如何通过鼠标事件在QListWidget中交换QListWidgetItem？

listWidget->setDragDropMode(QAbstractItemView::DragDrop);

void MyListWidget::mousePressEvent(QMouseEvent *event)
{
    if (event->button() == Qt::LeftButton) {
        // 记录鼠标按下时的位置和选中的QListWidgetItem
        startPos = event->pos();
        QListWidgetItem *item = itemAt(event->pos());
        if (item)
            selectedItems.append(item);
    }
    QListWidget::mousePressEvent(event);
}

void MyListWidget::mouseMoveEvent(QMouseEvent *event)
{
    if (event->buttons() & Qt::LeftButton) {
        // 判断是否开始拖放操作
        int distance = (event->pos() - startPos).manhattanLength();
        if (distance >= QApplication::startDragDistance()) {
            // 设置拖放的数据
            QMimeData *mimeData = new QMimeData;
            QByteArray encodedData;
            QDataStream stream(&encodedData, QIODevice::WriteOnly);
            for (int i = 0; i < selectedItems.size(); ++i) {
                QListWidgetItem *item = selectedItems.at(i);
                QString text = item->text();
                stream << text;
            }
            mimeData->setData("application/x-qabstractitemmodeldatalist", encodedData);
            QDrag *drag = new QDrag(this);
            drag->setMimeData(mimeData);
            drag->exec(Qt::MoveAction);
        }
    }
    QListWidget::mouseMoveEvent(event);
}

void MyListWidget::dropEvent(QDropEvent *event)
{
    if (event->mimeData()->hasFormat("application/x-qabstractitemmodeldatalist")) {
        // 获取拖放的数据
        QByteArray encodedData = event->mimeData()->data("application/x-qabstractitemmodeldatalist");
        QDataStream stream(&encodedData, QIODevice::ReadOnly);
        QStringList strings;
        while (!stream.atEnd()) {
            QString text;
            stream >> text;
            strings.append(text);
        }

        // 根据鼠标释放的位置确定插入的位置
        int index = indexAt(event->pos()).row();
        if (index == -1)
            index = count();

        // 交换QListWidgetItem的位置
        for (int i = 0; i < selectedItems.size(); ++i) {
            QListWidgetItem *item = selectedItems.at(i);
            takeItem(row(item));
            insertItem(index + i, item);
        }

        event->setDropAction(Qt::MoveAction);
        event->accept();
    }
    QListWidget::dropEvent(event);
}