1 | /* |
2 | * Copyright (C) 2016 Apple 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 |
6 | * are met: |
7 | * 1. Redistributions of source code must retain the above copyright |
8 | * notice, this list of conditions and the following disclaimer. |
9 | * 2. Redistributions in binary form must reproduce the above copyright |
10 | * notice, this list of conditions and the following disclaimer in the |
11 | * documentation and/or other materials provided with the distribution. |
12 | * |
13 | * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' |
14 | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, |
15 | * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
16 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS |
17 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
18 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
19 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
20 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
21 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
22 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF |
23 | * THE POSSIBILITY OF SUCH DAMAGE. |
24 | */ |
25 | |
26 | #pragma once |
27 | |
28 | #if ENABLE(CSS_SCROLL_SNAP) |
29 | |
30 | #include "AxisScrollSnapOffsets.h" |
31 | #include "PlatformWheelEvent.h" |
32 | #include "ScrollTypes.h" |
33 | #include <wtf/Optional.h> |
34 | #include <wtf/Seconds.h> |
35 | |
36 | namespace WebCore { |
37 | |
38 | class FloatPoint; |
39 | class FloatSize; |
40 | |
41 | class ScrollingMomentumCalculator { |
42 | public: |
43 | ScrollingMomentumCalculator(const FloatSize& viewportSize, const FloatSize& contentSize, const FloatPoint& initialOffset, const FloatSize& initialDelta, const FloatSize& initialVelocity); |
44 | static std::unique_ptr<ScrollingMomentumCalculator> create(const FloatSize& viewportSize, const FloatSize& contentSize, const FloatPoint& initialOffset, const FloatSize& initialDelta, const FloatSize& initialVelocity); |
45 | WEBCORE_EXPORT static void setPlatformMomentumScrollingPredictionEnabled(bool); |
46 | virtual ~ScrollingMomentumCalculator() = default; |
47 | |
48 | virtual FloatPoint scrollOffsetAfterElapsedTime(Seconds) = 0; |
49 | virtual Seconds animationDuration() = 0; |
50 | virtual FloatSize predictedDestinationOffset(); |
51 | void setRetargetedScrollOffset(const FloatSize&); |
52 | |
53 | protected: |
54 | const FloatSize& retargetedScrollOffset() const { return m_retargetedScrollOffset.value(); } |
55 | virtual void retargetedScrollOffsetDidChange() { } |
56 | |
57 | FloatSize m_initialDelta; |
58 | FloatSize m_initialVelocity; |
59 | FloatSize m_initialScrollOffset; |
60 | FloatSize m_viewportSize; |
61 | FloatSize m_contentSize; |
62 | |
63 | private: |
64 | Optional<FloatSize> m_retargetedScrollOffset; |
65 | }; |
66 | |
67 | class BasicScrollingMomentumCalculator final : public ScrollingMomentumCalculator { |
68 | public: |
69 | BasicScrollingMomentumCalculator(const FloatSize& viewportSize, const FloatSize& contentSize, const FloatPoint& initialOffset, const FloatSize& initialDelta, const FloatSize& initialVelocity); |
70 | |
71 | private: |
72 | FloatPoint scrollOffsetAfterElapsedTime(Seconds) final; |
73 | Seconds animationDuration() final; |
74 | void initializeInterpolationCoefficientsIfNecessary(); |
75 | void initializeSnapProgressCurve(); |
76 | float animationProgressAfterElapsedTime(Seconds) const; |
77 | FloatSize linearlyInterpolatedOffsetAtProgress(float progress); |
78 | FloatSize cubicallyInterpolatedOffsetAtProgress(float progress) const; |
79 | |
80 | float m_snapAnimationCurveMagnitude { 0 }; |
81 | float m_snapAnimationDecayFactor { 0 }; |
82 | FloatSize m_snapAnimationCurveCoefficients[4] { }; |
83 | bool m_forceLinearAnimationCurve { false }; |
84 | bool m_momentumCalculatorRequiresInitialization { true }; |
85 | Optional<FloatSize> m_predictedDestinationOffset; |
86 | }; |
87 | |
88 | } // namespace WebCore |
89 | |
90 | #endif // ENABLE(CSS_SCROLL_SNAP) |
91 | |