Implementing Drag and Drop with QTreeView

jonasqt

I am trying to implement drag and drop for a TreeView using a model based off of QAbstractItemModel, taken from this example.

As instructed here I have enabled my TreeView for drag&drop like so:

view->setDragDropMode(QAbstractItemView::InternalMove);
view->setSelectionMode(QAbstractItemView::ExtendedSelection);
view->setDragEnabled(true);
view->setAcceptDrops(true);
view->setDropIndicatorShown(true);

I have set the appropriate flags in my model as well:

Qt::ItemFlags TreeModel::flags(const QModelIndex &index) const
{
    if (!index.isValid())
        return 0;

    return Qt::ItemIsDragEnabled | Qt::ItemIsDropEnabled | Qt::ItemIsEditable | QAbstractItemModel::flags(index);
}

And reimplemented QAbstractItemModel::supportedDropActions()

Qt::DropActions TreeModel::supportedDropActions() const
{
    return Qt::CopyAction | Qt::MoveAction;
}

I have also implemented DropMimeData() as follow, still no luck though.

bool TreeModel::dropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent){

    if(!canDropMimeData(data, action, row, column, parent))
            return false;

    if (action == Qt::IgnoreAction)
        return true;

    int beginRow;

    if (row != -1)
        beginRow = row;
    else if (parent.isValid())
        beginRow = parent.row();
    else
        beginRow = rowCount(QModelIndex());

   QModelIndex grandParent = parent.parent();
    insertRow(beginRow, grandParent);
    setData(parent.child(beginRow, 0), data);

    return true;

}

The result is that I insert a brand new row into where the item is dropped. The old row isn't deleted and the new one contains no data.

When hovering over another before dropping a box appears around a row but not a line between two rows indicating insertion. My model is trying to add the dropped item as a child: I found that the row and column passed to dropMimeData are both -1. While the parent's QModelIndex, points to the place where the item has been dropped. Do I need to set this "insert" behaviour somewhere?

Perhaps my model is unsuitable?