How to get widgets (QGraphicsProxyWidget) of QGraphicsScene?

Question

I am making use of a QGraphicsScene and I am adding regular widgets (QLineEdit, QComboBox, etc.) to it via implicitly created QGraphicsProxyWidget objects:

m_pLineEdit = new QLineEdit("", 0);
m_pProxy = m_pGraphicsScene->addWidget(m_pLineEdit);

I am currently searching for a way to later retrieve those widgets from the scene again for processing, but am not able to find one.

I tried the following approaches already:

1. Since I cannot pass the graphics scene as parent to the widget constructor, retrieving the widgets via m_pGraphicsScene->findChildren(QLineEdit*) does not work, since there is no direct relation.
2. The graphics scene does have a QGraphicsSceneBspTreeIndex child, but that is not part of the official Qt API and therefore relying on it cannot be the way to go.

Bottom-line: How can I get all the QGraphicsProxyWidget objects from a Qt graphics scene? Can this be done in the Qt standard or do I have to subclass QGraphicsScene and try to manage the widgets myself?

Answer 1

Just after posting the question I by chance found a solution in the Qt source code. The widget proxies are treated as regular QGraphicsItem internally and can be casted via qgraphicsitem_cast:

QList<QGraphicsItem*> graphicsItemList = m_pGraphicsScene->items();
foreach(QGraphicsItem* pGraphicsItems, graphicsItemList)
{
    QGraphicsProxyWidget* pProxy = qgraphicsitem_cast<QGraphicsProxyWidget*>(pGraphicsItems);
    if(pProxy)
    {
        QLineEdit* pLineEdit = qobject_cast<QLineEdit*>(pProxy->widget());
        if(pLineEdit)
            // do stuff
    }
}   

If someone knows a simpler/faster method, I'd be happy to hear about it. Until then I will use the approach outlined above.