poly_util.h

/* Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.

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. */
#pragma once

#ifndef POLY_UTIL_H_
#define POLY_UTIL_H_

#include <vector>

#include "paddle/phi/kernels/funcs/gpc.h"

namespace phi {
namespace funcs {

using phi::funcs::gpc_free_polygon;
using phi::funcs::gpc_polygon_clip;

template <class T>
class Point_ {
 public:
  // default constructor
  Point_() {}
  Point_(T _x, T _y) {}
  Point_(const Point_& pt) {}

  Point_& operator=(const Point_& pt);
  // conversion to another data type
  // template<typename _T> operator Point_<_T>() const;
  // conversion to the old-style C structures
  // operator Vec<T, 2>() const;

  // checks whether the point is inside the specified rectangle
  // bool inside(const Rect_<T>& r) const;
  T x;  //!< x coordinate of the point
  T y;  //!< y coordinate of the point
};

template <class T>
void Array2PointVec(const T* box,
                    const size_t box_size,
                    std::vector<Point_<T>>* vec) {
  size_t pts_num = box_size / 2;
  (*vec).resize(pts_num);
  for (size_t i = 0; i < pts_num; i++) {
    (*vec).at(i).x = box[2 * i];
    (*vec).at(i).y = box[2 * i + 1];
  }
}

template <class T>
void Array2Poly(const T* box,
                const size_t box_size,
                phi::funcs::gpc_polygon* poly) {
  size_t pts_num = box_size / 2;
  (*poly).num_contours = 1;
  (*poly).hole = reinterpret_cast<int*>(malloc(sizeof(int)));
  (*poly).hole[0] = 0;
  (*poly).contour =
      (phi::funcs::gpc_vertex_list*)malloc(sizeof(phi::funcs::gpc_vertex_list));
  (*poly).contour->num_vertices = pts_num;
  (*poly).contour->vertex =
      (phi::funcs::gpc_vertex*)malloc(sizeof(phi::funcs::gpc_vertex) * pts_num);
  for (size_t i = 0; i < pts_num; ++i) {
    (*poly).contour->vertex[i].x = box[2 * i];
    (*poly).contour->vertex[i].y = box[2 * i + 1];
  }
}

template <class T>
void PointVec2Poly(const std::vector<Point_<T>>& vec,
                   phi::funcs::gpc_polygon* poly) {
  int pts_num = vec.size();
  (*poly).num_contours = 1;
  (*poly).hole = reinterpret_cast<int*>(malloc(sizeof(int)));
  (*poly).hole[0] = 0;
  (*poly).contour =
      (phi::funcs::gpc_vertex_list*)malloc(sizeof(phi::funcs::gpc_vertex_list));
  (*poly).contour->num_vertices = pts_num;
  (*poly).contour->vertex =
      (phi::funcs::gpc_vertex*)malloc(sizeof(phi::funcs::gpc_vertex) * pts_num);
  for (size_t i = 0; i < pts_num; ++i) {
    (*poly).contour->vertex[i].x = vec[i].x;
    (*poly).contour->vertex[i].y = vec[i].y;
  }
}

template <class T>
void Poly2PointVec(const phi::funcs::gpc_vertex_list& contour,
                   std::vector<Point_<T>>* vec) {
  int pts_num = contour.num_vertices;
  (*vec).resize(pts_num);
  for (int i = 0; i < pts_num; i++) {
    (*vec).at(i).x = contour.vertex[i].x;
    (*vec).at(i).y = contour.vertex[i].y;
  }
}

template <class T>
T GetContourArea(const std::vector<Point_<T>>& vec) {
  size_t pts_num = vec.size();
  if (pts_num < 3) return T(0.);
  T area = T(0.);
  for (size_t i = 0; i < pts_num; ++i) {
    area += vec[i].x * vec[(i + 1) % pts_num].y -
            vec[i].y * vec[(i + 1) % pts_num].x;
  }
  return std::fabs(area / 2.0);
}

template <class T>
T PolyArea(const T* box, const size_t box_size, const bool normalized UNUSED) {
  // If coordinate values are is invalid
  // if area size <= 0,  return 0.
  std::vector<Point_<T>> vec;
  Array2PointVec<T>(box, box_size, &vec);
  return GetContourArea<T>(vec);
}

template <class T>
T PolyOverlapArea(const T* box1,
                  const T* box2,
                  const size_t box_size,
                  const bool normalized UNUSED) {
  phi::funcs::gpc_polygon poly1;
  phi::funcs::gpc_polygon poly2;
  Array2Poly<T>(box1, box_size, &poly1);
  Array2Poly<T>(box2, box_size, &poly2);
  phi::funcs::gpc_polygon respoly;
  phi::funcs::gpc_op op = phi::funcs::GPC_INT;
  phi::funcs::gpc_polygon_clip(op, &poly2, &poly1, &respoly);

  T inter_area = T(0.);
  int contour_num = respoly.num_contours;
  for (int i = 0; i < contour_num; ++i) {
    std::vector<Point_<T>> resvec;
    Poly2PointVec<T>(respoly.contour[i], &resvec);
    // inter_area += std::fabs(cv::contourArea(resvec)) + 0.5f *
    // (cv::arcLength(resvec, true));
    inter_area += GetContourArea<T>(resvec);
  }

  phi::funcs::gpc_free_polygon(&poly1);
  phi::funcs::gpc_free_polygon(&poly2);
  phi::funcs::gpc_free_polygon(&respoly);
  return inter_area;
}

}  // namespace funcs
}  // namespace phi

#endif