| /* |
| * Copyright (C) 2014 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 com.android.server.EventLogTags; |
| import com.android.server.LocalServices; |
| |
| import android.annotation.Nullable; |
| import android.hardware.Sensor; |
| import android.hardware.SensorEvent; |
| import android.hardware.SensorEventListener; |
| import android.hardware.SensorManager; |
| import android.hardware.display.BrightnessConfiguration; |
| import android.hardware.display.DisplayManagerInternal.DisplayPowerRequest; |
| import android.os.Handler; |
| import android.os.Looper; |
| import android.os.Message; |
| import android.os.PowerManager; |
| import android.os.SystemClock; |
| import android.os.Trace; |
| import android.text.format.DateUtils; |
| import android.util.EventLog; |
| import android.util.MathUtils; |
| import android.util.Slog; |
| import android.util.TimeUtils; |
| |
| import java.io.PrintWriter; |
| |
| class AutomaticBrightnessController { |
| private static final String TAG = "AutomaticBrightnessController"; |
| |
| private static final boolean DEBUG = false; |
| private static final boolean DEBUG_PRETEND_LIGHT_SENSOR_ABSENT = false; |
| |
| // If true, enables the use of the screen auto-brightness adjustment setting. |
| private static final boolean USE_SCREEN_AUTO_BRIGHTNESS_ADJUSTMENT = true; |
| |
| // How long the current sensor reading is assumed to be valid beyond the current time. |
| // This provides a bit of prediction, as well as ensures that the weight for the last sample is |
| // non-zero, which in turn ensures that the total weight is non-zero. |
| private static final long AMBIENT_LIGHT_PREDICTION_TIME_MILLIS = 100; |
| |
| // Debounce for sampling user-initiated changes in display brightness to ensure |
| // the user is satisfied with the result before storing the sample. |
| private static final int BRIGHTNESS_ADJUSTMENT_SAMPLE_DEBOUNCE_MILLIS = 10000; |
| |
| // Timeout after which we remove the effects any user interactions might've had on the |
| // brightness mapping. This timeout doesn't start until we transition to a non-interactive |
| // display policy so that we don't reset while users are using their devices, but also so that |
| // we don't erroneously keep the short-term model if the device is dozing but the display is |
| // fully on. |
| private static final int SHORT_TERM_MODEL_TIMEOUT_MILLIS = 30000; |
| |
| private static final int MSG_UPDATE_AMBIENT_LUX = 1; |
| private static final int MSG_BRIGHTNESS_ADJUSTMENT_SAMPLE = 2; |
| private static final int MSG_INVALIDATE_SHORT_TERM_MODEL = 3; |
| |
| // Length of the ambient light horizon used to calculate the long term estimate of ambient |
| // light. |
| private static final int AMBIENT_LIGHT_LONG_HORIZON_MILLIS = 10000; |
| |
| // Length of the ambient light horizon used to calculate short-term estimate of ambient light. |
| private static final int AMBIENT_LIGHT_SHORT_HORIZON_MILLIS = 2000; |
| |
| // Callbacks for requesting updates to the display's power state |
| private final Callbacks mCallbacks; |
| |
| // The sensor manager. |
| private final SensorManager mSensorManager; |
| |
| // The light sensor, or null if not available or needed. |
| private final Sensor mLightSensor; |
| |
| // The mapper to translate ambient lux to screen brightness in the range [0, 1.0]. |
| private final BrightnessMappingStrategy mBrightnessMapper; |
| |
| // The minimum and maximum screen brightnesses. |
| private final int mScreenBrightnessRangeMinimum; |
| private final int mScreenBrightnessRangeMaximum; |
| private final float mDozeScaleFactor; |
| |
| // Initial light sensor event rate in milliseconds. |
| private final int mInitialLightSensorRate; |
| |
| // Steady-state light sensor event rate in milliseconds. |
| private final int mNormalLightSensorRate; |
| |
| // The current light sensor event rate in milliseconds. |
| private int mCurrentLightSensorRate; |
| |
| // Stability requirements in milliseconds for accepting a new brightness level. This is used |
| // for debouncing the light sensor. Different constants are used to debounce the light sensor |
| // when adapting to brighter or darker environments. This parameter controls how quickly |
| // brightness changes occur in response to an observed change in light level that exceeds the |
| // hysteresis threshold. |
| private final long mBrighteningLightDebounceConfig; |
| private final long mDarkeningLightDebounceConfig; |
| |
| // If true immediately after the screen is turned on the controller will try to adjust the |
| // brightness based on the current sensor reads. If false, the controller will collect more data |
| // and only then decide whether to change brightness. |
| private final boolean mResetAmbientLuxAfterWarmUpConfig; |
| |
| // Period of time in which to consider light samples in milliseconds. |
| private final int mAmbientLightHorizon; |
| |
| // The intercept used for the weighting calculation. This is used in order to keep all possible |
| // weighting values positive. |
| private final int mWeightingIntercept; |
| |
| // accessor object for determining thresholds to change brightness dynamically |
| private final HysteresisLevels mDynamicHysteresis; |
| |
| // Amount of time to delay auto-brightness after screen on while waiting for |
| // the light sensor to warm-up in milliseconds. |
| // May be 0 if no warm-up is required. |
| private int mLightSensorWarmUpTimeConfig; |
| |
| // Set to true if the light sensor is enabled. |
| private boolean mLightSensorEnabled; |
| |
| // The time when the light sensor was enabled. |
| private long mLightSensorEnableTime; |
| |
| // The currently accepted nominal ambient light level. |
| private float mAmbientLux; |
| |
| // True if mAmbientLux holds a valid value. |
| private boolean mAmbientLuxValid; |
| |
| // The ambient light level threshold at which to brighten or darken the screen. |
| private float mBrighteningLuxThreshold; |
| private float mDarkeningLuxThreshold; |
| |
| // The most recent light sample. |
| private float mLastObservedLux; |
| |
| // The time of the most light recent sample. |
| private long mLastObservedLuxTime; |
| |
| // The number of light samples collected since the light sensor was enabled. |
| private int mRecentLightSamples; |
| |
| // A ring buffer containing all of the recent ambient light sensor readings. |
| private AmbientLightRingBuffer mAmbientLightRingBuffer; |
| |
| // The handler |
| private AutomaticBrightnessHandler mHandler; |
| |
| // The screen brightness level that has been chosen by the auto-brightness |
| // algorithm. The actual brightness should ramp towards this value. |
| // We preserve this value even when we stop using the light sensor so |
| // that we can quickly revert to the previous auto-brightness level |
| // while the light sensor warms up. |
| // Use -1 if there is no current auto-brightness value available. |
| private int mScreenAutoBrightness = -1; |
| |
| // The current display policy. This is useful, for example, for knowing when we're dozing, |
| // where the light sensor may not be available. |
| private int mDisplayPolicy = DisplayPowerRequest.POLICY_OFF; |
| |
| // True if we are collecting a brightness adjustment sample, along with some data |
| // for the initial state of the sample. |
| private boolean mBrightnessAdjustmentSamplePending; |
| private float mBrightnessAdjustmentSampleOldLux; |
| private int mBrightnessAdjustmentSampleOldBrightness; |
| |
| // When the short term model is invalidated, we don't necessarily reset it (i.e. clear the |
| // user's adjustment) immediately, but wait for a drastic enough change in the ambient light. |
| // The anchor determines what were the light levels when the user has set her preference, and |
| // we use a relative threshold to determine when to revert to the OEM curve. |
| private boolean mShortTermModelValid; |
| private float mShortTermModelAnchor; |
| private float SHORT_TERM_MODEL_THRESHOLD_RATIO = 0.6f; |
| |
| public AutomaticBrightnessController(Callbacks callbacks, Looper looper, |
| SensorManager sensorManager, BrightnessMappingStrategy mapper, |
| int lightSensorWarmUpTime, int brightnessMin, int brightnessMax, float dozeScaleFactor, |
| int lightSensorRate, int initialLightSensorRate, long brighteningLightDebounceConfig, |
| long darkeningLightDebounceConfig, boolean resetAmbientLuxAfterWarmUpConfig, |
| int ambientLightHorizon, HysteresisLevels dynamicHysteresis) { |
| mCallbacks = callbacks; |
| mSensorManager = sensorManager; |
| mBrightnessMapper = mapper; |
| mScreenBrightnessRangeMinimum = brightnessMin; |
| mScreenBrightnessRangeMaximum = brightnessMax; |
| mLightSensorWarmUpTimeConfig = lightSensorWarmUpTime; |
| mDozeScaleFactor = dozeScaleFactor; |
| mNormalLightSensorRate = lightSensorRate; |
| mInitialLightSensorRate = initialLightSensorRate; |
| mCurrentLightSensorRate = -1; |
| mBrighteningLightDebounceConfig = brighteningLightDebounceConfig; |
| mDarkeningLightDebounceConfig = darkeningLightDebounceConfig; |
| mResetAmbientLuxAfterWarmUpConfig = resetAmbientLuxAfterWarmUpConfig; |
| mAmbientLightHorizon = ambientLightHorizon; |
| mWeightingIntercept = ambientLightHorizon; |
| mDynamicHysteresis = dynamicHysteresis; |
| mShortTermModelValid = true; |
| mShortTermModelAnchor = -1; |
| |
| mHandler = new AutomaticBrightnessHandler(looper); |
| mAmbientLightRingBuffer = |
| new AmbientLightRingBuffer(mNormalLightSensorRate, mAmbientLightHorizon); |
| |
| if (!DEBUG_PRETEND_LIGHT_SENSOR_ABSENT) { |
| mLightSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_LIGHT); |
| } |
| } |
| |
| public int getAutomaticScreenBrightness() { |
| if (!mAmbientLuxValid) { |
| return -1; |
| } |
| if (mDisplayPolicy == DisplayPowerRequest.POLICY_DOZE) { |
| return (int) (mScreenAutoBrightness * mDozeScaleFactor); |
| } |
| return mScreenAutoBrightness; |
| } |
| |
| public float getAutomaticScreenBrightnessAdjustment() { |
| return mBrightnessMapper.getAutoBrightnessAdjustment(); |
| } |
| |
| public void configure(boolean enable, @Nullable BrightnessConfiguration configuration, |
| float brightness, boolean userChangedBrightness, float adjustment, |
| boolean userChangedAutoBrightnessAdjustment, int displayPolicy) { |
| // While dozing, the application processor may be suspended which will prevent us from |
| // receiving new information from the light sensor. On some devices, we may be able to |
| // switch to a wake-up light sensor instead but for now we will simply disable the sensor |
| // and hold onto the last computed screen auto brightness. We save the dozing flag for |
| // debugging purposes. |
| boolean dozing = (displayPolicy == DisplayPowerRequest.POLICY_DOZE); |
| boolean changed = setBrightnessConfiguration(configuration); |
| changed |= setDisplayPolicy(displayPolicy); |
| if (userChangedAutoBrightnessAdjustment) { |
| changed |= setAutoBrightnessAdjustment(adjustment); |
| } |
| if (userChangedBrightness && enable) { |
| // Update the brightness curve with the new user control point. It's critical this |
| // happens after we update the autobrightness adjustment since it may reset it. |
| changed |= setScreenBrightnessByUser(brightness); |
| } |
| final boolean userInitiatedChange = |
| userChangedBrightness || userChangedAutoBrightnessAdjustment; |
| if (userInitiatedChange && enable && !dozing) { |
| prepareBrightnessAdjustmentSample(); |
| } |
| changed |= setLightSensorEnabled(enable && !dozing); |
| if (changed) { |
| updateAutoBrightness(false /*sendUpdate*/); |
| } |
| } |
| |
| public boolean hasUserDataPoints() { |
| return mBrightnessMapper.hasUserDataPoints(); |
| } |
| |
| public boolean isDefaultConfig() { |
| return mBrightnessMapper.isDefaultConfig(); |
| } |
| |
| public BrightnessConfiguration getDefaultConfig() { |
| return mBrightnessMapper.getDefaultConfig(); |
| } |
| |
| private boolean setDisplayPolicy(int policy) { |
| if (mDisplayPolicy == policy) { |
| return false; |
| } |
| final int oldPolicy = mDisplayPolicy; |
| mDisplayPolicy = policy; |
| if (DEBUG) { |
| Slog.d(TAG, "Display policy transitioning from " + oldPolicy + " to " + policy); |
| } |
| if (!isInteractivePolicy(policy) && isInteractivePolicy(oldPolicy)) { |
| mHandler.sendEmptyMessageDelayed(MSG_INVALIDATE_SHORT_TERM_MODEL, |
| SHORT_TERM_MODEL_TIMEOUT_MILLIS); |
| } else if (isInteractivePolicy(policy) && !isInteractivePolicy(oldPolicy)) { |
| mHandler.removeMessages(MSG_INVALIDATE_SHORT_TERM_MODEL); |
| } |
| return true; |
| } |
| |
| private static boolean isInteractivePolicy(int policy) { |
| return policy == DisplayPowerRequest.POLICY_BRIGHT |
| || policy == DisplayPowerRequest.POLICY_DIM |
| || policy == DisplayPowerRequest.POLICY_VR; |
| } |
| |
| private boolean setScreenBrightnessByUser(float brightness) { |
| if (!mAmbientLuxValid) { |
| // If we don't have a valid ambient lux then we don't have a valid brightness anyways, |
| // and we can't use this data to add a new control point to the short-term model. |
| return false; |
| } |
| mBrightnessMapper.addUserDataPoint(mAmbientLux, brightness); |
| mShortTermModelValid = true; |
| mShortTermModelAnchor = mAmbientLux; |
| if (DEBUG) { |
| Slog.d(TAG, "ShortTermModel: anchor=" + mShortTermModelAnchor); |
| } |
| return true; |
| } |
| |
| private void resetShortTermModel() { |
| mBrightnessMapper.clearUserDataPoints(); |
| mShortTermModelValid = true; |
| mShortTermModelAnchor = -1; |
| } |
| |
| private void invalidateShortTermModel() { |
| if (DEBUG) { |
| Slog.d(TAG, "ShortTermModel: invalidate user data"); |
| } |
| mShortTermModelValid = false; |
| } |
| |
| public boolean setBrightnessConfiguration(BrightnessConfiguration configuration) { |
| return mBrightnessMapper.setBrightnessConfiguration(configuration); |
| } |
| |
| public void dump(PrintWriter pw) { |
| pw.println(); |
| pw.println("Automatic Brightness Controller Configuration:"); |
| pw.println(" mScreenBrightnessRangeMinimum=" + mScreenBrightnessRangeMinimum); |
| pw.println(" mScreenBrightnessRangeMaximum=" + mScreenBrightnessRangeMaximum); |
| pw.println(" mLightSensorWarmUpTimeConfig=" + mLightSensorWarmUpTimeConfig); |
| pw.println(" mBrighteningLightDebounceConfig=" + mBrighteningLightDebounceConfig); |
| pw.println(" mDarkeningLightDebounceConfig=" + mDarkeningLightDebounceConfig); |
| pw.println(" mResetAmbientLuxAfterWarmUpConfig=" + mResetAmbientLuxAfterWarmUpConfig); |
| |
| pw.println(); |
| pw.println("Automatic Brightness Controller State:"); |
| pw.println(" mLightSensor=" + mLightSensor); |
| pw.println(" mLightSensorEnabled=" + mLightSensorEnabled); |
| pw.println(" mLightSensorEnableTime=" + TimeUtils.formatUptime(mLightSensorEnableTime)); |
| pw.println(" mAmbientLux=" + mAmbientLux); |
| pw.println(" mAmbientLuxValid=" + mAmbientLuxValid); |
| pw.println(" mAmbientLightHorizon=" + mAmbientLightHorizon); |
| pw.println(" mBrighteningLuxThreshold=" + mBrighteningLuxThreshold); |
| pw.println(" mDarkeningLuxThreshold=" + mDarkeningLuxThreshold); |
| pw.println(" mLastObservedLux=" + mLastObservedLux); |
| pw.println(" mLastObservedLuxTime=" + TimeUtils.formatUptime(mLastObservedLuxTime)); |
| pw.println(" mRecentLightSamples=" + mRecentLightSamples); |
| pw.println(" mAmbientLightRingBuffer=" + mAmbientLightRingBuffer); |
| pw.println(" mScreenAutoBrightness=" + mScreenAutoBrightness); |
| pw.println(" mDisplayPolicy=" + mDisplayPolicy); |
| pw.println(" mShortTermModelAnchor=" + mShortTermModelAnchor); |
| |
| pw.println(); |
| mBrightnessMapper.dump(pw); |
| } |
| |
| private boolean setLightSensorEnabled(boolean enable) { |
| if (enable) { |
| if (!mLightSensorEnabled) { |
| mLightSensorEnabled = true; |
| mLightSensorEnableTime = SystemClock.uptimeMillis(); |
| mCurrentLightSensorRate = mInitialLightSensorRate; |
| mSensorManager.registerListener(mLightSensorListener, mLightSensor, |
| mCurrentLightSensorRate * 1000, mHandler); |
| return true; |
| } |
| } else if (mLightSensorEnabled) { |
| mLightSensorEnabled = false; |
| mAmbientLuxValid = !mResetAmbientLuxAfterWarmUpConfig; |
| mRecentLightSamples = 0; |
| mAmbientLightRingBuffer.clear(); |
| mCurrentLightSensorRate = -1; |
| mHandler.removeMessages(MSG_UPDATE_AMBIENT_LUX); |
| mSensorManager.unregisterListener(mLightSensorListener); |
| } |
| return false; |
| } |
| |
| private void handleLightSensorEvent(long time, float lux) { |
| Trace.traceCounter(Trace.TRACE_TAG_POWER, "ALS", (int) lux); |
| mHandler.removeMessages(MSG_UPDATE_AMBIENT_LUX); |
| |
| if (mAmbientLightRingBuffer.size() == 0) { |
| // switch to using the steady-state sample rate after grabbing the initial light sample |
| adjustLightSensorRate(mNormalLightSensorRate); |
| } |
| applyLightSensorMeasurement(time, lux); |
| updateAmbientLux(time); |
| } |
| |
| private void applyLightSensorMeasurement(long time, float lux) { |
| mRecentLightSamples++; |
| mAmbientLightRingBuffer.prune(time - mAmbientLightHorizon); |
| mAmbientLightRingBuffer.push(time, lux); |
| |
| // Remember this sample value. |
| mLastObservedLux = lux; |
| mLastObservedLuxTime = time; |
| } |
| |
| private void adjustLightSensorRate(int lightSensorRate) { |
| // if the light sensor rate changed, update the sensor listener |
| if (lightSensorRate != mCurrentLightSensorRate) { |
| if (DEBUG) { |
| Slog.d(TAG, "adjustLightSensorRate: " + |
| "previousRate=" + mCurrentLightSensorRate + ", " + |
| "currentRate=" + lightSensorRate); |
| } |
| mCurrentLightSensorRate = lightSensorRate; |
| mSensorManager.unregisterListener(mLightSensorListener); |
| mSensorManager.registerListener(mLightSensorListener, mLightSensor, |
| lightSensorRate * 1000, mHandler); |
| } |
| } |
| |
| private boolean setAutoBrightnessAdjustment(float adjustment) { |
| return mBrightnessMapper.setAutoBrightnessAdjustment(adjustment); |
| } |
| |
| private void setAmbientLux(float lux) { |
| if (DEBUG) { |
| Slog.d(TAG, "setAmbientLux(" + lux + ")"); |
| } |
| if (lux < 0) { |
| Slog.w(TAG, "Ambient lux was negative, ignoring and setting to 0"); |
| lux = 0; |
| } |
| mAmbientLux = lux; |
| mBrighteningLuxThreshold = mDynamicHysteresis.getBrighteningThreshold(lux); |
| mDarkeningLuxThreshold = mDynamicHysteresis.getDarkeningThreshold(lux); |
| |
| // If the short term model was invalidated and the change is drastic enough, reset it. |
| if (!mShortTermModelValid && mShortTermModelAnchor != -1) { |
| final float minAmbientLux = |
| mShortTermModelAnchor - mShortTermModelAnchor * SHORT_TERM_MODEL_THRESHOLD_RATIO; |
| final float maxAmbientLux = |
| mShortTermModelAnchor + mShortTermModelAnchor * SHORT_TERM_MODEL_THRESHOLD_RATIO; |
| if (minAmbientLux < mAmbientLux && mAmbientLux < maxAmbientLux) { |
| if (DEBUG) { |
| Slog.d(TAG, "ShortTermModel: re-validate user data, ambient lux is " + |
| minAmbientLux + " < " + mAmbientLux + " < " + maxAmbientLux); |
| } |
| mShortTermModelValid = true; |
| } else { |
| Slog.d(TAG, "ShortTermModel: reset data, ambient lux is " + mAmbientLux + |
| "(" + minAmbientLux + ", " + maxAmbientLux + ")"); |
| resetShortTermModel(); |
| } |
| } |
| } |
| |
| private float calculateAmbientLux(long now, long horizon) { |
| if (DEBUG) { |
| Slog.d(TAG, "calculateAmbientLux(" + now + ", " + horizon + ")"); |
| } |
| final int N = mAmbientLightRingBuffer.size(); |
| if (N == 0) { |
| Slog.e(TAG, "calculateAmbientLux: No ambient light readings available"); |
| return -1; |
| } |
| |
| // Find the first measurement that is just outside of the horizon. |
| int endIndex = 0; |
| final long horizonStartTime = now - horizon; |
| for (int i = 0; i < N-1; i++) { |
| if (mAmbientLightRingBuffer.getTime(i + 1) <= horizonStartTime) { |
| endIndex++; |
| } else { |
| break; |
| } |
| } |
| if (DEBUG) { |
| Slog.d(TAG, "calculateAmbientLux: selected endIndex=" + endIndex + ", point=(" + |
| mAmbientLightRingBuffer.getTime(endIndex) + ", " + |
| mAmbientLightRingBuffer.getLux(endIndex) + ")"); |
| } |
| float sum = 0; |
| float totalWeight = 0; |
| long endTime = AMBIENT_LIGHT_PREDICTION_TIME_MILLIS; |
| for (int i = N - 1; i >= endIndex; i--) { |
| long eventTime = mAmbientLightRingBuffer.getTime(i); |
| if (i == endIndex && eventTime < horizonStartTime) { |
| // If we're at the final value, make sure we only consider the part of the sample |
| // within our desired horizon. |
| eventTime = horizonStartTime; |
| } |
| final long startTime = eventTime - now; |
| float weight = calculateWeight(startTime, endTime); |
| float lux = mAmbientLightRingBuffer.getLux(i); |
| if (DEBUG) { |
| Slog.d(TAG, "calculateAmbientLux: [" + startTime + ", " + endTime + "]: " + |
| "lux=" + lux + ", " + |
| "weight=" + weight); |
| } |
| totalWeight += weight; |
| sum += lux * weight; |
| endTime = startTime; |
| } |
| if (DEBUG) { |
| Slog.d(TAG, "calculateAmbientLux: " + |
| "totalWeight=" + totalWeight + ", " + |
| "newAmbientLux=" + (sum / totalWeight)); |
| } |
| return sum / totalWeight; |
| } |
| |
| private float calculateWeight(long startDelta, long endDelta) { |
| return weightIntegral(endDelta) - weightIntegral(startDelta); |
| } |
| |
| // Evaluates the integral of y = x + mWeightingIntercept. This is always positive for the |
| // horizon we're looking at and provides a non-linear weighting for light samples. |
| private float weightIntegral(long x) { |
| return x * (x * 0.5f + mWeightingIntercept); |
| } |
| |
| private long nextAmbientLightBrighteningTransition(long time) { |
| final int N = mAmbientLightRingBuffer.size(); |
| long earliestValidTime = time; |
| for (int i = N - 1; i >= 0; i--) { |
| if (mAmbientLightRingBuffer.getLux(i) <= mBrighteningLuxThreshold) { |
| break; |
| } |
| earliestValidTime = mAmbientLightRingBuffer.getTime(i); |
| } |
| return earliestValidTime + mBrighteningLightDebounceConfig; |
| } |
| |
| private long nextAmbientLightDarkeningTransition(long time) { |
| final int N = mAmbientLightRingBuffer.size(); |
| long earliestValidTime = time; |
| for (int i = N - 1; i >= 0; i--) { |
| if (mAmbientLightRingBuffer.getLux(i) >= mDarkeningLuxThreshold) { |
| break; |
| } |
| earliestValidTime = mAmbientLightRingBuffer.getTime(i); |
| } |
| return earliestValidTime + mDarkeningLightDebounceConfig; |
| } |
| |
| private void updateAmbientLux() { |
| long time = SystemClock.uptimeMillis(); |
| mAmbientLightRingBuffer.prune(time - mAmbientLightHorizon); |
| updateAmbientLux(time); |
| } |
| |
| private void updateAmbientLux(long time) { |
| // If the light sensor was just turned on then immediately update our initial |
| // estimate of the current ambient light level. |
| if (!mAmbientLuxValid) { |
| final long timeWhenSensorWarmedUp = |
| mLightSensorWarmUpTimeConfig + mLightSensorEnableTime; |
| if (time < timeWhenSensorWarmedUp) { |
| if (DEBUG) { |
| Slog.d(TAG, "updateAmbientLux: Sensor not ready yet: " + |
| "time=" + time + ", " + |
| "timeWhenSensorWarmedUp=" + timeWhenSensorWarmedUp); |
| } |
| mHandler.sendEmptyMessageAtTime(MSG_UPDATE_AMBIENT_LUX, |
| timeWhenSensorWarmedUp); |
| return; |
| } |
| setAmbientLux(calculateAmbientLux(time, AMBIENT_LIGHT_SHORT_HORIZON_MILLIS)); |
| mAmbientLuxValid = true; |
| if (DEBUG) { |
| Slog.d(TAG, "updateAmbientLux: Initializing: " + |
| "mAmbientLightRingBuffer=" + mAmbientLightRingBuffer + ", " + |
| "mAmbientLux=" + mAmbientLux); |
| } |
| updateAutoBrightness(true); |
| } |
| |
| long nextBrightenTransition = nextAmbientLightBrighteningTransition(time); |
| long nextDarkenTransition = nextAmbientLightDarkeningTransition(time); |
| // Essentially, we calculate both a slow ambient lux, to ensure there's a true long-term |
| // change in lighting conditions, and a fast ambient lux to determine what the new |
| // brightness situation is since the slow lux can be quite slow to converge. |
| // |
| // Note that both values need to be checked for sufficient change before updating the |
| // proposed ambient light value since the slow value might be sufficiently far enough away |
| // from the fast value to cause a recalculation while its actually just converging on |
| // the fast value still. |
| float slowAmbientLux = calculateAmbientLux(time, AMBIENT_LIGHT_LONG_HORIZON_MILLIS); |
| float fastAmbientLux = calculateAmbientLux(time, AMBIENT_LIGHT_SHORT_HORIZON_MILLIS); |
| |
| if ((slowAmbientLux >= mBrighteningLuxThreshold && |
| fastAmbientLux >= mBrighteningLuxThreshold && |
| nextBrightenTransition <= time) |
| || |
| (slowAmbientLux <= mDarkeningLuxThreshold && |
| fastAmbientLux <= mDarkeningLuxThreshold && |
| nextDarkenTransition <= time)) { |
| setAmbientLux(fastAmbientLux); |
| if (DEBUG) { |
| Slog.d(TAG, "updateAmbientLux: " + |
| ((fastAmbientLux > mAmbientLux) ? "Brightened" : "Darkened") + ": " + |
| "mBrighteningLuxThreshold=" + mBrighteningLuxThreshold + ", " + |
| "mAmbientLightRingBuffer=" + mAmbientLightRingBuffer + ", " + |
| "mAmbientLux=" + mAmbientLux); |
| } |
| updateAutoBrightness(true); |
| nextBrightenTransition = nextAmbientLightBrighteningTransition(time); |
| nextDarkenTransition = nextAmbientLightDarkeningTransition(time); |
| } |
| long nextTransitionTime = Math.min(nextDarkenTransition, nextBrightenTransition); |
| // If one of the transitions is ready to occur, but the total weighted ambient lux doesn't |
| // exceed the necessary threshold, then it's possible we'll get a transition time prior to |
| // now. Rather than continually checking to see whether the weighted lux exceeds the |
| // threshold, schedule an update for when we'd normally expect another light sample, which |
| // should be enough time to decide whether we should actually transition to the new |
| // weighted ambient lux or not. |
| nextTransitionTime = |
| nextTransitionTime > time ? nextTransitionTime : time + mNormalLightSensorRate; |
| if (DEBUG) { |
| Slog.d(TAG, "updateAmbientLux: Scheduling ambient lux update for " + |
| nextTransitionTime + TimeUtils.formatUptime(nextTransitionTime)); |
| } |
| mHandler.sendEmptyMessageAtTime(MSG_UPDATE_AMBIENT_LUX, nextTransitionTime); |
| } |
| |
| private void updateAutoBrightness(boolean sendUpdate) { |
| if (!mAmbientLuxValid) { |
| return; |
| } |
| |
| float value = mBrightnessMapper.getBrightness(mAmbientLux); |
| |
| int newScreenAutoBrightness = |
| clampScreenBrightness(Math.round(value * PowerManager.BRIGHTNESS_ON)); |
| if (mScreenAutoBrightness != newScreenAutoBrightness) { |
| if (DEBUG) { |
| Slog.d(TAG, "updateAutoBrightness: " + |
| "mScreenAutoBrightness=" + mScreenAutoBrightness + ", " + |
| "newScreenAutoBrightness=" + newScreenAutoBrightness); |
| } |
| |
| mScreenAutoBrightness = newScreenAutoBrightness; |
| if (sendUpdate) { |
| mCallbacks.updateBrightness(); |
| } |
| } |
| } |
| |
| private int clampScreenBrightness(int value) { |
| return MathUtils.constrain(value, |
| mScreenBrightnessRangeMinimum, mScreenBrightnessRangeMaximum); |
| } |
| |
| private void prepareBrightnessAdjustmentSample() { |
| if (!mBrightnessAdjustmentSamplePending) { |
| mBrightnessAdjustmentSamplePending = true; |
| mBrightnessAdjustmentSampleOldLux = mAmbientLuxValid ? mAmbientLux : -1; |
| mBrightnessAdjustmentSampleOldBrightness = mScreenAutoBrightness; |
| } else { |
| mHandler.removeMessages(MSG_BRIGHTNESS_ADJUSTMENT_SAMPLE); |
| } |
| |
| mHandler.sendEmptyMessageDelayed(MSG_BRIGHTNESS_ADJUSTMENT_SAMPLE, |
| BRIGHTNESS_ADJUSTMENT_SAMPLE_DEBOUNCE_MILLIS); |
| } |
| |
| private void cancelBrightnessAdjustmentSample() { |
| if (mBrightnessAdjustmentSamplePending) { |
| mBrightnessAdjustmentSamplePending = false; |
| mHandler.removeMessages(MSG_BRIGHTNESS_ADJUSTMENT_SAMPLE); |
| } |
| } |
| |
| private void collectBrightnessAdjustmentSample() { |
| if (mBrightnessAdjustmentSamplePending) { |
| mBrightnessAdjustmentSamplePending = false; |
| if (mAmbientLuxValid && mScreenAutoBrightness >= 0) { |
| if (DEBUG) { |
| Slog.d(TAG, "Auto-brightness adjustment changed by user: " + |
| "lux=" + mAmbientLux + ", " + |
| "brightness=" + mScreenAutoBrightness + ", " + |
| "ring=" + mAmbientLightRingBuffer); |
| } |
| |
| EventLog.writeEvent(EventLogTags.AUTO_BRIGHTNESS_ADJ, |
| mBrightnessAdjustmentSampleOldLux, |
| mBrightnessAdjustmentSampleOldBrightness, |
| mAmbientLux, |
| mScreenAutoBrightness); |
| } |
| } |
| } |
| |
| private final class AutomaticBrightnessHandler extends Handler { |
| public AutomaticBrightnessHandler(Looper looper) { |
| super(looper, null, true /*async*/); |
| } |
| |
| @Override |
| public void handleMessage(Message msg) { |
| switch (msg.what) { |
| case MSG_UPDATE_AMBIENT_LUX: |
| updateAmbientLux(); |
| break; |
| |
| case MSG_BRIGHTNESS_ADJUSTMENT_SAMPLE: |
| collectBrightnessAdjustmentSample(); |
| break; |
| |
| case MSG_INVALIDATE_SHORT_TERM_MODEL: |
| invalidateShortTermModel(); |
| break; |
| } |
| } |
| } |
| |
| private final SensorEventListener mLightSensorListener = new SensorEventListener() { |
| @Override |
| public void onSensorChanged(SensorEvent event) { |
| if (mLightSensorEnabled) { |
| final long time = SystemClock.uptimeMillis(); |
| final float lux = event.values[0]; |
| handleLightSensorEvent(time, lux); |
| } |
| } |
| |
| @Override |
| public void onAccuracyChanged(Sensor sensor, int accuracy) { |
| // Not used. |
| } |
| }; |
| |
| /** Callbacks to request updates to the display's power state. */ |
| interface Callbacks { |
| void updateBrightness(); |
| } |
| |
| /** |
| * A ring buffer of ambient light measurements sorted by time. |
| * |
| * Each entry consists of a timestamp and a lux measurement, and the overall buffer is sorted |
| * from oldest to newest. |
| */ |
| private static final class AmbientLightRingBuffer { |
| // Proportional extra capacity of the buffer beyond the expected number of light samples |
| // in the horizon |
| private static final float BUFFER_SLACK = 1.5f; |
| private float[] mRingLux; |
| private long[] mRingTime; |
| private int mCapacity; |
| |
| // The first valid element and the next open slot. |
| // Note that if mCount is zero then there are no valid elements. |
| private int mStart; |
| private int mEnd; |
| private int mCount; |
| |
| public AmbientLightRingBuffer(long lightSensorRate, int ambientLightHorizon) { |
| mCapacity = (int) Math.ceil(ambientLightHorizon * BUFFER_SLACK / lightSensorRate); |
| mRingLux = new float[mCapacity]; |
| mRingTime = new long[mCapacity]; |
| } |
| |
| public float getLux(int index) { |
| return mRingLux[offsetOf(index)]; |
| } |
| |
| public long getTime(int index) { |
| return mRingTime[offsetOf(index)]; |
| } |
| |
| public void push(long time, float lux) { |
| int next = mEnd; |
| if (mCount == mCapacity) { |
| int newSize = mCapacity * 2; |
| |
| float[] newRingLux = new float[newSize]; |
| long[] newRingTime = new long[newSize]; |
| int length = mCapacity - mStart; |
| System.arraycopy(mRingLux, mStart, newRingLux, 0, length); |
| System.arraycopy(mRingTime, mStart, newRingTime, 0, length); |
| if (mStart != 0) { |
| System.arraycopy(mRingLux, 0, newRingLux, length, mStart); |
| System.arraycopy(mRingTime, 0, newRingTime, length, mStart); |
| } |
| mRingLux = newRingLux; |
| mRingTime = newRingTime; |
| |
| next = mCapacity; |
| mCapacity = newSize; |
| mStart = 0; |
| } |
| mRingTime[next] = time; |
| mRingLux[next] = lux; |
| mEnd = next + 1; |
| if (mEnd == mCapacity) { |
| mEnd = 0; |
| } |
| mCount++; |
| } |
| |
| public void prune(long horizon) { |
| if (mCount == 0) { |
| return; |
| } |
| |
| while (mCount > 1) { |
| int next = mStart + 1; |
| if (next >= mCapacity) { |
| next -= mCapacity; |
| } |
| if (mRingTime[next] > horizon) { |
| // Some light sensors only produce data upon a change in the ambient light |
| // levels, so we need to consider the previous measurement as the ambient light |
| // level for all points in time up until we receive a new measurement. Thus, we |
| // always want to keep the youngest element that would be removed from the |
| // buffer and just set its measurement time to the horizon time since at that |
| // point it is the ambient light level, and to remove it would be to drop a |
| // valid data point within our horizon. |
| break; |
| } |
| mStart = next; |
| mCount -= 1; |
| } |
| |
| if (mRingTime[mStart] < horizon) { |
| mRingTime[mStart] = horizon; |
| } |
| } |
| |
| public int size() { |
| return mCount; |
| } |
| |
| public void clear() { |
| mStart = 0; |
| mEnd = 0; |
| mCount = 0; |
| } |
| |
| @Override |
| public String toString() { |
| StringBuffer buf = new StringBuffer(); |
| buf.append('['); |
| for (int i = 0; i < mCount; i++) { |
| final long next = i + 1 < mCount ? getTime(i + 1) : SystemClock.uptimeMillis(); |
| if (i != 0) { |
| buf.append(", "); |
| } |
| buf.append(getLux(i)); |
| buf.append(" / "); |
| buf.append(next - getTime(i)); |
| buf.append("ms"); |
| } |
| buf.append(']'); |
| return buf.toString(); |
| } |
| |
| private int offsetOf(int index) { |
| if (index >= mCount || index < 0) { |
| throw new ArrayIndexOutOfBoundsException(index); |
| } |
| index += mStart; |
| if (index >= mCapacity) { |
| index -= mCapacity; |
| } |
| return index; |
| } |
| } |
| } |
