qt label显示圆形图片

QPixmap MainWindow::PixmapToRound(QPixmap &src, int radius)

{

    if (src.isNull()) {

        return QPixmap();

    }

    QSize size(2*radius, 2*radius);

    QBitmap mask(size);

    QPainter painter(&mask);

    painter.setRenderHint(QPainter::Antialiasing);

    painter.setRenderHint(QPainter::SmoothPixmapTransform);

    painter.fillRect(0, 0, size.width(), size.height(), Qt::white);

    painter.setBrush(QColor(0, 0, 0));

    painter.drawRoundedRect(0, 0, size.width(), size.height(), 99, 99);

    QPixmap image = src.scaled(size);

    image.setMask(mask);

    return image;

}