flutter_flutter/sky/engine/platform/geometry/Region.h

/*
 * Copyright (C) 2010, 2011 Apple Inc. 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 APPLE INC. AND ITS 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 APPLE INC. OR ITS 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 SKY_ENGINE_PLATFORM_GEOMETRY_REGION_H_
#define SKY_ENGINE_PLATFORM_GEOMETRY_REGION_H_

#include "flutter/sky/engine/platform/PlatformExport.h"
#include "flutter/sky/engine/platform/geometry/IntRect.h"
#include "flutter/sky/engine/wtf/Vector.h"

namespace blink {

class PLATFORM_EXPORT Region {
 public:
  Region();
  Region(const IntRect&);

  IntRect bounds() const { return m_bounds; }
  bool isEmpty() const { return m_bounds.isEmpty(); }
  bool isRect() const { return m_shape.isRect(); }

  Vector<IntRect> rects() const;

  void unite(const Region&);
  void intersect(const Region&);
  void subtract(const Region&);

  void translate(const IntSize&);

  // Returns true if the query region is a subset of this region.
  bool contains(const Region&) const;

  bool contains(const IntPoint&) const;

  // Returns true if the query region intersects any part of this region.
  bool intersects(const Region&) const;

  unsigned totalArea() const;

#ifndef NDEBUG
  void dump() const;
#endif

 private:
  struct Span {
    Span(int y, size_t segmentIndex) : y(y), segmentIndex(segmentIndex) {}

    int y;
    size_t segmentIndex;
  };

  class Shape {
   public:
    Shape();
    Shape(const IntRect&);
    Shape(size_t segmentsCapacity, size_t spansCapacity);

    IntRect bounds() const;
    bool isEmpty() const { return m_spans.isEmpty(); }
    bool isRect() const {
      return m_spans.size() <= 2 && m_segments.size() <= 2;
    }

    typedef const Span* SpanIterator;
    SpanIterator spansBegin() const;
    SpanIterator spansEnd() const;
    size_t spansSize() const { return m_spans.size(); }

    typedef const int* SegmentIterator;
    SegmentIterator segmentsBegin(SpanIterator) const;
    SegmentIterator segmentsEnd(SpanIterator) const;
    size_t segmentsSize() const { return m_segments.size(); }

    static Shape unionShapes(const Shape& shape1, const Shape& shape2);
    static Shape intersectShapes(const Shape& shape1, const Shape& shape2);
    static Shape subtractShapes(const Shape& shape1, const Shape& shape2);

    void translate(const IntSize&);
    void swap(Shape&);

    struct CompareContainsOperation;
    struct CompareIntersectsOperation;

    template <typename CompareOperation>
    static bool compareShapes(const Shape& shape1, const Shape& shape2);
    void trimCapacities();

#ifndef NDEBUG
    void dump() const;
#endif

   private:
    struct UnionOperation;
    struct IntersectOperation;
    struct SubtractOperation;

    template <typename Operation>
    static Shape shapeOperation(const Shape& shape1, const Shape& shape2);

    void appendSegment(int x);
    void appendSpan(int y);
    void appendSpan(int y, SegmentIterator begin, SegmentIterator end);
    void appendSpans(const Shape&, SpanIterator begin, SpanIterator end);

    bool canCoalesce(SegmentIterator begin, SegmentIterator end);

    Vector<int, 32> m_segments;
    Vector<Span, 16> m_spans;

    friend bool operator==(const Shape&, const Shape&);
  };

  IntRect m_bounds;
  Shape m_shape;

  friend bool operator==(const Region&, const Region&);
  friend bool operator==(const Shape&, const Shape&);
  friend bool operator==(const Span&, const Span&);
};

static inline Region intersect(const Region& a, const Region& b) {
  Region result(a);
  result.intersect(b);

  return result;
}

static inline Region subtract(const Region& a, const Region& b) {
  Region result(a);
  result.subtract(b);

  return result;
}

static inline Region translate(const Region& region, const IntSize& offset) {
  Region result(region);
  result.translate(offset);

  return result;
}

inline bool operator==(const Region& a, const Region& b) {
  return a.m_bounds == b.m_bounds && a.m_shape == b.m_shape;
}

inline bool operator==(const Region::Shape& a, const Region::Shape& b) {
  return a.m_spans == b.m_spans && a.m_segments == b.m_segments;
}

inline bool operator==(const Region::Span& a, const Region::Span& b) {
  return a.y == b.y && a.segmentIndex == b.segmentIndex;
}

}  // namespace blink

#endif  // SKY_ENGINE_PLATFORM_GEOMETRY_REGION_H_