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Usage of the CScrollView class to add scrolling functionality to your application

, 28 Jun 2002
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Step by step usage of the CScrollView class to add scrolling to your application

Introduction

This code helps you to load a bitmap from a resource or from a file and show it in a MDI View. It enables scrolling and also scrolls the bitmap accordingly.

Steps to follow

Follow the following seven easy steps :-

Step 1

Create a MDI Application by selecting Multiple Documents Interface in Step 1 of the app-wizard process.

Step 2

In the 6th step, select the View class and in the combo box called base class , select CScrollView and then click Finish.

Step 3

Create the following variables in the View class (yourview.h file)

  • CDC m_MemDC;
  • CBitmap m_bmpView;
  • int m_nBmpWidth,m_nBmpHeight;

Step 4

In the View class , select the OnInitialUpdate function and change the code like this.

void CMDIView::OnInitialUpdate() 
{
    CDC *pDC = this->GetDC();

    m_MemDC.CreateCompatibleDC(pDC);

    m_bmpView.LoadBitmap(IDB_BMP_BKGND);    
    // Here IDB_BMP_BKGND is a bitmap included in the resource
    // Note : You can also load a bitmap from a file in the 
    // hard disk instead of using the bmp in the resource.

    m_MemDC.SelectObject(&m_bmpView);

    BITMAP Bitmap;
    m_bmpView.GetBitmap(&Bitmap);

    m_nBmpHeight = Bitmap.bmHeight;
    m_nBmpWidth = Bitmap.bmWidth;

    CSize size(m_nBmpWidth,m_nBmpHeight);
    SetScrollSizes(MM_TEXT,size);

    this->ReleaseDC(pDC);    
}

Step 5

Select the OnDraw function and change the code inside like this

void CMDIView::OnDraw(CDC* pDC)
{
    pDC->BitBlt(0,0,m_nBmpWidth,m_nBmpHeight,
        &m_MemDC,0,0,SRCCOPY);

    SetScrollSizes(MM_TEXT, CSize(m_nBmpWidth,m_nBmpHeight));
    CChildFrame *pParentFrame =
        (CChildFrame *)this->GetParentFrame();
    pParentFrame->RecalcLayout();
    ResizeParentToFit();    
}

Step 6

To prevent flickering of the bitmap when its being scrolled, override the View's OnEraseBkgnd and the ChildFrame's OnEraseBkgnd like this.

BOOL CMDIView::OnEraseBkgnd(CDC* pDC) 
{
    return TRUE;
}   

BOOL CChildFrame::OnEraseBkgnd(CDC* pDC) 
{
    return FALSE;
}

Step 7

Compile your project and run it. That's it. Now, you have a scrolling window which displays a bitmap too.  All luck and have a great time.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

About the Author

VGirish
Founder
India India
No Biography provided

Comments and Discussions

 
QuestionChildFrame????? PinmemberFurries25-Nov-04 2:28 
AnswerRe: ChildFrame????? PinmemberPeteOlcott19-Aug-07 5:22 
GeneralThanks PinmemberAjay_Chopra17-Jun-04 2:15 
GeneralAre these calls all needed PinmemberCJN8-Oct-03 21:50 
QuestionHow to load bitmap from disk file PinmemberCJN8-Oct-03 16:02 
AnswerRe: How to load bitmap from disk file PinsussAnonymous14-Oct-04 2:25 
GeneralRe: How to load bitmap from disk file Pinmembershizulooi13-Jul-09 23:01 
GeneralTop of the class PinsussAndy Kuiper30-May-03 2:05 
Generalthanks PinsussAnonymous3-Sep-02 19:36 

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