Starting Drag from QListWidget initiates Unwanted Selection

ModelTech

I have created the start of a drag action from a QListWidget. This QListWidget has selection mode ExtendedSelection, see also http://doc.qt.io/qt-4.8/qabstractitemview.html#SelectionMode-enum I would l like to keep this behavior except for the fact that it shouldn't do the selection behavior originating from drag events. How can I exclude selecting items by dragging with selection mode ExtendedSelection?

SGaist

Hi,

What do you mean by you *you created the start of a grad action" ? Aren't you using the already implemented in Qt's item view classes ?

ModelTech

Here is the code for the QWidget where the QDrag starts

void ClassList::mousePressEvent(QMouseEvent *Event) {

    if (Event->button() == Qt::LeftButton)
        DragStartPosition = Event->pos();
    QListWidget::mousePressEvent(Event);
}

void ClassList::mouseMoveEvent(QMouseEvent *Event) {

    if (Event->buttons() & Qt::LeftButton) {
        int Distance = (Event->pos() - DragStartPosition).manhattanLength();
        if (Distance >= QApplication::startDragDistance())
            performDrag();
    }
    QListWidget::mouseMoveEvent(Event);
}

void ClassList::performDrag() {

    if (currentItem())
        if (currentItem()->foreground() == Qt::black) {
            InstantiableItem *Current = static_cast<InstantiableItem *>(currentItem());
            InstantiableMime *Mime = new InstantiableMime(Current->item());
            Mime->setText(QString(Current->item()->name()));
            QDrag *Drag = new QDrag(this);
            Drag->setMimeData(Mime);
            Drag->setPixmap(Current->icon().pixmap(QSize(20, 20)));
            Drag->exec(Qt::MoveAction);
        }
}

InstantiableItem is my subclass of QListWidgetItem and InstantiableMine is my subclass of QMimeData. ClassList is a subclass of QListWidget.

SGaist

I'd recommend rather implementing your own list model based on the drag and drop model described here.

That will likely make your implementation simpler and cleaner.