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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef mozilla_layout_AsyncScrollBase_h_
#define mozilla_layout_AsyncScrollBase_h_
#include "mozilla/TimeStamp.h"
#include "nsPoint.h"
#include "nsSMILKeySpline.h"
namespace mozilla {
// This is the base class for driving scroll wheel animation on both the
// compositor and main thread.
class AsyncScrollBase
{
public:
typedef mozilla::TimeStamp TimeStamp;
typedef mozilla::TimeDuration TimeDuration;
explicit AsyncScrollBase(nsPoint aStartPos);
void Update(TimeStamp aTime,
nsPoint aDestination,
const nsSize& aCurrentVelocity);
// Get the velocity at a point in time in nscoords/sec.
nsSize VelocityAt(TimeStamp aTime) const;
// Returns the expected scroll position at a given point in time, in app
// units, relative to the scroll frame.
nsPoint PositionAt(TimeStamp aTime) const;
bool IsFinished(TimeStamp aTime) {
return aTime > mStartTime + mDuration;
}
protected:
double ProgressAt(TimeStamp aTime) const {
return clamped((aTime - mStartTime) / mDuration, 0.0, 1.0);
}
nscoord VelocityComponent(double aTimeProgress,
const nsSMILKeySpline& aTimingFunction,
nscoord aStart, nscoord aDestination) const;
// Calculate duration, possibly dynamically according to events rate and
// event origin. (also maintain previous timestamps - which are only used
// here).
TimeDuration ComputeDuration(TimeStamp aTime);
// Initialize event history.
void InitializeHistory(TimeStamp aTime);
// Initializes the timing function in such a way that the current velocity is
// preserved.
void InitTimingFunction(nsSMILKeySpline& aTimingFunction,
nscoord aCurrentPos, nscoord aCurrentVelocity,
nscoord aDestination);
// mPrevEventTime holds previous 3 timestamps for intervals averaging (to
// reduce duration fluctuations). When AsyncScroll is constructed and no
// previous timestamps are available (indicated with mIsFirstIteration),
// initialize mPrevEventTime using imaginary previous timestamps with maximum
// relevant intervals between them.
TimeStamp mPrevEventTime[3];
bool mIsFirstIteration;
TimeStamp mStartTime;
// Cached Preferences value.
//
// These values are minimum and maximum animation duration per event origin,
// and a global ratio which defines how longer is the animation's duration
// compared to the average recent events intervals (such that for a relatively
// consistent events rate, the next event arrives before current animation ends)
int32_t mOriginMinMS;
int32_t mOriginMaxMS;
double mIntervalRatio;
nsPoint mStartPos;
TimeDuration mDuration;
nsPoint mDestination;
nsSMILKeySpline mTimingFunctionX;
nsSMILKeySpline mTimingFunctionY;
};
// Helper for accelerated wheel deltas. This can be called from the main thread
// or the APZ Controller thread.
static inline double
ComputeAcceleratedWheelDelta(double aDelta, int32_t aCounter, int32_t aFactor)
{
if (!aDelta) {
return aDelta;
}
return (aDelta * aCounter * double(aFactor) / 10);
}
static const uint32_t kScrollSeriesTimeoutMs = 80; // in milliseconds
} // namespace mozilla
#endif // mozilla_layout_AsyncScrollBase_h_
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