Using Multiview

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Introduction

Have you ever want to build an aplication which have more than one view? You can implement it by using a splitter, or multiple views. This article with discuss about using mutiple views, how to use those views, and change between views. Implementation of this, is the html editor, which can change view from design view to html view. These views can have single document or more than one document. In this article, I only use single document.

Using the code

Step 1 Making a new view

Add a new view by inserting a new class with CView / CScrollView / CHtmlView / something else. as the base class. In this tutorial, I will name that class COtherView. Change the constructor and destructor access from protected to public, so that you can call it. Make two CView/CSrollView object, according the base class you created before, named m_pOtherView and m_pOtherView. m_pOtherView is used to store the new view and m_pFirstView to store the first view, so that you can go back to that view.

    CView m_pOtherView;
</CODE>    CView m_pFirstView;

Remember to write the above code and code in step 1 in your App header file. Create a CCreateContext variable to connect the view to the a document, in this case it`s the default document. You can use your own created document if you want, but it`s a bit complex, so i won`t discuss it here. Name the variable context. You will pass this variable as a parameter to create the view. The attribute which store the current document is m_pCurrentDoc.

    CDocument* pDoc = ((CFrameWnd*)m_pMainWnd)->GetActiveDocument();
    CCreateContext context;
    context.m_pCurrentDoc = pDoc;

Before creating the new view, create a new variable m_ID, which hold the new view ID. Set the m_ID base on the first view ID plus 1. AFX_IDW_PANE_FIRST is the first view ID, adding it by one will make sure there is no ID conflict.

    UINT m_ID = AFX_IDW_PANE_FIRST + 1;

    m_pOtherView->Create(NULL, NULL, WS_CHILD, rect, 
      m_pMainWnd, m_ID, &context);

Step 2 Selecting and viewing the view

First exchange the view ID that we want to show with the previous view ID. You have to do this , so that RecalcLayout do it`s job to the right view, the view that we want to see. Use the SetWindowWord and GetWindowWord to work on the m_hWnd, which is 16-bit.

     UINT temp = ::GetWindowWord(m_pOtherView->m_hWnd, GWL_ID);
    ::SetWindowWord(m_pOtherView->m_hWnd, GWL_ID, 
         ::GetWindowWord(m_pFirstView->m_hWnd, GWL_ID));
    ::SetWindowWord(m_pFirstView->m_hWnd, GWL_ID, temp);

Hide the previous view and show the next view.

    m_pOtherView->ShowWindow(SW_HIDE);
    m_pFirstView->ShowWindow(SW_SHOW); 

Set the aplication active view with the view we`ve created. Call RecalcLayout to put things in their order.

    ((CFrameWnd*)m_pMainWnd)->SetActiveView(m_pFirstView); 
    ((CFrameWnd*)m_pMainWnd)->RecalcLayout();
    m_pFirstView->Invalidate();

To get access to the active document, change the code on COtherView::OnDraw. But first include the document header in your source file view. In COtherView add Member Function with function type CMultiViewDoc* and with the name GetDocument(). Write the code below to the function created.

    CMultiViewDoc* COtherView::GetDocument()
    {
        return (CMultiViewDoc*)m_pDocument;
    }

    void COtherView::OnDraw(CDC* pDC)
    {
        CMultiViewDoc* pDoc = GetDocument();
        pDC->TextOut(400,320,pDoc->m_str); 
                // m_str is a member of CMultiViewDoc
    }

Draw on the view as you draw with the usual view.

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