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