QLinearGradient 绘制渐变效果

    void paintEvent(QPaintEvent* e) {        QPainter p(this);        p.setRenderHints(QPainter::Antialiasing |                         QPainter::SmoothPixmapTransform);        QLinearGradient lightLinearGrad;        lightLinearGrad.setSpread(QGradient::PadSpread);        lightLinearGrad.setStart(x(), 0);        lightLinearGrad.setFinalStop(x(), height());        p.setPen(Qt::NoPen);        lightLinearGrad.setColorAt(0, QColor(248, 248, 248, 248));        lightLinearGrad.setColorAt(1, QColor(255, 255, 255, 0));    //    QPainterPath path;        p.setBrush(QBrush(lightLinearGrad));        p.drawRect(this->rect());    }