VC对话框实现垂直滚动效果

    CRect rc;  
    GetClientRect(&rc);  
    SCROLLINFO si = {sizeof(SCROLLINFO)};  
    si.fMask = SIF_PAGE | SIF_POS | SIF_RANGE;  
    si.nPos = si.nMin = 1;  
    si.nMax = rc.Height() * 3;  
    si.nPage = rc.Height();  
    SetScrollInfo(SB_VERT, &si, FALSE);

    void CPrintDlgAppDlg::OnVScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar)
    {
        SetVScrool(SB_VERT, nSBCode);

        CDialog::OnVScroll(nSBCode, nPos, pScrollBar);
    }

    void CPrintDlgAppDlg::ScrollClient(int nBar, int nPos)  
    {  
        static int s_prevx = 1;  
        static int s_prevy = 1;  

        int cx = 0;  
        int cy = 0;  

        int& delta = cy;  
        int& prev = s_prevy;

        delta = prev - nPos;  
        prev = nPos;  

        if(cx || cy)  
        {  
            ScrollWindow(cx, cy, NULL, NULL);  
        }  
    }  

    int CPrintDlgAppDlg::GetScrollPos(int nBar, UINT nSBCode)  
    {  
        SCROLLINFO si;  
        si.cbSize = sizeof(SCROLLINFO);  
        si.fMask = SIF_PAGE | SIF_POS | SIF_RANGE | SIF_TRACKPOS;  
        GetScrollInfo(nBar, &si);  

        const int minPos = si.nMin;  
        const int maxPos = si.nMax - (si.nPage - 1);  

        int result = -1;  

        switch(nSBCode)  
        {  
        case SB_LINEUP /*SB_LINELEFT*/:  
            result = max(si.nPos - 1, minPos);  
            break;  
        case SB_LINEDOWN /*SB_LINERIGHT*/:  
            result = min(si.nPos + 1, maxPos);  
            break;  
        case SB_PAGEUP /*SB_PAGELEFT*/:  
            result = max(si.nPos - (int)si.nPage, minPos);  
            break;  
        case SB_PAGEDOWN /*SB_PAGERIGHT*/:  
            result = min(si.nPos + (int)si.nPage, maxPos);  
            break;  
        case SB_THUMBPOSITION:  
            // do nothing   
            break;  
        case SB_THUMBTRACK:  
            result = si.nTrackPos;  
            break;  
        case SB_TOP /*SB_LEFT*/:  
            result = minPos;  
            break;  
        case SB_BOTTOM /*SB_RIGHT*/:  
            result = maxPos;  
            break;  
        case SB_ENDSCROLL:  
            // do nothing   
            break;  
        }  

        return result;  
    }  

    void CPrintDlgAppDlg::SetVScrool(int nBar, UINT nSBCode)  
    {  
        const int scrollPos = GetScrollPos(nBar, nSBCode);  

        if(scrollPos == -1)  
            return;  

        SetScrollPos(nBar, scrollPos, TRUE);  
        ScrollClient(nBar, scrollPos);  
    }