Hi guys,
I have written the given below sample program. I have two questions

1) I draw some lines (straight lines). Why the coordinates of the line gets changed???
2) The line should appear like rubberBand on mouseMoveEvent too . How to achieve it???

Qt Code: 
  1. class graphicView : public QGraphicsView
  2. {
  3. 	Q_OBJECT
  4. public:
  5. 	graphicView(QGraphicsScene* s);
  6. 	~graphicView(){}	
  7. private:	
  8. 	QPointF m_firstPt;
  9. 	QPointF m_lastPt;		
  10. 	QGraphicsLineItem* m_edgeItem;
  11. 	QGraphicsScene* m_canvas;
  12. 	QVector<QLineF> m_vectorLine;
  13. protected:
  14. 	void mousePressEvent( QMouseEvent* e );	
  15. 	void mouseMoveEvent( QMouseEvent* e );
  16. 	void mouseReleaseEvent( QMouseEvent* e );
  17. 	void drawItems(QPainter *painter,
  18.                              int numItems,
  19.                              QGraphicsItem *items[],
  20.                              const QStyleOptionGraphicsItem options[]);
  21.  
  22.  
  23. };
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Qt Code: 
  1. graphicView::graphicView(QGraphicsScene* s)
  2. :QGraphicsView(s), m_canvas(s){	     
  3. 	 m_edgeItem = new QGraphicsLineItem( 0, m_canvas );	 
  4. }
  5.  
  6. void graphicView::mousePressEvent( QMouseEvent* e ){
  7. 	m_firstPt = e->pos();
  8. 	m_lastPt = e->pos();
  9. }
  10. void graphicView::mouseMoveEvent( QMouseEvent* e ){
  11. 	m_lastPt = e->pos();
  12. }
  13. void graphicView::mouseReleaseEvent( QMouseEvent* e ){
  14. 	m_lastPt = e->pos();	
  15. 	m_edgeItem->setLine( QLineF( m_firstPt, m_lastPt ) );
  16. 	m_vectorLine << QLineF( m_firstPt, m_lastPt );
  17. }
  18. void graphicView::drawItems(QPainter *painter,
  19.                              int numItems,
  20.                              QGraphicsItem *items[],
  21.                              const QStyleOptionGraphicsItem options[]){	
  22. 	painter->setPen(Qt::black );
  23. 	painter->drawLines( m_vectorLine );
  24. }
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Thanks