android-34/com/android/internal/display/BrightnessSynchronizer.java - platform/prebuilts/fullsdk/sources - Git at Google

 /*
  * Copyright (C) 2019 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.internal.display;

 import android.content.ContentResolver;
 import android.content.Context;
 import android.database.ContentObserver;
 import android.hardware.display.DisplayManager;
 import android.hardware.display.DisplayManager.DisplayListener;
 import android.net.Uri;
 import android.os.Handler;
 import android.os.Looper;
 import android.os.Message;
 import android.os.PowerManager;
 import android.os.SystemClock;
 import android.os.UserHandle;
 import android.provider.Settings;
 import android.util.MathUtils;
 import android.util.Slog;
 import android.view.Display;

 import com.android.internal.annotations.VisibleForTesting;

 import java.io.PrintWriter;

 /**
  * BrightnessSynchronizer helps convert between the int (old) system and float
  * (new) system for storing the brightness. It has methods to convert between the two and also
  * observes for when one of the settings is changed and syncs this with the other.
  */
 public class BrightnessSynchronizer {
     private static final String TAG = "BrightnessSynchronizer";

     private static final boolean DEBUG = false;
     private static final Uri BRIGHTNESS_URI =
             Settings.System.getUriFor(Settings.System.SCREEN_BRIGHTNESS);

     private static final long WAIT_FOR_RESPONSE_MILLIS = 200;

     private static final int MSG_RUN_UPDATE = 1;

     // The tolerance within which we consider brightness values approximately equal to eachother.
     // This value is approximately 1/3 of the smallest possible brightness value.
     public static final float EPSILON = 0.001f;

     private static int sBrightnessUpdateCount = 1;

     private final Context mContext;
     private final BrightnessSyncObserver mBrightnessSyncObserver;
     private final Clock mClock;
     private final Handler mHandler;

     private DisplayManager mDisplayManager;
     private int mLatestIntBrightness;
     private float mLatestFloatBrightness;
     private BrightnessUpdate mCurrentUpdate;
     private BrightnessUpdate mPendingUpdate;

     public BrightnessSynchronizer(Context context) {
         this(context, Looper.getMainLooper(), SystemClock::uptimeMillis);
     }

     @VisibleForTesting
     public BrightnessSynchronizer(Context context, Looper looper, Clock clock) {
         mContext = context;
         mClock = clock;
         mBrightnessSyncObserver = new BrightnessSyncObserver();
         mHandler = new BrightnessSynchronizerHandler(looper);
     }

     /**
      * Starts brightnessSyncObserver to ensure that the float and int brightness values stay
      * in sync.
      * This also ensures that values are synchronized at system start up too.
      * So we force an update to the int value, since float is the source of truth. Fallback to int
      * value, if float is invalid. If both are invalid, use default float value from config.
      */
     public void startSynchronizing() {
         if (mDisplayManager == null) {
             mDisplayManager = mContext.getSystemService(DisplayManager.class);
         }
         if (mBrightnessSyncObserver.isObserving()) {
             Slog.wtf(TAG, "Brightness sync observer requesting synchronization a second time.");
             return;
         }
         mLatestFloatBrightness = getScreenBrightnessFloat();
         mLatestIntBrightness = getScreenBrightnessInt();
         Slog.i(TAG, "Initial brightness readings: " + mLatestIntBrightness + "(int), "
                 + mLatestFloatBrightness + "(float)");

         if (!Float.isNaN(mLatestFloatBrightness)) {
             mPendingUpdate = new BrightnessUpdate(BrightnessUpdate.TYPE_FLOAT,
                     mLatestFloatBrightness);
         } else if (mLatestIntBrightness != PowerManager.BRIGHTNESS_INVALID) {
             mPendingUpdate = new BrightnessUpdate(BrightnessUpdate.TYPE_INT,
                     mLatestIntBrightness);
         } else {
             final float defaultBrightness = mContext.getResources().getFloat(
                     com.android.internal.R.dimen.config_screenBrightnessSettingDefaultFloat);
             mPendingUpdate = new BrightnessUpdate(BrightnessUpdate.TYPE_FLOAT, defaultBrightness);
             Slog.i(TAG, "Setting initial brightness to default value of: " + defaultBrightness);
         }

         mBrightnessSyncObserver.startObserving(mHandler);
         mHandler.sendEmptyMessageAtTime(MSG_RUN_UPDATE, mClock.uptimeMillis());
     }

     /**
      * Prints data on dumpsys.
      */
     public void dump(PrintWriter pw) {
         pw.println("BrightnessSynchronizer");
         pw.println("  mLatestIntBrightness=" + mLatestIntBrightness);
         pw.println("  mLatestFloatBrightness=" + mLatestFloatBrightness);
         pw.println("  mCurrentUpdate=" + mCurrentUpdate);
         pw.println("  mPendingUpdate=" + mPendingUpdate);
     }

     /**
      * Converts between the int brightness system and the float brightness system.
      */
     public static float brightnessIntToFloat(int brightnessInt) {
         if (brightnessInt == PowerManager.BRIGHTNESS_OFF) {
             return PowerManager.BRIGHTNESS_OFF_FLOAT;
         } else if (brightnessInt == PowerManager.BRIGHTNESS_INVALID) {
             return PowerManager.BRIGHTNESS_INVALID_FLOAT;
         } else {
             final float minFloat = PowerManager.BRIGHTNESS_MIN;
             final float maxFloat = PowerManager.BRIGHTNESS_MAX;
             final float minInt = PowerManager.BRIGHTNESS_OFF + 1;
             final float maxInt = PowerManager.BRIGHTNESS_ON;
             return MathUtils.constrainedMap(minFloat, maxFloat, minInt, maxInt, brightnessInt);
         }
     }

     /**
      * Converts between the float brightness system and the int brightness system.
      */
     public static int brightnessFloatToInt(float brightnessFloat) {
         return Math.round(brightnessFloatToIntRange(brightnessFloat));
     }

     /**
      * Translates specified value from the float brightness system to the int brightness system,
      * given the min/max of each range. Accounts for special values such as OFF and invalid values.
      * Value returned as a float primitive (to preserve precision), but is a value within the
      * int-system range.
      */
     public static float brightnessFloatToIntRange(float brightnessFloat) {
         if (floatEquals(brightnessFloat, PowerManager.BRIGHTNESS_OFF_FLOAT)) {
             return PowerManager.BRIGHTNESS_OFF;
         } else if (Float.isNaN(brightnessFloat)) {
             return PowerManager.BRIGHTNESS_INVALID;
         } else {
             final float minFloat = PowerManager.BRIGHTNESS_MIN;
             final float maxFloat = PowerManager.BRIGHTNESS_MAX;
             final float minInt = PowerManager.BRIGHTNESS_OFF + 1;
             final float maxInt = PowerManager.BRIGHTNESS_ON;
             return MathUtils.constrainedMap(minInt, maxInt, minFloat, maxFloat, brightnessFloat);
         }
     }

     /**
      * Consumes a brightness change event for the float-based brightness.
      *
      * @param brightness Float brightness.
      */
     private void handleBrightnessChangeFloat(float brightness) {
         mLatestFloatBrightness = brightness;
         handleBrightnessChange(BrightnessUpdate.TYPE_FLOAT, brightness);
     }

     /**
      * Consumes a brightness change event for the int-based brightness.
      *
      * @param brightness Int brightness.
      */
     private void handleBrightnessChangeInt(int brightness) {
         mLatestIntBrightness = brightness;
         handleBrightnessChange(BrightnessUpdate.TYPE_INT, brightness);
     }

     /**
      * Consumes a brightness change event.
      *
      * @param type Type of the brightness change (int/float)
      * @param brightness brightness.
      */
     private void handleBrightnessChange(int type, float brightness) {
         boolean swallowUpdate = mCurrentUpdate != null
                 && mCurrentUpdate.swallowUpdate(type, brightness);
         BrightnessUpdate prevUpdate = null;
         if (!swallowUpdate) {
             prevUpdate = mPendingUpdate;
             mPendingUpdate = new BrightnessUpdate(type, brightness);
         }
         runUpdate();

         // If we created a new update and it is still pending after the update, add a log.
         if (!swallowUpdate && mPendingUpdate != null) {
             Slog.i(TAG, "New PendingUpdate: " + mPendingUpdate + ", prev=" + prevUpdate);
         }
     }

     /**
      * Runs updates for current and pending BrightnessUpdates.
      */
     private void runUpdate() {
         if (DEBUG) {
             Slog.d(TAG, "Running update mCurrent="  + mCurrentUpdate
                     + ", mPending=" + mPendingUpdate);
         }

         // do-while instead of while to allow mCurrentUpdate to get set if there's a pending update.
         do {
             if (mCurrentUpdate != null) {
                 mCurrentUpdate.update();
                 if (mCurrentUpdate.isRunning()) {
                     break; // current update is still running, nothing to do.
                 } else if (mCurrentUpdate.isCompleted()) {
                     if (mCurrentUpdate.madeUpdates()) {
                         Slog.i(TAG, "Completed Update: " + mCurrentUpdate);
                     }
                     mCurrentUpdate = null;
                 }
             }
             // No current update any more, lets start the next update if there is one.
             if (mCurrentUpdate == null && mPendingUpdate != null) {
                 mCurrentUpdate = mPendingUpdate;
                 mPendingUpdate = null;
             }
         } while (mCurrentUpdate != null);
     }

     /**
      * Gets the stored screen brightness float value from the display brightness setting.
      * @return brightness
      */
     private float getScreenBrightnessFloat() {
         return mDisplayManager.getBrightness(Display.DEFAULT_DISPLAY);
     }

     /**
      * Gets the stored screen brightness int from the system settings.
      * @return brightness
      */
     private int getScreenBrightnessInt() {
         return Settings.System.getIntForUser(mContext.getContentResolver(),
                 Settings.System.SCREEN_BRIGHTNESS, PowerManager.BRIGHTNESS_INVALID,
                 UserHandle.USER_CURRENT);
     }

     /**
      * Tests whether two brightness float values are within a small enough tolerance
      * of each other.
      * @param a first float to compare
      * @param b second float to compare
      * @return whether the two values are within a small enough tolerance value
      */
     public static boolean floatEquals(float a, float b) {
         if (a == b) {
             return true;
         } else if (Float.isNaN(a) && Float.isNaN(b)) {
             return true;
         } else if (Math.abs(a - b) < EPSILON) {
             return true;
         } else {
             return false;
         }
     }

     /**
      * Encapsulates a brightness change event and contains logic for synchronizing the appropriate
      * settings for the specified brightness change.
      */
     @VisibleForTesting
     public class BrightnessUpdate {
         static final int TYPE_INT = 0x1;
         static final int TYPE_FLOAT = 0x2;

         private static final int STATE_NOT_STARTED = 1;
         private static final int STATE_RUNNING = 2;
         private static final int STATE_COMPLETED = 3;

         private final int mSourceType;
         private final float mBrightness;

         private long mTimeUpdated;
         private int mState;
         private int mUpdatedTypes;
         private int mConfirmedTypes;
         private int mId;

         BrightnessUpdate(int sourceType, float brightness) {
             mId = sBrightnessUpdateCount++;
             mSourceType = sourceType;
             mBrightness = brightness;
             mTimeUpdated = 0;
             mUpdatedTypes = 0x0;
             mConfirmedTypes = 0x0;
             mState = STATE_NOT_STARTED;
         }

         @Override
         public String toString() {
             return "{[" + mId + "] " + toStringLabel(mSourceType, mBrightness)
                     + ", mUpdatedTypes=" + mUpdatedTypes + ", mConfirmedTypes=" + mConfirmedTypes
                     + ", mTimeUpdated=" + mTimeUpdated + "}";
         }

         /**
          * Runs the synchronization process, moving forward through the internal state machine.
          */
         void update() {
             if (mState == STATE_NOT_STARTED) {
                 mState = STATE_RUNNING;

                 // check if we need to update int
                 int brightnessInt = getBrightnessAsInt();
                 if (mLatestIntBrightness != brightnessInt) {
                     Settings.System.putIntForUser(mContext.getContentResolver(),
                             Settings.System.SCREEN_BRIGHTNESS, brightnessInt,
                             UserHandle.USER_CURRENT);
                     mLatestIntBrightness = brightnessInt;
                     mUpdatedTypes |= TYPE_INT;
                 }

                 // check if we need to update float
                 float brightnessFloat = getBrightnessAsFloat();
                 if (!floatEquals(mLatestFloatBrightness, brightnessFloat)) {
                     mDisplayManager.setBrightness(Display.DEFAULT_DISPLAY, brightnessFloat);
                     mLatestFloatBrightness = brightnessFloat;
                     mUpdatedTypes |= TYPE_FLOAT;
                 }

                 // If we made updates, lets wait for responses.
                 if (mUpdatedTypes != 0x0) {
                     // Give some time for our updates to return a confirmation response. If they
                     // don't return by that time, MSG_RUN_UPDATE will get sent and we will stop
                     // listening for responses and mark this update as complete.
                     if (DEBUG) {
                         Slog.d(TAG, "Sending MSG_RUN_UPDATE for "
                                 + toStringLabel(mSourceType, mBrightness));
                     }
                     Slog.i(TAG, "[" + mId + "] New Update "
                             + toStringLabel(mSourceType, mBrightness) + " set brightness values: "
                             + toStringLabel(mUpdatedTypes & TYPE_FLOAT, brightnessFloat) + " "
                             + toStringLabel(mUpdatedTypes & TYPE_INT, brightnessInt));

                     mHandler.sendEmptyMessageAtTime(MSG_RUN_UPDATE,
                             mClock.uptimeMillis() + WAIT_FOR_RESPONSE_MILLIS);
                 }
                 mTimeUpdated = mClock.uptimeMillis();
             }

             if (mState == STATE_RUNNING) {
                 // If we're not waiting on any more confirmations or the time has expired, move to
                 // completed state.
                 if (mConfirmedTypes == mUpdatedTypes
                         || (mTimeUpdated + WAIT_FOR_RESPONSE_MILLIS) < mClock.uptimeMillis()) {
                     mState = STATE_COMPLETED;
                 }
             }
         }

         /**
          * Attempts to consume the specified brightness change if it is determined that the change
          * is a notification of a change previously made by this class.
          *
          * @param type The type of change (int|float)
          * @param brightness The brightness value.
          * @return True if the change was caused by this class, thus swallowed.
          */
         boolean swallowUpdate(int type, float brightness) {
             if ((mUpdatedTypes & type) != type || (mConfirmedTypes & type) != 0x0) {
                 // It's either a type we didn't update, or one we've already confirmed.
                 return false;
             }

             final boolean floatUpdateConfirmed =
                     type == TYPE_FLOAT && floatEquals(getBrightnessAsFloat(), brightness);
             final boolean intUpdateConfirmed =
                     type == TYPE_INT && getBrightnessAsInt() == (int) brightness;

             if (floatUpdateConfirmed || intUpdateConfirmed) {
                 mConfirmedTypes |= type;
                 Slog.i(TAG, "Swallowing update of " + toStringLabel(type, brightness)
                         + " by update: " + this);
                 return true;
             }
             return false;
         }

         boolean isRunning() {
             return mState == STATE_RUNNING;
         }

         boolean isCompleted() {
             return mState == STATE_COMPLETED;
         }

         boolean madeUpdates() {
             return mUpdatedTypes != 0x0;
         }

         private int getBrightnessAsInt() {
             if (mSourceType == TYPE_INT) {
                 return (int) mBrightness;
             }
             return brightnessFloatToInt(mBrightness);
         }

         private float getBrightnessAsFloat() {
             if (mSourceType == TYPE_FLOAT) {
                 return mBrightness;
             }
             return brightnessIntToFloat((int) mBrightness);
         }

         private String toStringLabel(int type, float brightness) {
             return (type == TYPE_INT) ? ((int) brightness) + "(i)"
                     : ((type == TYPE_FLOAT) ? brightness + "(f)"
                     : "");
         }
     }

     /** Functional interface for providing time. */
     @VisibleForTesting
     public interface Clock {
         /** @return system uptime in milliseconds. */
         long uptimeMillis();
     }

     class BrightnessSynchronizerHandler extends Handler {
         BrightnessSynchronizerHandler(Looper looper) {
             super(looper);
         }

         @Override
         public void handleMessage(Message msg) {
             switch (msg.what) {
                 case MSG_RUN_UPDATE:
                     if (DEBUG) {
                         Slog.d(TAG, "MSG_RUN_UPDATE");
                     }
                     runUpdate();
                     break;
                 default:
                     super.handleMessage(msg);
             }

         }
     };

     private class BrightnessSyncObserver {
         private boolean mIsObserving;

         private final DisplayListener mListener = new DisplayListener() {
             @Override
             public void onDisplayAdded(int displayId) {}

             @Override
             public void onDisplayRemoved(int displayId) {}

             @Override
             public void onDisplayChanged(int displayId) {
                 handleBrightnessChangeFloat(getScreenBrightnessFloat());
             }
         };

         private ContentObserver createBrightnessContentObserver(Handler handler) {
             return new ContentObserver(handler) {
                 @Override
                 public void onChange(boolean selfChange, Uri uri) {
                     if (selfChange) {
                         return;
                     }
                     if (BRIGHTNESS_URI.equals(uri)) {
                         handleBrightnessChangeInt(getScreenBrightnessInt());
                     }
                 }
             };
         }

         boolean isObserving() {
             return mIsObserving;
         }

         void startObserving(Handler handler) {
             final ContentResolver cr = mContext.getContentResolver();
             cr.registerContentObserver(BRIGHTNESS_URI, false,
                     createBrightnessContentObserver(handler), UserHandle.USER_ALL);
             mDisplayManager.registerDisplayListener(mListener, handler,
                     DisplayManager.EVENT_FLAG_DISPLAY_BRIGHTNESS);
             mIsObserving = true;
         }
     }
 }
	/*
	* Copyright (C) 2019 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.internal.display;

	import android.content.ContentResolver;
	import android.content.Context;
	import android.database.ContentObserver;
	import android.hardware.display.DisplayManager;
	import android.hardware.display.DisplayManager.DisplayListener;
	import android.net.Uri;
	import android.os.Handler;
	import android.os.Looper;
	import android.os.Message;
	import android.os.PowerManager;
	import android.os.SystemClock;
	import android.os.UserHandle;
	import android.provider.Settings;
	import android.util.MathUtils;
	import android.util.Slog;
	import android.view.Display;

	import com.android.internal.annotations.VisibleForTesting;

	import java.io.PrintWriter;

	/**
	* BrightnessSynchronizer helps convert between the int (old) system and float
	* (new) system for storing the brightness. It has methods to convert between the two and also
	* observes for when one of the settings is changed and syncs this with the other.
	*/
	public class BrightnessSynchronizer {
	private static final String TAG = "BrightnessSynchronizer";

	private static final boolean DEBUG = false;
	private static final Uri BRIGHTNESS_URI =
	Settings.System.getUriFor(Settings.System.SCREEN_BRIGHTNESS);

	private static final long WAIT_FOR_RESPONSE_MILLIS = 200;

	private static final int MSG_RUN_UPDATE = 1;

	// The tolerance within which we consider brightness values approximately equal to eachother.
	// This value is approximately 1/3 of the smallest possible brightness value.
	public static final float EPSILON = 0.001f;

	private static int sBrightnessUpdateCount = 1;

	private final Context mContext;
	private final BrightnessSyncObserver mBrightnessSyncObserver;
	private final Clock mClock;
	private final Handler mHandler;

	private DisplayManager mDisplayManager;
	private int mLatestIntBrightness;
	private float mLatestFloatBrightness;
	private BrightnessUpdate mCurrentUpdate;
	private BrightnessUpdate mPendingUpdate;

	public BrightnessSynchronizer(Context context) {
	this(context, Looper.getMainLooper(), SystemClock::uptimeMillis);
	}

	@VisibleForTesting
	public BrightnessSynchronizer(Context context, Looper looper, Clock clock) {
	mContext = context;
	mClock = clock;
	mBrightnessSyncObserver = new BrightnessSyncObserver();
	mHandler = new BrightnessSynchronizerHandler(looper);
	}

	/**
	* Starts brightnessSyncObserver to ensure that the float and int brightness values stay
	* in sync.
	* This also ensures that values are synchronized at system start up too.
	* So we force an update to the int value, since float is the source of truth. Fallback to int
	* value, if float is invalid. If both are invalid, use default float value from config.
	*/
	public void startSynchronizing() {
	if (mDisplayManager == null) {
	mDisplayManager = mContext.getSystemService(DisplayManager.class);
	}
	if (mBrightnessSyncObserver.isObserving()) {
	Slog.wtf(TAG, "Brightness sync observer requesting synchronization a second time.");
	return;
	}
	mLatestFloatBrightness = getScreenBrightnessFloat();
	mLatestIntBrightness = getScreenBrightnessInt();
	Slog.i(TAG, "Initial brightness readings: " + mLatestIntBrightness + "(int), "
	+ mLatestFloatBrightness + "(float)");

	if (!Float.isNaN(mLatestFloatBrightness)) {
	mPendingUpdate = new BrightnessUpdate(BrightnessUpdate.TYPE_FLOAT,
	mLatestFloatBrightness);
	} else if (mLatestIntBrightness != PowerManager.BRIGHTNESS_INVALID) {
	mPendingUpdate = new BrightnessUpdate(BrightnessUpdate.TYPE_INT,
	mLatestIntBrightness);
	} else {
	final float defaultBrightness = mContext.getResources().getFloat(
	com.android.internal.R.dimen.config_screenBrightnessSettingDefaultFloat);
	mPendingUpdate = new BrightnessUpdate(BrightnessUpdate.TYPE_FLOAT, defaultBrightness);
	Slog.i(TAG, "Setting initial brightness to default value of: " + defaultBrightness);
	}

	mBrightnessSyncObserver.startObserving(mHandler);
	mHandler.sendEmptyMessageAtTime(MSG_RUN_UPDATE, mClock.uptimeMillis());
	}

	/**
	* Prints data on dumpsys.
	*/
	public void dump(PrintWriter pw) {
	pw.println("BrightnessSynchronizer");
	pw.println(" mLatestIntBrightness=" + mLatestIntBrightness);
	pw.println(" mLatestFloatBrightness=" + mLatestFloatBrightness);
	pw.println(" mCurrentUpdate=" + mCurrentUpdate);
	pw.println(" mPendingUpdate=" + mPendingUpdate);
	}

	/**
	* Converts between the int brightness system and the float brightness system.
	*/
	public static float brightnessIntToFloat(int brightnessInt) {
	if (brightnessInt == PowerManager.BRIGHTNESS_OFF) {
	return PowerManager.BRIGHTNESS_OFF_FLOAT;
	} else if (brightnessInt == PowerManager.BRIGHTNESS_INVALID) {
	return PowerManager.BRIGHTNESS_INVALID_FLOAT;
	} else {
	final float minFloat = PowerManager.BRIGHTNESS_MIN;
	final float maxFloat = PowerManager.BRIGHTNESS_MAX;
	final float minInt = PowerManager.BRIGHTNESS_OFF + 1;
	final float maxInt = PowerManager.BRIGHTNESS_ON;
	return MathUtils.constrainedMap(minFloat, maxFloat, minInt, maxInt, brightnessInt);
	}
	}

	/**
	* Converts between the float brightness system and the int brightness system.
	*/
	public static int brightnessFloatToInt(float brightnessFloat) {
	return Math.round(brightnessFloatToIntRange(brightnessFloat));
	}

	/**
	* Translates specified value from the float brightness system to the int brightness system,
	* given the min/max of each range. Accounts for special values such as OFF and invalid values.
	* Value returned as a float primitive (to preserve precision), but is a value within the
	* int-system range.
	*/
	public static float brightnessFloatToIntRange(float brightnessFloat) {
	if (floatEquals(brightnessFloat, PowerManager.BRIGHTNESS_OFF_FLOAT)) {
	return PowerManager.BRIGHTNESS_OFF;
	} else if (Float.isNaN(brightnessFloat)) {
	return PowerManager.BRIGHTNESS_INVALID;
	} else {
	final float minFloat = PowerManager.BRIGHTNESS_MIN;
	final float maxFloat = PowerManager.BRIGHTNESS_MAX;
	final float minInt = PowerManager.BRIGHTNESS_OFF + 1;
	final float maxInt = PowerManager.BRIGHTNESS_ON;
	return MathUtils.constrainedMap(minInt, maxInt, minFloat, maxFloat, brightnessFloat);
	}
	}

	/**
	* Consumes a brightness change event for the float-based brightness.
	*
	* @param brightness Float brightness.
	*/
	private void handleBrightnessChangeFloat(float brightness) {
	mLatestFloatBrightness = brightness;
	handleBrightnessChange(BrightnessUpdate.TYPE_FLOAT, brightness);
	}

	/**
	* Consumes a brightness change event for the int-based brightness.
	*
	* @param brightness Int brightness.
	*/
	private void handleBrightnessChangeInt(int brightness) {
	mLatestIntBrightness = brightness;
	handleBrightnessChange(BrightnessUpdate.TYPE_INT, brightness);
	}

	/**
	* Consumes a brightness change event.
	*
	* @param type Type of the brightness change (int/float)
	* @param brightness brightness.
	*/
	private void handleBrightnessChange(int type, float brightness) {
	boolean swallowUpdate = mCurrentUpdate != null
	&& mCurrentUpdate.swallowUpdate(type, brightness);
	BrightnessUpdate prevUpdate = null;
	if (!swallowUpdate) {
	prevUpdate = mPendingUpdate;
	mPendingUpdate = new BrightnessUpdate(type, brightness);
	}
	runUpdate();

	// If we created a new update and it is still pending after the update, add a log.
	if (!swallowUpdate && mPendingUpdate != null) {
	Slog.i(TAG, "New PendingUpdate: " + mPendingUpdate + ", prev=" + prevUpdate);
	}
	}

	/**
	* Runs updates for current and pending BrightnessUpdates.
	*/
	private void runUpdate() {
	if (DEBUG) {
	Slog.d(TAG, "Running update mCurrent=" + mCurrentUpdate
	+ ", mPending=" + mPendingUpdate);
	}

	// do-while instead of while to allow mCurrentUpdate to get set if there's a pending update.
	do {
	if (mCurrentUpdate != null) {
	mCurrentUpdate.update();
	if (mCurrentUpdate.isRunning()) {
	break; // current update is still running, nothing to do.
	} else if (mCurrentUpdate.isCompleted()) {
	if (mCurrentUpdate.madeUpdates()) {
	Slog.i(TAG, "Completed Update: " + mCurrentUpdate);
	}
	mCurrentUpdate = null;
	}
	}
	// No current update any more, lets start the next update if there is one.
	if (mCurrentUpdate == null && mPendingUpdate != null) {
	mCurrentUpdate = mPendingUpdate;
	mPendingUpdate = null;
	}
	} while (mCurrentUpdate != null);
	}

	/**
	* Gets the stored screen brightness float value from the display brightness setting.
	* @return brightness
	*/
	private float getScreenBrightnessFloat() {
	return mDisplayManager.getBrightness(Display.DEFAULT_DISPLAY);
	}

	/**
	* Gets the stored screen brightness int from the system settings.
	* @return brightness
	*/
	private int getScreenBrightnessInt() {
	return Settings.System.getIntForUser(mContext.getContentResolver(),
	Settings.System.SCREEN_BRIGHTNESS, PowerManager.BRIGHTNESS_INVALID,
	UserHandle.USER_CURRENT);
	}

	/**
	* Tests whether two brightness float values are within a small enough tolerance
	* of each other.
	* @param a first float to compare
	* @param b second float to compare
	* @return whether the two values are within a small enough tolerance value
	*/
	public static boolean floatEquals(float a, float b) {
	if (a == b) {
	return true;
	} else if (Float.isNaN(a) && Float.isNaN(b)) {
	return true;
	} else if (Math.abs(a - b) < EPSILON) {
	return true;
	} else {
	return false;
	}
	}

	/**
	* Encapsulates a brightness change event and contains logic for synchronizing the appropriate
	* settings for the specified brightness change.
	*/
	@VisibleForTesting
	public class BrightnessUpdate {
	static final int TYPE_INT = 0x1;
	static final int TYPE_FLOAT = 0x2;

	private static final int STATE_NOT_STARTED = 1;
	private static final int STATE_RUNNING = 2;
	private static final int STATE_COMPLETED = 3;

	private final int mSourceType;
	private final float mBrightness;

	private long mTimeUpdated;
	private int mState;
	private int mUpdatedTypes;
	private int mConfirmedTypes;
	private int mId;

	BrightnessUpdate(int sourceType, float brightness) {
	mId = sBrightnessUpdateCount++;
	mSourceType = sourceType;
	mBrightness = brightness;
	mTimeUpdated = 0;
	mUpdatedTypes = 0x0;
	mConfirmedTypes = 0x0;
	mState = STATE_NOT_STARTED;
	}

	@Override
	public String toString() {
	return "{[" + mId + "] " + toStringLabel(mSourceType, mBrightness)
	+ ", mUpdatedTypes=" + mUpdatedTypes + ", mConfirmedTypes=" + mConfirmedTypes
	+ ", mTimeUpdated=" + mTimeUpdated + "}";
	}

	/**
	* Runs the synchronization process, moving forward through the internal state machine.
	*/
	void update() {
	if (mState == STATE_NOT_STARTED) {
	mState = STATE_RUNNING;

	// check if we need to update int
	int brightnessInt = getBrightnessAsInt();
	if (mLatestIntBrightness != brightnessInt) {
	Settings.System.putIntForUser(mContext.getContentResolver(),
	Settings.System.SCREEN_BRIGHTNESS, brightnessInt,
	UserHandle.USER_CURRENT);
	mLatestIntBrightness = brightnessInt;
	mUpdatedTypes \|= TYPE_INT;
	}

	// check if we need to update float
	float brightnessFloat = getBrightnessAsFloat();
	if (!floatEquals(mLatestFloatBrightness, brightnessFloat)) {
	mDisplayManager.setBrightness(Display.DEFAULT_DISPLAY, brightnessFloat);
	mLatestFloatBrightness = brightnessFloat;
	mUpdatedTypes \|= TYPE_FLOAT;
	}

	// If we made updates, lets wait for responses.
	if (mUpdatedTypes != 0x0) {
	// Give some time for our updates to return a confirmation response. If they
	// don't return by that time, MSG_RUN_UPDATE will get sent and we will stop
	// listening for responses and mark this update as complete.
	if (DEBUG) {
	Slog.d(TAG, "Sending MSG_RUN_UPDATE for "
	+ toStringLabel(mSourceType, mBrightness));
	}
	Slog.i(TAG, "[" + mId + "] New Update "
	+ toStringLabel(mSourceType, mBrightness) + " set brightness values: "
	+ toStringLabel(mUpdatedTypes & TYPE_FLOAT, brightnessFloat) + " "
	+ toStringLabel(mUpdatedTypes & TYPE_INT, brightnessInt));

	mHandler.sendEmptyMessageAtTime(MSG_RUN_UPDATE,
	mClock.uptimeMillis() + WAIT_FOR_RESPONSE_MILLIS);
	}
	mTimeUpdated = mClock.uptimeMillis();
	}

	if (mState == STATE_RUNNING) {
	// If we're not waiting on any more confirmations or the time has expired, move to
	// completed state.
	if (mConfirmedTypes == mUpdatedTypes
	\|\| (mTimeUpdated + WAIT_FOR_RESPONSE_MILLIS) < mClock.uptimeMillis()) {
	mState = STATE_COMPLETED;
	}
	}
	}

	/**
	* Attempts to consume the specified brightness change if it is determined that the change
	* is a notification of a change previously made by this class.
	*
	* @param type The type of change (int\|float)
	* @param brightness The brightness value.
	* @return True if the change was caused by this class, thus swallowed.
	*/
	boolean swallowUpdate(int type, float brightness) {
	if ((mUpdatedTypes & type) != type \|\| (mConfirmedTypes & type) != 0x0) {
	// It's either a type we didn't update, or one we've already confirmed.
	return false;
	}

	final boolean floatUpdateConfirmed =
	type == TYPE_FLOAT && floatEquals(getBrightnessAsFloat(), brightness);
	final boolean intUpdateConfirmed =
	type == TYPE_INT && getBrightnessAsInt() == (int) brightness;

	if (floatUpdateConfirmed \|\| intUpdateConfirmed) {
	mConfirmedTypes \|= type;
	Slog.i(TAG, "Swallowing update of " + toStringLabel(type, brightness)
	+ " by update: " + this);
	return true;
	}
	return false;
	}

	boolean isRunning() {
	return mState == STATE_RUNNING;
	}

	boolean isCompleted() {
	return mState == STATE_COMPLETED;
	}

	boolean madeUpdates() {
	return mUpdatedTypes != 0x0;
	}

	private int getBrightnessAsInt() {
	if (mSourceType == TYPE_INT) {
	return (int) mBrightness;
	}
	return brightnessFloatToInt(mBrightness);
	}

	private float getBrightnessAsFloat() {
	if (mSourceType == TYPE_FLOAT) {
	return mBrightness;
	}
	return brightnessIntToFloat((int) mBrightness);
	}

	private String toStringLabel(int type, float brightness) {
	return (type == TYPE_INT) ? ((int) brightness) + "(i)"
	: ((type == TYPE_FLOAT) ? brightness + "(f)"
	: "");
	}
	}

	/** Functional interface for providing time. */
	@VisibleForTesting
	public interface Clock {
	/** @return system uptime in milliseconds. */
	long uptimeMillis();
	}

	class BrightnessSynchronizerHandler extends Handler {
	BrightnessSynchronizerHandler(Looper looper) {
	super(looper);
	}

	@Override
	public void handleMessage(Message msg) {
	switch (msg.what) {
	case MSG_RUN_UPDATE:
	if (DEBUG) {
	Slog.d(TAG, "MSG_RUN_UPDATE");
	}
	runUpdate();
	break;
	default:
	super.handleMessage(msg);
	}

	}
	};

	private class BrightnessSyncObserver {
	private boolean mIsObserving;

	private final DisplayListener mListener = new DisplayListener() {
	@Override
	public void onDisplayAdded(int displayId) {}

	@Override
	public void onDisplayRemoved(int displayId) {}

	@Override
	public void onDisplayChanged(int displayId) {
	handleBrightnessChangeFloat(getScreenBrightnessFloat());
	}
	};

	private ContentObserver createBrightnessContentObserver(Handler handler) {
	return new ContentObserver(handler) {
	@Override
	public void onChange(boolean selfChange, Uri uri) {
	if (selfChange) {
	return;
	}
	if (BRIGHTNESS_URI.equals(uri)) {
	handleBrightnessChangeInt(getScreenBrightnessInt());
	}
	}
	};
	}

	boolean isObserving() {
	return mIsObserving;
	}

	void startObserving(Handler handler) {
	final ContentResolver cr = mContext.getContentResolver();
	cr.registerContentObserver(BRIGHTNESS_URI, false,
	createBrightnessContentObserver(handler), UserHandle.USER_ALL);
	mDisplayManager.registerDisplayListener(mListener, handler,
	DisplayManager.EVENT_FLAG_DISPLAY_BRIGHTNESS);
	mIsObserving = true;
	}
	}
	}