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
39namespace blink {
40
41ScrollAnimator::ScrollAnimator(ScrollableArea* scrollableArea)
42    : m_scrollableArea(scrollableArea)
43    , m_currentPosX(0)
44    , m_currentPosY(0)
45{
46}
47
48ScrollAnimator::~ScrollAnimator()
49{
50}
51
52bool 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
65void ScrollAnimator::scrollToOffsetWithoutAnimation(const FloatPoint& offset)
66{
67    m_currentPosX = offset.x();
68    m_currentPosY = offset.y();
69    notifyPositionChanged();
70}
71
72bool 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
123void ScrollAnimator::setCurrentPosition(const FloatPoint& position)
124{
125    m_currentPosX = position.x();
126    m_currentPosY = position.y();
127}
128
129FloatPoint ScrollAnimator::currentPosition() const
130{
131    return FloatPoint(m_currentPosX, m_currentPosY);
132}
133
134void ScrollAnimator::notifyPositionChanged()
135{
136    m_scrollableArea->setScrollOffsetFromAnimation(IntPoint(m_currentPosX, m_currentPosY));
137}
138
139float 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