QPointF QGraphicsItem::mapToScene(const QPointF &point) const

QPointF QGraphicsItem::mapToScene(const QPointF &point) const{    if (d_ptr->hasTranslateOnlySceneTransform())        return QPointF(point.x() + d_ptr->sceneTransform.dx(), point.y() + d_ptr->sceneTransform.dy());    return d_ptr->sceneTransform.map(point);}/*!    \fn QPointF QGraphicsItem::mapToScene(qreal x, qreal y) const    \overload    This convenience function is equivalent to calling mapToScene(QPointF(\a    x, \a y)).*//*!    Maps the rectangle \a rect, which is in this item's coordinate system, to    \a item's coordinate system, and returns the mapped rectangle as a polygon.    If \a item is 0, this function returns the same as mapToScene().    \sa itemTransform(), mapToParent(), mapToScene(), mapFromItem(), {The    Graphics View Coordinate System}*/

这个mapToScene()返回的倒底是什么？