public class PositionedSceneElement {
  
  /**
   * the picture that this element holds
   **/
  private Picture myPic;
  
  /**
   * the next element in the list
   **/
  private PositionedSceneElement next;
  
  /**
   * Make a new element with a picture as input, and
   * next as null.
   * @param heldPic Picture for element to hold
   **/
  public PositionedSceneElement(Picture heldPic){
    myPic = heldPic;
    next = null;
  }
  
  /**
   * Methods to set and get next elements
   * @param nextOne next element in list
   **/
  public void setNext(PositionedSceneElement nextOne){
    this.next = nextOne;
  }
  
  public PositionedSceneElement getNext(){
    return this.next;
  }
  
  /**
   * Returns the picture in the node.
   * @return the picture in the node
   **/
  public Picture getPicture(){
    return this.myPic;
  }
  
  /**
   * Method to draw from this node on in the list, using bluescreen.
   * Each new element has it's lower-left corner at the lower-right 
   * of the previous node. Starts drawing from left-bottom
   * @param bg Picture to draw drawing on
   **/
  public void drawFromMeOn(Picture bg) {
    PositionedSceneElement current;
    int currentX=0, currentY = bg.getHeight()-1;
    
    current = this;
    while (current != null)
    {
      current.drawMeOn(bg,currentX, currentY);
      currentX = currentX + current.getPicture().getWidth();
      current = current.getNext();
    }
  }
  
  /**
   * Method to draw from this picture, using bluescreen.
   * @param bg Picture to draw drawing on
   * @param left x position to draw from
   * @param bottom y position to draw from
   **/

  private void drawMeOn(Picture bg, int left, int bottom) {
    // Bluescreen takes an upper left corner
    this.getPicture().bluescreen(bg,left,
                                 bottom-this.getPicture().getHeight());
  }
  
  /** Method to remove node from list, fixing links appropriately.
   * @param node element to remove from list.
   **/
  public void remove(PositionedSceneElement node){
    if (node==this)
    {
      System.out.println("I can't remove the first node from the list.");
      return;
    };
    
    PositionedSceneElement current = this;
    // While there are more nodes to consider
    while (current.getNext() != null)
    {
      if (current.getNext() == node){
        // Simply make node's next be this next
        current.setNext(node.getNext());
        // Make this node point to nothing
        node.setNext(null);
        return;
      }
      current = current.getNext();
    }
  }
  
  /**
   * Insert the input node after this node.
   * @param node element to insert after this.
   **/
  public void insertAfter(PositionedSceneElement node){
    // Save what "this" currently points at
    PositionedSceneElement oldNext = this.getNext();
    this.setNext(node);
    node.setNext(oldNext);
  }
}