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 "core/page/scrolling/ScrollingConstraints.h"
28
29 namespace WebCore {
30
layerPositionForViewportRect(const FloatRect & viewportRect) const31 FloatPoint 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
computeStickyOffset(const FloatRect & viewportRect) const48 FloatSize 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
layerPositionForViewportRect(const FloatRect & viewportRect) const95 FloatPoint 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