Drag & drop with model/view (Qt4)

[wysota]

You need to remplement mouse events and rendering-related methods (which in practice makes up most if not all of the view code).

[Nickolay]

In very simple case, in current default implementation, to implement row moving inside one table,
what is the best approach with functions removeRows and insertRows?
Could I use them directly one after another inside dropMimeData?
So I can pack in MIME number of line of dragged item and inside dropMimeData I retrieve number of drop line.

[wysota]

what is the best approach with functions removeRows and insertRows?
Could I use them directly one after another inside dropMimeData?

I would say it is better to use QAbstractItemModel::beginMoveRows() and QAbstractItemModel::endMoveRows() in this case. In a general case dropMimeData() would only insert rows and rows removal would be done in the code when the drag is started when a "move" operation is detected.

[Nickolay]

I'm not clearly understand what do you mean.
generally I didn't get what sense of QAbstractItemModel::beginMoveRows() and QAbstractItemModel::endMoveRows()

By docs I should use them from removeRows, like

bool TableModel::removeRows(int position, int rows, const QModelIndex& index)
{
Q_UNUSED(index);
beginRemoveRows(QModelIndex(), position, position + rows - 1);
endRemoveRows();
return true;
}

But dragging begins from const func mimeData, where I can't call non const method.

and rows removal would be done in the code when the drag is started when a "move" operation is detected.

Where that place you have mentioned?

[wysota]

I suggest you read a little about model-view framework in Qt. Everything should become clearer then. One hint -- drag and drop in Qt is handled in the model and not in the view.