Qt: Reordering ListView Items using drag and drop - qt

Question

I have implemented the following methods for drag and drop
void mousePressEvent(QMouseEvent *event);
void dragEnterEvent(QDragEnterEvent *event);
void dragMoveEvent(QDragMoveEvent *event);
void dropEvent(QDropEvent *event);
void startDrag(Qt::DropActions supportedActions);
I have a QListView and have used setIndexWidget() to show a custom widget at each modelindex. I am trying to arrange the items in the listview using drag and drop, However the items in the listview are not arranged properly, I have written the following code:-
MyListView::MyListView(QWidget *parent) :
QListView(parent)
{
setSelectionMode(QAbstractItemView::SingleSelection);
setDragEnabled(true);
setAcceptDrops(true);
setDragDropMode(QAbstractItemView::InternalMove);
setDefaultDropAction(Qt::MoveAction);
setDropIndicatorShown(true);
setDragDropOverwriteMode(true);
setMovement(QListView::Snap);
setFlow(QListView::TopToBottom);
// setStyleSheet("QListView::item {"
// "height: 50px;"
// "border: 1px solid black;}");
}
void MyListView::setModel(QAbstractItemModel *model)
{
QListView::setModel(model);
for (int i=0; i<model->rowCount(); i++)
{
QModelIndex index = model->index(i,0);
ListWidgetItem *widget = new ListWidgetItem;
widget->setIndex(i);;
setIndexWidget(index,widget);
}
}
void MyListView::mousePressEvent(QMouseEvent *event)
{
QModelIndex i = indexAt(event->pos());
if (event->button() == Qt::LeftButton)
{
ListWidgetItem *item = dynamic_cast<ListWidgetItem *>(childAt(event->pos()));
if (!item)
return;
y = event->pos().y()-item->pos().y();
QModelIndex indx = indexAt(event->pos());
currentPixmap = QPixmap::grabWidget(item);
dragPoint = event->pos();
if (event->pos().x() < 25 && indx.row() >= 0)
startDrag(Qt::MoveAction);
}
}
void MyListView::dragEnterEvent(QDragEnterEvent *event)
{
if (event->mimeData()->hasFormat("application/x-QListView-DragAndDrop"))
{
event->accept();
}
else
event->ignore();
}
void MyListView::dragMoveEvent(QDragMoveEvent *event)
{
ListWidgetItem *item = dynamic_cast<ListWidgetItem *>(childAt(event->pos()));
if(!item)
return;
itemList.append(item);
foreach (ListWidgetItem *widget,itemList)
{
if (widget == item)
widget->setStyleSheet("#ListWidget { border-top: 2px solid red; }");
else
widget->setStyleSheet("#ListWidget { border-top: 0px solid black; }");
}
if (event->mimeData()->hasFormat("application/x-QListView-DragAndDrop"))
{
event->setDropAction(Qt::MoveAction);
event->accept();
} else
event->ignore();
}
void MyListView::dropEvent(QDropEvent *event)
{
if (event->mimeData()->hasFormat("application/x-QListView-DragAndDrop")) {
QByteArray itemData = event->mimeData()->data("application/x-QListView-DragAndDrop");
QDataStream dataStream(&itemData,QIODevice::ReadOnly);
QPoint itemPoint;
dataStream >> itemPoint;
ListWidgetItem *item = dynamic_cast<ListWidgetItem *> (childAt(itemPoint));
if(!item)
return;
QModelIndex index = indexAt(event->pos());
int row = index.row();
model()->insertRows(row,1);
QModelIndex idx =model()->index(row,0);
setIndexWidget(idx,item);
if (event->source() == this) {
event->setDropAction(Qt::MoveAction);
foreach (ListWidgetItem *widget,itemList)
{
widget->setStyleSheet("#ListWidget { border-top: 0px solid black; }");
}
itemList.clear();
// model()->removeRow(n+1);
event->accept();
}
} else{
event->ignore();
}
}
void MyListView::startDrag(Qt::DropActions supportedActions)
{
QByteArray itemData;
QDataStream dataStream(&itemData, QIODevice::WriteOnly);
ListWidgetItem *item = dynamic_cast<ListWidgetItem *>(childAt(dragPoint));
dataStream << dragPoint;
QMimeData *mimeData = new QMimeData;
mimeData->setData("application/x-QListView-DragAndDrop", itemData);
drag = new QDrag(this);
drag->setMimeData(mimeData);
drag->setHotSpot(mapToParent(QPoint(item->x(),y)));
drag->setPixmap(currentPixmap);
QModelIndex indx = indexAt(dragPoint);
if (drag->exec(Qt::MoveAction | Qt::CopyAction) == Qt::MoveAction)
{
model()->removeRow(indx.row());
}
}
I have searched but didnt get any proper solution.
Thanks

Answer 1

Have you looked at QAbstractItemView's DragDropMode ? http://qt-project.org/doc/qt-4.8/qabstractitemview.html#dragDropMode-prop
It sounds as though this ius what you are trying to achieve.