How to load a QML file into a QGraphicsScene in Qt5

问题

I tried to load a qml file into a QGraphicsScene using this code :

QGraphicsScene* scene = new QGraphicsScene;
QQmlEngine *engine = new QQmlEngine;
QQmlComponent component(engine,"main.qml",QQmlComponent::PreferSynchronous);
qDebug()<<component.errors();
QGraphicsObject *object =
 qobject_cast<QGraphicsObject *>(component.create());
scene->addItem(object);

errors() returns nothing and the app output says :

QGraphicsScene::addItem: cannot add null item

回答1:

You can't use QtQuick2 (Qt5's new version of QtQuick/QML) with QGraphicsScene. You need to use it with QQuickView.

If you need to zoom the QML file to make it fit the QQuickView, just use QQuickView::setResizeMode to resize the root object to your view(QQuickView::SizeRootObjectToView).

回答2:

You cannot cast this QObject into a QGraphicsObject. The object instance from QQmlComponent is not a subclass of QGraphicsObject. That's why your cast returns a 0 pointer.

来源：https://stackoverflow.com/questions/18192968/how-to-load-a-qml-file-into-a-qgraphicsscene-in-qt5