Вызов сигнала в mousePressEvent

// абстрактный класс
class NodeEdgeParent : public QGraphicsItem
{
public:
    NodeEdgeParent(GraphWidget *graphWidget);
    enum { Type = UserType + 1 };
    virtual void setTextContent(QString text) = 0;
    virtual QString textContent() const = 0;
    void mousePressEvent(QGraphicsSceneMouseEvent *event) override;
    GraphWidget *graph;
};

class Node : public NodeEdgeParent
class Edge : public NodeEdgeParent

#include "nodeedgeparent.h"
#include <QDebug>
class GraphWidget;

NodeEdgeParent::NodeEdgeParent(GraphWidget *graphWidget): graph(graphWidget)
{

}

void NodeEdgeParent::mousePressEvent(QGraphicsSceneMouseEvent *event)
{
    if (event->button() == Qt::RightButton) {
        qDebug() << "RightButton";
        scene()->clearSelection();
        setSelected(true);
//        emit graph->editItem();
    }
    QGraphicsItem::mousePressEvent(event);
}