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      1 /*
      2  * Copyright (C) 2010, 2011 Apple Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
     14  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
     15  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     16  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
     17  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     18  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     19  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     20  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     21  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     22  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
     23  * THE POSSIBILITY OF SUCH DAMAGE.
     24  */
     25 
     26 #ifndef Region_h
     27 #define Region_h
     28 
     29 #include "platform/PlatformExport.h"
     30 #include "platform/geometry/IntRect.h"
     31 #include "wtf/Vector.h"
     32 
     33 namespace WebCore {
     34 
     35 class PLATFORM_EXPORT Region {
     36 public:
     37     Region();
     38     Region(const IntRect&);
     39 
     40     IntRect bounds() const { return m_bounds; }
     41     bool isEmpty() const { return m_bounds.isEmpty(); }
     42     bool isRect() const { return m_shape.isRect(); }
     43 
     44     Vector<IntRect> rects() const;
     45 
     46     void unite(const Region&);
     47     void intersect(const Region&);
     48     void subtract(const Region&);
     49 
     50     void translate(const IntSize&);
     51 
     52     // Returns true if the query region is a subset of this region.
     53     bool contains(const Region&) const;
     54 
     55     bool contains(const IntPoint&) const;
     56 
     57     // Returns true if the query region intersects any part of this region.
     58     bool intersects(const Region&) const;
     59 
     60     unsigned totalArea() const;
     61 
     62 #ifndef NDEBUG
     63     void dump() const;
     64 #endif
     65 
     66 private:
     67     struct Span {
     68         Span(int y, size_t segmentIndex)
     69             : y(y), segmentIndex(segmentIndex)
     70         {
     71         }
     72 
     73         int y;
     74         size_t segmentIndex;
     75     };
     76 
     77     class Shape {
     78     public:
     79         Shape();
     80         Shape(const IntRect&);
     81         Shape(size_t segmentsCapacity, size_t spansCapacity);
     82 
     83         IntRect bounds() const;
     84         bool isEmpty() const { return m_spans.isEmpty(); }
     85         bool isRect() const { return m_spans.size() <= 2 && m_segments.size() <= 2; }
     86 
     87         typedef const Span* SpanIterator;
     88         SpanIterator spansBegin() const;
     89         SpanIterator spansEnd() const;
     90         size_t spansSize() const { return m_spans.size(); }
     91 
     92         typedef const int* SegmentIterator;
     93         SegmentIterator segmentsBegin(SpanIterator) const;
     94         SegmentIterator segmentsEnd(SpanIterator) const;
     95         size_t segmentsSize() const { return m_segments.size(); }
     96 
     97         static Shape unionShapes(const Shape& shape1, const Shape& shape2);
     98         static Shape intersectShapes(const Shape& shape1, const Shape& shape2);
     99         static Shape subtractShapes(const Shape& shape1, const Shape& shape2);
    100 
    101         void translate(const IntSize&);
    102         void swap(Shape&);
    103 
    104         struct CompareContainsOperation;
    105         struct CompareIntersectsOperation;
    106 
    107         template<typename CompareOperation>
    108         static bool compareShapes(const Shape& shape1, const Shape& shape2);
    109         void trimCapacities();
    110 
    111 #ifndef NDEBUG
    112         void dump() const;
    113 #endif
    114 
    115     private:
    116         struct UnionOperation;
    117         struct IntersectOperation;
    118         struct SubtractOperation;
    119 
    120         template<typename Operation>
    121         static Shape shapeOperation(const Shape& shape1, const Shape& shape2);
    122 
    123         void appendSegment(int x);
    124         void appendSpan(int y);
    125         void appendSpan(int y, SegmentIterator begin, SegmentIterator end);
    126         void appendSpans(const Shape&, SpanIterator begin, SpanIterator end);
    127 
    128         bool canCoalesce(SegmentIterator begin, SegmentIterator end);
    129 
    130         Vector<int, 32> m_segments;
    131         Vector<Span, 16> m_spans;
    132 
    133         friend bool operator==(const Shape&, const Shape&);
    134     };
    135 
    136     IntRect m_bounds;
    137     Shape m_shape;
    138 
    139     friend bool operator==(const Region&, const Region&);
    140     friend bool operator==(const Shape&, const Shape&);
    141     friend bool operator==(const Span&, const Span&);
    142 };
    143 
    144 static inline Region intersect(const Region& a, const Region& b)
    145 {
    146     Region result(a);
    147     result.intersect(b);
    148 
    149     return result;
    150 }
    151 
    152 static inline Region subtract(const Region& a, const Region& b)
    153 {
    154     Region result(a);
    155     result.subtract(b);
    156 
    157     return result;
    158 }
    159 
    160 static inline Region translate(const Region& region, const IntSize& offset)
    161 {
    162     Region result(region);
    163     result.translate(offset);
    164 
    165     return result;
    166 }
    167 
    168 inline bool operator==(const Region& a, const Region& b)
    169 {
    170     return a.m_bounds == b.m_bounds && a.m_shape == b.m_shape;
    171 }
    172 
    173 inline bool operator==(const Region::Shape& a, const Region::Shape& b)
    174 {
    175     return a.m_spans == b.m_spans && a.m_segments == b.m_segments;
    176 }
    177 
    178 inline bool operator==(const Region::Span& a, const Region::Span& b)
    179 {
    180     return a.y == b.y && a.segmentIndex == b.segmentIndex;
    181 }
    182 
    183 } // namespace WebCore
    184 
    185 #endif // Region_h
    186