How can I add the graphics rect items to a certain place

[Grimlock]

From Assistant

void QGraphicsItem::setPos ( const QPointF & pos )

Sets the position of the item to pos, which is in parent coordinates. For items with no parent, pos is in scene coordinates.

The position of the item describes its origin (local coordinate (0, 0)) in parent coordinates.

See also pos(), scenePos(), and The Graphics View Coordinate System.

void QGraphicsItem::setPos ( qreal x, qreal y )

This is an overloaded function.

This convenience function is equivalent to calling setPos(QPointF(x, y)).