/*
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* Copyright (C) 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License
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*/
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package com.android.systemui.doze.util
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import android.util.MathUtils
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private const val MILLIS_PER_MINUTES = 1000 * 60f
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private const val BURN_IN_PREVENTION_PERIOD_Y = 521f
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private const val BURN_IN_PREVENTION_PERIOD_X = 83f
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/**
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* Returns the translation offset that should be used to avoid burn in at
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* the current time (in pixels.)
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*
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* @param amplitude Maximum translation that will be interpolated.
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* @param xAxis If we're moving on X or Y.
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*/
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fun getBurnInOffset(amplitude: Int, xAxis: Boolean): Int {
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return zigzag(System.currentTimeMillis() / MILLIS_PER_MINUTES,
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amplitude.toFloat(),
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if (xAxis) BURN_IN_PREVENTION_PERIOD_X else BURN_IN_PREVENTION_PERIOD_Y).toInt()
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}
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/**
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* Implements a continuous, piecewise linear, periodic zig-zag function
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*
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* Can be thought of as a linear approximation of abs(sin(x)))
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*
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* @param period period of the function, ie. zigzag(x + period) == zigzag(x)
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* @param amplitude maximum value of the function
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* @return a value between 0 and amplitude
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*/
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private fun zigzag(x: Float, amplitude: Float, period: Float): Float {
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val xprime = x % period / (period / 2)
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val interpolationAmount = if (xprime <= 1) xprime else 2 - xprime
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return MathUtils.lerp(0f, amplitude, interpolationAmount)
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}
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