Method Fit

deps/tesseract/textord/tabvector.cpp:788–871

(Re)Fit a line to the stored points. Returns false if the line is degenerate. Althougth the TabVector code mostly doesn't care about the direction of lines, XAtY would give silly results for a horizontal line. The class is mostly aimed at use for vertical lines representing horizontal tab stops.

// The class is mostly aimed at use for vertical lines representing
// horizontal tab stops.
bool TabVector::Fit(ICOORD vertical, bool force_parallel) {
  needs_refit_ = false;
  if (boxes_.empty()) {
    // Don't refit something with no boxes, as that only happens
    // in Evaluate, and we don't want to end up with a zero vector.
    if (!force_parallel)
      return false;
    // If we are forcing parallel, then we just need to set the sort_key_.
    ICOORD midpt = startpt_;
    midpt += endpt_;
    midpt /= 2;
    sort_key_ = SortKey(vertical, midpt.x(), midpt.y());
    return startpt_.y() != endpt_.y();
  }
  if (!force_parallel && !IsRagged()) {
    // Use a fitted line as the vertical.
    DetLineFit linepoints;
    BLOBNBOX_C_IT it(&boxes_);
    // Fit a line to all the boxes in the list.
    for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
      BLOBNBOX* bbox = it.data();
      const TBOX& box = bbox->bounding_box();
      int x1 = IsRightTab() ? box.right() : box.left();
      ICOORD boxpt(x1, box.bottom());
      linepoints.Add(boxpt);
      if (it.at_last()) {
        ICOORD top_pt(x1, box.top());
        linepoints.Add(top_pt);
      }
    }
    linepoints.Fit(&startpt_, &endpt_);
    if (startpt_.y() != endpt_.y()) {
      vertical = endpt_;
      vertical -= startpt_;
    }
  }
  int start_y = startpt_.y();
  int end_y = endpt_.y();
  sort_key_ = IsLeftTab() ? MAX_INT32 : -MAX_INT32;
  BLOBNBOX_C_IT it(&boxes_);
  // Choose a line parallel to the vertical such that all boxes are on the
  // correct side of it.
  mean_width_ = 0;
  int width_count = 0;
  for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
    BLOBNBOX* bbox = it.data();
    const TBOX& box = bbox->bounding_box();
    mean_width_ += box.width();
    ++width_count;
    int x1 = IsRightTab() ? box.right() : box.left();
    // Test both the bottom and the top, as one will be more extreme, depending
    // on the direction of skew.
    int bottom_y = box.bottom();
    int top_y = box.top();
    int key = SortKey(vertical, x1, bottom_y);
    if (IsLeftTab() == (key < sort_key_)) {
      sort_key_ = key;
      startpt_ = ICOORD(x1, bottom_y);