) ::MapViewOfFile(hPrevInstance, FILE_MAP_READ | FILE_MAP_WRITE, 0, 0, nMMFSize);
if (pInstanceData != NULL) //Opening the MMF should work
{
// Lock the data prior to reading from it
CSingleLock dataLock(&m_instanceDataMutex, TRUE);
//activate the old window
ASSERT(pInstanceData->hMainWnd); //Something gone wrong with the MMF
HWND hWindow = pInstanceData->hMainWnd;
if (hWindow)
{
CWnd wndPrev;
wndPrev.Attach(hWindow);
CWnd* pWndChild = wndPrev.GetLastActivePopup();
// Restore the focus to the previous instance and bring it to the foreground
if (wndPrev.IsIconic())
wndPrev.ShowWindow(SW_RESTORE);
pWndChild->SetForegroundWindow();
//Detach the CWnd we were using
wndPrev.Detach();
}
//Unmap the MMF we were using
::UnmapViewOfFile(pInstanceData);
//Close the file handle now that we
::CloseHandle(hPrevInstance);
//return the Window handle of the previous instance
return hWindow;
}
//Close the file handle now that we
::CloseHandle(hPrevInstance);
//When we have activate the previous instance, we can release the lock
ReleaseLock();
}
return NULL;
}
//Activate the Previous Instance of our Application.
HWND CInstanceChecker::ActivatePreviousInstance(LPCTSTR lpCmdLine, ULONG_PTR dwCopyDataItemData, DWORD dwTimeout)
{
//What will be the return value from this function (assume the worst)
HWND hWindow = NULL;
//Try to open the previous instances MMF
HANDLE hPrevInstance = OpenFileMapping(FILE_MAP_ALL_ACCESS, FALSE, GetMMFFilename());
if (hPrevInstance)
{
//Open up the MMF
int nMMFSize = sizeof(CWindowInstance);
CWindowInstance* pInstanceData = static_cast<CWindowInstance*>(MapViewOfFile(hPrevInstance, FILE_MAP_READ | FILE_MAP_WRITE, 0, 0, nMMFSize));
if (pInstanceData) //Opening the MMF should work
{
//Lock the data prior to reading from it
CSingleLock dataLock(&m_instanceDataMutex, TRUE);
//activate the old window
ASSERT(pInstanceData->hMainWnd); //Something gone wrong with the MMF
hWindow = pInstanceData->hMainWnd;
if (::IsWindow(hWindow))
{
CWnd wndPrev;
wndPrev.Attach(hWindow);
CWnd* pWndChild = wndPrev.GetLastActivePopup();
//Restore the focus to the previous instance and bring it to the foreground
if (wndPrev.IsIconic())
wndPrev.ShowWindow(SW_RESTORE);
if (pWndChild)
pWndChild->SetForegroundWindow();
if (lpCmdLine)
{
//Send the current apps command line to the previous instance using WM_COPYDATA
COPYDATASTRUCT cds;
cds.dwData = dwCopyDataItemData;
DWORD dwCmdLength = static_cast<DWORD>(_tcslen(lpCmdLine) + 1);
cds.cbData = dwCmdLength * sizeof(TCHAR);
TCHAR* pszLocalCmdLine = new TCHAR[dwCmdLength]; //We use a local buffer so that we can specify a constant parameter
//to this function
#if (_MSC_VER >= 1400)
_tcscpy_s(pszLocalCmdLine, dwCmdLength, lpCmdLine);
#else
_tcscpy(pszLocalCmdLine, lpCmdLine);
#endif
cds.lpData = pszLocalCmdLine;
CWnd* pMainWindow = AfxGetMainWnd();
HWND hSender = NULL;
if (pMainWindow)
hSender = pMainWindow->GetSafeHwnd();
//Send the message to the previous instance. Use SendMessageTimeout instead of SendMessage to ensure we
//do not hang if the previous instance itself is hung
DWORD_PTR dwResult = 0;
if (SendMessageTimeout(hWindow, WM_COPYDATA, reinterpret_cast<WPARAM>(hSender), reinterpret_cast<LPARAM>(&cds),
SMTO_ABORTIFHUNG, dwTimeout, &dwResult) == 0)
{
//Previous instance is not responding to messages
hWindow = NULL;
}
//Tidy up the heap memory we have used
delete [] pszLocalCmdLine;
}
//Detach the CWnd we were using
wndPrev.Detach();
}
//Unmap the MMF we were using
UnmapViewOfFile(pInstanceData);
}
//Close the file handle now that we
CloseHandle(hPrevInstance);
//When we have activate the previous instance, we can release the lock
ReleaseLock();
}
return hWindow;
}
//Track the first instance of our App.
//return TRUE on success, else FALSE
BOOL CInstanceChecker::TrackFirstInstanceRunning()
{
//If a previous instance is running, just return prematurely
if (PreviousInstanceRunning())
return FALSE;
//If this is the first instance then copy in our info into the shared memory
//First create the MMF
int nMMFSize = sizeof(CWindowInstance);
g_sinstanceData.hInstanceData = CreateFileMapping(INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE, 0, nMMFSize, GetMMFFilename());
if (g_sinstanceData.hInstanceData == NULL)
{
TRACE(_T("Failed to create the MMF even though this is the first instance, you might want to consider overriding GetMMFFilename()\n"));
return FALSE;
}
//Open the MMF
CWindowInstance* pInstanceData = static_cast<CWindowInstance*>(MapViewOfFile(g_sinstanceData.hInstanceData, FILE_MAP_READ | FILE_MAP_WRITE, 0, 0, nMMFSize));
ASSERT(pInstanceData != NULL); //Opening the MMF should work
//Lock the data prior to updating it
CSingleLock dataLock(&m_instanceDataMutex, TRUE);
pInstanceData->hMainWnd = GetWindowToTrack();
UnmapViewOfFile(pInstanceData);
//Since this will be the last function that will be called
//when this is the first instance we can release the lock
ReleaseLock();
return TRUE;
}
