QRadialGradient 使用绘制过滤图像

   QRectF rect(boundingRect());

    QPen pen;

    pen.setWidthF(0);

    pen.setColor(m_color);

    painter->setPen(pen);

    QRadialGradient g(rect.width()/2,rect.height()/2,rect.width()/2,rect.width()/2,height()/2);

    g.setColorAt(0.0,Qt::white);

    g.setColorAt(1.0,m_color);

    painter->setBrush(g);

    painter->drawEllipse(rect);