在QT4中实现方法：

        QFontMetrics    metr(m_Font);
        int             nWidth, nHeigh;
        qreal           rx, ry;
        QPointF         qPos, qpf;
        QRectF          rect; // m_rect为原始绘制区域

        nWidth = metr.size(Qt::TextDontClip, strTemp).width();
        nHeigh = metr.size(Qt::TextDontClip, strTemp).height();
        rx = (qreal)m_rect.width() / (qreal)nWidth;
        ry = (qreal)m_rect.height() / (qreal)nHeigh;
        qPos = boundingRect().topLeft();
        qpf = QPointF(m_rect.topLeft());

        painter->translate(qpf);
        painter->scale(rx, ry);
        rect = QRectF(0, 0, m_rect.width(), m_rect.height());
        painter->setPen(m_nClrText);
        painter->drawText(rect, strTemp);

在QT5中实现有所不同：

        QTextOption option;
        option.setAlignment(m_euAlign); // 这里设置文字其他属性
        option.setWrapMode(QTextOption::WrapMode::WrapAtWordBoundaryOrAnywhere);
        painter->drawText(m_rect, strTemp, option);