VSWAP32 samples are available for multiple-view switching in a single-document interface (SDI) application

MORE INFORMATION

The most important implementations of this are in: The standard InitInstance code creates an initial document template, document, and view during the call to ProcessShellCommand. The code added to the end of InitInstance creates the view objects for the extra views used in this application and stores their pointers in a CVswapApp member array. It then cycles through a loop which creates the windows for the view objects. Each view window is created with a unique child window ID and a CCreateContext object that associates each view with the same CDocument object, which was created by ProcessShellCommand. Finally, the sample code triggers the OnInitialUpdate for the extra views.

In this sample, both views persist for the lifetime of the application; however, the application could create the new view dynamically.

The SwitchView function created in this sample swaps the current view with a previously hidden view. It accomplishes this by first switching their child window IDs. This step is necessary because MFC relies on the standard view pane having the child window ID of AFX_IDW_PANE_FIRST. The rest of the code hides the current view and tells MFC to repaint and begin using the new view.

The SaveActiveViewsData is used to save the information from the active view to the document object. It is called by SwitchView whenever a view is switched. SaveActiveViewsData subsequently calls SetToDoc, which actually updates the data from the form view to the document by using MFC's DDX/DDV mechanisms in DoDataExchange.

Sample code

      CView* CVswapApp::SwitchView( UINT nIndex )
      {
          ASSERT( nIndex >=0 && nIndex < NUMVIEWS );

          CView* pNewView = m_pViews[nIndex];

          CView* pActiveView =
          ((CFrameWnd*) m_pMainWnd)->GetActiveView();

          if ( !pActiveView )    // No currently active view.
              return NULL;

          if ( pNewView == pActiveView )    // Already there.
              return pActiveView;

          // Update Doc's data if needed
          // Don't change view if data validation fails
          if ( ! SaveActiveViewsData() )
          {
              return pActiveView;
          }

          m_nCurView = nIndex;    // Store the new current view's index.

          // Exchange view window ID's so RecalcLayout() works.
          UINT temp = ::GetWindowLong(pActiveView->m_hWnd, GWL_ID);
          ::SetWindowLong(pActiveView->m_hWnd, GWL_ID,
                ::GetWindowLong(pNewView->m_hWnd, GWL_ID));
          ::SetWindowLong(pNewView->m_hWnd, GWL_ID, temp);

          // Display and update the new current view - hide the old one.
          pActiveView->ShowWindow(SW_HIDE);
          pNewView->ShowWindow(SW_SHOW);
          ((CFrameWnd*) m_pMainWnd)->SetActiveView(pNewView);
          ((CFrameWnd*) m_pMainWnd)->RecalcLayout();
          pNewView->Invalidate();
          return pActiveView;
      }
				

   COLLECT   (SDI)
   ENROLL    (SDI)
   VWRPLC32  (MDI)
   SPLIT32   (Splitter).