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 "IntRect.h"
30#include <wtf/Vector.h>
31
32namespace WebCore {
33
34class Region {
35    WTF_MAKE_FAST_ALLOCATED;
36
37public:
38    Region();
39    Region(const IntRect&);
40
41    IntRect bounds() const { return m_bounds; }
42    bool isEmpty() const { return m_bounds.isEmpty(); }
43    bool isRect() const { return m_shape.isRect(); }
44
45    Vector<IntRect> rects() const;
46
47    void unite(const Region&);
48    void intersect(const Region&);
49    void subtract(const Region&);
50
51    void translate(const IntSize&);
52
53    // Returns true if the query region is a subset of this region.
54    bool contains(const Region&) const;
55
56    bool contains(const IntPoint&) const;
57
58    // Returns true if the query region intersects any part of this region.
59    bool intersects(const Region&) const;
60
61    unsigned totalArea() const;
62
63    unsigned gridSize() const { return m_shape.gridSize(); }
64
65#ifndef NDEBUG
66    void dump() const;
67#endif
68
69    bool isValid() const { return m_shape.isValid(); }
70
71    // This is internal to Region, but exposed just for encoding.
72    // FIXME: figure out a better way to encode WebCore classes.
73    struct Span {
74        Span()
75            : y(0)
76            , segmentIndex(0)
77        {
78        }
79
80        Span(int y, size_t segmentIndex)
81            : y(y)
82            , segmentIndex(segmentIndex)
83        {
84        }
85
86        int y;
87        size_t segmentIndex;
88    };
89
90    // For encoding/decoding only.
91    const Vector<int, 32>& shapeSegments() const { return m_shape.segments(); }
92    const Vector<Span, 16>& shapeSpans() const { return m_shape.spans(); }
93
94    void setShapeSegments(const Vector<int>& segments) { m_shape.setSegments(segments); }
95    void setShapeSpans(const Vector<Span>& spans) { m_shape.setSpans(spans); }
96    void updateBoundsFromShape();
97
98private:
99
100    class Shape {
101    public:
102        Shape();
103        Shape(const IntRect&);
104
105        IntRect bounds() const;
106        bool isEmpty() const { return m_spans.isEmpty(); }
107        bool isRect() const { return m_spans.size() <= 2 && m_segments.size() <= 2; }
108        unsigned gridSize() const { return m_spans.size() * m_segments.size(); }
109
110        typedef const Span* SpanIterator;
111        SpanIterator spans_begin() const;
112        SpanIterator spans_end() const;
113
114        typedef const int* SegmentIterator;
115        SegmentIterator segments_begin(SpanIterator) const;
116        SegmentIterator segments_end(SpanIterator) const;
117
118        static Shape unionShapes(const Shape& shape1, const Shape& shape2);
119        static Shape intersectShapes(const Shape& shape1, const Shape& shape2);
120        static Shape subtractShapes(const Shape& shape1, const Shape& shape2);
121
122        void translate(const IntSize&);
123        void swap(Shape&);
124
125        struct CompareContainsOperation;
126        struct CompareIntersectsOperation;
127
128        template<typename CompareOperation>
129        static bool compareShapes(const Shape& shape1, const Shape& shape2);
130
131        bool isValid() const;
132
133        // For encoding/decoding only.
134        const Vector<int, 32>& segments() const { return m_segments; }
135        const Vector<Span, 16>& spans() const { return m_spans; }
136
137        void setSegments(const Vector<int>& segments) { m_segments = segments; }
138        void setSpans(const Vector<Span>& spans) { m_spans = spans; }
139
140#ifndef NDEBUG
141        void dump() const;
142#endif
143
144    private:
145        struct UnionOperation;
146        struct IntersectOperation;
147        struct SubtractOperation;
148
149        template<typename Operation>
150        static Shape shapeOperation(const Shape& shape1, const Shape& shape2);
151
152        void appendSegment(int x);
153        void appendSpan(int y);
154        void appendSpan(int y, SegmentIterator begin, SegmentIterator end);
155        void appendSpans(const Shape&, SpanIterator begin, SpanIterator end);
156
157        bool canCoalesce(SegmentIterator begin, SegmentIterator end);
158
159        Vector<int, 32> m_segments;
160        Vector<Span, 16> m_spans;
161
162        friend bool operator==(const Shape&, const Shape&);
163    };
164
165    IntRect m_bounds;
166    Shape m_shape;
167
168    friend bool operator==(const Region&, const Region&);
169    friend bool operator==(const Shape&, const Shape&);
170    friend bool operator==(const Span&, const Span&);
171};
172
173static inline Region intersect(const Region& a, const Region& b)
174{
175    Region result(a);
176    result.intersect(b);
177
178    return result;
179}
180
181static inline Region subtract(const Region& a, const Region& b)
182{
183    Region result(a);
184    result.subtract(b);
185
186    return result;
187}
188
189static inline Region translate(const Region& region, const IntSize& offset)
190{
191    Region result(region);
192    result.translate(offset);
193
194    return result;
195}
196
197inline bool operator==(const Region& a, const Region& b)
198{
199    return a.m_bounds == b.m_bounds && a.m_shape == b.m_shape;
200}
201
202inline bool operator==(const Region::Shape& a, const Region::Shape& b)
203{
204    return a.m_spans == b.m_spans && a.m_segments == b.m_segments;
205}
206
207inline bool operator==(const Region::Span& a, const Region::Span& b)
208{
209    return a.y == b.y && a.segmentIndex == b.segmentIndex;
210}
211
212} // namespace WebCore
213
214#endif // Region_h
215