change "+" symbol to other symbol when dragging an item from listview to treeview .

Chris Kawa

You should handle these events on the widget you want to handle the drop (the listview), not on main window. That's one.

Second - why are you creating new QDrag objects in every move event? There are gonna be tons of them and you are not releasing any of them! There is already a drag in progress. Don't create new ones.

Don't change the cursor in move event. Set a cursor for drag object where you create it (I'm guessing in mouse press of the treeview?) and don't touch again. It will change when you accept or not a move event.

Ratzz

@Chris-Kawa
How to create the events on widgets? like show below??

void QListView::dragMoveEvent(QDragMoveEvent *event)
{
//
}

I do not want to to change the cursor on entire drag event from listview to treeview. I just want to change the cursor when there is empty space as shown here and not when like this.

Chris Kawa

Subclass QListView and override dragEnterEvent, dragMoveEvent and dropEvent.

In dragEnterEvent check the mime type in parameter and event->acceptProposedAction if it's something you can drop onto the list.
In dragMoveEvent check cursor position and event->acceptProposedAction() or event->ignore(), depending on the cursor position.
In dropEvent get the event data and physically insert item into list.

You don't really need to set any cursors. It will change automatically when you accept or ignore the event in the dragMoveEvent.

Ratzz

@Chris-Kawa
I tried this way. Is this the way to do??

void QlistView::dragMoveEvent(QDragMoveEvent *event) Q_DECL_OVERRIDE
{
    QPoint cursorPosition = event->pos() ;
    QModelIndex index = BusAnalyzerWindow::ui->listView_Messages->indexAt(cursorPosition);
    if(index.isValid())
        event->acceptProposedAction();
}

void QListView::dragEnterEvent(QDragEnterEvent *event) Q_DECL_OVERRIDE
{
    if (event->mimeData()->hasFormat("application/x-qabstractitemmodeldatalist"))
        event->acceptProposedAction();
}
void QListView::dropEvent(QDropEvent *event)
{
    event->setDropAction(Qt::MoveAction);
    event->accept();
}

But dragEnterEvent is not member of Qlistview So it failed.

Chris Kawa

You can't just overwrite QListView methods. As I said - subclass QListView and override the methods there.

Aside from that you should also event->ignore() in a dragMoveEvent else clause.

Ratzz

@Chris-Kawa
I dono how to subclass QListView and override .

Chris Kawa

If you don't know how inheritance works in c++ maybe you should start with some basics before getting into ui development with Qt? You can start here, but I suggest a good book that covers these topics, maybe one of these?

Ratzz

@Chris-Kawa
I will look into it.

Ratzz

@Chris-Kawa
I tried these ways . But none of the two is working.

myWindow::myWindow(QWidget *parent,QMdiArea *mdiParent):
    QWidget(parent),
    QListView(parent)
    ui(new Ui::myWindow)
{
    ui->setupUi(this);
//
}

nor this as suggested here .

class myWindow: public QWidget
{
    Q_OBJECT
 
public:
    explicit myWindow(QWidget *parent = 0, QMdiArea *mdiParent=0)
        : QListView (paren,mdiParent ){}
      ......

Is there any document giving info about subclass?

Ratzz

I used dragMoveEvent to restrict the + symbol.

        void dragMoveEvent(QDragMoveEvent *event)
        {
            QPoint cursorPosition = event->pos() ;
            QModelIndex index = indexAt(cursorPosition);
            if(index.parent().isValid())
            {
                event->acceptProposedAction();
            }
            else
                event->ignore();
        }