1 /*
2 * Copyright (c) 2010, 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 #include "config.h"
32 #include "platform/scroll/ScrollAnimator.h"
33
34 #include "platform/geometry/FloatPoint.h"
35 #include "platform/scroll/ScrollableArea.h"
36 #include "wtf/PassOwnPtr.h"
37 #include <algorithm>
38
39 namespace blink {
40
ScrollAnimator(ScrollableArea * scrollableArea)41 ScrollAnimator::ScrollAnimator(ScrollableArea* scrollableArea)
42 : m_scrollableArea(scrollableArea)
43 , m_currentPosX(0)
44 , m_currentPosY(0)
45 {
46 }
47
~ScrollAnimator()48 ScrollAnimator::~ScrollAnimator()
49 {
50 }
51
scroll(ScrollbarOrientation orientation,ScrollGranularity,float step,float delta)52 bool ScrollAnimator::scroll(ScrollbarOrientation orientation, ScrollGranularity, float step, float delta)
53 {
54 float& currentPos = (orientation == HorizontalScrollbar) ? m_currentPosX : m_currentPosY;
55 float newPos = clampScrollPosition(orientation, currentPos + step * delta);
56 if (currentPos == newPos)
57 return false;
58 currentPos = newPos;
59
60 notifyPositionChanged();
61
62 return true;
63 }
64
scrollToOffsetWithoutAnimation(const FloatPoint & offset)65 void ScrollAnimator::scrollToOffsetWithoutAnimation(const FloatPoint& offset)
66 {
67 m_currentPosX = offset.x();
68 m_currentPosY = offset.y();
69 notifyPositionChanged();
70 }
71
handleWheelEvent(const PlatformWheelEvent & e)72 bool ScrollAnimator::handleWheelEvent(const PlatformWheelEvent& e)
73 {
74 bool canScrollX = m_scrollableArea->userInputScrollable(HorizontalScrollbar);
75 bool canScrollY = m_scrollableArea->userInputScrollable(VerticalScrollbar);
76
77 // Accept the event if we are scrollable in that direction and can still
78 // scroll any further.
79 float deltaX = canScrollX ? e.deltaX() : 0;
80 float deltaY = canScrollY ? e.deltaY() : 0;
81
82 bool handled = false;
83
84 #if !OS(MACOSX)
85 ScrollGranularity granularity = e.hasPreciseScrollingDeltas() ? ScrollByPrecisePixel : ScrollByPixel;
86 #else
87 ScrollGranularity granularity = ScrollByPixel;
88 #endif
89
90 IntSize maxForwardScrollDelta = m_scrollableArea->maximumScrollPosition() - m_scrollableArea->scrollPosition();
91 IntSize maxBackwardScrollDelta = m_scrollableArea->scrollPosition() - m_scrollableArea->minimumScrollPosition();
92 if ((deltaX < 0 && maxForwardScrollDelta.width() > 0)
93 || (deltaX > 0 && maxBackwardScrollDelta.width() > 0)
94 || (deltaY < 0 && maxForwardScrollDelta.height() > 0)
95 || (deltaY > 0 && maxBackwardScrollDelta.height() > 0)) {
96 handled = true;
97
98 if (deltaY) {
99 if (e.granularity() == ScrollByPageWheelEvent) {
100 bool negative = deltaY < 0;
101 deltaY = m_scrollableArea->pageStep(VerticalScrollbar);
102 if (negative)
103 deltaY = -deltaY;
104 }
105
106 scroll(VerticalScrollbar, granularity, m_scrollableArea->pixelStep(VerticalScrollbar), -deltaY);
107 }
108
109 if (deltaX) {
110 if (e.granularity() == ScrollByPageWheelEvent) {
111 bool negative = deltaX < 0;
112 deltaX = m_scrollableArea->pageStep(HorizontalScrollbar);
113 if (negative)
114 deltaX = -deltaX;
115 }
116
117 scroll(HorizontalScrollbar, granularity, m_scrollableArea->pixelStep(HorizontalScrollbar), -deltaX);
118 }
119 }
120 return handled;
121 }
122
setCurrentPosition(const FloatPoint & position)123 void ScrollAnimator::setCurrentPosition(const FloatPoint& position)
124 {
125 m_currentPosX = position.x();
126 m_currentPosY = position.y();
127 }
128
currentPosition() const129 FloatPoint ScrollAnimator::currentPosition() const
130 {
131 return FloatPoint(m_currentPosX, m_currentPosY);
132 }
133
notifyPositionChanged()134 void ScrollAnimator::notifyPositionChanged()
135 {
136 m_scrollableArea->setScrollOffsetFromAnimation(IntPoint(m_currentPosX, m_currentPosY));
137 }
138
clampScrollPosition(ScrollbarOrientation orientation,float pos)139 float ScrollAnimator::clampScrollPosition(ScrollbarOrientation orientation, float pos)
140 {
141 float maxScrollPos = m_scrollableArea->maximumScrollPosition(orientation);
142 float minScrollPos = m_scrollableArea->minimumScrollPosition(orientation);
143 return std::max(std::min(pos, maxScrollPos), minScrollPos);
144 }
145
146 } // namespace blink
147