C++ How to enumerate QGraphicsItem's? - c++

Question

Using this function, I can delete selected QGraphicsItem's from a QGraphicsView.
How can I get my ellipses enumerated in order to receive a notification like "Deleted ellipse n°...".
void MainWindow::deleteItem()
{
foreach (QGraphicsItem *item, scene->selectedItems()) {
if (item->type() == ellipse->Type) {
scene->removeItem(item);
delete item;
QMessageBox::information(this,"Notification", "Deleted");
}
}
}

Answer 1

A few ways
Assuming you only care about that iteration:
int ix = 0; // add this
foreach (QGraphicsItem *item, scene->selectedItems()) {
if (item->type() == ellipse->Type) {
scene->removeItem(item);
delete item;
std::cout << "Deleted ellipse number " << ix++ << std::endl; // and add this
QMessageBox::information(this,"Notification", "Deleted");
}
}
The above only works if your ordering only corresponds to that foreach() loop. If your items are in some arbitrary order:
std::unordered_map<QGraphicsItem*, int> mGraphicsItems;
That's assuming you can populate it, of course. If you can, do a lookup before calling delete(), to get the value which is the enumeration. Not very elegant though, and adds space.
Other way is to subclass QGraphicsItem [Untested code but you get the idea]
class MyGraphicsItem : public QGraphicsItem
{
Q_OBJECT
public:
// snip
int index() const { return mIndex; }
void setIndex( int i ) { mIndex = i; }
private:
int mIndex;
};
Just set the index in whatever way you want when the QGraphicsItem is created, and before calling delete, print out (or do whatever) with item->index();