Qt将扩展的QGraphicsItem添加到场景

Question

I have created a class Atom that extends the Qt class QGraphicsItem like this:

Atom::Atom(qreal rad, qreal mass, int element, int state) : QGraphicsItem()
{
    // Initialization code
}
void Atom::changeState(int newState)
{
    // Code...
}

Then, I add my atom to the scene like this:

Atom *a=new Atom(rad,mass,element,state);
a->setPos(pos);
scene->addItem(a);

However, Qt converts my Atom class to a QGraphicsItem class. Now, when I call scene->items() , I get a QList of QGraphicsItems, which do not have the properties and methods of my Atom class.

So, I am asking the question: How would I go about getting a list of the Atoms that I have added to my QGraphicsScene?

Thanks.

Answer 1

You'll need to cast the QGraphicsItems to Atoms. Please see this question for details:

Subclassing QGraphicsItem prevents me from being able to use itemAt() on a QGraphicsScene/View

Answer 2

No. Your items are not converted to anything. They are still of your custom type. In C++, all objects of a derived class are also of class they derive from. Nothing is converted so nothing is lost.

Do a dynamic_cast<Atom*>(item) and you will get your item back.