//設置字體
    QFont font;
    font.setFamily("Microsoft YaHei");
    font.setPointSize(8);
    QFontMetrics fm(font);
    QRect rec = fm.boundingRect("這是要獲取寬度和高度的字符串");
    //字符串所占的像素寬度,高度
    int textWidth = rec.width();
    int textHeight = rec.height();