Prevent QGraphicsItem from moving outside of QGraphicsScene

Question

I have a scene which has fixed dimensions from (0;0) to (481;270):

scene->setSceneRect(0, 0, 481, 270);

Inside of it, I have a custom

Answer 1

Warning: The suggested solutions won't work for multiply selected items. The problem is, only one of the items receives a mouse move event in that case.

Actually, the Qt Documentation on QGraphicsItem provides an example which exactly solves the problem of limiting the movement of items to the scene rect:

QVariant Component::itemChange(GraphicsItemChange change, const QVariant &value)
{
    if (change == ItemPositionChange && scene()) {
        // value is the new position.
        QPointF newPos = value.toPointF();
        QRectF rect = scene()->sceneRect();
        if (!rect.contains(newPos)) {
            // Keep the item inside the scene rect.
            newPos.setX(qMin(rect.right(), qMax(newPos.x(), rect.left())));
            newPos.setY(qMin(rect.bottom(), qMax(newPos.y(), rect.top())));
            return newPos;
        }
    }
    return QGraphicsItem::itemChange(change, value);
}

Note I: You'd have to enable the QGraphicsItem::ItemSendsScenePositionChanges flag:

item->setFlags(QGraphicsItem::ItemIsMovable
               | QGraphicsItem::ItemIsSelectable
               | QGraphicsItem::ItemSendsScenePositionChanges);

Note II: If you only want to react on finished movement, consider using the GraphicsItemChange flag ItemPositionHasChanged