1 /*
2 * Copyright (C) 2018 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License
15 */
16
17 package com.android.systemui.doze.util
18
19 import android.util.MathUtils
20
21 private const val MILLIS_PER_MINUTES = 1000 * 60f
22 private const val BURN_IN_PREVENTION_PERIOD_Y = 521f
23 private const val BURN_IN_PREVENTION_PERIOD_X = 83f
24 private const val BURN_IN_PREVENTION_PERIOD_SCALE = 181f
25 private const val BURN_IN_PREVENTION_PERIOD_PROGRESS = 89f
26
27 /**
28 * Returns the translation offset that should be used to avoid burn in at
29 * the current time (in pixels.)
30 *
31 * @param amplitude Maximum translation that will be interpolated.
32 * @param xAxis If we're moving on X or Y.
33 */
getBurnInOffsetnull34 fun getBurnInOffset(amplitude: Int, xAxis: Boolean): Int {
35 return zigzag(System.currentTimeMillis() / MILLIS_PER_MINUTES,
36 amplitude.toFloat(),
37 if (xAxis) BURN_IN_PREVENTION_PERIOD_X else BURN_IN_PREVENTION_PERIOD_Y).toInt()
38 }
39
40 /**
41 * Returns a progress offset (between 0f and 1.0f) that should be used to avoid burn in at
42 * the current time.
43 */
getBurnInProgressOffsetnull44 fun getBurnInProgressOffset(): Float {
45 return zigzag(System.currentTimeMillis() / MILLIS_PER_MINUTES,
46 1f, BURN_IN_PREVENTION_PERIOD_PROGRESS)
47 }
48
49 /**
50 * Returns a value to scale a view in order to avoid burn in.
51 */
getBurnInScalenull52 fun getBurnInScale(): Float {
53 return 0.8f + zigzag(System.currentTimeMillis() / MILLIS_PER_MINUTES,
54 0.2f, BURN_IN_PREVENTION_PERIOD_SCALE)
55 }
56
57 /**
58 * Implements a continuous, piecewise linear, periodic zig-zag function
59 *
60 * Can be thought of as a linear approximation of abs(sin(x)))
61 *
62 * @param period period of the function, ie. zigzag(x + period) == zigzag(x)
63 * @param amplitude maximum value of the function
64 * @return a value between 0 and amplitude
65 */
zigzagnull66 private fun zigzag(x: Float, amplitude: Float, period: Float): Float {
67 val xprime = x % period / (period / 2)
68 val interpolationAmount = if (xprime <= 1) xprime else 2 - xprime
69 return MathUtils.lerp(0f, amplitude, interpolationAmount)
70 }