import java.util.*;

/**
 * A scene.
 *
 * A scene may contain:
 *    1) coordinates (class Coordinates)
 *    2) line segments (class Vector)
 *    3) scenery (class Scenery)
 */

public class Scene extends Observable
{
   private Vector _v;

   /**
    * The constructor.
    */

   public Scene()
   {
      _v = new Vector();
   }

   /**
    * Scene manipulation.
    */

   public void add(Object o)
   {
      _v.addElement(o);
   }

   public void remove(Object o)
   {
      _v.removeElement(o);
   }

   public Enumeration elements()
   {
      return _v.elements();
   }

   /**
    * Apply the supplied transformation.
    */

   public void transform(Transformation tr)
   {
      Enumeration enum = _v.elements();

      while (enum.hasMoreElements())
      {
         Object obj = enum.nextElement();

         if (obj instanceof Scenery)
         {
            synchronized (obj)
            {
               ((Scenery)obj).transform(tr);
            }
         }
         else if (obj instanceof Vector)
         {
            tr.transform(((Vector)obj).elements());
         }
         else if (obj instanceof Coordinates)
         {
            tr.transform((Coordinates)obj);
         }
      }

      setChanged();

      notifyObservers();
   }
}