Ok, nice, these three answers (StackView / StackLayout / Loader + Component) were what I was looking for. I tried each one and I think I'll stick with the StackView and the replace method as it's easy to have a fading transition with it. And I've already found a use to improve my code for the Loader so I also thank you for that.
Thx for the help.
No and that's the point, I want to resize my image with the optimized size to display it.
The size could be the size maximum that I can load depending on the memory available.
And so my question is precisely, how to calculate this optimized size for resizing my image depending on the memory available, to display my image even if it is too large (in a QPixmap added within a QGraphicsScene through a QGraphicsPixmapItem)?
IMHO the problem is that QJsonValue QJsonValue::fromVariant(const QVariant & variant) (http://doc.qt.io/qt-5/qjsonvalue.html#fromVariant) can't convert BookMark to QJsonObject. I don't think that adding a custom converter with QMetatype::registerConverter() would help. Looks like you have to do the conversion to QJsonArray yourself.