Qt之SVG：Qt简单使用SVG的介绍_qt svg-CSDN博客 

<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"
"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">

<svg xmlns="http://www.w3.org/2000/svg" version="1.1">
  <circle cx="100" cy="50" r="40" stroke="black"
  stroke-width="2" fill="green" />
</svg>

svg标签中包含了一个circle标签，circle元素的属性定义了这个圆的特性。

圆心：(100,50)，半径：40

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1.

QGraphicsSvgItem：可用于呈现SVG文件内容的QGraphicsItem

    QString path = QApplication::applicationDirPath() + "/circle.svg";
    qDebug() << "[" << __FILE__ << __LINE__ << "]" << path;
    QGraphicsSvgItem * item = new QGraphicsSvgItem(path);
    item->setFlag(QGraphicsItem::ItemIsMovable);
    QGraphicsScene scene;
    scene.addItem(item);

    QGraphicsView view;
    view.setScene(&scene);
    view.show();

2.

    QString path = QApplication::applicationDirPath() + "/circle.svg";
    qDebug() << "[" << __FILE__ << __LINE__ << "]" << path;

    QSvgWidget w(path);
    w.resize(300,300);
    w.show();

3.

    QString path = QApplication::applicationDirPath() + "/circle.svg";
    qDebug() << "[" << __FILE__ << __LINE__ << "]" << path;

    QSvgRenderer render;
    render.load(path);

    QSize size = render.defaultSize();
    qDebug() << "[" << __FILE__ << __LINE__ << "]" << size;
    //(82,82):    40 + 40 + 2
    QPixmap pix(size * 5);
    qDebug() << "[" << __FILE__ << __LINE__ << "]" <<pix.size();
    //pix.fill(Qt::transparent);
    pix.fill(Qt::red);

    QPainter painter(&pix);
    painter.setRenderHint(QPainter::Antialiasing);
    render.render(&painter);

    QLabel label;
    label.setPixmap(pix);
    label.setAlignment(Qt::AlignTop);
    label.show();