C++ TBOX::y_overlap方法代码示例

// Search vertically for a blob that is aligned with the input bbox.
// The search parameters are determined by AlignedBlobParams.
// top_to_bottom tells whether to search down or up.
// The return value is nullptr if nothing was found in the search box
// or if a blob was found in the gutter. On a nullptr return, end_y
// is set to the edge of the search box or the leading edge of the
// gutter blob if one was found.
BLOBNBOX* AlignedBlob::FindAlignedBlob(const AlignedBlobParams& p,
                                       bool top_to_bottom, BLOBNBOX* bbox,
                                       int x_start, int* end_y) {
  TBOX box = bbox->bounding_box();
  // If there are separator lines, get the column edges.
  int left_column_edge = bbox->left_rule();
  int right_column_edge = bbox->right_rule();
  // start_y is used to guarantee that forward progress is made and the
  // search does not go into an infinite loop. New blobs must extend the
  // line beyond start_y.
  int start_y = top_to_bottom ? box.bottom() : box.top();
  if (WithinTestRegion(2, x_start, start_y)) {
    tprintf("Column edges for blob at (%d,%d)->(%d,%d) are [%d, %d]\n",
            box.left(), box.top(), box.right(), box.bottom(),
            left_column_edge, right_column_edge);
  }
  // Compute skew tolerance.
  int skew_tolerance = p.max_v_gap / kMaxSkewFactor;
  // Calculate xmin and xmax of the search box so that it contains
  // all possibly relevant boxes up to p.max_v_gap above or below accoording
  // to top_to_bottom.
  // Start with a notion of vertical with the current estimate.
  int x2 = (p.max_v_gap * p.vertical.x() + p.vertical.y()/2) / p.vertical.y();
  if (top_to_bottom) {
    x2 = x_start - x2;
    *end_y = start_y - p.max_v_gap;
  } else {
    x2 = x_start + x2;
    *end_y = start_y + p.max_v_gap;
  }
  // Expand the box by an additional skew tolerance
  int xmin = std::min(x_start, x2) - skew_tolerance;
  int xmax = std::max(x_start, x2) + skew_tolerance;
  // Now add direction-specific tolerances.
  if (p.right_tab) {
    xmax += p.min_gutter;
    xmin -= p.l_align_tolerance;
  } else {
    xmax += p.r_align_tolerance;
    xmin -= p.min_gutter;
  }
  // Setup a vertical search for an aligned blob.
  GridSearch<BLOBNBOX, BLOBNBOX_CLIST, BLOBNBOX_C_IT> vsearch(this);
  if (WithinTestRegion(2, x_start, start_y))
    tprintf("Starting %s %s search at %d-%d,%d, search_size=%d, gutter=%d\n",
            p.ragged ? "Ragged" : "Aligned", p.right_tab ? "Right" : "Left",
            xmin, xmax, start_y, p.max_v_gap, p.min_gutter);
  vsearch.StartVerticalSearch(xmin, xmax, start_y);
  // result stores the best real return value.
  BLOBNBOX* result = nullptr;
  // The backup_result is not a tab candidate and can be used if no
  // real tab candidate result is found.
  BLOBNBOX* backup_result = nullptr;
  // neighbour is the blob that is currently being investigated.
  BLOBNBOX* neighbour = nullptr;
  while ((neighbour = vsearch.NextVerticalSearch(top_to_bottom)) != nullptr) {
    if (neighbour == bbox)
      continue;
    TBOX nbox = neighbour->bounding_box();
    int n_y = (nbox.top() + nbox.bottom()) / 2;
    if ((!top_to_bottom && n_y > start_y + p.max_v_gap) ||
        (top_to_bottom && n_y < start_y - p.max_v_gap)) {
      if (WithinTestRegion(2, x_start, start_y))
        tprintf("Neighbour too far at (%d,%d)->(%d,%d)\n",
                nbox.left(), nbox.bottom(), nbox.right(), nbox.top());
      break;  // Gone far enough.
    }
    // It is CRITICAL to ensure that forward progress is made, (strictly
    // in/decreasing n_y) or the caller could loop infinitely, while
    // waiting for a sequence of blobs in a line to end.
    // NextVerticalSearch alone does not guarantee this, as there may be
    // more than one blob in a grid cell. See comment in AlignTabs.
    if ((n_y < start_y) != top_to_bottom || nbox.y_overlap(box))
      continue;  // Only look in the required direction.
    if (result != nullptr && result->bounding_box().y_gap(nbox) > gridsize())
      return result;  // This result is clear.
    if (backup_result != nullptr && p.ragged && result == nullptr &&
        backup_result->bounding_box().y_gap(nbox) > gridsize())
      return backup_result;  // This result is clear.

    // If the neighbouring blob is the wrong side of a separator line, then it
    // "doesn't exist" as far as we are concerned.
    int x_at_n_y = x_start + (n_y - start_y) * p.vertical.x() / p.vertical.y();
    if (x_at_n_y < neighbour->left_crossing_rule() ||
        x_at_n_y > neighbour->right_crossing_rule())
      continue;  // Separator line in the way.
    int n_left = nbox.left();
    int n_right = nbox.right();
    int n_x = p.right_tab ? n_right : n_left;
    if (WithinTestRegion(2, x_start, start_y))
      tprintf("neighbour at (%d,%d)->(%d,%d), n_x=%d, n_y=%d, xatn=%d\n",
              nbox.left(), nbox.bottom(), nbox.right(), nbox.top(),
              n_x, n_y, x_at_n_y);
//.........这里部分代码省略.........