Method SplitByNode

deps/tesseract/cube/beam_search.cpp:368–451

Backtracks from the given lattice node and return the corresponding char mapped segments and character count. The character bounding boxes are optional return arguments, if non-NULL values are passed in.

// char mapped segments and character count. The character bounding
// boxes are optional return arguments, if non-NULL values are passed in.
CharSamp **BeamSearch::SplitByNode(SearchObject *srch_obj,
                                   SearchNode *srch_node,
                                   int *char_cnt,
                                   Boxa **char_boxes) const {
  // Count the characters (could be less than the path length when in
  // phrase mode)
  *char_cnt = 0;
  SearchNode *node = srch_node;
  while (node) {
    node = node->ParentNode();
    (*char_cnt)++;
  }

  if (*char_cnt == 0)
    return NULL;

  // Allocate box array
  if (char_boxes) {
    if (*char_boxes)
      boxaDestroy(char_boxes);  // clear existing value
    *char_boxes = boxaCreate(*char_cnt);
    if (*char_boxes == NULL)
      return NULL;
  }

  // Allocate memory for CharSamp array.
  CharSamp **chars = new CharSamp *[*char_cnt];

  int ch_idx = *char_cnt - 1;
  int seg_pt_cnt = srch_obj->SegPtCnt();
  bool success=true;
  while (srch_node && ch_idx >= 0) {
    // Parent node (could be null)
    SearchNode *parent_node = srch_node->ParentNode();

    // Get the seg pts corresponding to the search node
    int st_col = !parent_node ? 0 : parent_node->ColIdx() + 1;
    int st_seg_pt = st_col <= 0 ? -1 : st_col - 1;
    int end_col = srch_node->ColIdx();
    int end_seg_pt = end_col >= seg_pt_cnt ? seg_pt_cnt : end_col;

    // Get a char sample corresponding to the segmentation points
    CharSamp *samp = srch_obj->CharSample(st_seg_pt, end_seg_pt);
    if (!samp) {
      success = false;
      break;
    }
    samp->SetLabel(srch_node->NodeString());
    chars[ch_idx] = samp;
    if (char_boxes) {
      // Create the corresponding character bounding box
      Box *char_box = boxCreate(samp->Left(), samp->Top(),
                                samp->Width(), samp->Height());
      if (!char_box) {
        success = false;
        break;
      }
      boxaAddBox(*char_boxes, char_box, L_INSERT);