| /* |
| * Copyright (C) 2016 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.android.server.display; |
| |
| import android.util.Slog; |
| |
| import com.android.internal.annotations.VisibleForTesting; |
| |
| import java.io.PrintWriter; |
| import java.util.Arrays; |
| |
| /** |
| * A helper class for handling access to illuminance hysteresis level values. |
| */ |
| @VisibleForTesting |
| public class HysteresisLevels { |
| private static final String TAG = "HysteresisLevels"; |
| |
| // Default hysteresis constraints for brightening or darkening. |
| // The recent value must have changed by at least this fraction relative to the |
| // current value before a change will be considered. |
| private static final float DEFAULT_BRIGHTENING_HYSTERESIS = 0.10f; |
| private static final float DEFAULT_DARKENING_HYSTERESIS = 0.20f; |
| |
| private static final boolean DEBUG = false; |
| |
| private final float[] mBrighteningThresholds; |
| private final float[] mDarkeningThresholds; |
| private final float[] mThresholdLevels; |
| |
| /** |
| * Creates a {@code HysteresisLevels} object with the given equal-length |
| * integer arrays. |
| * @param brighteningThresholds an array of brightening hysteresis constraint constants. |
| * @param darkeningThresholds an array of darkening hysteresis constraint constants. |
| * @param thresholdLevels a monotonically increasing array of threshold levels. |
| */ |
| HysteresisLevels(int[] brighteningThresholds, int[] darkeningThresholds, |
| int[] thresholdLevels) { |
| if (brighteningThresholds.length != darkeningThresholds.length |
| || darkeningThresholds.length != thresholdLevels.length + 1) { |
| throw new IllegalArgumentException("Mismatch between hysteresis array lengths."); |
| } |
| mBrighteningThresholds = setArrayFormat(brighteningThresholds, 1000.0f); |
| mDarkeningThresholds = setArrayFormat(darkeningThresholds, 1000.0f); |
| mThresholdLevels = setArrayFormat(thresholdLevels, 1.0f); |
| } |
| |
| /** |
| * Return the brightening hysteresis threshold for the given value level. |
| */ |
| public float getBrighteningThreshold(float value) { |
| float brightConstant = getReferenceLevel(value, mBrighteningThresholds); |
| float brightThreshold = value * (1.0f + brightConstant); |
| if (DEBUG) { |
| Slog.d(TAG, "bright hysteresis constant=" + brightConstant + ", threshold=" |
| + brightThreshold + ", value=" + value); |
| } |
| return brightThreshold; |
| } |
| |
| /** |
| * Return the darkening hysteresis threshold for the given value level. |
| */ |
| public float getDarkeningThreshold(float value) { |
| float darkConstant = getReferenceLevel(value, mDarkeningThresholds); |
| float darkThreshold = value * (1.0f - darkConstant); |
| if (DEBUG) { |
| Slog.d(TAG, "dark hysteresis constant=: " + darkConstant + ", threshold=" |
| + darkThreshold + ", value=" + value); |
| } |
| return darkThreshold; |
| } |
| |
| /** |
| * Return the hysteresis constant for the closest threshold value from the given array. |
| */ |
| private float getReferenceLevel(float value, float[] referenceLevels) { |
| int index = 0; |
| while (mThresholdLevels.length > index && value >= mThresholdLevels[index]) { |
| ++index; |
| } |
| return referenceLevels[index]; |
| } |
| |
| /** |
| * Return a float array where each i-th element equals {@code configArray[i]/divideFactor}. |
| */ |
| private float[] setArrayFormat(int[] configArray, float divideFactor) { |
| float[] levelArray = new float[configArray.length]; |
| for (int index = 0; levelArray.length > index; ++index) { |
| levelArray[index] = (float)configArray[index] / divideFactor; |
| } |
| return levelArray; |
| } |
| |
| void dump(PrintWriter pw) { |
| pw.println("HysteresisLevels"); |
| pw.println(" mBrighteningThresholds=" + Arrays.toString(mBrighteningThresholds)); |
| pw.println(" mDarkeningThresholds=" + Arrays.toString(mDarkeningThresholds)); |
| pw.println(" mThresholdLevels=" + Arrays.toString(mThresholdLevels)); |
| } |
| } |