Set this in the program:
MusicLabel=new QCPItemText(MusicCustomPlot);
MusicLabel->setFont(QFont("微软雅黑", 11));
MusicLabe->setColor(Qt::white);
MusicLabel->setPositionAlignment(Qt::AlignHCenter | Qt::AlignVCenter);
MusicLabel->position->setCoords(MusicEQcurve->CurvePF, MusicEQcurve->CurveGain);
MusicLabel->setText(" "+QString::number(i+1)+" ");
MusicLabel->setBrush(QImage(":/image/yuan.png"));