如何重新实现QGraphicsPixmapItem的itemChange和mouseMoveEvent？

QVariant MyGraphicsPixmapItem::itemChange(QGraphicsItem::GraphicsItemChange change, const QVariant &value)
{
    if (change == QGraphicsItem::ItemPositionChange) {
        // 在此处处理位置变化的逻辑
        QPointF newPos = value.toPointF();
        // ...
        return newPos;
    }
    else if (change == QGraphicsItem::ItemScaleChange) {
        // 在此处处理缩放变化的逻辑
        qreal newScale = value.toReal();
        // ...
        return newScale;
    }
    
    return QGraphicsItem::itemChange(change, value);
}

void MyGraphicsPixmapItem::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
{
    if (event->buttons() & Qt::LeftButton) {
        // 在此处处理鼠标移动的逻辑
        QPointF newPos = event->scenePos();
        // ...
        setPos(newPos);
    }
    
    QGraphicsItem::mouseMoveEvent(event);
}