1/*
2 * Copyright (C) 2013 Google 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 are
6 * met:
7 *
8 *     * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *     * Redistributions in binary form must reproduce the above
11 * copyright notice, this list of conditions and the following disclaimer
12 * in the documentation and/or other materials provided with the
13 * distribution.
14 *     * Neither the name of Google Inc. nor the names of its
15 * contributors may be used to endorse or promote products derived from
16 * this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31#ifndef ViewportAnchor_h
32#define ViewportAnchor_h
33
34#include "platform/geometry/FloatSize.h"
35#include "platform/geometry/IntPoint.h"
36#include "platform/geometry/IntRect.h"
37#include "platform/geometry/LayoutRect.h"
38#include "platform/heap/Handle.h"
39#include "wtf/RefCounted.h"
40
41namespace blink {
42
43class EventHandler;
44class IntSize;
45class Node;
46class ScrollView;
47
48// ViewportAnchor provides a way to anchor a viewport origin to a DOM node.
49// In particular, the user supplies the current viewport (in CSS coordinates)
50// and an anchor point (in view coordinates, e.g., (0, 0) == viewport origin,
51// (0.5, 0) == viewport top center). The anchor point tracks the underlying DOM
52// node; as the node moves or the view is resized, the viewport anchor maintains
53// its orientation relative to the node, and the viewport origin maintains its
54// orientation relative to the anchor.
55class ViewportAnchor {
56    STACK_ALLOCATED();
57public:
58    explicit ViewportAnchor(EventHandler*);
59
60    void setAnchor(const IntRect& outerViewRect, const IntRect& innerViewRect, const FloatSize& anchorInViewCoords);
61
62    void computeOrigins(const ScrollView&, const FloatSize& innerSize,
63        IntPoint& mainFrameOffset, FloatPoint& pinchViewportOffset) const;
64
65private:
66    FloatPoint getInnerOrigin(const FloatSize& innerSize) const;
67
68private:
69    RawPtrWillBeMember<EventHandler> m_eventHandler;
70
71    // Inner viewport origin in the reference frame of the document in CSS pixels
72    FloatPoint m_pinchViewportInDocument;
73
74    // Inner viewport origin in the reference frame of the outer viewport
75    // normalized to the outer viewport size.
76    FloatSize m_normalizedPinchViewportOffset;
77
78    RefPtrWillBeMember<Node> m_anchorNode;
79    LayoutRect m_anchorNodeBounds;
80
81    FloatSize m_anchorInInnerViewCoords;
82    FloatSize m_anchorInNodeCoords;
83};
84
85} // namespace blink
86
87#endif
88