third_party/WebKit/Source/platform/geometry/FloatPolygon.h

/*
 * Copyright (C) 2012 Adobe Systems Incorporated. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above
 *    copyright notice, this list of conditions and the following
 *    disclaimer.
 * 2. Redistributions in binary form must reproduce the above
 *    copyright notice, this list of conditions and the following
 *    disclaimer in the documentation and/or other materials
 *    provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef FloatPolygon_h
#define FloatPolygon_h

#include "platform/PODIntervalTree.h"
#include "platform/geometry/FloatPoint.h"
#include "platform/geometry/FloatRect.h"
#include "platform/graphics/GraphicsTypes.h"
#include "wtf/Allocator.h"
#include "wtf/Vector.h"
#include <memory>

namespace blink {

class FloatPolygonEdge;

// This class is used by PODIntervalTree for debugging.
#ifndef NDEBUG
template <class>
struct ValueToString;
#endif

class PLATFORM_EXPORT FloatPolygon {
  USING_FAST_MALLOC(FloatPolygon);
  WTF_MAKE_NONCOPYABLE(FloatPolygon);

 public:
  FloatPolygon(std::unique_ptr<Vector<FloatPoint>> vertices, WindRule fillRule);

  const FloatPoint& vertexAt(unsigned index) const {
    return (*m_vertices)[index];
  }
  unsigned numberOfVertices() const { return m_vertices->size(); }

  WindRule fillRule() const { return m_fillRule; }

  const FloatPolygonEdge& edgeAt(unsigned index) const {
    return m_edges[index];
  }
  unsigned numberOfEdges() const { return m_edges.size(); }

  FloatRect boundingBox() const { return m_boundingBox; }
  bool overlappingEdges(float minY,
                        float maxY,
                        Vector<const FloatPolygonEdge*>& result) const;
  bool contains(const FloatPoint&) const;
  bool isEmpty() const { return m_empty; }

 private:
  typedef PODInterval<float, FloatPolygonEdge*> EdgeInterval;
  typedef PODIntervalTree<float, FloatPolygonEdge*> EdgeIntervalTree;

  bool containsNonZero(const FloatPoint&) const;
  bool containsEvenOdd(const FloatPoint&) const;

  std::unique_ptr<Vector<FloatPoint>> m_vertices;
  WindRule m_fillRule;
  FloatRect m_boundingBox;
  bool m_empty;
  Vector<FloatPolygonEdge> m_edges;
  EdgeIntervalTree m_edgeTree;  // Each EdgeIntervalTree node stores minY, maxY,
                                // and a ("UserData") pointer to a
                                // FloatPolygonEdge.
};

class PLATFORM_EXPORT VertexPair {
 public:
  virtual ~VertexPair() {}

  virtual const FloatPoint& vertex1() const = 0;
  virtual const FloatPoint& vertex2() const = 0;

  float minX() const { return std::min(vertex1().x(), vertex2().x()); }
  float minY() const { return std::min(vertex1().y(), vertex2().y()); }
  float maxX() const { return std::max(vertex1().x(), vertex2().x()); }
  float maxY() const { return std::max(vertex1().y(), vertex2().y()); }

  bool intersection(const VertexPair&, FloatPoint&) const;
};

class PLATFORM_EXPORT FloatPolygonEdge final : public VertexPair {
  DISALLOW_NEW_EXCEPT_PLACEMENT_NEW();
  friend class FloatPolygon;

 public:
  const FloatPoint& vertex1() const override {
    ASSERT(m_polygon);
    return m_polygon->vertexAt(m_vertexIndex1);
  }

  const FloatPoint& vertex2() const override {
    ASSERT(m_polygon);
    return m_polygon->vertexAt(m_vertexIndex2);
  }

  const FloatPolygonEdge& previousEdge() const {
    ASSERT(m_polygon && m_polygon->numberOfEdges() > 1);
    return m_polygon->edgeAt((m_edgeIndex + m_polygon->numberOfEdges() - 1) %
                             m_polygon->numberOfEdges());
  }

  const FloatPolygonEdge& nextEdge() const {
    ASSERT(m_polygon && m_polygon->numberOfEdges() > 1);
    return m_polygon->edgeAt((m_edgeIndex + 1) % m_polygon->numberOfEdges());
  }

  const FloatPolygon* polygon() const { return m_polygon; }
  unsigned vertexIndex1() const { return m_vertexIndex1; }
  unsigned vertexIndex2() const { return m_vertexIndex2; }
  unsigned edgeIndex() const { return m_edgeIndex; }

 private:
  // Edge vertex index1 is less than index2, except the last edge, where index2
  // is 0. When a polygon edge is defined by 3 or more colinear vertices, index2
  // can be the the index of the last colinear vertex.
  unsigned m_vertexIndex1;
  unsigned m_vertexIndex2;
  unsigned m_edgeIndex;
  const FloatPolygon* m_polygon;
};

// These structures are used by PODIntervalTree for debugging.
#ifndef NDEBUG
template <>
struct ValueToString<float> {
  STATIC_ONLY(ValueToString);
  static String toString(const float value) { return String::number(value); }
};

template <>
struct ValueToString<FloatPolygonEdge*> {
  STATIC_ONLY(ValueToString);
  static String toString(const FloatPolygonEdge* edge) {
    return String::format("%p (%f,%f %f,%f)", edge, edge->vertex1().x(),
                          edge->vertex1().y(), edge->vertex2().x(),
                          edge->vertex2().y());
  }
};
#endif

}  // namespace blink

#endif  // FloatPolygon_h