由於不同的字用不同的樣式，所以需要用到html來設定：

//add take buttons with tips
//設置text和樣式
    QTextDocument Text_finish;
    Text_finish.setHtml("<font size='28' color='white'>取貨完成</font><br><font size='4' color='white'>請先関好蓋並拉好門</font>");
//放入pixmap中
    QPixmap pixmap_finish(Text_finish.size().width(), Text_finish.size().height());
    pixmap_finish.fill( Qt::transparent );
//使用painter畫
    QPainter painter_finish( &pixmap_finish );
    Text_finish.drawContents(&painter_finish, pixmap_finish.rect());

    QIcon ButtonIcon_finish(pixmap_finish);
    ui->btn_take_takepage_finish->setIcon(ButtonIcon_finish);
    ui->btn_take_takepage_finish->setIconSize(pixmap_finish.rect().size());