Dragging from an inherited QTableView - qt

Question

I have in my app a table view called "partsview" which is descended from a QTableView, this is on the main form. The relevant header code looks like:
class partsiew : public QTableView
{
Q_OBJECT
public:
explicit partsview(QWidget *parent = 0);
public:
QStringList mimeTypes() const;
QMimeData *mimeData(const QModelIndexList &indexes) const;
};
I have also added the following into the constructor of "partsview":
this->setSelectionMode(QAbstractItemView::ExtendedSelection);
this->setDragEnabled(true);
this->setAcceptDrops(true);
this->setDropIndicatorShown(true);
though the last two are probably not needed.
When dragging, I can pick up a row and drag it to a target - a QTreeView - and I get the appropriate cursor and even a dropMimeData event is fired on the treeview.
However, the row and column values in the dropMimeData() method are always -1 and the two methods in the "partsview" are not called.
I'm guessing that the first error may have something to do with the second. Have I declared the mimeType() and mimeData() methods correctly for them to be called during a drag operation.
I have been following this page in the documentation QT4.6 - Using Model/View Classes

Answer 1

Here is the link for the most recent documentation on it:
http://doc.qt.io/qt-5/model-view-programming.html#using-drag-and-drop-with-item-views
I recently worked on some code for doing an internal move of cells on a single table, but while I was researching it, I found some other useful links.
http://qt-project.org/forums/viewthread/14197
I used the code in the above link and translated it to use QTableView instead of QTableWidget:
void MyTableView::dropEvent(QDropEvent *event)
{
// TODO: switch to using EyeTrackerModel::dropMimeData instead
QPoint old_coordinates = QPoint(-1,-1);
int dropAction = event->dropAction();
if(currentIndex().isValid()) //Check if user is not accessing empty cell
{
old_coordinates = QPoint( currentIndex().row(), currentIndex().column() );
}
QTableView::dropEvent(event);
qDebug() << "Detected drop event...";
event->acceptProposedAction();
if( this->indexAt(event->pos()).isValid() && old_coordinates != QPoint(-1, -1))
{
qDebug() << "Drop Event Accepted.";
qDebug() << "Source: " << old_coordinates.x() << old_coordinates.y()
<< "Destination: " << this->indexAt(event->pos()).row()
<< this->indexAt(event->pos()).column()
<< "Type: " << dropAction;
emit itemDropped( old_coordinates.x(), old_coordinates.y(),
this->indexAt(event->pos()).row(),
this->indexAt(event->pos()).column(),
dropAction);
}
// resize rows and columns right after a move!
this->doAdjustSize();
}
Even though the following answer is for Python, it still helped me when checking for what I could be missing.
QT: internal drag and drop of rows in QTableView, that changes order of rows in QTableModel
Here are some code snippets from my recent project related to drag and drop. I think you have most of them already, but I included them below for completeness.
QAbstractTableModel::dropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent)
Qt::ItemFlags QAbstractTableModel::flags(const QModelIndex &index) const
{
Q_UNUSED(index)
// if(index.isValid())
return Qt::ItemIsDragEnabled | Qt::ItemIsDropEnabled | Qt::ItemIsEditable | Qt::ItemIsEnabled | Qt::ItemIsSelectable;
// else
// return Qt::ItemIsDropEnabled | Qt::ItemIsEditable | Qt::ItemIsEnabled | Qt::ItemIsSelectable;
}
QAbstractTableView(QWidget *parent) :
QTableView(parent)
{
setAcceptDrops(true);
setDefaultDropAction(Qt::MoveAction);
}
Hope that helps.