#ifndef LINK_H#define LINK_H#include <QGraphicsLineItem>class Node;class Link : public QGraphicsLineItem{public:    Link(Node *fromNode, Node *toNode);    ~Link();    Node *fromNode() const;    Node *toNode() const;    void setColor(const QColor &color);    QColor color() const;    void trackNodes();private:    Node *myFromNode;    Node *myToNode;};#endif