学习：滚动条

实现的结构体为：SCROLLINFO

BOOL CMy4Dlg::OnInitDialog()
{
    CDialogEx::OnInitDialog();

    SCROLLINFO si;
    si.cbSize = sizeof(SCROLLINFO);
    si.fMask = SIF_ALL;
    si.nMax = 100;
    si.nMin = 0;
    si.nPage = 10;
    m_scrollbar.SetScrollInfo(&si);
}

void CMy4Dlg::OnHScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar)// nPos为事件发生的时候，当前Scroll的滚动大小
{

    SCROLLINFO sc = { 0 };
    sc.cbSize = sizeof(SCROLLINFO);
    sc.fMask = SIF_ALL;
    m_scrollbar.GetScrollInfo(&sc, true); //初始化窗口中的si结构体赋值给当前sc的结构体

    int NewPos = sc.nPos;


    switch (nSBCode)
    {
    case SB_THUMBTRACK: //拖动
        NewPos = nPos;
        break;
    case SB_LINELEFT: //左箭头
        NewPos = NewPos - 10;
        break;
    case SB_LINERIGHT:  //右箭头
        NewPos = NewPos + 10;
        break;
    case SB_PAGELEFT: //左拖动行
        NewPos = NewPos - sc.nPage;
        break;
    case SB_PAGERIGHT: //右拖动行
        NewPos = NewPos + sc.nPage;
        break;
    default:
        break;
    }
    bool ret;

    ret = m_scrollbar.SetScrollPos(NewPos); //判断是否设置成功

    if (NewPos > sc.nMax) {
        NewPos = sc.nMax;
    }

    if (NewPos < sc.nMin) {
        NewPos = sc.nMin;
    }
    

    wchar_t szbuffer[1024];
    SetDlgItemText(IDC_STATIC_1, _itow(NewPos, szbuffer, 10));
    CDialogEx::OnHScroll(nSBCode, nPos, pScrollBar);
}