重新实现mousePressEvent后无法在QGraphicsView中拖动项目

void MyGraphicsView::mousePressEvent(QMouseEvent *event)
{
    QGraphicsView::mousePressEvent(event);
    // 其他事件处理逻辑
}

void MyGraphicsView::mousePressEvent(QMouseEvent *event)
{
    QGraphicsView::mousePressEvent(event);
    
    if (event->button() == Qt::LeftButton && itemAt(event->pos()) != nullptr)
    {
        m_dragging = true;
        m_lastPos = event->pos();
    }
}

void MyGraphicsView::mouseMoveEvent(QMouseEvent *event)
{
    QGraphicsView::mouseMoveEvent(event);
    
    if (m_dragging)
    {
        QPointF offset = event->pos() - m_lastPos;
        m_lastPos = event->pos();
        
        QGraphicsItem *item = itemAt(event->pos());
        if (item != nullptr)
        {
            item->moveBy(offset.x(), offset.y());
        }
    }
}

void MyGraphicsView::mouseReleaseEvent(QMouseEvent *event)
{
    QGraphicsView::mouseReleaseEvent(event);
    
    m_dragging = false;
}