1/*
2 * Copyright (C) 2012 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 ScrollingConstraints_h
27#define ScrollingConstraints_h
28
29#include "platform/geometry/FloatRect.h"
30
31namespace WebCore {
32
33// ViewportConstraints classes encapsulate data and logic required to reposition elements whose layout
34// depends on the viewport rect (positions fixed and sticky), when scrolling and zooming.
35class ViewportConstraints {
36public:
37    enum ConstraintType {
38        FixedPositionConstaint,
39        StickyPositionConstraint
40    };
41
42    enum AnchorEdgeFlags {
43        AnchorEdgeLeft = 1 << 0,
44        AnchorEdgeRight = 1 << 1,
45        AnchorEdgeTop = 1 << 2,
46        AnchorEdgeBottom = 1 << 3
47    };
48    typedef unsigned AnchorEdges;
49
50    ViewportConstraints(const ViewportConstraints& other)
51        : m_alignmentOffset(other.m_alignmentOffset)
52        , m_anchorEdges(other.m_anchorEdges)
53    { }
54
55    virtual ~ViewportConstraints() { }
56
57    virtual ConstraintType constraintType() const = 0;
58
59    AnchorEdges anchorEdges() const { return m_anchorEdges; }
60    bool hasAnchorEdge(AnchorEdgeFlags flag) const { return m_anchorEdges & flag; }
61    void addAnchorEdge(AnchorEdgeFlags edgeFlag) { m_anchorEdges |= edgeFlag; }
62    void setAnchorEdges(AnchorEdges edges) { m_anchorEdges = edges; }
63
64    FloatSize alignmentOffset() const { return m_alignmentOffset; }
65    void setAlignmentOffset(const FloatSize& offset) { m_alignmentOffset = offset; }
66
67protected:
68    ViewportConstraints()
69        : m_anchorEdges(0)
70    { }
71
72    FloatSize m_alignmentOffset;
73    AnchorEdges m_anchorEdges;
74};
75
76class FixedPositionViewportConstraints FINAL : public ViewportConstraints {
77public:
78    FixedPositionViewportConstraints()
79        : ViewportConstraints()
80    { }
81
82    FixedPositionViewportConstraints(const FixedPositionViewportConstraints& other)
83        : ViewportConstraints(other)
84        , m_viewportRectAtLastLayout(other.m_viewportRectAtLastLayout)
85        , m_layerPositionAtLastLayout(other.m_layerPositionAtLastLayout)
86    { }
87
88    FloatPoint layerPositionForViewportRect(const FloatRect& viewportRect) const;
89
90    const FloatRect& viewportRectAtLastLayout() const { return m_viewportRectAtLastLayout; }
91    void setViewportRectAtLastLayout(const FloatRect& rect) { m_viewportRectAtLastLayout = rect; }
92
93    const FloatPoint& layerPositionAtLastLayout() const { return m_layerPositionAtLastLayout; }
94    void setLayerPositionAtLastLayout(const FloatPoint& point) { m_layerPositionAtLastLayout = point; }
95
96    bool operator==(const FixedPositionViewportConstraints& other) const
97    {
98        return m_alignmentOffset == other.m_alignmentOffset
99            && m_anchorEdges == other.m_anchorEdges
100            && m_viewportRectAtLastLayout == other.m_viewportRectAtLastLayout
101            && m_layerPositionAtLastLayout == other.m_layerPositionAtLastLayout;
102    }
103
104    bool operator!=(const FixedPositionViewportConstraints& other) const { return !(*this == other); }
105
106private:
107    virtual ConstraintType constraintType() const OVERRIDE { return FixedPositionConstaint; }
108
109    FloatRect m_viewportRectAtLastLayout;
110    FloatPoint m_layerPositionAtLastLayout;
111};
112
113class StickyPositionViewportConstraints FINAL : public ViewportConstraints {
114public:
115    StickyPositionViewportConstraints()
116        : m_leftOffset(0)
117        , m_rightOffset(0)
118        , m_topOffset(0)
119        , m_bottomOffset(0)
120    { }
121
122    StickyPositionViewportConstraints(const StickyPositionViewportConstraints& other)
123        : ViewportConstraints(other)
124        , m_leftOffset(other.m_leftOffset)
125        , m_rightOffset(other.m_rightOffset)
126        , m_topOffset(other.m_topOffset)
127        , m_bottomOffset(other.m_bottomOffset)
128        , m_absoluteContainingBlockRect(other.m_absoluteContainingBlockRect)
129        , m_absoluteStickyBoxRect(other.m_absoluteStickyBoxRect)
130        , m_stickyOffsetAtLastLayout(other.m_stickyOffsetAtLastLayout)
131        , m_layerPositionAtLastLayout(other.m_layerPositionAtLastLayout)
132    { }
133
134    FloatSize computeStickyOffset(const FloatRect& viewportRect) const;
135
136    const FloatSize stickyOffsetAtLastLayout() const { return m_stickyOffsetAtLastLayout; }
137    void setStickyOffsetAtLastLayout(const FloatSize& offset) { m_stickyOffsetAtLastLayout = offset; }
138
139    FloatPoint layerPositionForViewportRect(const FloatRect& viewportRect) const;
140
141    const FloatPoint& layerPositionAtLastLayout() const { return m_layerPositionAtLastLayout; }
142    void setLayerPositionAtLastLayout(const FloatPoint& point) { m_layerPositionAtLastLayout = point; }
143
144    float leftOffset() const { return m_leftOffset; }
145    float rightOffset() const { return m_rightOffset; }
146    float topOffset() const { return m_topOffset; }
147    float bottomOffset() const { return m_bottomOffset; }
148
149    void setLeftOffset(float offset) { m_leftOffset = offset; }
150    void setRightOffset(float offset) { m_rightOffset = offset; }
151    void setTopOffset(float offset) { m_topOffset = offset; }
152    void setBottomOffset(float offset) { m_bottomOffset = offset; }
153
154    FloatRect absoluteContainingBlockRect() const { return m_absoluteContainingBlockRect; }
155    void setAbsoluteContainingBlockRect(const FloatRect& rect) { m_absoluteContainingBlockRect = rect; }
156
157    FloatRect absoluteStickyBoxRect() const { return m_absoluteStickyBoxRect; }
158    void setAbsoluteStickyBoxRect(const FloatRect& rect) { m_absoluteStickyBoxRect = rect; }
159
160    bool operator==(const StickyPositionViewportConstraints& other) const
161    {
162        return m_leftOffset == other.m_leftOffset
163            && m_rightOffset == other.m_rightOffset
164            && m_topOffset == other.m_topOffset
165            && m_bottomOffset == other.m_bottomOffset
166            && m_absoluteContainingBlockRect == other.m_absoluteContainingBlockRect
167            && m_absoluteStickyBoxRect == other.m_absoluteStickyBoxRect
168            && m_stickyOffsetAtLastLayout == other.m_stickyOffsetAtLastLayout
169            && m_layerPositionAtLastLayout == other.m_layerPositionAtLastLayout;
170    }
171
172    bool operator!=(const StickyPositionViewportConstraints& other) const { return !(*this == other); }
173
174private:
175    virtual ConstraintType constraintType() const OVERRIDE { return StickyPositionConstraint; }
176
177    float m_leftOffset;
178    float m_rightOffset;
179    float m_topOffset;
180    float m_bottomOffset;
181    FloatRect m_absoluteContainingBlockRect;
182    FloatRect m_absoluteStickyBoxRect;
183    FloatSize m_stickyOffsetAtLastLayout;
184    FloatPoint m_layerPositionAtLastLayout;
185};
186
187} // namespace WebCore
188
189#endif // ScrollingConstraints_h
190