Graph.java

import java.awt.*;
import java.awt.geom.*;
import java.io.*;
import java.util.*;
import java.util.List;

/**
   A graph consisting of selectable nodes and edges.
*/
public abstract class Graph implements Serializable
{
   /**
      Constructs a graph with no nodes or edges.
   */
   public Graph()
   {
      nodes = new ArrayList<Node>();
      edges = new ArrayList<Edge>();
   }

   /**
      Adds an edge to the graph that joins the nodes containing
      the given points. If the points aren't both inside nodes,
      then no edge is added.
      @param e the edge to add
      @param p1 a point in the starting node
      @param p2 a point in the ending node
   */
   public boolean connect(Edge e, Point2D p1, Point2D p2)
   {
      Node n1 = findNode(p1);
      Node n2 = findNode(p2);
      if (n1 != null && n2 != null)
      {
         e.connect(n1, n2);
         edges.add(e);
         return true;
      }
      return false;
   }

   /**
      Adds a node to the graph so that the top left corner of
      the bounding rectangle is at the given point.
      @param n the node to add
      @param p the desired location
   */
   public boolean add(Node n, Point2D p)
   {
      Rectangle2D bounds = n.getBounds();
      n.translate(p.getX() - bounds.getX(),
         p.getY() - bounds.getY());
      nodes.add(n);
      return true;
   }

   /**
      Finds a node containing the given point.
      @param p a point
      @return a node containing p or null if no nodes contain p
   */
   public Node findNode(Point2D p)
   {
      for (int i = nodes.size() - 1; i >= 0; i--)
      {
         Node n = nodes.get(i);
         if (n.contains(p)) return n;
      }
      return null;
   }

   /**
      Finds an edge containing the given point.
      @param p a point
      @return an edge containing p or null if no edges contain p
   */
   public Edge findEdge(Point2D p)
   {
      for (int i = edges.size() - 1; i >= 0; i--)
      {
         Edge e = edges.get(i);
         if (e.contains(p)) return e;
      }
      return null;
   }

   /**
      Draws the graph
      @param g2 the graphics context
   */
   public void draw(Graphics2D g2)
   {
      for (Node n : nodes)
         n.draw(g2);

      for (Edge e : edges)
         e.draw(g2);

   }

   /**
      Removes a node and all edges that start or end with that node
      @param n the node to remove
   */
   public void removeNode(Node n)
   {
      for (int i = edges.size() - 1; i >= 0; i--)
      {
         Edge e = edges.get(i);
         if (e.getStart() == n || e.getEnd() == n)
            edges.remove(e);
      }
      nodes.remove(n);
   }

   /**
      Removes an edge from the graph.
      @param e the edge to remove
   */
   public void removeEdge(Edge e)
   {
      edges.remove(e);
   }

   /**
      Gets the smallest rectangle enclosing the graph
      @param g2 the graphics context
      @return the bounding rectangle
   */
   public Rectangle2D getBounds(Graphics2D g2)
   {
      Rectangle2D r = null;
      for (Node n : nodes)
      {
         Rectangle2D b = n.getBounds();
         if (r == null) r = b;
         else r.add(b);
      }
      for (Edge e : edges)
         r.add(e.getBounds(g2));
      return r == null ? new Rectangle2D.Double() : r;
   }

   /**
      Gets the node types of a particular graph type.
      @return an array of node prototypes
   */
   public abstract Node[] getNodePrototypes();

   /**
      Gets the edge types of a particular graph type.
      @return an array of edge prototypes
   */
   public abstract Edge[] getEdgePrototypes();

   /**
      Gets the nodes of this graph.
      @return an unmodifiable list of the nodes
   */
   public List<Node> getNodes()
   {
      return Collections.unmodifiableList(nodes); }

   /**
      Gets the edges of this graph.
      @return an unmodifiable list of the edges
   */
   public List<Edge> getEdges()
   {
      return Collections.unmodifiableList(edges);
   }

   private ArrayList<Node> nodes;
   private ArrayList<Edge> edges;
}