1  import java.awt.*;

  2  import java.awt.geom.*;

  3  

  4  /**

  5     A class that supplies convenience implementations for 

  6     a number of methods in the Edge interface type.

  7  */

  8  public abstract class AbstractEdge implements Edge

  9  {  

 10     public Object clone()

 11     {

 12        try

 13        {

 14           return super.clone();

 15        }

 16        catch (CloneNotSupportedException exception)

 17        {

 18           return null;

 19        }

 20     }

 21  

 22     public void connect(Node s, Node e)

 23     {  

 24        start = s;

 25        end = e;

 26     }

 27  

 28     public Node getStart()

 29     {

 30        return start;

 31     }

 32  

 33     public Node getEnd()

 34     {

 35        return end;

 36     }

 37  

 38     public Rectangle2D getBounds(Graphics2D g2)

 39     {

 40        Line2D conn = getConnectionPoints();      

 41        Rectangle2D r = new Rectangle2D.Double();

 42        r.setFrameFromDiagonal(conn.getX1(), conn.getY1(),

 43              conn.getX2(), conn.getY2());

 44        return r;

 45     }

 46  

 47     public Line2D getConnectionPoints()

 48     {

 49        Rectangle2D startBounds = start.getBounds();

 50        Rectangle2D endBounds = end.getBounds();

 51        Point2D startCenter = new Point2D.Double(

 52              startBounds.getCenterX(), startBounds.getCenterY());

 53        Point2D endCenter = new Point2D.Double(

 54              endBounds.getCenterX(), endBounds.getCenterY());

 55        return new Line2D.Double(

 56              start.getConnectionPoint(endCenter),

 57              end.getConnectionPoint(startCenter));

 58     }

 59  

 60     private Node start;

 61     private Node end;

 62  }