Dynamically Create Different Views for SDI Projects

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Environment: Any flavour of MFC (Doc/View) including VC6, VC7, and Embedded Visual C++

Sometimes you have an SDI-based project and you do not want to be restricted to a single view (single template). In this article, a piece of code will be presented that will let you change your view of your SDI project dynamically to any other view. In the Windows CE environment, the Visual Embedded Studio does not give you the option of creating MDI projects; this is the perfect alternative for it.

To write this code, I have debugged into the MFC Library and learned few things; I finally took a copy of CSingleDocTemplate::OpenDocumentFile and modified it into a new method called: DynamicOpenDocumentFile(…)

I have Derived a class from CSingleDocTemplate, called CDynamicSingleDocTemplate. It has a new method called DynamicOpenDocumentFile(…) with similar parameters to OpenDocumentFile(…)

CDocument *CDynamicSingleDocTemplate::DynamicOpenDocumentFile

           (LPCTSTR lpszPathName, BOOL bMakeVisible)

{

  // destroy the current view along with its document

  AfxGetMainWnd()->GetDlgItem(AFX_IDW_PANE_FIRST)->DestroyWindow();

  CWinThread* pThread = AfxGetThread();

  pThread->m_pMainWnd = NULL;
  CDocument* pDocument = NULL;

  CFrameWnd* pFrame = NULL;

  BOOL bCreated = FALSE;      // => doc and frame created

  BOOL bWasModified = FALSE;
  if (m_pOnlyDoc != NULL)

  {

    // already have a document — reinit it

    pDocument = m_pOnlyDoc;

    if (!pDocument->SaveModified())

      return NULL;        // leave the original one
    pFrame = (CFrameWnd*) AfxGetMainWnd();

    ASSERT(pFrame != NULL);

    ASSERT_KINDOF(CFrameWnd, pFrame);

    ASSERT_VALID(pFrame);

  }

  else

  {

    // create a new document

    pDocument = CreateNewDocument();

    ASSERT(pFrame == NULL);     // will be created below

    bCreated = TRUE;

  }
  if (pDocument == NULL)

  {

    AfxMessageBox(AFX_IDP_FAILED_TO_CREATE_DOC);

    return NULL;

  }

  ASSERT(pDocument == m_pOnlyDoc);
  pFrame = (CFrameWnd*) AfxGetMainWnd();
  // create our view

  CCreateContext context;

  context.m_pCurrentFrame = NULL; // pFrame

  context.m_pCurrentDoc = pDocument;

  context.m_pLastView = NULL;

  context.m_pNewDocTemplate = this;

  context.m_pNewViewClass = m_pViewClass;
  CWnd *pView = pFrame->CreateView(&context);

  if (!pView)

    return NULL;
  if (lpszPathName == NULL)

  {

    // create a new document

    SetDefaultTitle(pDocument);
    // avoid creating temporary compound file when starting

    // up invisible

    if (!bMakeVisible)

      pDocument->m_bEmbedded = TRUE;
    if (!pDocument->OnNewDocument())

    {

      // user has been alerted to what failed in OnNewDocument

      TRACE0(“CDocument::OnNewDocument returned FALSE.\n”);

      if (bCreated)

        pFrame->DestroyWindow();    // will destroy document

      return NULL;

    }

  }

  else

  {

    CWaitCursor wait;
    // open an existing document

    bWasModified = pDocument->IsModified();

    pDocument->SetModifiedFlag(FALSE);  // not dirty for open
    if (!pDocument->OnOpenDocument(lpszPathName))

    {

      // user has been alerted to what failed in OnOpenDocument

      TRACE0(“CDocument::OnOpenDocument returned FALSE.\n”);

      if (bCreated)

      {

        pFrame->DestroyWindow();    // will destroy document

      }

      else if (!pDocument->IsModified())

      {

        // original document is untouched

        pDocument->SetModifiedFlag(bWasModified);

      }

      else

      {

        // we corrupted the original document

        SetDefaultTitle(pDocument);
        if (!pDocument->OnNewDocument())

        {

          TRACE0(“Error: OnNewDocument failed after trying to open

                 a document – trying to continue.\n”);

          // assume we can continue

        }

      }

      return NULL;        // open failed

    }

    pDocument->SetPathName(lpszPathName);

  }
  pThread->m_pMainWnd = pFrame;
  InitialUpdateFrame(pFrame, pDocument, bMakeVisible);

  pFrame->RecalcLayout();
  return pDocument;

}

Downloads

Download demo project – 44 Kb

Download source – 2 Kb