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;

}