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 41 ScrollAnimator::ScrollAnimator(ScrollableArea* scrollableArea) 42 : m_scrollableArea(scrollableArea) 43 , m_currentPosX(0) 44 , m_currentPosY(0) 45 { 46 } 47 48 ScrollAnimator::~ScrollAnimator() 49 { 50 } 51 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 65 void ScrollAnimator::scrollToOffsetWithoutAnimation(const FloatPoint& offset) 66 { 67 m_currentPosX = offset.x(); 68 m_currentPosY = offset.y(); 69 notifyPositionChanged(); 70 } 71 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 } 122 123 void ScrollAnimator::setCurrentPosition(const FloatPoint& position) 124 { 125 m_currentPosX = position.x(); 126 m_currentPosY = position.y(); 127 } 128 129 FloatPoint ScrollAnimator::currentPosition() const 130 { 131 return FloatPoint(m_currentPosX, m_currentPosY); 132 } 133 134 void ScrollAnimator::notifyPositionChanged() 135 { 136 m_scrollableArea->setScrollOffsetFromAnimation(IntPoint(m_currentPosX, m_currentPosY)); 137 } 138 139 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