[SOLVED] supportedDropActions() in QAbstractItemModel

Anticross · wrote on 12 Sept 2011, 12:02

I've got class based on QAbstractItemModel and need realize drag'n'drop using it. Model is based on a 2-level tree structure. 2-level elements can be draged and dropped inside its parent and from one parent to another. I done almost all and stacked in supportedDropActions(). I need to move items by default and copy them if Ctrl key is pressed when dropping. But I can't return right flag to do this. Looking for examples or anything that can help.

Anticross · wrote on 12 Sept 2011, 13:26

I reimplement :dropMimeData, mimeData and mimeTypes functions and now my supportedDropActions functions looks like this:
@Qt::DropActions GroupsModel::supportedDropActions() const
{
return Qt::CopyAction | Qt::MoveAction;
}@
But only move action works.

goetz · wrote on 13 Sept 2011, 06:42

Define "works"! Do you actually support the copy in your model?

Anticross · wrote on 13 Sept 2011, 07:06

All that I've got is : DropMImeData function:
@
bool GroupsModel::dropMimeData( const QMimeData * data, Qt::DropAction action, int row, int col, const QModelIndex & parent )
{
QByteArray encodedData = data->data("text/plain");
QDataStream stream(&encodedData, QIODevice::ReadOnly);

int takedGpIndex, takedSubIndex;

while (!stream.atEnd()) {
stream >> takedGpIndex >> takedSubIndex;

if(takedGpIndex == -1 || takedSubIndex == -1)
continue;

// *********************************take item calculations ***********************//

// get place in structure
Group * takedGp = m_groups.getGroupByIndex(takedGpIndex);

if(takedGp == NULL)
continue;

GroupSubscriber * sub = takedGp->getSubscriberByIndex(takedSubIndex);

if(sub == NULL)
continue;

// ********************************* drop place calculations ***********************//

// get place in structure

int putGpNdx = -1;

if(parent.isValid())
if(parent.internalId() != -1)
putGpNdx = parent.row();
else
putGpNdx = row;

if(putGpNdx == -1)
continue;

Group * putGp = m_groups.getGroupByIndex(putGpNdx);

if(putGp == NULL)
continue;

// put data

QModelIndex putParent = index(putGpNdx,eID,m_null);

if(takedGp == putGp)
{
if(row == -1)
continue;

if(row >= putGp->count())
{
int pRow = putGp->count();
beginInsertRows(putParent,pRow,pRow);
GroupSubscriber * newSub = new GroupSubscriber(*sub);
putGp->addSubscriber(newSub);
endInsertRows();
}
else
{
beginInsertRows(putParent,row,row);
takedGp->copySubscriber(takedSubIndex,row);
endInsertRows();

if(takedSubIndex>row)
 takedSubIndex++;

}
}
else
{
if(row == -1)
{
int pRow = putGp->count();
beginInsertRows(putParent,pRow,pRow);
GroupSubscriber * newSub = new GroupSubscriber(*sub);
putGp->addSubscriber(newSub);
endInsertRows();
}
else
{
beginInsertRows(putParent,row,row);
GroupSubscriber * newSub = new GroupSubscriber(*sub);
putGp->insertSubscriber(newSub,row);
endInsertRows();
}
}

m_bChanged = true;

if(action == Qt::MoveAction)
{
QModelIndex takeParent = index(takedGpIndex,eID,m_null);
// if non-copy event need to delete old item and structure data

//remove data from structure
beginRemoveRows(takeParent,takedSubIndex,takedSubIndex);
takedGp->removeSubscriber(takedSubIndex);
endRemoveRows();
}

}

return true;
}@
MimeData :
@QMimeData * GroupsModel::mimeData( const QModelIndexList & indexes ) const
{
QMimeData * mimeData = new QMimeData();
QByteArray encodedData;

QDataStream stream(&encodedData, QIODevice::WriteOnly);

foreach (QModelIndex index, indexes) {
if (index.isValid() == false)
continue;

if(index.column() != eID)
continue;

int gpNdx = -1;
int subNdx = -1;

if(index.parent().isValid())
{
// this is subscriber
gpNdx = index.parent().row();
subNdx = index.row();
}

stream << gpNdx << subNdx;
}

mimeData->setData("text/plain", encodedData);
return mimeData;
}@
MimeTypes:
@
QStringList GroupsModel::mimeTypes() const
{
QStringList types;
types << "text/plain";
return types;
}@
And supportedDropActions. I made standart treeView in *.ui file and set this model to it. So what I need to do to support copy in my model?

Anticross · wrote on 14 Sept 2011, 08:11

When I put a breakpoint and get to dropMimeData function action always is MoveAction, but visually I can see "+" near my item when holding "ctrl" key.

Anticross · wrote on 14 Sept 2011, 10:43

One more question: did I need reimplement removeRow() function from QAbstractItemModel, can it be the reason why action doesn't changes ?

Anticross · wrote on 15 Sept 2011, 07:24

Eureka ! Only one thing that I need to do just change dragDropMode in QTreeView from InternalMove to DragDrop. And Modified version of dropMimeData now looks like this :
@bool GroupsModel::dropMimeData( const QMimeData * data, Qt::DropAction action, int row, int col, const QModelIndex & parent )
{
QByteArray encodedData = data->data("text/plain");
QDataStream stream(&encodedData, QIODevice::ReadOnly);

int takedGpIndex, takedSubIndex;

QModelIndexList deleteList;

while (!stream.atEnd()) {
stream >> takedGpIndex >> takedSubIndex;

if (takedGpIndex < 0 || takedSubIndex < 0)
continue;

// ********************************* take item calculations ***********************//

// get place in structure
Group * takedGp = m_groups.getGroupByIndex(takedGpIndex);
if (takedGp == NULL)
continue;

GroupSubscriber * sub = takedGp->getSubscriberByIndex(takedSubIndex);
if(sub == NULL)
continue;