Hello forum,


I would like to discuss some design issues which may not related directly to Qt, but in some way it is because i am using the graphics view network to get around with this.

I have a class ArrowGraphicsItem (Subclass of QGraphicsItem) as follows:

Qt Code: 
  1. class ArrowGraphicsItem : public QGraphicsItem
  2. {
  3. public:
  4.  
  5.     /**
  6.       * \param the source graphics item for the arrow
  7.       * \param the destination graphics item for the arrow, by default it is ZERO
  8.       */
  9.     ArrowGraphicsItem(QGraphicsItem *sourceItem,
  10.                       QGraphicsItem *destinationItem = 0);
  11.  
  12.     ~ArrowGraphicsItem();
  13.  
  14.     enum { Type = UserType + UserTypesArrowGraphicsItem };
  15.  
  16.     /**
  17.       * Retruns the type of this class.Necessary for all  QGraphicsItem subclasses
  18.       * \return The type of this class
  19.       */
  20.     int type() const;
  21.  
  22.     /**
  23.       * The bounding rect for the arrow graphics item
  24.       * \return The bounding rect
  25.       */
  26.     QRectF boundingRect() const;
  27.  
  28. ................................................................
  29.  
  30. ................................................................
  31.  
  32. protected:
  33.  
  34.     virtual QPainterPath shape() const = 0;
  35.  
  36.     void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget);
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I have several subclasses which only over-rides the shape() function in their respective subclasses and paint functional definition is always grabbed from default implementation in the ArrowGraphicsItem.


Is that a good design technique ?




Regards
Sajjad