EDLines.h

/**************************************************************************************************************
 * EDLines source codes.
 * Copyright (C) Cuneyt Akinlar & Cihan Topal
 * E-mails of the authors: cuneytakinlar@gmail.com, cihantopal@gmail.com
 *
 * Please cite the following papers if you use EDLines library:
 *
 * [1] C. Akinlar and C. Topal, “EDLines: A Real-time Line Segment Detector with a False Detection
 *Control,” Pattern Recognition Letters, 32(13), 1633-1642, DOI: 10.1016/j.patrec.2011.06.001
 *(2011).
 *
 * [2] C. Akinlar and C. Topal, “EDLines: Realtime Line Segment Detection by Edge Drawing (ED),”
 *     IEEE Int’l Conf. on Image Processing (ICIP), Sep. 2011.
 **************************************************************************************************************/

#ifndef _EDLines_
#define _EDLines_

#include "ED.h"
#include "EDColor.h"
#include "NFA.h"

#define SS 0
#define SE 1
#define ES 2
#define EE 3

// light weight struct for Start & End coordinates of the line segment
struct LS
{
  cv::Point2d start;
  cv::Point2d end;

  LS(cv::Point2d _start, cv::Point2d _end)
  {
    start = _start;
    end = _end;
  }
};

struct LineSegment
{
  double a, b;  // y = a + bx (if invert = 0) || x = a + by (if invert = 1)
  int invert;

  double sx, sy;  // starting x & y coordinates
  double ex, ey;  // ending x & y coordinates

  int segmentNo;        // Edge segment that this line belongs to
  int firstPixelIndex;  // Index of the first pixel within the segment of pixels
  int len;              // No of pixels making up the line segment

  LineSegment(double _a, double _b, int _invert, double _sx, double _sy, double _ex, double _ey,
              int _segmentNo, int _firstPixelIndex, int _len)
  {
    a = _a;
    b = _b;
    invert = _invert;
    sx = _sx;
    sy = _sy;
    ex = _ex;
    ey = _ey;
    segmentNo = _segmentNo;
    firstPixelIndex = _firstPixelIndex;
    len = _len;
  }
};

class EDLines : public ED
{
 public:
  EDLines(cv::Mat srcImage, double _line_error = 1.0, int _min_line_len = -1,
          double _max_distance_between_two_lines = 6.0, double _max_error = 1.3);
  EDLines(ED obj, double _line_error = 1.0, int _min_line_len = -1,
          double _max_distance_between_two_lines = 6.0, double _max_error = 1.3);
  EDLines(EDColor obj, double _line_error = 1.0, int _min_line_len = -1,
          double _max_distance_between_two_lines = 6.0, double _max_error = 1.3);
  EDLines();

  std::vector<LS> getLines();
  int getLinesNo();
  cv::Mat getLineImage();
  cv::Mat drawOnImage();

  // EDCircle uses this one
  static void SplitSegment2Lines(double *x, double *y, int noPixels, int segmentNo,
                                 std::vector<LineSegment> &lines, int min_line_len = 6,
                                 double line_error = 1.0);

 private:
  std::vector<LineSegment> lines;
  std::vector<LineSegment> invalidLines;
  std::vector<LS> linePoints;
  int linesNo;
  int min_line_len;
  double line_error;
  double max_distance_between_two_lines;
  double max_error;
  double prec;
  std::shared_ptr<NFALUT> nfa;

  int ComputeMinLineLength();
  void SplitSegment2Lines(double *x, double *y, int noPixels, int segmentNo);
  void JoinCollinearLines();

  void ValidateLineSegments();
  bool ValidateLineSegmentRect(std::vector<int> &x, std::vector<int> &y, LineSegment *ls);
  bool TryToJoinTwoLineSegments(LineSegment *ls1, LineSegment *ls2, int changeIndex);

  static double ComputeMinDistance(double x1, double y1, double a, double b, int invert);
  static void ComputeClosestPoint(double x1, double y1, double a, double b, int invert,
                                  double &xOut, double &yOut);
  static void LineFit(double *x, double *y, int count, double &a, double &b, int invert);
  static void LineFit(double *x, double *y, int count, double &a, double &b, double &e,
                      int &invert);
  static double ComputeMinDistanceBetweenTwoLines(LineSegment *ls1, LineSegment *ls2, int *pwhich);
  static void UpdateLineParameters(LineSegment *ls);
  static void EnumerateRectPoints(double sx, double sy, double ex, double ey,
                                  std::vector<int> &ptsx, std::vector<int> &ptsy, int *pNoPoints);

  // Utility math functions
};

#endif