зеркало из https://github.com/mozilla/gecko-dev.git
95 строки
3.4 KiB
C++
95 строки
3.4 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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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_ScrollAnimationBezierPhysics_h_
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#define mozilla_layout_ScrollAnimationBezierPhysics_h_
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#include "ScrollAnimationPhysics.h"
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#include "nsSMILKeySpline.h"
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namespace mozilla {
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struct ScrollAnimationBezierPhysicsSettings
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{
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// These values are minimum and maximum animation duration per event,
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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 mMinMS;
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int32_t mMaxMS;
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double mIntervalRatio;
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};
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// This class implements a cubic bezier timing function and automatically
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// adapts the animation duration based on the scrolling rate.
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class ScrollAnimationBezierPhysics : public ScrollAnimationPhysics
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{
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public:
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explicit ScrollAnimationBezierPhysics(const nsPoint& aStartPos,
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const ScrollAnimationBezierPhysicsSettings& aSettings);
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void Update(const TimeStamp& aTime,
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const nsPoint& aDestination,
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const nsSize& aCurrentVelocity) override;
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// Get the velocity at a point in time in nscoords/sec.
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nsSize VelocityAt(const TimeStamp& aTime) override;
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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(const TimeStamp& aTime) override;
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bool IsFinished(const TimeStamp& aTime) override {
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return aTime > mStartTime + mDuration;
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}
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protected:
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double ProgressAt(const 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(const 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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// Initialize event history.
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void InitializeHistory(const TimeStamp& aTime);
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// Cached Preferences values.
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ScrollAnimationBezierPhysicsSettings mSettings;
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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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TimeStamp mStartTime;
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nsPoint mStartPos;
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nsPoint mDestination;
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TimeDuration mDuration;
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nsSMILKeySpline mTimingFunctionX;
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nsSMILKeySpline mTimingFunctionY;
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bool mIsFirstIteration;
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};
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} // namespace mozilla
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#endif // mozilla_layout_ScrollAnimationBezierPhysics_h_
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