void QMemberData::resizeImage(QImage * image)
{
    if (image != nullptr) {
      //按比例缩放
        QSize size  = {48,48};
        *image = image->scaled (size.width (),size.height (),Qt::KeepAspectRatio);
        //变为圆角
        QPixmap pixmOld =  QPixmap::fromImage (*image);
        QPixmap pixmap(size);
        pixmap.fill (Qt::transparent);
        QPainter painter(&pixmap);
        painter.setRenderHints (QPainter::Antialiasing | QPainter::SmoothPixmapTransform);
        QPainterPath path;
        QRect rect = QRect(QPoint(0,0),size);
        path.addRoundedRect (rect,24,24);
        painter.setClipPath (path);
        painter.drawPixmap (rect,pixmOld);
        *image = pixmap.toImage ();
     }
}

image.png