双缓冲显示字幕（卡拉ok字幕）

思路：

1.设置定时器SetTime，在Ontime()里面确定显示矩形的大小，让后用DrawText把字铁道矩形上面；

2.

int nTextHei = dc.GetTextExtent( m_strText ).cy; // length of horizontal label文字的高度
int nTextWei = dc.GetTextExtent( m_strText ).cx; // length of horizontal label文字的宽度

获取文字高度和宽度。

3.设置矩形的大小

矩形的宽度可以每次都加1；

void CShowFontView::OnTimer(UINT nIDEvent)
{

    CClientDC dc(this);
    CFont font;
    CRect rt;
    GetClientRect( &rt );
    TEXTMETRIC tm;
    dc.GetTextMetrics(&tm);
    static int nindex = ;

    m_nWithRect += ;
    if( !nindex )
     m_strText = GetGeci( nindex );
    int nTextHei = dc.GetTextExtent( m_strText ).cy; // length of horizontal label文字的高度
    int nTextWei = dc.GetTextExtent( m_strText ).cx; // length of horizontal label文字的宽度
    RectShow.SetRect(  ,  , +nTextWei+ , + nTextHei );

    if( m_nWithRect > nTextWei )
    {
        m_nWithRect = ;
        nindex ++;
        m_strText = GetGeci( nindex );
        Sleep();
    }

    rectRetangle.SetRect( nTextWei + - m_nWithRect ,  , nTextWei + , +nTextHei );
    rectColor.SetRect(  ,  , +m_nWithRect , +nTextHei );
    Sleep();
    DrawText( m_strText );

    CView::OnTimer(nIDEvent);
}

然后呢就把字贴出来；怎样贴呢就根据需求；

void CShowFontView::DrawText( CString strText )
{
    if( strText.IsEmpty() )
    {
        return;
    }
    static int ncout = ;
    CClientDC dc( this );
    CRect rtclient;
    GetClientRect( &rtclient );
    CBitmap MemBitmap;
    CDC MemDC; //首先定义一个显示设备对象
    MemDC.CreateCompatibleDC( &dc );
    MemBitmap.CreateCompatibleBitmap( &dc , rtclient.Width() , rtclient.Height() );
    MemDC.SelectObject( &MemBitmap );
    MemDC.FillSolidRect(   , , rtclient.Width() , rtclient.Height() , RGB(  ,  , ));
    MemDC.SetTextColor( RGB(  ,  , ));
    MemDC.DrawText( strText , &rectRetangle , DT_LEFT );//字幕向左滚动；

    MemDC.SetTextColor( RGB(  ,  ,  ) );//先把这段歌词全部显示
    MemDC.DrawText( strText , &RectShow , DT_LEFT );

    MemDC.SetTextColor( RGB( ,  ,  ));//在把要变色的再显示一遍；
    MemDC.DrawText( strText , &rectColor , DT_LEFT );

    dc.BitBlt(  ,  , rtclient.Width() , rtclient.Height() , &MemDC , ,  , SRCCOPY );
    MemBitmap.DeleteObject();
    MemDC.DeleteDC();
    ncout ++;

}
int CShowFontView::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
    if (CView::OnCreate(lpCreateStruct) == -)
        return -;
    readGeci();
    SetTimer(  ,  , );
    return ;
}

BOOL CShowFontView::OnEraseBkgnd(CDC* pDC)
{

    return CView::OnEraseBkgnd(pDC);
}
void CShowFontView::readGeci()
{
    CStdioFile dlg;
    if(    dlg.Open("res\\text.txt" , CFile::modeRead ) )
    {
        CString strText;
        while ( dlg.ReadString( strText ))
        {
            m_ListCtring.AddHead( strText );
        }
        dlg.Close();
    }
}
CString CShowFontView::GetGeci( int nindex )
{
    CString strText;
    if( nindex < m_ListCtring.GetCount()&& m_ListCtring.GetCount()> )
        strText = m_ListCtring.GetAt( m_ListCtring.FindIndex( m_ListCtring.GetCount() -nindex -  ));
    else
        KillTimer();
    return strText;
}