Q152029: HOWTO: Prevent Creation of Initial Macintosh Document

Article: Q152029
Product(s): Microsoft C Compiler
Version(s): MACINTOSH:2.0,4.0
Operating System(s): 
Keyword(s): kbDocView kbHWMAC kbMFC kbVC200 kbVC400 kbVC420 kbGrpDSMFCATL kbNoUpdate
Last Modified: 07-MAY-2001

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The information in this article applies to:

- Microsoft Visual C++, Macintosh Cross-Development Addon, versions 2.0, 4.0 
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SUMMARY
=======

Sometimes it is preferable not to initially open a new document in an MFC
application. To implement this behavior on Windows, you can remove the call to
OnFileNew() or ParseCommandLine() from InitInstance. On the Macintosh, you need
to override CWinApp::CreateInitialDocument(). This article describes how to
accomplish these behaviors.

MORE INFORMATION
================

In a Windows MFC application, a new document is initially created if the Command
Line is empty. Since Macintosh applications do not have Command Lines, the open
application Apple Event is sent to the application and is handled by
_AfxOpenAppHandler(), which calls CreateInitialDocument() to open a new
document:

    // From Visual C++ 4.0
     OSErr PASCAL _AfxOpenAppHandler(AppleEvent* pae,
                                     AppleEvent* paeReply,
                                     long lRefcon)
     {
       CWinApp* pApp;
       OSErr err = HandlerCommon(pae, lRefcon, pApp);
       if (err == noErr)
       {
         if (pApp->CreateInitialDocument())
           err = noErr;
         else
           err = errAEEventNotHandled;
       }
       AfxOleSetUserCtrl(TRUE);
       return err;
     }

     // From Visual C++ 4.0
     BOOL CWinApp::CreateInitialDocument()
     {
       if (m_pMainWnd != NULL)
         m_pMainWnd->SendMessage(WM_COMMAND, ID_FILE_NEW);
       else if (m_pDocManager != NULL)
       {
         POSITION pos = m_pDocManager->GetFirstDocTemplatePosition();
         if (pos != NULL)
         {
           CDocTemplate* pTemplate = m_pDocManager->GetNextDocTemplate(pos);

           // if MDI, or SDI but we haven't opened any documents yet,
           // open a new one
           if (pTemplate != NULL &&
             (pTemplate->IsKindOf(RUNTIME_CLASS(CMultiDocTemplate)) ||
             m_pDocManager->GetOpenDocumentCount() == 0))
           {
             OnFileNew();
           }
         }
       }
       return TRUE;
     }

When a new document is not needed, you can override CreateInitialDocument() and
have it return TRUE. This is desirable to prevent the file type dialog from
appearing in applications supporting multiple document types:

     BOOL CMyWinApp::CreateInitialDocument()
     {
       return TRUE;
     }

REFERENCES
==========

See "Creating Initial Documents" in the Macintosh Porting Guide within the
Online Documentation.

Additional query words: WM_MACINTOSH WLM_MACEVENT

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Keywords          : kbDocView kbHWMAC kbMFC kbVC200 kbVC400 kbVC420 kbGrpDSMFCATL kbNoUpdate 
Technology        : kbVCsearch kbHWMAC kbOSMAC kbAudDeveloper kbVCXDev200Mac kbVCXDev400Mac
Version           : MACINTOSH:2.0,4.0
Issue type        : kbhowto

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