void Node dragEnterEvent QGraphicsSceneDragDr opEvent event if event-

  void Node::dragEnterEvent(QGraphicsSceneDragDropEvent *event)
 {
     if (event->mimeData()->hasColor()){
         event->setAccepted(true);
         dragOver = true;
         update();
     } else {
         event->setAccepted(false);
     }
 }

 void Node::dragLeaveEvent(QGraphicsSceneDragDropEvent *event)
 {
     Q_UNUSED(event);
     dragOver = false;
     update();
 }

 void Node::dropEvent(QGraphicsSceneDragDropEvent *event)
 {
     dragOver = false;
     if (event->mimeData()->hasColor())
         color = qVariantValue<QColor>(event->mimeData()->colorData());
     else if (event->mimeData()->hasImage())
         pixmap = qVariantValue<QPixmap>(event->mimeData()->imageData());
     update();
     this->xpos = this->x();
     this->ypos = this->y();
 }