How to create a QList<QGraphicsItem>

frnklu20

It would help me a lot if i could do tis, but it gives me an error if i try to

SGaist

Hi,

What are you doing ?
What errors do you get ?

frnklu20

hi,

QList<QGraphicsItem> list;

in the code it doesn't show any error, but in the compiler it says
"ivalid abstract return type 'QGraphicsItem'"

mrjj

Hi
Should that not be
QList<QGraphicsItem *>
so its a list of pointers to QGraphicsItem's
also the scene has such list already. (just in case)
https://doc.qt.io/qt-5/qgraphicsscene.html#items

spobit

QList will call follow code to create object:

template <typename T>
Q_INLINE_TEMPLATE void QList<T>::node_construct(Node *n, const T &t)
{
    if (QTypeInfo<T>::isLarge || QTypeInfo<T>::isStatic) n->v = new T(t);
    else if (QTypeInfo<T>::isComplex) new (n) T(t);
#if (defined(__GNUC__) || defined(__INTEL_COMPILER) || defined(__IBMCPP__)) && !defined(__OPTIMIZE__)
    // This violates pointer aliasing rules, but it is known to be safe (and silent)
    // in unoptimized GCC builds (-fno-strict-aliasing). The other compilers which
    // set the same define are assumed to be safe.
    else *reinterpret_cast<T*>(n) = t;
#else
    // This is always safe, but penaltizes unoptimized builds a lot.
    else ::memcpy(n, static_cast<const void *>(&t), sizeof(T));
#endif
}

But QGraphicsItem is a abstract class, See, boundingRect(), paint(), that causes compilation to failed.