On 21/08/12 23:55, Stephen Chu wrote: > On 8/21/12 4:26 PM, Nikos Chantziaras wrote: >> On 21/08/12 22:45, Stephen Chu wrote: >>> On 8/21/12 3:35 PM, Christoph Feck wrote: >>>> On Tuesday 21 August 2012 20:55:00 Stephen Chu wrote: >>>>> Is there a way to store a 64-bit internal ID in QModelIndex? The >>>>> function QModelIndex::internalId() returns a 64-bit number but >>>>> there's no way to put one in. The constructor takes only a 32-bit >>>>> integer. >>>> >>>> Try using the overload that takes the void * pointer. The return value >>>> is 64 bit, because pointers can also be 64 bit, and C++ doesn't allow >>>> different overloads with different return values. >>> >>> Thanks for the help. But my app is currently 32-bit. :( >> >> Would a pointer to a qint64 work? > > Yes, it will. I was thinking about that but got stuck trying to figuring > out how I can manage the memory since QModelIndedx does not own the > object/memory pointed by the void* > > Say I allocate a QList<int64_t> and create indices with internal pointer > pointing to elements in the list. When I need to update the model from > external data, I will have to re-allocate the list and the existing > pointers will be left dangling. What is the proper steps to update the > model data in this case?
Note that I didn't work with QAbstractItemModel before, so perhaps I'm not the most suitable person here to give advice. With that being said, you might be able to allocate like this: createIndex(row, column, new qint64(value)); Access the value with: *(qint64*)internalPointer(); And when you don't need the QModelIndex anymore, you deallocate like this: delete (qint64*)internalPointer(); You should probably create wrappers for those operations. Or work out a subclass model. But again, I didn't work with that part of Qt before, so I might be talking gibberish here ;-) _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
