Qt: QListView change behaviour of MultiSelection selection mode

Question

I have QListView with MultiSelection option for selecting items.

listView->setSelectionMode(MultiSelection);

It is exactly what I want except one thing. I don't want a deselect behaviour on drag select(When I'm dragging over selected items they become unselected). I want items below drag selection to be always selected.

Is there a way to change this behaviour?

UPDATE: Wrapping is enabled so items are drawn in a couple of lines.

Answer 1

To change the selection behaviour of the QListView you should re-implement QAbstractItemView::selectionCommand function. Here is an example:

mylistwidget.h

#ifndef MYLISTWIDGET_H
#define MYLISTWIDGET_H

#include <QListWidget>
#include <QItemSelectionModel>

class MyListWidget : public QListWidget
{
    Q_OBJECT
public:
    explicit MyListWidget(QWidget *parent = 0);

protected:
    virtual QItemSelectionModel::SelectionFlags selectionCommand(const QModelIndex &index,
                                                                 const QEvent *event = 0) const;
};

#endif // MYLISTWIDGET_H

mylistwidget.cpp

MyListWidget::MyListWidget(QWidget *parent) :
    QListWidget(parent)
{
}

QItemSelectionModel::SelectionFlags MyListWidget::selectionCommand(const QModelIndex & index, const QEvent * event) const
{
    QItemSelectionModel::SelectionFlags flags = QAbstractItemView::selectionCommand(index, event);

    if (event->type() == QEvent::MouseMove)
    {
        flags &= ~QItemSelectionModel::Toggle;
        flags |= QItemSelectionModel::Select;
    }

    return flags;
}