Qt的卡拉OK歌词效果

先上图一张..

实现卡拉OK效果, 主要是使用了QPainter的叠加, 

pTmp.setCompositionMode(QPainter::CompositionMode_Source);
pTmp.fillRect(QRect(0, 0, paintw, rtText.height()), QBrush(Qt::white));
pTmp.fillRect(QRect(0, 0, mPrecent, rtText.height()), QBrush(Qt::blue));

pTmp.setCompositionMode(QPainter::CompositionMode_DestinationIn);
pTmp.drawImage(0, 0, pmMask);
pTmp.setCompositionMode(QPainter::CompositionMode_DestinationOver);

主要函数:

void testLyrics::DrawLyric(QPainter &p, const QRect& rt)
{
    p.setBrush(Qt::darkGray);
    p.drawRect(rect());

    const QString strLyric = mCurLyrics.lyric;
    QFont m_ftLyric(QString::fromLocal8Bit("微软雅黑"), 24, QFont::Bold);

    QPainter pTmp;

    QFontMetrics fm(m_ftLyric);
    QSize textSize = fm.size(Qt::TextSingleLine, strLyric);
    QRect textRect(QPoint(0,0),textSize);
    int paintw = textSize.width();
    int playedW = textSize.width()*0.5;

    QRect rtText = rect();

    //  pTmp.setRenderHints(QPainter::TextAntialiasing, true);
    QImage pmMask(paintw, rtText.height(),QImage::Format_ARGB32);
    pmMask.fill(Qt::transparent);
    if (pTmp.begin(&pmMask))
    {
        pTmp.setFont(m_ftLyric);
        pTmp.setPen(Qt::black);

        pTmp.drawText(pmMask.rect(), strLyric);
    }
    pTmp.end();

    QImage pmFG(paintw, rtText.height(),QImage::Format_ARGB32);
    if (pTmp.begin(&pmFG))
    {
        pTmp.setCompositionMode(QPainter::CompositionMode_Source);
        pTmp.fillRect(QRect(0, 0, paintw, rtText.height()), QBrush(Qt::white));
        pTmp.fillRect(QRect(0, 0, mPrecent, rtText.height()), QBrush(Qt::blue));

        pTmp.setCompositionMode(QPainter::CompositionMode_DestinationIn);
        pTmp.drawImage(0, 0, pmMask);
        pTmp.setCompositionMode(QPainter::CompositionMode_DestinationOver);

        // shadow
        pTmp.setFont(m_ftLyric);
        pTmp.setPen(QColor(0,0,0,0x80));

        pTmp.drawText(pmMask.rect(), strLyric);
    }
    pTmp.end();

    p.drawImage(rtText.left(), rtText.top(), pmFG);
}

实例下载:http://download.csdn.net/detail/robertkun/7297947

转自：http://blog.csdn.net/robertkun/article/details/25059463