findseam.cpp

/* -*-C-*-
 ********************************************************************************
 *
 * File:        findseam.c  (Formerly findseam.c)
 * Description:
 * Author:       Mark Seaman, OCR Technology
 * Created:      Fri Oct 16 14:37:00 1987
 * Modified:     Tue Jul 30 15:44:59 1991 (Mark Seaman) marks@hpgrlt
 * Language:     C
 * Package:      N/A
 * Status:       Reusable Software Component
 *
 * (c) Copyright 1987, Hewlett-Packard Company.
 ** Licensed under the Apache License, Version 2.0 (the "License");
 ** you may not use this file except in compliance with the License.
 ** You may obtain a copy of the License at
 ** http://www.apache.org/licenses/LICENSE-2.0
 ** Unless required by applicable law or agreed to in writing, software
 ** distributed under the License is distributed on an "AS IS" BASIS,
 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 ** See the License for the specific language governing permissions and
 ** limitations under the License.
 *
 *********************************************************************************/
/*----------------------------------------------------------------------
              I n c l u d e s
----------------------------------------------------------------------*/
#include "findseam.h"
#include "gradechop.h"
#include "olutil.h"
#include "plotedges.h"
#include "outlines.h"
#include "freelist.h"
#include "seam.h"
#include "wordrec.h"

// Include automatically generated configuration file if running autoconf.
#ifdef HAVE_CONFIG_H
#include "config_auto.h"
#endif

/*----------------------------------------------------------------------
              T y p e s
----------------------------------------------------------------------*/
#define SPLIT_CLOSENESS        20/* Difference in x value */
                                 /* How many to keep */
#define MAX_NUM_SEAMS          150
                                 /* How many to keep */
#define MAX_OLD_SEAMS          150
#define NO_FULL_PRIORITY       -1/* Special marker for pri. */
                                 /* Evalute right away */
#define BAD_PRIORITY           9999.0

/*----------------------------------------------------------------------
              F u n c t i o n s
----------------------------------------------------------------------*/
namespace tesseract {

/**********************************************************************
 * add_seam_to_queue
 *
 * Adds the given new_seam to the seams priority queue, unless it is full
 * and the new seam is worse than the worst.
 **********************************************************************/
void Wordrec::add_seam_to_queue(float new_priority, SEAM *new_seam,
                                SeamQueue* seams) {
  if (new_seam == NULL) return;
  if (chop_debug) {
    tprintf("Pushing new seam with priority %g :", new_priority);
    print_seam("seam: ", new_seam);
  }
  if (seams->size() >= MAX_NUM_SEAMS) {
    SeamPair old_pair(0, NULL);
    if (seams->PopWorst(&old_pair) && old_pair.key() <= new_priority) {
      if (chop_debug) {
        tprintf("Old seam staying with priority %g\n", old_pair.key());
      }
      delete new_seam;
      seams->Push(&old_pair);
      return;
    } else if (chop_debug) {
      tprintf("New seam with priority %g beats old worst seam with %g\n",
              new_priority, old_pair.key());
    }
  }
  SeamPair new_pair(new_priority, new_seam);
  seams->Push(&new_pair);
}


/**********************************************************************
 * choose_best_seam
 *
 * Choose the best seam that can be created by assembling this a
 * collection of splits.  A queue of all the possible seams is
 * maintained.  Each new split received is placed in that queue with
 * its partial priority value.  These values in the seam queue are
 * evaluated and combined until a good enough seam is found.  If no
 * further good seams are being found then this function returns to the
 * caller, who will send more splits.  If this function is called with
 * a split of NULL, then no further splits can be supplied by the
 * caller.
 **********************************************************************/
void Wordrec::choose_best_seam(SeamQueue* seam_queue,
                               SPLIT *split,
                               PRIORITY priority,
                               SEAM **seam_result,
                               TBLOB *blob,
                               SeamPile* seam_pile) {
  SEAM *seam;
  char str[80];
  float my_priority;
  /* Add seam of split */
  my_priority = priority;
  if (split != NULL) {
    TPOINT split_point = split->point1->pos;
    split_point += split->point2->pos;
    split_point /= 2;
    seam = new SEAM(my_priority, split_point, split, NULL, NULL);
    if (chop_debug > 1)
      print_seam ("Partial priority    ", seam);
    add_seam_to_queue(my_priority, seam, seam_queue);

    if (my_priority > chop_good_split)
      return;
  }

  TBOX bbox = blob->bounding_box();
  /* Queue loop */
  while (!seam_queue->empty()) {
    SeamPair seam_pair;
    seam_queue->Pop(&seam_pair);
    seam = seam_pair.extract_data();
    /* Set full priority */
    my_priority = seam_priority(seam, bbox.left(), bbox.right());
    if (chop_debug) {
      sprintf (str, "Full my_priority %0.0f,  ", my_priority);
      print_seam(str, seam);
    }

    if ((*seam_result == NULL || (*seam_result)->priority > my_priority) &&
        my_priority < chop_ok_split) {
      /* No crossing */
      if (constrained_split(seam->split1, blob)) {
        delete *seam_result;
        *seam_result = new SEAM(*seam);
        (*seam_result)->priority = my_priority;
      } else {
        delete seam;
        seam = NULL;
        my_priority = BAD_PRIORITY;
      }
    }

    if (my_priority < chop_good_split) {
      if (seam)
        delete seam;
      return;                    /* Made good answer */
    }

    if (seam) {
      /* Combine with others */
      if (seam_pile->size() < chop_seam_pile_size) {
        combine_seam(*seam_pile, seam, seam_queue);
        SeamDecPair pair(seam_pair.key(), seam);
        seam_pile->Push(&pair);
      } else if (chop_new_seam_pile &&
                 seam_pile->size() == chop_seam_pile_size &&
                 seam_pile->PeekTop().key() > seam_pair.key()) {
        combine_seam(*seam_pile, seam, seam_queue);
        SeamDecPair pair;
        seam_pile->Pop(&pair);  // pop the worst.
        // Replace the seam in pair (deleting the old one) with
        // the new seam and score, then push back into the heap.
        pair.set_key(seam_pair.key());
        pair.set_data(seam);
        seam_pile->Push(&pair);
      } else {
        delete seam;
      }
    }

    my_priority = seam_queue->empty() ? NO_FULL_PRIORITY
                                      : seam_queue->PeekTop().key();
    if ((my_priority > chop_ok_split) ||
      (my_priority > chop_good_split && split))
      return;
  }
}


/**********************************************************************
 * combine_seam
 *
 * Find other seams to combine with this one.  The new seams that result
 * from this union should be added to the seam queue.  The return value
 * tells whether or not any additional seams were added to the queue.
 **********************************************************************/
void Wordrec::combine_seam(const SeamPile& seam_pile,
                           const SEAM* seam, SeamQueue* seam_queue) {
  register inT16 dist;
  inT16 bottom1, top1;
  inT16 bottom2, top2;

  SEAM *new_one;
  const SEAM *this_one;

  bottom1 = seam->split1->point1->pos.y;
  if (seam->split1->point2->pos.y >= bottom1)
    top1 = seam->split1->point2->pos.y;
  else {
    top1 = bottom1;
    bottom1 = seam->split1->point2->pos.y;
  }
  if (seam->split2 != NULL) {
    bottom2 = seam->split2->point1->pos.y;
    if (seam->split2->point2->pos.y >= bottom2)
      top2 = seam->split2->point2->pos.y;
    else {
      top2 = bottom2;
      bottom2 = seam->split2->point2->pos.y;
    }
  }
  else {
    bottom2 = bottom1;
    top2 = top1;
  }
  for (int x = 0; x < seam_pile.size(); ++x) {
    this_one = seam_pile.get(x).data();
    dist = seam->location.x - this_one->location.x;
    if (-SPLIT_CLOSENESS < dist &&
      dist < SPLIT_CLOSENESS &&
    seam->priority + this_one->priority < chop_ok_split) {
      inT16 split1_point1_y = this_one->split1->point1->pos.y;
      inT16 split1_point2_y = this_one->split1->point2->pos.y;
      inT16 split2_point1_y = 0;
      inT16 split2_point2_y = 0;
      if (this_one->split2) {
        split2_point1_y = this_one->split2->point1->pos.y;
        split2_point2_y = this_one->split2->point2->pos.y;
      }
      if (
        /*!tessedit_fix_sideways_chops || */
        (
          /* this_one->split1 always exists */
          (
            ((split1_point1_y >= top1 && split1_point2_y >= top1) ||
             (split1_point1_y <= bottom1 && split1_point2_y <= bottom1))
            &&
            ((split1_point1_y >= top2 && split1_point2_y >= top2) ||
             (split1_point1_y <= bottom2 && split1_point2_y <= bottom2))
          )
        )
        &&
        (
          this_one->split2 == NULL ||
          (
            ((split2_point1_y >= top1 && split2_point2_y >= top1) ||
             (split2_point1_y <= bottom1 && split2_point2_y <= bottom1))
            &&
            ((split2_point1_y >= top2 && split2_point2_y >= top2) ||
             (split2_point1_y <= bottom2 && split2_point2_y <= bottom2))
          )
        )
      ) {
        new_one = join_two_seams (seam, this_one);
        if (new_one != NULL) {
          if (chop_debug > 1)
            print_seam ("Combo priority       ", new_one);
          add_seam_to_queue(new_one->priority, new_one, seam_queue);
        }
      }
    }
  }
}


/**********************************************************************
 * constrained_split
 *
 * Constrain this split to obey certain rules.  It must not cross any
 * inner outline.  It must not cut off a small chunk of the outline.
 **********************************************************************/
inT16 Wordrec::constrained_split(SPLIT *split, TBLOB *blob) {
  TESSLINE *outline;

  if (is_little_chunk (split->point1, split->point2))
    return (FALSE);

  for (outline = blob->outlines; outline; outline = outline->next) {
    if (split_bounds_overlap (split, outline) &&
    crosses_outline (split->point1, split->point2, outline->loop)) {
      return (FALSE);
    }
  }
  return (TRUE);
}

/**********************************************************************
 * pick_good_seam
 *
 * Find and return a good seam that will split this blob into two pieces.
 * Work from the outlines provided.
 **********************************************************************/
SEAM *Wordrec::pick_good_seam(TBLOB *blob) {
  SeamPile seam_pile(chop_seam_pile_size);
  EDGEPT *points[MAX_NUM_POINTS];
  EDGEPT_CLIST new_points;
  SEAM *seam = NULL;
  TESSLINE *outline;
  inT16 num_points = 0;

#ifndef GRAPHICS_DISABLED
  if (chop_debug > 2)
    wordrec_display_splits.set_value(true);

  draw_blob_edges(blob);
#endif

  PointHeap point_heap(MAX_NUM_POINTS);
  for (outline = blob->outlines; outline; outline = outline->next)
    prioritize_points(outline, &point_heap);

  while (!point_heap.empty() && num_points < MAX_NUM_POINTS) {
    points[num_points++] = point_heap.PeekTop().data;
    point_heap.Pop(NULL);
  }

  /* Initialize queue */
  SeamQueue seam_queue(MAX_NUM_SEAMS);

  try_point_pairs(points, num_points, &seam_queue, &seam_pile, &seam, blob);
  try_vertical_splits(points, num_points, &new_points,
                      &seam_queue, &seam_pile, &seam, blob);

  if (seam == NULL) {
    choose_best_seam(&seam_queue, NULL, BAD_PRIORITY, &seam, blob, &seam_pile);
  }
  else if (seam->priority > chop_good_split) {
    choose_best_seam(&seam_queue, NULL, seam->priority,
                     &seam, blob, &seam_pile);
  }

  EDGEPT_C_IT it(&new_points);
  for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
    EDGEPT *inserted_point = it.data();
    if (!point_used_by_seam(seam, inserted_point)) {
      for (outline = blob->outlines; outline; outline = outline->next) {
        if (outline->loop == inserted_point) {
          outline->loop = outline->loop->next;
        }
      }
      remove_edgept(inserted_point);
    }
  }

  if (seam) {
    if (seam->priority > chop_ok_split) {
      delete seam;
      seam = NULL;
    }
#ifndef GRAPHICS_DISABLED
    else if (wordrec_display_splits) {
      if (seam->split1)
        mark_split (seam->split1);
      if (seam->split2)
        mark_split (seam->split2);
      if (seam->split3)
        mark_split (seam->split3);
      if (chop_debug > 2) {
        update_edge_window();
        edge_window_wait();
      }
    }
#endif
  }

  if (chop_debug)
    wordrec_display_splits.set_value(false);

  return (seam);
}


/**********************************************************************
 * seam_priority
 *
 * Assign a full priority value to the seam.
 **********************************************************************/
PRIORITY Wordrec::seam_priority(SEAM *seam, inT16 xmin, inT16 xmax) {
  PRIORITY priority;

  if (seam->split1 == NULL)
    priority = 0;

  else if (seam->split2 == NULL) {
    priority = (seam->priority +
      full_split_priority (seam->split1, xmin, xmax));
  }

  else if (seam->split3 == NULL) {
    split_outline (seam->split2->point1, seam->split2->point2);
    priority = (seam->priority +
      full_split_priority (seam->split1, xmin, xmax));
    unsplit_outlines (seam->split2->point1, seam->split2->point2);
  }

  else {
    split_outline (seam->split2->point1, seam->split2->point2);
    split_outline (seam->split3->point1, seam->split3->point2);
    priority = (seam->priority +
      full_split_priority (seam->split1, xmin, xmax));
    unsplit_outlines (seam->split3->point1, seam->split3->point2);
    unsplit_outlines (seam->split2->point1, seam->split2->point2);
  }

  return (priority);
}


/**********************************************************************
 * try_point_pairs
 *
 * Try all the splits that are produced by pairing critical points
 * together.  See if any of them are suitable for use.  Use a seam
 * queue and seam pile that have already been initialized and used.
 **********************************************************************/
void Wordrec::try_point_pairs(EDGEPT * points[MAX_NUM_POINTS],
                              inT16 num_points,
                              SeamQueue* seam_queue,
                              SeamPile* seam_pile,
                              SEAM ** seam,
                              TBLOB * blob) {
  inT16 x;
  inT16 y;
  SPLIT *split;
  PRIORITY priority;

  for (x = 0; x < num_points; x++) {
    for (y = x + 1; y < num_points; y++) {

      if (points[y] &&
          weighted_edgept_dist(points[x], points[y],
                               chop_x_y_weight) < chop_split_length &&
          points[x] != points[y]->next &&
          points[y] != points[x]->next &&
          !is_exterior_point(points[x], points[y]) &&
          !is_exterior_point(points[y], points[x])) {
        split = new_split (points[x], points[y]);
        priority = partial_split_priority (split);

        choose_best_seam(seam_queue, split, priority, seam, blob, seam_pile);
      }
    }
  }
}


/**********************************************************************
 * try_vertical_splits
 *
 * Try all the splits that are produced by vertical projection to see
 * if any of them are suitable for use.  Use a seam queue and seam pile
 * that have already been initialized and used.
 * Return in new_points a collection of points that were inserted into
 * the blob while examining vertical splits and which may safely be
 * removed once a seam is chosen if they are not part of the seam.
 **********************************************************************/
void Wordrec::try_vertical_splits(EDGEPT * points[MAX_NUM_POINTS],
                                  inT16 num_points,
                                  EDGEPT_CLIST *new_points,
                                  SeamQueue* seam_queue,
                                  SeamPile* seam_pile,
                                  SEAM ** seam,
                                  TBLOB * blob) {
  EDGEPT *vertical_point = NULL;
  SPLIT *split;
  inT16 x;
  PRIORITY priority;
  TESSLINE *outline;

  for (x = 0; x < num_points; x++) {
    vertical_point = NULL;
    for (outline = blob->outlines; outline; outline = outline->next) {
      vertical_projection_point(points[x], outline->loop,
                                &vertical_point, new_points);
    }

    if (vertical_point &&
      points[x] != vertical_point->next &&
      vertical_point != points[x]->next &&
      weighted_edgept_dist(points[x], vertical_point,
                           chop_x_y_weight) < chop_split_length) {

      split = new_split (points[x], vertical_point);
      priority = partial_split_priority (split);

      choose_best_seam(seam_queue, split, priority, seam, blob, seam_pile);
    }
  }
}

}