PRB: Convert Dialog Doesn't Appear for OLE Object in MS Excel

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This article was previously published under Q135765

SYMPTOMS

When the Edit|<Object>|Convert... menu item is selected for an OLE object that is embedded within a Microsoft Excel document, the Convert dialog box does not appear.

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Microsoft Excel displays the Convert dialog for an object only if WriteFmtUserTypeStg has been used to write out a clipboard format and user-readable name for the contents of the object. The MFC libraries do not call this function when creating or saving OLE objects.

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RESOLUTION

Call WriteFmtUserTypeStg in the Serialize method of your server's document class.

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STATUS

This behavior is by design.

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MORE INFORMATION

WriteFmtUserTypeStg should be called as part of your server's implementation of IPersistStorage::InitNew and IPersistStorage::Save. By default, MFC OLE server applications do not call WriteFmtUserTypeStg in their implementation of IPersistStorage::InitNew and IPersistStorage::Save. One simple way to achieve this functionality in an MFC application is to make the call to WriteFmtUserTypeStg in the Serialize method of the server's document class.

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Steps to Add a Call to WriteFmtUserTypeStg

Provide a private clipboard format for your object.

WriteFmtUserTypeStg serializes a clipboard format and user-readable name for the contents of an object to its storage. The HIERSVR sample shows how to provide a private clipboard format for your object if you do not already have one.
Add the DoWriteFmtUserTypeStg helper function to your document class.

This helper function is used to encapsulate retrieving the clipboard format and user-readable name when calling WriteFmtUserTypeStg. The code in the "Sample Code" section of this article shows how to implement this function for the HIERSVR sample.
Modify the server document's Serialize() method and add a call to the DoWriteFmtUserTypeStg helper function, as shown in the following sample code.

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Sample Code

   void CServerDoc::DoWriteFmtUserTypeStg(LPSTORAGE lpStorage)
   {
      LPOLEOBJECT lpObject = (LPOLEOBJECT)GetInterface(&IID_IOleObject);
      ASSERT(lpObject != NULL);
      CLSID clsid;
      lpObject->GetUserClassID(&clsid);

      LPTSTR pszUserType = NULL;
      OleRegGetUserType(clsid, USERCLASSTYPE_FULL, (LPOLESTR
   *)&pszUserType);

      if (pszUserType)
      {

         WriteClassStg(lpStorage, clsid);
         WriteFmtUserTypeStg(lpStorage, m_cfPrivate,
   (LPOLESTR)pszUserType);
         CoTaskMemFree(pszUserType);
      }
   }

   void CServerDoc::Serialize(CArchive& ar)
   {
     ASSERT(m_pRoot != NULL);

     if(IsEmbedded() && ar.IsStoring())
     {
       ASSERT(m_lpRootStg != NULL);
       DoWriteFmtUserTypeStg(m_lpRootStg);
     }

     SerializeFontInfo(ar);
     m_pRoot->Serialize(ar);
   }

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