third_party/WebKit/Source/platform/scroll/ScrollAnimator.cpp

   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
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   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
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  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/RuntimeEnabledFeatures.h"
  35 #include "platform/geometry/FloatPoint.h"
  36 #include "platform/scroll/ScrollableArea.h"
  37 #include "wtf/PassOwnPtr.h"
  38 #include <algorithm>
  39
  40 namespace blink {
  41
  42 ScrollAnimator::ScrollAnimator(ScrollableArea* scrollableArea)
  43     : m_scrollableArea(scrollableArea)
  44     , m_currentPosX(0)
  45     , m_currentPosY(0)
  46 {
  47 }
  48
  49 ScrollAnimator::~ScrollAnimator()
  50 {
  51 }
  52
  53 ScrollResultOneDimensional ScrollAnimator::userScroll(ScrollbarOrientation orientation, ScrollGranularity, float step, float delta)
  54 {
  55     float& currentPos = (orientation == HorizontalScrollbar) ? m_currentPosX : m_currentPosY;
  56     float newPos = clampScrollPosition(orientation, currentPos + step * delta);
  57     if (currentPos == newPos)
  58         return ScrollResultOneDimensional(false, delta);
  59
  60     float usedDelta = (newPos - currentPos) / step;
  61     currentPos = newPos;
  62
  63     notifyPositionChanged();
  64
  65     return ScrollResultOneDimensional(true, delta - usedDelta);
  66 }
  67
  68 void ScrollAnimator::scrollToOffsetWithoutAnimation(const FloatPoint& offset)
  69 {
  70     m_currentPosX = offset.x();
  71     m_currentPosY = offset.y();
  72     notifyPositionChanged();
  73 }
  74
  75 void ScrollAnimator::setCurrentPosition(const FloatPoint& position)
  76 {
  77     m_currentPosX = position.x();
  78     m_currentPosY = position.y();
  79 }
  80
  81 FloatPoint ScrollAnimator::currentPosition() const
  82 {
  83     return FloatPoint(m_currentPosX, m_currentPosY);
  84 }
  85
  86 void ScrollAnimator::notifyPositionChanged()
  87 {
  88     m_scrollableArea->scrollPositionChanged(DoublePoint(m_currentPosX, m_currentPosY), UserScroll);
  89 }
  90
  91 float ScrollAnimator::clampScrollPosition(ScrollbarOrientation orientation, float pos)
  92 {
  93     float maxScrollPos = m_scrollableArea->maximumScrollPosition(orientation);
  94     float minScrollPos = m_scrollableArea->minimumScrollPosition(orientation);
  95     return std::max(std::min(pos, maxScrollPos), minScrollPos);
  96 }
  97
  98 } // namespace blink