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Preventing more than one doc. from opening in MDI


BLR CSG -- T_SAMAL_C1@blrv1.verifone.com
Wednesday, September 18, 1996

Environment : VC4.0 , Win95
Hi,
 I have an app that uses multiple document templates. One of these 
templates shouldn't have more than one document open.
 My question is if i can prevent a document from being opened if a document 
of that type is already open.
 I've currently done it by having a class member variable
static int XDoc::IsOpen, and incrementing this var in XDoc::OnOpenDocument() 
and decrementing it in XDoc::OnCloseDocument().
If the member is 0 I return FALSE in OnOpenDocument(). I can't use a simple 
BOOL type because OnCloseDocument() gets called even if i return FALSE in 
OnOpenDocument().
 I feel there must be a better (hopefully more standard) way of doing 
this.
Any suggestions??
Thanks/Samal.
Verifone, Bangalore.


Chet Murphy -- cmurphy@modelworks.com
Friday, September 20, 1996

[Mini-digest: 2 responses]

> Environment : VC4.0 , Win95
> Hi,
>  I have an app that uses multiple document templates. One of these 
> templates shouldn't have more than one document open.
>  My question is if i can prevent a document from being opened if a document 
> of that type is already open.
>  I've currently done it by having a class member variable
> static int XDoc::IsOpen, and incrementing this var in XDoc::OnOpenDocument() 
> and decrementing it in XDoc::OnCloseDocument().
> If the member is 0 I return FALSE in OnOpenDocument(). I can't use a simple 
> BOOL type because OnCloseDocument() gets called even if i return FALSE in 
> OnOpenDocument().
>  I feel there must be a better (hopefully more standard) way of doing 
> this.

I solved this problem by creating a new CDocTemplate using code like the
following:

CDocument* CWorkspaceTemplate::OpenDocumentFile(LPCTSTR lpszPathName, BOOL
bMakeVisible)
{
	...
	if (m_WorkspaceDoc != NULL)
	{
		// already have a document - close it
		CString path = m_WorkspaceDoc->GetPathName();
		ASSERT(path.IsEmpty() == FALSE);
		m_WorkspaceDoc->OnSaveDocument(path);
		theApp.CloseAllUserDocuments();
		CloseAllDocuments(FALSE);
		gProjectPanel->CloseAllViews();
	}
	...
}

to prevent more than one document to being opened at a time.  Then I just
create the template in my InitInstance() along with all my other templates:

		// add workspace template 
		pWorkspaceTemplate = new CWorkspaceTemplate(IDR_WORKSPACETYPE,
			RUNTIME_CLASS(CWorkspaceDoc),
			NULL,
			NULL);
		AddDocTemplate(pWorkspaceTemplate);


Chet Murphy
ModelWorks Software - Editors for Java, JavaScript, VBScript, HTML and VRML
cmurphy@modelworks.com
http://www.modelworks.com/express
-----From: "David Holliday" 

I have no idea if this is the best way to do this, but it's how I do it.

Keep a varriable m_pYourWnd in CYourApp.  In the constructor for CYourWnd
set m_pYourWnd to this (GetCYourApp()->SetpYourWnd(this);).  In the
destructor set m_pYourWnd to NULL (GetCYourApp()->SetpYourWnd(NULL);).  Now
you can test to see if a window for your Doc is open.

//**************************
class CYourApp : public CWinApp
{
...

  CYourWnd* m_ pYourWnd ;   // points Your window 
... 
  void SetpYourWnd(CYourWnd* pYourWnd) {m_ pYourWnd = pYourWnd;}
...
private: 
	// member pointers to document templates
	CMultiDocTemplate *m_pMDITemplateYour; 
public:
	// access functions to member pointers to document templates
	CMultiDocTemplate* GetMDITemplateYour()const {return m_pMDITemplateYour;}
...
};




//************************
CYourApp::CYourApp() 
{
	// TODO: add construction code here,
	// Place all significant initialization in InitInstance 
...
	m_pYourDocWnd = NULL; // no window (or Doc) is open
...
}


//******************************
BOOL CYourApp::InitInstance()
{
...
  AddDocTemplate(m_pMDITemplateYour = new CMultiDocTemplate(IDR_MAINFRAME,
		RUNTIME_CLASS(CYourDoc),
		RUNTIME_CLASS(CYourWnd
		RUNTIME_CLASS(CYourView)));
...
	return TRUE;
}


//************************************
void CYourApp::OnOpenYourDoc()
{
	// TODO: Add your command handler code here  
	if(!m_pYourWnd)  // the window is not open
	{
	  	GetMDITemplateYour()->OpenDocumentFile(NULL);
	}
	else  // the Button window is open
	{
		 m_pYourWnd->BringWindowToTop();
	}
}




//********************
CYourWnd:: CYourWnd()
{
	GetCYourApp()->SetpYourWnd(this);
}

//*********************
CYourWnd::~ CYourWnd()
{ 
	GetCYourApp()->SetpYourWnd(NULL);
}

Hope this helps,
--David


rkumar@mail.cswl.com
Tuesday, September 24, 1996

     
     Every doc template maintains a list of documents opened by it.u can 
     traverse the list by using GetFirstDocPosition and GetNextDoc 
     functions. Do GetFirstDocPosition if it returns NULL open the document 
     otherwise don't. 
     For this u may have to maintain a pointer to the doc template in the 
     app class.
                                                                Ratan.
                                                                rkumar@cswl.com

______________________________ Reply Separator _________________________________
Subject: Preventing more than one doc. from opening in MDI
Author:  mfc-l@netcom.com at internet
Date:    20/09/96 11:57 PM


Environment : VC4.0 , Win95
Hi,
 I have an app that uses multiple document templates. One of these 
templates shouldn't have more than one document open.
 My question is if i can prevent a document from being opened if a document 
of that type is already open.
 I've currently done it by having a class member variable
static int XDoc::IsOpen, and incrementing this var in XDoc::OnOpenDocument() 
and decrementing it in XDoc::OnCloseDocument().
If the member is 0 I return FALSE in OnOpenDocument(). I can't use a simple 
BOOL type because OnCloseDocument() gets called even if i return FALSE in 
OnOpenDocument().
 I feel there must be a better (hopefully more standard) way of doing 
this.
Any suggestions??
Thanks/Samal.
Verifone, Bangalore.


John Bundgaard -- johnb@image.dk
Tuesday, September 24, 1996

When you register the documenttype in your app-object, the store the
CDocTemplate handle returned, in say m_pDocTemplate.

You can the determine if a document is open by calling
m_pDocTemplate->GetFirstDocPosition().
If the returned value is NULL, the there is no document open.

John Bundgaard
johnb@image.dk

----------
>  I have an app that uses multiple document templates. One of these 
> templates shouldn't have more than one document open.
>  My question is if i can prevent a document from being opened if a
document 
> of that type is already open.

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