C_BLOB::C_BLOB(                              //constructor
               C_OUTLINE_LIST *outline_list  //in random order
              ) {
  C_OUTLINE *outline;            //current outline
  C_OUTLINE_IT it = outline_list;//iterator

  while (!it.empty ()) {         //grab the list
    outline = it.extract ();     //get off the list
                                 //put it in place
    position_outline(outline, &outlines);
    if (!it.empty ())
      it.forward ();
  }
  it.set_to_list (&outlines);
  for (it.mark_cycle_pt (); !it.cycled_list (); it.forward ()) {
    outline = it.data ();
    if (outline->turn_direction () < 0) {
      outline->reverse ();
      reverse_outline_list (outline->child ());
      outline->set_flag (COUT_INVERSE, TRUE);
    }
    else {
      outline->set_flag (COUT_INVERSE, FALSE);
    }
  }
}
inT32 C_OUTLINE::area() {  //winding number
  int stepindex;                 //current step
  inT32 total_steps;             //steps to do
  inT32 total;                   //total area
  ICOORD pos;                    //position of point
  ICOORD next_step;              //step to next pix
  C_OUTLINE_IT it = child ();

  pos = start_pos ();
  total_steps = pathlength ();
  total = 0;
  for (stepindex = 0; stepindex < total_steps; stepindex++) {
                                 //all intersected
    next_step = step (stepindex);
    if (next_step.x () < 0)
      total += pos.y ();
    else if (next_step.x () > 0)
      total -= pos.y ();
    pos += next_step;
  }
  for (it.mark_cycle_pt (); !it.cycled_list (); it.forward ())
    total += it.data ()->area ();//add areas of children

  return total;
}
/**********************************************************************
 * position_outline
 *
 * Position the outline in the given list at the relevant place
 * according to its nesting.
 **********************************************************************/
static void position_outline(                          //put in place
                             C_OUTLINE *outline,       //thing to place
                             C_OUTLINE_LIST *destlist  //desstination list
                            ) {
  C_OUTLINE *dest_outline;       //outline from dest list
  C_OUTLINE_IT it = destlist;    //iterator
                                 //iterator on children
  C_OUTLINE_IT child_it = outline->child ();

  if (!it.empty ()) {
    do {
      dest_outline = it.data (); //get destination
                                 //encloses dest
      if (*dest_outline < *outline) {
                                 //take off list
        dest_outline = it.extract ();
                                 //put this in place
        it.add_after_then_move (outline);
                                 //make it a child
        child_it.add_to_end (dest_outline);
        while (!it.at_last ()) {
          it.forward ();         //do rest of list
                                 //check for other children
          dest_outline = it.data ();
          if (*dest_outline < *outline) {
                                 //take off list
            dest_outline = it.extract ();
            child_it.add_to_end (dest_outline);
            //make it a child
            if (it.empty ())
              break;
          }
        }
        return;                  //finished
      }
                                 //enclosed by dest
      else if (*outline < *dest_outline) {
        position_outline (outline, dest_outline->child ());
        //place in child list
        return;                  //finished
      }
      it.forward ();
    }
    while (!it.at_first ());
  }
  it.add_to_end (outline);       //at outer level
}
inT32 C_OUTLINE::perimeter() {
  inT32 total_steps;             // Return value.
  C_OUTLINE_IT it = child();

  total_steps = pathlength();
  for (it.mark_cycle_pt(); !it.cycled_list(); it.forward())
    total_steps += it.data()->pathlength();  // Add perimeters of children.

  return total_steps;
}
TBOX C_BLOB::bounding_box() {  //bounding box
  C_OUTLINE *outline;            //current outline
  C_OUTLINE_IT it = &outlines;   //outlines of blob
  TBOX box;                       //bounding box

  for (it.mark_cycle_pt (); !it.cycled_list (); it.forward ()) {
    outline = it.data ();
    box += outline->bounding_box ();
  }
  return box;
}
inT32 C_BLOB::outer_area() {  //area
  C_OUTLINE *outline;            //current outline
  C_OUTLINE_IT it = &outlines;   //outlines of blob
  inT32 total;                   //total area

  total = 0;
  for (it.mark_cycle_pt (); !it.cycled_list (); it.forward ()) {
    outline = it.data ();
    total += outline->outer_area ();
  }
  return total;
}
inT32 C_BLOB::perimeter() {
  C_OUTLINE *outline;            // current outline
  C_OUTLINE_IT it = &outlines;   // outlines of blob
  inT32 total;                   // total perimeter

  total = 0;
  for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
    outline = it.data();
    total += outline->perimeter();
  }
  return total;
}
static void reverse_outline_list(                      //reverse outlines
                                 C_OUTLINE_LIST *list  //outline to reverse
                                ) {
  C_OUTLINE *outline;            //current outline
  C_OUTLINE_IT it = list;        //iterator

  for (it.mark_cycle_pt (); !it.cycled_list (); it.forward ()) {
    outline = it.data ();
    outline->reverse ();         //reverse it
    if (!outline->child ()->empty ())
      reverse_outline_list (outline->child ());
  }
}
inT32 C_BLOB::count_transitions(                 //area
                                inT32 threshold  //on size
                               ) {
  C_OUTLINE *outline;            //current outline
  C_OUTLINE_IT it = &outlines;   //outlines of blob
  inT32 total;                   //total area

  total = 0;
  for (it.mark_cycle_pt (); !it.cycled_list (); it.forward ()) {
    outline = it.data ();
    total += outline->count_transitions (threshold);
  }
  return total;
}
static void plot_outline_list(                       //draw outlines
                              C_OUTLINE_LIST *list,  //outline to draw
                              ScrollView* window,         //window to draw in
                              ScrollView::Color colour,         //colour to use
                              ScrollView::Color child_colour    //colour of children
                             ) {
  C_OUTLINE *outline;            //current outline
  C_OUTLINE_IT it = list;        //iterator

  for (it.mark_cycle_pt (); !it.cycled_list (); it.forward ()) {
    outline = it.data ();
                                 //draw it
    outline->plot (window, colour);
    if (!outline->child ()->empty ())
      plot_outline_list (outline->child (), window,
        child_colour, child_colour);
  }
}