ScrollingMomentumCalculator.h [plain text]
#pragma once
#if ENABLE(CSS_SCROLL_SNAP)
#include "AxisScrollSnapOffsets.h"
#include "PlatformWheelEvent.h"
#include "ScrollTypes.h"
#include <wtf/Seconds.h>
namespace WebCore {
class FloatPoint;
class FloatSize;
class ScrollingMomentumCalculator {
public:
ScrollingMomentumCalculator(const FloatSize& viewportSize, const FloatSize& contentSize, const FloatPoint& initialOffset, const FloatPoint& targetOffset, const FloatSize& initialDelta, const FloatSize& initialVelocity);
static std::unique_ptr<ScrollingMomentumCalculator> create(const FloatSize& viewportSize, const FloatSize& contentSize, const FloatPoint& initialOffset, const FloatPoint& targetOffset, const FloatSize& initialDelta, const FloatSize& initialVelocity);
virtual ~ScrollingMomentumCalculator() { }
virtual FloatPoint scrollOffsetAfterElapsedTime(Seconds) = 0;
virtual Seconds animationDuration() = 0;
protected:
FloatSize m_initialDelta;
FloatSize m_initialVelocity;
FloatSize m_initialScrollOffset;
FloatSize m_targetScrollOffset;
FloatSize m_viewportSize;
FloatSize m_contentSize;
};
class BasicScrollingMomentumCalculator final : public ScrollingMomentumCalculator {
public:
BasicScrollingMomentumCalculator(const FloatSize& viewportSize, const FloatSize& contentSize, const FloatPoint& initialOffset, const FloatPoint& targetOffset, const FloatSize& initialDelta, const FloatSize& initialVelocity);
private:
FloatPoint scrollOffsetAfterElapsedTime(Seconds) final;
Seconds animationDuration() final;
void initializeInterpolationCoefficientsIfNecessary();
void initializeSnapProgressCurve();
float animationProgressAfterElapsedTime(Seconds) const;
FloatSize linearlyInterpolatedOffsetAtProgress(float progress) const;
FloatSize cubicallyInterpolatedOffsetAtProgress(float progress) const;
float m_snapAnimationCurveMagnitude { 0 };
float m_snapAnimationDecayFactor { 0 };
FloatSize m_snapAnimationCurveCoefficients[4] { };
bool m_forceLinearAnimationCurve { false };
bool m_momentumCalculatorRequiresInitialization { true };
};
}
#endif // ENABLE(CSS_SCROLL_SNAP)