Items after dropping from widget to widget missing

Huy Manh

After dragging and dropping an item from a list widget to a list widget, the item disappears in the target list widget.

I used eventFilter for only the list widgets in MainWindow.

bool MainWindow::eventFilter(QObject *target,QEvent *event){
    if (event->type() == QEvent::DragEnter)
       {
          QDragEnterEvent *tDragEnterEvent = static_cast<QDragEnterEvent *>(event);
          tDragEnterEvent->acceptProposedAction();

          return true;
       }
       else if (event->type() == QEvent::DragMove)
       {
          QDragMoveEvent *tDragMoveEvent = static_cast<QDragMoveEvent *>(event);
          tDragMoveEvent->acceptProposedAction();

          return true;
       }
        else if (event->type() == QEvent::Drop)
       {
          QDropEvent *tDropEvent = static_cast<QDropEvent *>(event);
          tDropEvent->acceptProposedAction();

          qDebug() << "OK, execute your task!";

          return true;
       }
       else
       {
           // standard event processing
           return QObject::eventFilter(target, event);
       }


    //return false;
}
//in MainWindow constructor
ui->listWidget->installEventFilter(this);

qDebug showed the debug string after dropping but the item went missing.

Christian Ehrlicher

You filter out the drop events and the wonder why the widget which should receive them don't receive them? Mhh.

Huy Manh

Sorry but I don't know your meaning, I've been using Qt for about 3 months and this is the first time I handle events, so I hope you can help me with this minor problem, thank you.

Christian Ehrlicher

See documentation for QObject::eventFilter(): "... if you want to filter the event out, i.e. stop it being handled further, return true; ..." which is exactly what you're doing.

Huy Manh

Oh, I get it. Can you suggest for me a solution? That is, if I drop an item into the list widget, I have a variable "count" plus 1 and if I drag an item out, "count" minus 1. I thought at first that eventFilter will help me.

Christian Ehrlicher

Drag'n'Drop from a QListWidget to another QListWidget should work out-of-the-box if dragEnabled/acceptDrops is active - see documentation