package org.opentrafficsim.trafficcontrol.trafcod;
   
   import java.awt.BorderLayout;
   import java.awt.Color;
   import java.awt.Component;
   import java.awt.Dimension;
   import java.awt.Graphics2D;
   import java.awt.event.ActionEvent;
   import java.awt.event.ActionListener;
  import java.awt.image.BufferedImage;
  import java.util.ArrayList;
  import java.util.Comparator;
  import java.util.LinkedHashMap;
  import java.util.LinkedHashSet;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  
  import javax.swing.BoxLayout;
  import javax.swing.ImageIcon;
  import javax.swing.JCheckBox;
  import javax.swing.JFrame;
  import javax.swing.JLabel;
  import javax.swing.JPanel;
  import javax.swing.JScrollPane;
  import javax.swing.SwingUtilities;
  
  import org.djutils.exceptions.Throw;
  import org.opentrafficsim.road.network.lane.object.trafficlight.TrafficLightException;
  import org.opentrafficsim.trafficcontrol.TrafficController;
  
  /**
   * Functions that can draw a schematic diagram of an intersection given the list of traffic streams. The traffic stream numbers
   * must follow the Dutch conventions.
   * <p>
   * Copyright (c) 2013-2022 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
   * BSD-style license. See <a href="http://opentrafficsim.org/node/13">OpenTrafficSim License</a>.
   * <p>
   * @version $Revision$, $LastChangedDate$, by $Author$, initial version Dec 1, 2016 <br>
   * @author <a href="http://www.tbm.tudelft.nl/averbraeck">Alexander Verbraeck</a>
   * @author <a href="http://www.tudelft.nl/pknoppers">Peter Knoppers</a>
   * @author <a href="http://www.transport.citg.tudelft.nl">Wouter Schakel</a>
   */
  public class Diagram
  {
      /** Numbering of the lateral objects/positions from the median to the shoulder. */
      /** Central divider. */
      static final int DIVIDER_1 = 0;
  
      /** Left turn area on roundabout. */
      static final int CAR_ROUNDABOUT_LEFT = 1;
  
      /** Public transit between divider and left turn lane. */
      static final int PT_DIV_L = 3;
  
      /** Divider between center public transit and left turn lane. */
      static final int DIVIDER_2 = 4;
  
      /** Left turn lane(s). */
      static final int CAR_LEFT = 5;
  
      /** No turn (center) lane(s). */
      static final int CAR_CENTER = 7;
  
      /** Right turn lane(s). */
      static final int CAR_RIGHT = 9;
  
      /** Divider between right turn lane and bicycle lane. */
      static final int DIVIDER_3 = 10;
  
      /** Public transit between right turn lane and bicycle lane. */
      static final int PT_RIGHT_BICYCLE = 11;
  
      /** Divider. */
      static final int DIVIDER_4 = 12;
  
      /** Bicycle lane. */
      static final int BICYCLE = 13;
  
      /** Divider. */
      static final int DIVIDER_5 = 14;
  
      /** Public transit between bicycle lane and right sidewalk. */
      static final int PT_BICYCLE_SIDEWALK = 15;
  
      /** Divider. */
      static final int DIVIDER_6 = 16;
  
      /** Sidewalk. */
      static final int SIDEWALK = 17;
  
      /** Divider. */
      static final int DIVIDER_7 = 18;
  
      /** Public transit right of right sidewalk. */
      static final int PT_SIDEWALK_SHOULDER = 19;
  
      /** Shoulder right of right sidewalk. */
      static final int SHOULDER = 20;
 
     /** Boundary of schematic intersection. */
     static final int BOUNDARY = 21;
 
     /** The streams crossing the intersection. */
     private final List<Short> streams;
 
     /** The routes through the intersection. */
     private final Map<Short, XYPair[]> routes = new LinkedHashMap<>();
 
     /**
      * Construct a new diagram.
      * @param streams Set&lt;Short&gt;; the streams (numbered according to the Dutch standard) that cross the intersection.
      * @throws TrafficLightException when a route is invalid
      */
     public Diagram(final Set<Short> streams) throws TrafficLightException
     {
         this.streams = new ArrayList<Short>(streams); // make a deep copy and sort by stream number
         this.streams.sort(new Comparator<Short>()
         {
 
             @Override
             public int compare(final Short o1, final Short o2)
             {
                 return o1 - o2;
             }
         });
         // System.out.println("streams:");
         // for (short stream : this.streams)
         // {
         // System.out.print(String.format(" %02d", stream));
         // }
         // System.out.println("");
 
         // Primary car streams
         //@formatter:off
         for (short stream = 1; stream <= 12; stream += 3)
         {
             int quadrant = (stream - 1) / 3;
             this.routes.put(stream, rotateRoute(quadrant, assembleRoute(
                     new RouteStep(-BOUNDARY, CAR_RIGHT), 
                     new RouteStep(-SHOULDER, CAR_RIGHT, Command.STOP_LINE_AND_ICON), 
                     new RouteStep(-CAR_CENTER, CAR_RIGHT), 
                     new RouteStep(-CAR_CENTER, BOUNDARY))));
             this.routes.put((short) (stream + 1), rotateRoute(quadrant, assembleRoute(
                     new RouteStep(-BOUNDARY, CAR_CENTER), 
                     new RouteStep(-SHOULDER, CAR_CENTER, Command.STOP_LINE_AND_ICON), 
                     new RouteStep(Command.IF, stream + 1 + 60), 
                         new RouteStep(-CAR_ROUNDABOUT_LEFT, CAR_CENTER), 
                     new RouteStep(Command.ELSE), 
                         new RouteStep(BOUNDARY, CAR_CENTER), 
                     new RouteStep(Command.END_IF))));
             this.routes.put((short) (stream + 2), rotateRoute(quadrant, assembleRoute(
                     new RouteStep(-BOUNDARY, CAR_LEFT), 
                     new RouteStep(-SHOULDER, CAR_LEFT, Command.STOP_LINE_AND_ICON), 
                     new RouteStep(Command.IF, stream + 2 + 60), 
                         new RouteStep(-CAR_ROUNDABOUT_LEFT, CAR_LEFT), 
                     new RouteStep(Command.ELSE_IF, (stream + 10) % 12 + 60),
                         new RouteStep(CAR_CENTER, CAR_LEFT), 
                         new RouteStep(CAR_CENTER, CAR_ROUNDABOUT_LEFT),
                     new RouteStep(Command.ELSE), 
                         new RouteStep(-CAR_LEFT, CAR_LEFT), 
                         new RouteStep(-CAR_LEFT, PT_DIV_L), 
                         new RouteStep(-CAR_ROUNDABOUT_LEFT, PT_DIV_L), 
                         new RouteStep(-CAR_ROUNDABOUT_LEFT, -CAR_LEFT), 
                         new RouteStep(PT_DIV_L, -CAR_LEFT),
                         new RouteStep(PT_DIV_L, -CAR_CENTER), 
                         new RouteStep(CAR_CENTER, -CAR_CENTER),
                         new RouteStep(CAR_CENTER, -BOUNDARY),
                     new RouteStep(Command.END_IF))));
         }
         // Bicycle streams
         for (short stream = 21; stream <= 28; stream += 2)
         {
             int quadrant = (stream - 19) / 2 % 4;
             this.routes.put(stream, rotateRoute(quadrant, assembleRoute(
                     new RouteStep(DIVIDER_1, BICYCLE, Command.ICON), 
                     new RouteStep(SHOULDER, BICYCLE),
                     new RouteStep(BOUNDARY, BICYCLE, Command.ICON))));
             this.routes.put((short) (stream + 1), rotateRoute(quadrant, assembleRoute(
                     new RouteStep(-BOUNDARY, BICYCLE), 
                     new RouteStep(-DIVIDER_3, BICYCLE, Command.ICON),
                     new RouteStep(Command.IF, stream), 
                     new RouteStep(-DIVIDER_1, BICYCLE, Command.ICON),
                     new RouteStep(Command.ELSE), 
                         new RouteStep(SHOULDER, BICYCLE), 
                         new RouteStep(BOUNDARY, BICYCLE, Command.ICON), 
                     new RouteStep(Command.END_IF))));
         }
         // Pedestrian streams
         for (short stream = 31; stream <= 38; stream += 2)
         {
             int quadrant = (stream - 29) / 2 % 4;
             this.routes.put(stream, rotateRoute(quadrant, assembleRoute(
                     new RouteStep(DIVIDER_1, SIDEWALK), 
                     new RouteStep(BOUNDARY, SIDEWALK))));
             this.routes.put((short) (stream + 1), rotateRoute(quadrant, assembleRoute(
                     new RouteStep(-BOUNDARY, SIDEWALK), 
                     new RouteStep(Command.IF, stream), 
                         new RouteStep(-DIVIDER_1, SIDEWALK), 
                     new RouteStep(Command.ELSE), 
                         new RouteStep(BOUNDARY, SIDEWALK),
                     new RouteStep(Command.END_IF))));
         }
         // Public transit streams
         for (short stream = 41; stream <= 52; stream += 3)
         {
             int quadrant = (stream - 41) / 3;
             this.routes.put(stream, rotateRoute(quadrant, assembleRoute(
                     new RouteStep(-BOUNDARY, PT_DIV_L), 
                     new RouteStep(-SHOULDER, PT_DIV_L, Command.STOP_LINE), 
                     new RouteStep(-PT_SIDEWALK_SHOULDER, PT_DIV_L, Command.ICON),
                     new RouteStep(-CAR_RIGHT, PT_DIV_L), 
                     new RouteStep(-CAR_RIGHT, CAR_LEFT), 
                     new RouteStep(-PT_DIV_L, CAR_LEFT), 
                     new RouteStep(-PT_DIV_L, SHOULDER), 
                     new RouteStep(-PT_DIV_L, BOUNDARY, Command.ICON))));
             this.routes.put((short) (stream + 1), rotateRoute(quadrant, assembleRoute(
                     new RouteStep(-BOUNDARY, PT_DIV_L), 
                     new RouteStep(-SHOULDER, PT_DIV_L, Command.STOP_LINE), 
                     new RouteStep(-PT_SIDEWALK_SHOULDER, PT_DIV_L, Command.ICON),
                     new RouteStep(SHOULDER, PT_DIV_L), 
                     new RouteStep(BOUNDARY, PT_DIV_L))));
             this.routes.put((short) (stream + 2), rotateRoute(quadrant, assembleRoute(
                     new RouteStep(-BOUNDARY, PT_DIV_L), 
                     new RouteStep(-SHOULDER, PT_DIV_L, Command.STOP_LINE), 
                     new RouteStep(-PT_SIDEWALK_SHOULDER, PT_DIV_L, Command.ICON),
                     new RouteStep(-CAR_RIGHT, PT_DIV_L), 
                     new RouteStep(-CAR_RIGHT, CAR_ROUNDABOUT_LEFT), 
                     new RouteStep(-PT_DIV_L, CAR_ROUNDABOUT_LEFT), 
                     new RouteStep(Command.IF, (stream + 2 - 40) % 12 + 60), 
                         new RouteStep(-PT_DIV_L, -PT_DIV_L), 
                         new RouteStep(PT_DIV_L, -PT_DIV_L), 
                     new RouteStep(Command.ELSE), 
                         new RouteStep(-PT_DIV_L, -CAR_CENTER), 
                         new RouteStep(CAR_ROUNDABOUT_LEFT, -CAR_CENTER), 
                         new RouteStep(CAR_ROUNDABOUT_LEFT, -CAR_RIGHT), 
                         new RouteStep(PT_DIV_L, -CAR_RIGHT), 
                     new RouteStep(Command.END_IF),
                     new RouteStep(PT_DIV_L, -SHOULDER), 
                     new RouteStep(PT_DIV_L, -BOUNDARY, Command.ICON))));
         }
         // Secondary car streams
         for (short stream = 62; stream <= 72; stream += 3)
         {
             int quadrant = (stream - 61) / 3;
             this.routes.put(stream, rotateRoute(quadrant, assembleRoute(
                     new RouteStep(-CAR_ROUNDABOUT_LEFT, CAR_CENTER), 
                     new RouteStep(CAR_ROUNDABOUT_LEFT, CAR_CENTER, Command.STOP_LINE_AND_ICON), 
                     new RouteStep(BOUNDARY, CAR_CENTER))));
             this.routes.put((short) (stream + 1), rotateRoute(quadrant, assembleRoute(
                     new RouteStep(-CAR_ROUNDABOUT_LEFT, CAR_LEFT), 
                     new RouteStep(CAR_ROUNDABOUT_LEFT, CAR_LEFT, Command.STOP_LINE_AND_ICON), 
                     new RouteStep(CAR_CENTER, CAR_LEFT), 
                     new RouteStep(Command.IF, ((stream - 61) + 11) % 12 + 60),
                     new RouteStep(CAR_CENTER, CAR_ROUNDABOUT_LEFT), 
                     new RouteStep(Command.ELSE), 
                     new RouteStep(CAR_CENTER, -BOUNDARY), 
                     new RouteStep(Command.END_IF))));
         }
        // @formatter:on
     }
 
     /**
      * Check that a particular stream exists. Beware that the keys in this.streams are Short.
      * @param stream short; the number of the stream to check
      * @return boolean; true if the stream exists; false if it does not exist
      */
     private boolean streamExists(final short stream)
     {
         return this.streams.contains(stream);
     }
 
     /**
      * Report if object is inaccessible to all traffic.
      * @param i int; the number of the object
      * @return boolean; true if the object is inaccessible to all traffic
      */
     public static final boolean isGrass(final int i)
     {
         return i == DIVIDER_1 || i == DIVIDER_2 || i == DIVIDER_3 || i == DIVIDER_4 || i == DIVIDER_5 || i == DIVIDER_6
                 || i == DIVIDER_7 || i == SHOULDER;
     }
 
     /**
      * Return the LaneType for a stream number.
      * @param streamNumber int; the standard Dutch traffic stream number
      * @return LaneType; the lane type of the stream; or null if the stream number is reserved or invalid
      */
     final LaneType laneType(final int streamNumber)
     {
         if (streamNumber < 20 || streamNumber > 60 && streamNumber <= 80)
         {
             return LaneType.CAR_LANE;
         }
         if (streamNumber >= 20 && streamNumber < 30)
         {
             return LaneType.BICYCLE_LANE;
         }
         if (streamNumber >= 30 && streamNumber < 40)
         {
             return LaneType.PEDESTRIAN_LANE;
         }
         if (streamNumber > 40 && streamNumber <= 52 || streamNumber >= 81 && streamNumber <= 92)
         {
             return LaneType.PUBLIC_TRANSIT_LANE;
         }
         return null;
     }
 
     /**
      * Types of lanes.
      */
     enum LaneType
     {
         /** Car. */
         CAR_LANE,
         /** BICYCLE. */
         BICYCLE_LANE,
         /** Public transit. */
         PUBLIC_TRANSIT_LANE,
         /** Pedestrian. */
         PEDESTRIAN_LANE,
     }
 
     /**
      * Return the rotated x value.
      * @param xyPair XYPair; the XYPair
      * @param rotation int; rotation in multiples of 90 degrees
      * @return int; the x component of the rotated coordinates
      */
     final int rotatedX(final XYPair xyPair, final int rotation)
     {
         switch (rotation % 4)
         {
             case 0:
                 return xyPair.getX();
             case 1:
                 return -xyPair.getY();
             case 2:
                 return -xyPair.getX();
             case 3:
                 return xyPair.getY();
             default:
                 break; // cannot happen
         }
         return 0; // cannot happen
     }
 
     /**
      * Return the rotated y value.
      * @param xyPair XYPair; the XYPair
      * @param rotation int; rotation in multiples of 90 degrees
      * @return int; the y component of the rotated coordinates
      */
     final int rotatedY(final XYPair xyPair, final int rotation)
     {
         switch (rotation % 4)
         {
             case 0:
                 return xyPair.getY();
             case 1:
                 return xyPair.getX();
             case 2:
                 return -xyPair.getY();
             case 3:
                 return -xyPair.getX();
             default:
                 break; // cannot happen
         }
         return 0; // cannot happen
     }
 
     /**
      * Commands used in RouteStep.
      */
     enum Command
     {
         /** No operation. */
         NO_OP,
         /** If. */
         IF,
         /** Else. */
         ELSE,
         /** Else if. */
         ELSE_IF,
         /** End if. */
         END_IF,
         /** Stop line. */
         STOP_LINE,
         /** Icon (bus, bicycle symbol). */
         ICON,
         /** Stop line AND icon. */
         STOP_LINE_AND_ICON,
     }
 
     /**
      * Step in a schematic route through the intersection.
      */
     class RouteStep
     {
         /** X object. */
         private final int x;
 
         /** Y object. */
         private final int y;
 
         /** Command of this step. */
         private final Command command;
 
         /** Condition for IF and ELSE_IF commands. */
         private final int streamCondition;
 
         /**
          * Construct a RouteStep that has a NO_OP command.
          * @param x int; the X object at the end of this route step
          * @param y int; the Y object at the end of this route step
          */
         RouteStep(final int x, final int y)
         {
             this.x = x;
             this.y = y;
             this.command = Command.NO_OP;
             this.streamCondition = TrafficController.NO_STREAM;
         }
 
         /**
          * Construct a RouteStep with a command condition.
          * @param x int; the X object at the end of this route step
          * @param y int; the Y object at the end of this route step
          * @param command Command; a STOP_LINE or NO_OP command
          * @throws TrafficLightException when an IF or ELSE_IF has an invalid streamCondition, or when an ELSE or END_IF has a
          *             valid streamCOndition
          */
         RouteStep(final int x, final int y, final Command command) throws TrafficLightException
         {
             Throw.when(
                     Command.STOP_LINE != command && Command.NO_OP != command && Command.ICON != command
                             && Command.STOP_LINE_AND_ICON != command,
                     TrafficLightException.class,
                     "X and Y should only be provided with a NO_OP, STOP_LINE, ICON, or STOP_LINE_AND_ICON command; not with "
                             + command);
             this.x = x;
             this.y = y;
             this.command = command;
             this.streamCondition = TrafficController.NO_STREAM;
         }
 
         /**
          * Construct a RouteStep with a command condition.
          * @param command Command; an IF, ELSE, ENDIF, or ELSE_IF command
          * @param streamCondition int; the stream that must exist for the condition to be true
          * @throws TrafficLightException when an IF or ELSE_IF has an invalid streamCondition, or when an ELSE or END_IF has a
          *             valid streamCOndition
          */
         RouteStep(final Command command, final int streamCondition) throws TrafficLightException
         {
             Throw.when(Command.IF != command && Command.ELSE_IF != command, TrafficLightException.class,
                     "RouteStep constructor with stream condition must use command IF or ELSE_IF");
             this.x = TrafficController.NO_STREAM;
             this.y = TrafficController.NO_STREAM;
             this.command = command;
             Throw.when(streamCondition == TrafficController.NO_STREAM, TrafficLightException.class,
                     "IF or ELSE_IF need a valid traffic stream number");
             this.streamCondition = streamCondition;
         }
 
         /**
          * Construct a RouteStep for ELSE or END_IF command.
          * @param command Command; either <code>Command.ELSE</code> or <code>Command.END_IF</code>
          * @throws TrafficLightException when the Command is not ELSE or END_IF
          */
         RouteStep(final Command command) throws TrafficLightException
         {
             Throw.when(Command.ELSE != command && Command.END_IF != command, TrafficLightException.class,
                     "RouteStep constructor with single command parameter requires ELSE or END_IF command");
             this.x = TrafficController.NO_STREAM;
             this.y = TrafficController.NO_STREAM;
             this.command = command;
             this.streamCondition = TrafficController.NO_STREAM;
         }
 
         /**
          * Retrieve the X object.
          * @return int; the X object
          */
         public int getX()
         {
             return this.x;
         }
 
         /**
          * Retrieve the Y object.
          * @return int; the Y object
          */
         public int getY()
         {
             return this.y;
         }
 
         /**
          * Retrieve the command.
          * @return Command
          */
         public Command getCommand()
         {
             return this.command;
         }
 
         /**
          * Retrieve the stream condition.
          * @return int; the streamCondition
          */
         public int getStreamCondition()
         {
             return this.streamCondition;
         }
 
         /** {@inheritDoc} */
         @Override
         public String toString()
         {
             return "RouteStep [x=" + this.x + ", y=" + this.y + ", command=" + this.command + ", streamCondition="
                     + this.streamCondition + "]";
         }
 
     }
 
     /**
      * Pack two integer coordinates in one object.
      */
     class XYPair
     {
         /** X. */
         private final int x;
 
         /** Y. */
         private final int y;
 
         /**
          * Construct a new XY pair.
          * @param x int; the X value
          * @param y int; the Y value
          */
         XYPair(final int x, final int y)
         {
             this.x = x;
             this.y = y;
         }
 
         /**
          * Construct a new XY pair from a route step.
          * @param routeStep RouteStep; the route step
          */
         XYPair(final RouteStep routeStep)
         {
             this.x = routeStep.getX();
             this.y = routeStep.getY();
         }
 
         /**
          * Construct a rotated version of an XYPair.
          * @param in XYPair; the initial version
          * @param quadrant int; the quadrant
          */
         XYPair(final XYPair in, final int quadrant)
         {
             this.x = rotatedX(in, quadrant);
             this.y = rotatedY(in, quadrant);
         }
 
         /**
          * Retrieve the X value.
          * @return int; the X value
          */
         public int getX()
         {
             return this.x;
         }
 
         /**
          * Retrieve the Y value.
          * @return int; the Y value
          */
         public int getY()
         {
             return this.y;
         }
 
         /** {@inheritDoc} */
         @Override
         public String toString()
         {
             return "XYPair [x=" + this.x + ", y=" + this.y + "]";
         }
 
     }
 
     /**
      * Construct a route.
      * @param quadrant int; the quadrant to assemble the route for
      * @param steps RouteStep...; an array, or series of arguments of type RouteStep
      * @return XYPair[]; an array of XY pairs describing the route through the intersection
      * @throws TrafficLightException when the route contains commands other than NO_OP and STOP_LINE
      */
     private XYPair[] rotateRoute(final int quadrant, final RouteStep... steps) throws TrafficLightException
     {
         List<XYPair> route = new ArrayList<>();
         boolean on = true;
 
         for (RouteStep step : steps)
         {
             switch (step.getCommand())
             {
                 case NO_OP:
                 case STOP_LINE:
                 case ICON:
                 case STOP_LINE_AND_ICON:
                     if (on)
                     {
                         route.add(new XYPair(new XYPair(step), quadrant));
                     }
                     break;
 
                 default:
                     throw new TrafficLightException("Bad command in rotateRoute: " + step.getCommand());
 
             }
         }
         return route.toArray(new XYPair[route.size()]);
     }
 
     /**
      * Construct a route through the intersection.
      * @param steps RouteStep...; the steps of the route description
      * @return RouteStep[]; the route through the intersection
      * @throws TrafficLightException when something is very wrong
      */
     private RouteStep[] assembleRoute(final RouteStep... steps) throws TrafficLightException
     {
         List<RouteStep> result = new ArrayList<>();
         RouteStep step;
         for (int pointNo = 0; null != (step = routePoint(pointNo, steps)); pointNo++)
         {
             result.add(step);
         }
         return result.toArray(new RouteStep[result.size()]);
     }
 
     /**
      * Return the Nth step in a route.
      * @param pointNo int; the rank of the requested step
      * @param steps RouteStep...; RouteStep... the steps
      * @return RouteStep; the Nth step in the route or null if the route does not have <code>pointNo</code> steps
      * @throws TrafficLightException when the command in a routestep is not recognized
      */
     private RouteStep routePoint(final int pointNo, final RouteStep... steps) throws TrafficLightException
     {
         boolean active = true;
         boolean beenActive = false;
         int index = 0;
 
         for (RouteStep routeStep : steps)
         {
             switch (routeStep.getCommand())
             {
                 case NO_OP:
                 case STOP_LINE:
                 case ICON:
                 case STOP_LINE_AND_ICON:
                     if (active)
                     {
                         if (index++ == pointNo)
                         {
                             return routeStep;
                         }
                     }
                     break;
 
                 case IF:
                     active = streamExists((short) routeStep.getStreamCondition());
                     beenActive = active;
                     break;
 
                 case ELSE_IF:
                     if (active)
                     {
                         active = false;
                     }
                     else if (!beenActive)
                     {
                         active = this.streams.contains(routeStep.getStreamCondition());
                     }
                     if (active)
                     {
                         beenActive = true;
                     }
                     break;
 
                 case ELSE:
                     active = !beenActive;
                     break;
 
                 case END_IF:
                     active = true;
                     break;
 
                 default:
                     throw new TrafficLightException("Bad switch: " + routeStep);
 
             }
         }
         return null;
     }
 
     /**
      * Create a BufferedImage and render the schematic on it.
      * @return BufferedImage
      */
     public BufferedImage render()
     {
         int range = 2 * BOUNDARY + 1;
         int cellSize = 10;
         BufferedImage result = new BufferedImage(range * cellSize, range * cellSize, BufferedImage.TYPE_INT_RGB);
         Graphics2D graphics = (Graphics2D) result.getGraphics();
         graphics.setColor(Color.GREEN);
         graphics.fillRect(0, 0, result.getWidth(), result.getHeight());
         for (Short stream : this.streams)
         {
             switch (laneType(stream))
             {
                 case BICYCLE_LANE:
                     graphics.setColor(Color.RED);
                     break;
 
                 case CAR_LANE:
                     graphics.setColor(Color.BLACK);
                     break;
 
                 case PEDESTRIAN_LANE:
                     graphics.setColor(Color.BLUE);
                     break;
 
                 case PUBLIC_TRANSIT_LANE:
                     graphics.setColor(Color.BLACK);
                     break;
 
                 default:
                     graphics.setColor(Color.WHITE);
                     break;
 
             }
             XYPair[] path = this.routes.get(stream);
             if (null == path)
             {
                 System.err.println("Cannot find path for stream " + stream);
                 continue;
             }
             XYPair prevPair = null;
             for (XYPair xyPair : path)
             {
                 if (null != prevPair)
                 {
                     int dx = (int) Math.signum(xyPair.getX() - prevPair.getX());
                     int dy = (int) Math.signum(xyPair.getY() - prevPair.getY());
                     int x = prevPair.getX() + dx;
                     int y = prevPair.getY() + dy;
                     while (x != xyPair.getX() || y != xyPair.getY())
                     {
                         fillXYPair(graphics, new XYPair(x, y));
                         if (x != xyPair.getX())
                         {
                             x += dx;
                         }
                         if (y != xyPair.getY())
                         {
                             y += dy;
                         }
                     }
 
                 }
                 fillXYPair(graphics, xyPair);
                 prevPair = xyPair;
             }
         }
         return result;
     }
 
     /**
      * Fill one box taking care to rotate to display conventions.
      * @param graphics Graphics2D; the graphics environment
      * @param xyPair XYPair; the box to fill
      */
     private void fillXYPair(final Graphics2D graphics, final XYPair xyPair)
     {
         int cellSize = 10;
         graphics.fillRect(cellSize * (BOUNDARY - xyPair.getX()), cellSize * (BOUNDARY - xyPair.getY()), cellSize, cellSize);
     }
 
     /**
      * Test the Diagram code.
      * @param args String[]; the command line arguments (not used)
      */
     public static void main(final String[] args)
     {
         SwingUtilities.invokeLater(new Runnable()
         {
             @Override
             public void run()
             {
                 JFrame frame = new JFrame("Diagram test");
                 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                 frame.setMinimumSize(new Dimension(1000, 1000));
                 JPanel mainPanel = new JPanel(new BorderLayout());
                 frame.add(mainPanel);
                 checkBoxPanel = new JPanel();
                 checkBoxPanel.setLayout(new BoxLayout(checkBoxPanel, BoxLayout.Y_AXIS));
                 JScrollPane scrollPane = new JScrollPane(checkBoxPanel);
                 scrollPane.setPreferredSize(new Dimension(150, 1000));
                 mainPanel.add(scrollPane, BorderLayout.LINE_START);
                 for (int stream = 1; stream <= 12; stream++)
                 {
                     checkBoxPanel.add(makeCheckBox(stream, stream % 3 == 2));
                 }
                 for (int stream = 21; stream <= 28; stream++)
                 {
                     checkBoxPanel.add(makeCheckBox(stream, false));
                 }
                 for (int stream = 31; stream <= 38; stream++)
                 {
                     checkBoxPanel.add(makeCheckBox(stream, false));
                 }
                 for (int stream = 41; stream <= 52; stream++)
                 {
                     checkBoxPanel.add(makeCheckBox(stream, false));
                 }
                 for (int stream = 61; stream <= 72; stream++)
                 {
                     if (stream % 3 == 1)
                     {
                         continue;
                     }
                     checkBoxPanel.add(makeCheckBox(stream, false));
                 }
                 testPanel = new JPanel();
                 rebuildTestPanel();
                 mainPanel.add(testPanel, BorderLayout.CENTER);
                 frame.setVisible(true);
             }
         });
 
     }
 
     /**
      * Make a check box to switch a particular stream number on or off.
      * @param stream int; the stream number
      * @param initialState boolean; if true; the check box will be checked
      * @return JCheckBox
      */
     public static JCheckBox makeCheckBox(final int stream, final boolean initialState)
     {
         JCheckBox result = new JCheckBox(String.format("Stream %02d", stream));
         result.setSelected(initialState);
         result.addActionListener(new ActionListener()
         {
 
             @Override
             public void actionPerformed(final ActionEvent e)
             {
                 rebuildTestPanel();
             }
         });
         return result;
     }
 
     /** JPanel used to render the intersection for testing. */
     private static JPanel testPanel = null;
 
     /** JPanel that holds all the check boxes. */
     private static JPanel checkBoxPanel = null;
 
     /**
      * Render the intersection.
      */
     static void rebuildTestPanel()
     {
         testPanel.removeAll();
         Set<Short> streamList = new LinkedHashSet<>();
         for (Component c : checkBoxPanel.getComponents())
         {
             if (c instanceof JCheckBox)
             {
                 JCheckBox checkBox = (JCheckBox) c;
                 if (checkBox.isSelected())
                 {
                     String caption = checkBox.getText();
                     String streamText = caption.substring(caption.length() - 2);
                     Short stream = Short.parseShort(streamText);
                     streamList.add(stream);
                 }
             }
         }
         try
         {
             Diagram diagram = new Diagram(streamList);
             testPanel.add(new JLabel(new ImageIcon(diagram.render())));
         }
         catch (TrafficLightException exception)
         {
             exception.printStackTrace();
         }
         testPanel.repaint();
         testPanel.revalidate();
     }
 
 }