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#include "config.h"
27#include "ScrollingConstraints.h"
28
29namespace WebCore {
30
31FloatPoint FixedPositionViewportConstraints::layerPositionForViewportRect(const FloatRect& viewportRect) const
32{
33    FloatSize offset;
34
35    if (hasAnchorEdge(AnchorEdgeLeft))
36        offset.setWidth(viewportRect.x() - m_viewportRectAtLastLayout.x());
37    else if (hasAnchorEdge(AnchorEdgeRight))
38        offset.setWidth(viewportRect.maxX() - m_viewportRectAtLastLayout.maxX());
39
40    if (hasAnchorEdge(AnchorEdgeTop))
41        offset.setHeight(viewportRect.y() - m_viewportRectAtLastLayout.y());
42    else if (hasAnchorEdge(AnchorEdgeBottom))
43        offset.setHeight(viewportRect.maxY() - m_viewportRectAtLastLayout.maxY());
44
45    return m_layerPositionAtLastLayout + offset;
46}
47
48FloatSize StickyPositionViewportConstraints::computeStickyOffset(const FloatRect& viewportRect) const
49{
50    FloatRect boxRect = m_absoluteStickyBoxRect;
51
52    if (hasAnchorEdge(AnchorEdgeRight)) {
53        float rightLimit = viewportRect.maxX() - m_rightOffset;
54        float rightDelta = std::min<float>(0, rightLimit - m_absoluteStickyBoxRect.maxX());
55        float availableSpace = std::min<float>(0, m_absoluteContainingBlockRect.x() - m_absoluteStickyBoxRect.x());
56        if (rightDelta < availableSpace)
57            rightDelta = availableSpace;
58
59        boxRect.move(rightDelta, 0);
60    }
61
62    if (hasAnchorEdge(AnchorEdgeLeft)) {
63        float leftLimit = viewportRect.x() + m_leftOffset;
64        float leftDelta = std::max<float>(0, leftLimit - m_absoluteStickyBoxRect.x());
65        float availableSpace = std::max<float>(0, m_absoluteContainingBlockRect.maxX() - m_absoluteStickyBoxRect.maxX());
66        if (leftDelta > availableSpace)
67            leftDelta = availableSpace;
68
69        boxRect.move(leftDelta, 0);
70    }
71
72    if (hasAnchorEdge(AnchorEdgeBottom)) {
73        float bottomLimit = viewportRect.maxY() - m_bottomOffset;
74        float bottomDelta = std::min<float>(0, bottomLimit - m_absoluteStickyBoxRect.maxY());
75        float availableSpace = std::min<float>(0, m_absoluteContainingBlockRect.y() - m_absoluteStickyBoxRect.y());
76        if (bottomDelta < availableSpace)
77            bottomDelta = availableSpace;
78
79        boxRect.move(0, bottomDelta);
80    }
81
82    if (hasAnchorEdge(AnchorEdgeTop)) {
83        float topLimit = viewportRect.y() + m_topOffset;
84        float topDelta = std::max<float>(0, topLimit - m_absoluteStickyBoxRect.y());
85        float availableSpace = std::max<float>(0, m_absoluteContainingBlockRect.maxY() - m_absoluteStickyBoxRect.maxY());
86        if (topDelta > availableSpace)
87            topDelta = availableSpace;
88
89        boxRect.move(0, topDelta);
90    }
91
92    return boxRect.location() - m_absoluteStickyBoxRect.location();
93}
94
95FloatPoint StickyPositionViewportConstraints::layerPositionForViewportRect(const FloatRect& viewportRect) const
96{
97    FloatSize offset = computeStickyOffset(viewportRect);
98    return m_layerPositionAtLastLayout + offset - m_stickyOffsetAtLastLayout;
99}
100
101} // namespace WebCore
102