Q118613: INFO: Accessing OLE 2.0 Embedded Object Dirties OLE 1.0 Client
Article: Q118613
Product(s): Microsoft C Compiler
Version(s): winnt:
Operating System(s):
Keyword(s): kbole kbActiveX kbAutomation kbCOMt kbContainer kbLocalSvr kbMFC kbVC150 kbVC200 kbVC21
Last Modified: 07-MAY-2001
-------------------------------------------------------------------------------
The information in this article applies to:
- The Microsoft Foundation Classes (MFC), used with:
- Microsoft Visual C++, versions 1.5, 1.51, 1.52
- Microsoft Visual C++ 32-bit Edition, versions 2.0, 2.1, 4.0, 4
-------------------------------------------------------------------------------
SUMMARY
=======
When an OLE 2.0 embedded object is opened and closed in an OLE 1.0 client
without being modified, the client document needs to be updated (that is, marked
as "dirty"). This causes the client to ask whether the user wants to save the
document.
To prevent the client from marking its document as dirty, you must modify the
implementations of IOleObject and IDataObject in your OLE 2.0 server. In an
MFC-based server application, this is most conveniently done by deriving a new
class from COleServerDoc and changing the application's server document class so
that it is derived from the new class.
MORE INFORMATION
================
This behavior can be observed using the Windows Write applet with any of the MFC
sample servers. To observe this behavior, perform the following steps:
1. Open a document in Write.
2. Embed a new object in the document.
3. Save the document.
4. Open the embedded object.
5. Immediately close the object to return to Write.
6. Exit Write. (You will be asked whether you want to save the updated
document.)
When an OLE 2.0 embedded object is closed, the object calls
IAdviseSink::OnClose() to notify its container. The OLE translation layer simply
translates this into a client callback of OLE_CLOSE, which causes the client to
receive an update of the embedded object's metafile. This in turn causes the
client to think its document is dirty and needs to be saved.
To avoid this behavior, perform the following steps:
1. Add a flag to the OLE 2.0 object that supports IDataObject, IPersistStorage,
and IOleObject.
2. During IOleObject::OnClose, set the flag to TRUE before the call to
IAdviseHolder::SendOnClose() and reset it after the call returns.
3. Modify the implementations of IDataObject::GetData() and
IDataObject::GetDataHere() to return E_FAIL when m_bDontSave is TRUE.
To implement the above steps using MFC, perform the following steps:
1. Create a new class, COleServerDocEx, derived from COleServerDoc.
2. Add a member variable, m_bDontSave, to COleServerDocEx.
3. Override OnCloseDocument() in COleServerDocEx. Set m_bDontSave to TRUE, call
the base class function, then reset m_bDontSave. This effectively brackets
the call to IAdviseHolder::OnClose().
4. Reimplement the IDataObject interface in COleServerDocEx. For all functions
except GetData() and GetDataHere(), simply delegate to the COleServerDoc
implementation of IDataObject.
5. In the implementations of GetData() and GetDataHere(), return E_FAIL if
m_bDontSave is TRUE.
6. Modify your application's document class so it is derived from
COleServerDocEx rather than COleServerDoc.
Sample Code
-----------
The following code implements the COleServerDocEx class mentioned above:
////////////////////////////////////////////////////////////////
// olesvrex.h : interface of the COleServerDocEx class
//
class COleServerDocEx : public COleServerDoc
{
DECLARE_DYNAMIC(COleServerDocEx)
// Constructors and Destructors
public:
COleServerDocEx();
// Implementation
public:
virtual ~COleServerDocEx();
#ifdef _DEBUG
virtual void AssertValid() const;
virtual void Dump(CDumpContext& dc) const;
#endif
// overridables for implementation
virtual void OnCloseDocument();
protected:
BOOL m_bDontSave;
// Message Maps
protected:
//{{AFX_MSG(COleServerDocEx)
//}}AFX_MSG
DECLARE_MESSAGE_MAP()
// Interface Maps
protected:
BEGIN_INTERFACE_PART(DataObjectEx, IDataObject)
STDMETHOD(GetData)(LPFORMATETC, LPSTGMEDIUM);
STDMETHOD(GetDataHere)(LPFORMATETC, LPSTGMEDIUM);
STDMETHOD(QueryGetData)(LPFORMATETC);
STDMETHOD(GetCanonicalFormatEtc)(LPFORMATETC, LPFORMATETC);
STDMETHOD(SetData)(LPFORMATETC, LPSTGMEDIUM, BOOL);
STDMETHOD(EnumFormatEtc)(DWORD, LPENUMFORMATETC FAR*);
STDMETHOD(DAdvise)(LPFORMATETC, DWORD, LPADVISESINK, LPDWORD);
STDMETHOD(DUnadvise)(DWORD);
STDMETHOD(EnumDAdvise)(LPENUMSTATDATA FAR*);
END_INTERFACE_PART(DataObjectEx)
DECLARE_INTERFACE_MAP()
};
//
// End of olesvrex.h
////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////
//
// olesvrex.cpp : implementation of the COleServerDocEx class
#include "stdafx.h"
#include "olesvrex.h"
#ifdef _DEBUG
#undef THIS_FILE
static char BASED_CODE THIS_FILE[] = __FILE__;
#endif
///////////////////////////////////////////////////////////////
// COleServerDocEx
IMPLEMENT_DYNAMIC(COleServerDocEx, COleServerDoc)
BEGIN_MESSAGE_MAP(COleServerDocEx, COleServerDoc)
//{{AFX_MSG_MAP(COleServerDocEx)
//}}AFX_MSG_MAP
END_MESSAGE_MAP()
///////////////////////////////////////////////////////////////
// COleServerDocEx construction/destruction
COleServerDocEx::COleServerDocEx()
{
m_bDontSave = FALSE;
}
COleServerDocEx::~COleServerDocEx()
{
}
////////////////////////////////////////////////////////////////
// COleServerDocEx default command handling
void COleServerDocEx::OnCloseDocument()
{
m_bDontSave = TRUE;
COleServerDoc::OnCloseDocument();
m_bDontSave = FALSE;
}
////////////////////////////////////////////////////////////////
// COleServerDocEx OLE interface implementation
BEGIN_INTERFACE_MAP(COleServerDocEx, COleServerDoc)
INTERFACE_PART(COleServerDocEx, IID_IDataObject, DataObjectEx)
END_INTERFACE_MAP()
////////////////////////////////////////////////////////////////
// COleServerDocEx::XDataObjectEx
STDMETHODIMP_(ULONG) COleServerDocEx::XDataObjectEx::AddRef()
{
METHOD_PROLOGUE(COleServerDocEx, DataObjectEx)
return (ULONG)pThis->ExternalAddRef();
}
STDMETHODIMP_(ULONG) COleServerDocEx::XDataObjectEx::Release()
{
METHOD_PROLOGUE(COleServerDocEx, DataObjectEx)
return (ULONG)pThis->ExternalRelease();
}
STDMETHODIMP COleServerDocEx::XDataObjectEx::QueryInterface(
REFIID iid, LPVOID far* ppvObj)
{
METHOD_PROLOGUE(COleServerDocEx, DataObjectEx)
return (HRESULT)pThis->ExternalQueryInterface(&iid, ppvObj);
}
STDMETHODIMP COleServerDocEx::XDataObjectEx::GetData(
LPFORMATETC lpFormatEtc, LPSTGMEDIUM lpStgMedium)
{
METHOD_PROLOGUE(COleServerDocEx, DataObjectEx)
ASSERT_VALID(pThis);
if (pThis->m_bDontSave)
return ResultFromScode(E_FAIL);
return pThis->m_xDataObject.GetData(lpFormatEtc, lpStgMedium);
}
STDMETHODIMP COleServerDocEx::XDataObjectEx::GetDataHere(
LPFORMATETC lpFormatEtc, LPSTGMEDIUM lpStgMedium)
{
METHOD_PROLOGUE(COleServerDocEx, DataObjectEx)
ASSERT_VALID(pThis);
if (pThis->m_bDontSave)
return ResultFromScode(E_FAIL);
return pThis->m_xDataObject.GetDataHere(lpFormatEtc, lpStgMedium);
}
STDMETHODIMP COleServerDocEx::XDataObjectEx::QueryGetData(
LPFORMATETC lpFormatEtc)
{
METHOD_PROLOGUE(COleServerDocEx, DataObjectEx)
ASSERT_VALID(pThis);
return pThis->m_xDataObject.QueryGetData(lpFormatEtc);
}
STDMETHODIMP COleServerDocEx::XDataObjectEx::GetCanonicalFormatEtc(
LPFORMATETC lpFormatEtcIn, LPFORMATETC lpFormatEtcOut)
{
METHOD_PROLOGUE(COleServerDocEx, DataObjectEx)
ASSERT_VALID(pThis);
return pThis->m_xDataObject.GetCanonicalFormatEtc(lpFormatEtcIn,
lpFormatEtcOut);
}
STDMETHODIMP COleServerDocEx::XDataObjectEx::SetData(
LPFORMATETC lpFormatEtc, LPSTGMEDIUM lpStgMedium, BOOL fRelease)
{
METHOD_PROLOGUE(COleServerDocEx, DataObjectEx)
ASSERT_VALID(pThis);
return pThis->m_xDataObject.SetData(lpFormatEtc, lpStgMedium,
fRelease);
}
STDMETHODIMP COleServerDocEx::XDataObjectEx::EnumFormatEtc(
DWORD dwDirection, LPENUMFORMATETC FAR* ppenumFormatEtc)
{
METHOD_PROLOGUE(COleServerDocEx, DataObjectEx)
ASSERT_VALID(pThis);
return pThis->m_xDataObject.EnumFormatEtc(dwDirection,
ppenumFormatEtc);
}
STDMETHODIMP COleServerDocEx::XDataObjectEx::DAdvise(
FORMATETC FAR* pFormatetc, DWORD advf,
LPADVISESINK pAdvSink, DWORD FAR* pdwConnection)
{
METHOD_PROLOGUE(COleServerDocEx, DataObjectEx)
ASSERT_VALID(pThis);
return pThis->m_xDataObject.DAdvise(pFormatetc, advf, pAdvSink,
pdwConnection);
}
STDMETHODIMP COleServerDocEx::XDataObjectEx::DUnadvise(DWORD dwConn)
{
METHOD_PROLOGUE(COleServerDocEx, DataObjectEx)
ASSERT_VALID(pThis);
return pThis->m_xDataObject.DUnadvise(dwConn);
}
STDMETHODIMP COleServerDocEx::XDataObjectEx::EnumDAdvise(
LPENUMSTATDATA FAR* ppenumAdvise)
{
METHOD_PROLOGUE(COleServerDocEx, DataObjectEx)
ASSERT_VALID(pThis);
return pThis->m_xDataObject.EnumDAdvise(ppenumAdvise);
}
////////////////////////////////////////////////////////////////
// COleServerDocEx diagnostics
#ifdef _DEBUG
void COleServerDocEx::AssertValid() const
{
COleServerDoc::AssertValid();
}
void COleServerDocEx::Dump(CDumpContext& dc) const
{
COleServerDoc::Dump(dc);
AFX_DUMP1(dc, "\nm_bDontSave = ", m_bDontSave);
}
#endif //_DEBUG
//
// End of olesvrex.cpp
////////////////////////////////////////////////////////////////
Additional query words: vc30bol kbinf 1.50 2.00 2.10 2.50 2.51 2.52 3.00 3.10 4.00 4.10
======================================================================
Keywords : kbole kbActiveX kbAutomation kbCOMt kbContainer kbLocalSvr kbMFC kbVC150 kbVC200 kbVC210 kbVC220 kbVC400 kbVC410 kbGrpDSMFCATL
Technology : kbAudDeveloper kbMFC
Version : winnt:
Issue type : kbinfo
=============================================================================
THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.
Copyright Microsoft Corporation 1986-2002.