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      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 using namespace std;
     40 
     41 namespace WebCore {
     42 
     43 ScrollAnimator::ScrollAnimator(ScrollableArea* scrollableArea)
     44     : m_scrollableArea(scrollableArea)
     45     , m_currentPosX(0)
     46     , m_currentPosY(0)
     47 {
     48 }
     49 
     50 ScrollAnimator::~ScrollAnimator()
     51 {
     52 }
     53 
     54 bool ScrollAnimator::scroll(ScrollbarOrientation orientation, ScrollGranularity, float step, float delta)
     55 {
     56     float& currentPos = (orientation == HorizontalScrollbar) ? m_currentPosX : m_currentPosY;
     57     float newPos = clampScrollPosition(orientation, currentPos + step * delta);
     58     if (currentPos == newPos)
     59         return false;
     60     currentPos = newPos;
     61 
     62     notifyPositionChanged();
     63 
     64     return true;
     65 }
     66 
     67 void ScrollAnimator::scrollToOffsetWithoutAnimation(const FloatPoint& offset)
     68 {
     69     m_currentPosX = offset.x();
     70     m_currentPosY = offset.y();
     71     notifyPositionChanged();
     72 }
     73 
     74 bool ScrollAnimator::handleWheelEvent(const PlatformWheelEvent& e)
     75 {
     76     bool canScrollX = m_scrollableArea->userInputScrollable(HorizontalScrollbar);
     77     bool canScrollY = m_scrollableArea->userInputScrollable(VerticalScrollbar);
     78 
     79     // Accept the event if we are scrollable in that direction and can still
     80     // scroll any further.
     81     float deltaX = canScrollX ? e.deltaX() : 0;
     82     float deltaY = canScrollY ? e.deltaY() : 0;
     83 
     84     bool handled = false;
     85 
     86 #if !OS(MACOSX)
     87     ScrollGranularity granularity = e.hasPreciseScrollingDeltas() ? ScrollByPrecisePixel : ScrollByPixel;
     88 #else
     89     ScrollGranularity granularity = ScrollByPixel;
     90 #endif
     91 
     92     IntSize maxForwardScrollDelta = m_scrollableArea->maximumScrollPosition() - m_scrollableArea->scrollPosition();
     93     IntSize maxBackwardScrollDelta = m_scrollableArea->scrollPosition() - m_scrollableArea->minimumScrollPosition();
     94     if ((deltaX < 0 && maxForwardScrollDelta.width() > 0)
     95         || (deltaX > 0 && maxBackwardScrollDelta.width() > 0)
     96         || (deltaY < 0 && maxForwardScrollDelta.height() > 0)
     97         || (deltaY > 0 && maxBackwardScrollDelta.height() > 0)) {
     98         handled = true;
     99 
    100         if (deltaY) {
    101             if (e.granularity() == ScrollByPageWheelEvent) {
    102                 bool negative = deltaY < 0;
    103                 deltaY = m_scrollableArea->pageStep(VerticalScrollbar);
    104                 if (negative)
    105                     deltaY = -deltaY;
    106             }
    107 
    108             scroll(VerticalScrollbar, granularity, m_scrollableArea->pixelStep(VerticalScrollbar), -deltaY);
    109         }
    110 
    111         if (deltaX) {
    112             if (e.granularity() == ScrollByPageWheelEvent) {
    113                 bool negative = deltaX < 0;
    114                 deltaX = m_scrollableArea->pageStep(HorizontalScrollbar);
    115                 if (negative)
    116                     deltaX = -deltaX;
    117             }
    118 
    119             scroll(HorizontalScrollbar, granularity, m_scrollableArea->pixelStep(HorizontalScrollbar), -deltaX);
    120         }
    121     }
    122     return handled;
    123 }
    124 
    125 void ScrollAnimator::setCurrentPosition(const FloatPoint& position)
    126 {
    127     m_currentPosX = position.x();
    128     m_currentPosY = position.y();
    129 }
    130 
    131 FloatPoint ScrollAnimator::currentPosition() const
    132 {
    133     return FloatPoint(m_currentPosX, m_currentPosY);
    134 }
    135 
    136 void ScrollAnimator::notifyPositionChanged()
    137 {
    138     m_scrollableArea->setScrollOffsetFromAnimation(IntPoint(m_currentPosX, m_currentPosY));
    139 }
    140 
    141 float ScrollAnimator::clampScrollPosition(ScrollbarOrientation orientation, float pos)
    142 {
    143     float maxScrollPos = m_scrollableArea->maximumScrollPosition(orientation);
    144     float minScrollPos = m_scrollableArea->minimumScrollPosition(orientation);
    145     return std::max(std::min(pos, maxScrollPos), minScrollPos);
    146 }
    147 
    148 } // namespace WebCore
    149