Re: Run App only once

From:

"Tom Serface" <tom.nospam@camaswood.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Fri, 13 Apr 2007 06:34:33 -0700

Message-ID:

<3859DF4B-FAD4-4A6D-B3F2-2EA1AF6677F1@microsoft.com>

Hi GT,

I use PJ's class and it has worked well for me all these years.

http://www.naughter.com/sinstance.html

It works with all kinds of applications (SDI, MDI, Dialog, Extension DLL,
etc.) and also has an easy built in mechanism to pass data to and bring the
the original application to the foreground before exiting a subsequent
start.

Tom

"GT" <ContactGT_remove_@hotmail.com> wrote in message
news:461f7b35$0$30254$c3e8da3@news.astraweb.com...

I want my app open only once. If a user opens a second instance I would
like to AfxMessageBox the user and make the original instance 'flash', then
close the second instance.

I have tried calling the following code in my App::InitInstance() - check
if this is the first instance and if it is, then register app, but it
doesn't work:

bool CCircaApp::FirstInstance()
{
CWnd* pWndMainFrm = (CMainFrame*) CWnd::FindWindow(_T("Circa_Main"),
NULL);

// Determine if another window with your class name exists (not this one
though!)...
if ((pWndMainFrm != NULL) && (pWndMainFrm != GetMainWnd()))
{
CWnd* pWndChild = pWndMainFrm->GetLastActivePopup();

AfxMessageBox("Another instance of Circa is already open");

// Can't just bring the main window back because it doesn't
// restore any tools that are also minimised, so just flash the
// toolbar, so the user finds it again.
pWndChild->FlashWindow(TRUE);

// and you are done activating the previous one.
return false;
}
// First instance. Proceed as normal.
else
return true;
}

bool CCircaApp::RegisterApp()
{
// Register your unique class name that you wish to use
WNDCLASS wndcls;
memset(&wndcls, 0, sizeof(WNDCLASS)); // start with NULL defaults
wndcls.style = CS_DBLCLKS | CS_HREDRAW | CS_VREDRAW;
wndcls.lpfnWndProc = ::DefWindowProc;
wndcls.hInstance = AfxGetInstanceHandle();
wndcls.hIcon = LoadIcon(IDR_MAINFRAME); // or load a different icon
wndcls.hCursor = LoadCursor( IDC_ARROW );
wndcls.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
wndcls.lpszMenuName = NULL;
// Specify your own class name for using FindWindow later
wndcls.lpszClassName = _T("Circa_Main");
// Register the new class and exit if it fails
if(!AfxRegisterClass(&wndcls))
{
TRACE("Class Registration Failed\n");
return false;
}

return true;
}