Multiple Views Using SDI

In order for this method to work correctly you need to make one simple change in the header of your CView derived classes. The default constructor for the view needs to be have the protected storage class changed to public ( See code sample below). This is due to the fact that we will be constructing the view on the fly when it is switched to the active view. We could create all the views at one time and have them available but that is wasteful of memory and resources and is not really needed. If you wish to do so, however the code can easily be changed to achive this.

class CMainView : public CFormView
{
protected: 	// create from serialization only   Change this to
public: 	// create from serialization only     this in all CView derived classes

 CMainView();
 DECLARE_DYNCREATE(CMainView)

The actual function that will swap the views is located in your CFrame derived class. This is the logical place to put it because in the SDI architecture the frame class controls the view class. It also allows us to centralize message handling for switching views in/out. As far as MFC member functions go it is pretty simple. It simply disconnects the old view and destroys it , creates a new CView derived class and attaches the document to it, sets a few flags, shows the view and we are in business. here it is.

void CMainFrame::SwitchToForm(int nForm)
{
 CView* pOldActiveView = GetActiveView();	// save old view
 CView* pNewActiveView = (CView*)GetDlgItem(nForm);  // get new view

 if (pNewActiveView == NULL)
 {
  switch(nForm) // these IDs are the dialog IDs of the view but can use anything
  {
   case IDD_MULTISCREEN_FORM:
    pNewActiveView = (CView*)new CMainView;
    break;

   case IDD_MULTISCREEN_FORM2:
    pNewActiveView = (CView*)new CView2;
    break;

   case IDD_MULTISCREEN_FORM3:
    pNewActiveView = (CView*)new CView3;
    break;

   case IDD_MULTISCREEN_FORM4:
    pNewActiveView = (CView*)new CView4;
    break;
  }

  CCreateContext context;       // attach the document to the new view
  context.m_pCurrentDoc = pOldActiveView->GetDocument();
  pNewActiveView->Create(NULL, NULL, 0L, CFrameWnd::rectDefault, // and the frame
   this, nForm, &context);
  pNewActiveView->OnInitialUpdate();
 }

 SetActiveView(pNewActiveView);		// change the active view
 pNewActiveView->ShowWindow(SW_SHOW);	// show the new window
 pOldActiveView->ShowWindow(SW_HIDE);	// hide the old


 ::SetWindowWord(pNewActiveView->m_hWnd, GWL_ID, AFX_IDW_PANE_FIRST);  // gotta have it
 RecalcLayout();		//	adjust frame
 delete	pOldActiveView;	//	kill old view
}

void CMainFrame::OnForm1()
{
 SwitchToForm(IDD_MULTISCREEN_FORM);
}

void CMainFrame::OnUpdateForm1(CCmdUI* pCmdUI)
{
 pCmdUI->Enable(GetActiveView()->GetRuntimeClass()!=RUNTIME_CLASS(CMainView));
}

Download demo project - 26 KB