com/android/systemui/settings/brightness/BrightnessController.java - platform/prebuilts/fullsdk/sources/android-31 - Git at Google

 /*
  * Copyright (C) 2020 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.systemui.settings.brightness;

 import static com.android.settingslib.display.BrightnessUtils.GAMMA_SPACE_MAX;
 import static com.android.settingslib.display.BrightnessUtils.convertGammaToLinearFloat;
 import static com.android.settingslib.display.BrightnessUtils.convertLinearToGammaFloat;

 import android.animation.ValueAnimator;
 import android.content.ContentResolver;
 import android.content.Context;
 import android.database.ContentObserver;
 import android.hardware.display.BrightnessInfo;
 import android.hardware.display.DisplayManager;
 import android.hardware.display.DisplayManager.DisplayListener;
 import android.net.Uri;
 import android.os.AsyncTask;
 import android.os.Handler;
 import android.os.Looper;
 import android.os.Message;
 import android.os.PowerManager;
 import android.os.RemoteException;
 import android.os.ServiceManager;
 import android.os.UserHandle;
 import android.os.UserManager;
 import android.provider.Settings;
 import android.service.vr.IVrManager;
 import android.service.vr.IVrStateCallbacks;
 import android.util.Log;
 import android.util.MathUtils;

 import com.android.internal.display.BrightnessSynchronizer;
 import com.android.internal.logging.MetricsLogger;
 import com.android.internal.logging.nano.MetricsProto.MetricsEvent;
 import com.android.settingslib.RestrictedLockUtilsInternal;
 import com.android.systemui.Dependency;
 import com.android.systemui.broadcast.BroadcastDispatcher;
 import com.android.systemui.settings.CurrentUserTracker;

 import java.util.ArrayList;

 import javax.inject.Inject;

 public class BrightnessController implements ToggleSlider.Listener {
     private static final String TAG = "StatusBar.BrightnessController";
     private static final int SLIDER_ANIMATION_DURATION = 3000;

     private static final int MSG_UPDATE_SLIDER = 1;
     private static final int MSG_ATTACH_LISTENER = 2;
     private static final int MSG_DETACH_LISTENER = 3;
     private static final int MSG_VR_MODE_CHANGED = 4;

     private static final Uri BRIGHTNESS_MODE_URI =
             Settings.System.getUriFor(Settings.System.SCREEN_BRIGHTNESS_MODE);
     private static final Uri BRIGHTNESS_FOR_VR_FLOAT_URI =
             Settings.System.getUriFor(Settings.System.SCREEN_BRIGHTNESS_FOR_VR_FLOAT);

     private final float mMinimumBacklightForVr;
     private final float mMaximumBacklightForVr;

     private final int mDisplayId;
     private final Context mContext;
     private final ToggleSlider mControl;
     private final DisplayManager mDisplayManager;
     private final CurrentUserTracker mUserTracker;
     private final IVrManager mVrManager;

     private final Handler mBackgroundHandler;
     private final BrightnessObserver mBrightnessObserver;

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

         @Override
         public void onDisplayRemoved(int displayId) {}

         @Override
         public void onDisplayChanged(int displayId) {
             mBackgroundHandler.post(mUpdateSliderRunnable);
             notifyCallbacks();
         }
     };

     private ArrayList<BrightnessStateChangeCallback> mChangeCallbacks =
             new ArrayList<BrightnessStateChangeCallback>();

     private volatile boolean mAutomatic;  // Brightness adjusted automatically using ambient light.
     private volatile boolean mIsVrModeEnabled;
     private boolean mListening;
     private boolean mExternalChange;
     private boolean mControlValueInitialized;
     private float mBrightnessMin = PowerManager.BRIGHTNESS_MIN;
     private float mBrightnessMax = PowerManager.BRIGHTNESS_MAX;

     private ValueAnimator mSliderAnimator;

     public interface BrightnessStateChangeCallback {
         /** Indicates that some of the brightness settings have changed */
         void onBrightnessLevelChanged();
     }

     /** ContentObserver to watch brightness */
     private class BrightnessObserver extends ContentObserver {

         BrightnessObserver(Handler handler) {
             super(handler);
         }

         @Override
         public void onChange(boolean selfChange, Uri uri) {
             if (selfChange) return;

             if (BRIGHTNESS_MODE_URI.equals(uri)) {
                 mBackgroundHandler.post(mUpdateModeRunnable);
                 mBackgroundHandler.post(mUpdateSliderRunnable);
             } else if (BRIGHTNESS_FOR_VR_FLOAT_URI.equals(uri)) {
                 mBackgroundHandler.post(mUpdateSliderRunnable);
             } else {
                 mBackgroundHandler.post(mUpdateModeRunnable);
                 mBackgroundHandler.post(mUpdateSliderRunnable);
             }
             notifyCallbacks();
         }

         public void startObserving() {
             final ContentResolver cr = mContext.getContentResolver();
             cr.unregisterContentObserver(this);
             cr.registerContentObserver(
                     BRIGHTNESS_MODE_URI,
                     false, this, UserHandle.USER_ALL);
             cr.registerContentObserver(
                     BRIGHTNESS_FOR_VR_FLOAT_URI,
                     false, this, UserHandle.USER_ALL);
             mDisplayManager.registerDisplayListener(mDisplayListener, mHandler,
                     DisplayManager.EVENT_FLAG_DISPLAY_BRIGHTNESS);
         }

         public void stopObserving() {
             final ContentResolver cr = mContext.getContentResolver();
             cr.unregisterContentObserver(this);
             mDisplayManager.unregisterDisplayListener(mDisplayListener);
         }

     }

     private final Runnable mStartListeningRunnable = new Runnable() {
         @Override
         public void run() {
             if (mListening) {
                 return;
             }
             mListening = true;

             if (mVrManager != null) {
                 try {
                     mVrManager.registerListener(mVrStateCallbacks);
                     mIsVrModeEnabled = mVrManager.getVrModeState();
                 } catch (RemoteException e) {
                     Log.e(TAG, "Failed to register VR mode state listener: ", e);
                 }
             }

             mBrightnessObserver.startObserving();
             mUserTracker.startTracking();

             // Update the slider and mode before attaching the listener so we don't
             // receive the onChanged notifications for the initial values.
             mUpdateModeRunnable.run();
             mUpdateSliderRunnable.run();

             mHandler.sendEmptyMessage(MSG_ATTACH_LISTENER);
         }
     };

     private final Runnable mStopListeningRunnable = new Runnable() {
         @Override
         public void run() {
             if (!mListening) {
                 return;
             }
             mListening = false;

             if (mVrManager != null) {
                 try {
                     mVrManager.unregisterListener(mVrStateCallbacks);
                 } catch (RemoteException e) {
                     Log.e(TAG, "Failed to unregister VR mode state listener: ", e);
                 }
             }

             mBrightnessObserver.stopObserving();
             mUserTracker.stopTracking();

             mHandler.sendEmptyMessage(MSG_DETACH_LISTENER);
         }
     };

     /**
      * Fetch the brightness mode from the system settings and update the icon. Should be called from
      * background thread.
      */
     private final Runnable mUpdateModeRunnable = new Runnable() {
         @Override
         public void run() {
             int automatic;
             automatic = Settings.System.getIntForUser(mContext.getContentResolver(),
                     Settings.System.SCREEN_BRIGHTNESS_MODE,
                     Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL,
                     UserHandle.USER_CURRENT);
             mAutomatic = automatic != Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL;
         }
     };

     /**
      * Fetch the brightness from the system settings and update the slider. Should be called from
      * background thread.
      */
     private final Runnable mUpdateSliderRunnable = new Runnable() {
         @Override
         public void run() {
             final boolean inVrMode = mIsVrModeEnabled;
             final BrightnessInfo info = mContext.getDisplay().getBrightnessInfo();
             if (info == null) {
                 return;
             }
             mBrightnessMax = info.brightnessMaximum;
             mBrightnessMin = info.brightnessMinimum;
             // Value is passed as intbits, since this is what the message takes.
             final int valueAsIntBits = Float.floatToIntBits(info.brightness);
             mHandler.obtainMessage(MSG_UPDATE_SLIDER, valueAsIntBits,
                     inVrMode ? 1 : 0).sendToTarget();
         }
     };

     private final IVrStateCallbacks mVrStateCallbacks = new IVrStateCallbacks.Stub() {
         @Override
         public void onVrStateChanged(boolean enabled) {
             mHandler.obtainMessage(MSG_VR_MODE_CHANGED, enabled ? 1 : 0, 0)
                     .sendToTarget();
         }
     };

     private final Handler mHandler = new Handler() {
         @Override
         public void handleMessage(Message msg) {
             mExternalChange = true;
             try {
                 switch (msg.what) {
                     case MSG_UPDATE_SLIDER:
                         updateSlider(Float.intBitsToFloat(msg.arg1), msg.arg2 != 0);
                         break;
                     case MSG_ATTACH_LISTENER:
                         mControl.setOnChangedListener(BrightnessController.this);
                         break;
                     case MSG_DETACH_LISTENER:
                         mControl.setOnChangedListener(null);
                         break;
                     case MSG_VR_MODE_CHANGED:
                         updateVrMode(msg.arg1 != 0);
                         break;
                     default:
                         super.handleMessage(msg);
                 }
             } finally {
                 mExternalChange = false;
             }
         }
     };

     public BrightnessController(Context context, ToggleSlider control,
             BroadcastDispatcher broadcastDispatcher) {
         mContext = context;
         mControl = control;
         mControl.setMax(GAMMA_SPACE_MAX);
         mBackgroundHandler = new Handler((Looper) Dependency.get(Dependency.BG_LOOPER));
         mUserTracker = new CurrentUserTracker(broadcastDispatcher) {
             @Override
             public void onUserSwitched(int newUserId) {
                 mBackgroundHandler.post(mUpdateModeRunnable);
                 mBackgroundHandler.post(mUpdateSliderRunnable);
             }
         };
         mBrightnessObserver = new BrightnessObserver(mHandler);

         mDisplayId = mContext.getDisplayId();
         PowerManager pm = context.getSystemService(PowerManager.class);
         mMinimumBacklightForVr = pm.getBrightnessConstraint(
                 PowerManager.BRIGHTNESS_CONSTRAINT_TYPE_MINIMUM_VR);
         mMaximumBacklightForVr = pm.getBrightnessConstraint(
                 PowerManager.BRIGHTNESS_CONSTRAINT_TYPE_MAXIMUM_VR);

         mDisplayManager = context.getSystemService(DisplayManager.class);
         mVrManager = IVrManager.Stub.asInterface(ServiceManager.getService(
                 Context.VR_SERVICE));
     }

     public void addStateChangedCallback(BrightnessStateChangeCallback cb) {
         mChangeCallbacks.add(cb);
     }

     public boolean removeStateChangedCallback(BrightnessStateChangeCallback cb) {
         return mChangeCallbacks.remove(cb);
     }

     public void registerCallbacks() {
         mBackgroundHandler.post(mStartListeningRunnable);
     }

     /** Unregister all call backs, both to and from the controller */
     public void unregisterCallbacks() {
         mBackgroundHandler.post(mStopListeningRunnable);
         mControlValueInitialized = false;
     }

     @Override
     public void onChanged(boolean tracking, int value, boolean stopTracking) {
         if (mExternalChange) return;

         if (mSliderAnimator != null) {
             mSliderAnimator.cancel();
         }

         final float minBacklight;
         final float maxBacklight;
         final int metric;

         if (mIsVrModeEnabled) {
             metric = MetricsEvent.ACTION_BRIGHTNESS_FOR_VR;
             minBacklight = mMinimumBacklightForVr;
             maxBacklight = mMaximumBacklightForVr;
         } else {
             metric = mAutomatic
                     ? MetricsEvent.ACTION_BRIGHTNESS_AUTO
                     : MetricsEvent.ACTION_BRIGHTNESS;
             minBacklight = mBrightnessMin;
             maxBacklight = mBrightnessMax;
         }
         final float valFloat = MathUtils.min(
                 convertGammaToLinearFloat(value, minBacklight, maxBacklight),
                 maxBacklight);
         if (stopTracking) {
             // TODO(brightnessfloat): change to use float value instead.
             MetricsLogger.action(mContext, metric,
                     BrightnessSynchronizer.brightnessFloatToInt(valFloat));

         }
         setBrightness(valFloat);
         if (!tracking) {
             AsyncTask.execute(new Runnable() {
                     public void run() {
                         mDisplayManager.setBrightness(mDisplayId, valFloat);
                     }
                 });
         }

         for (BrightnessStateChangeCallback cb : mChangeCallbacks) {
             cb.onBrightnessLevelChanged();
         }
     }

     public void checkRestrictionAndSetEnabled() {
         mBackgroundHandler.post(new Runnable() {
             @Override
             public void run() {
                 mControl.setEnforcedAdmin(
                         RestrictedLockUtilsInternal.checkIfRestrictionEnforced(mContext,
                                 UserManager.DISALLOW_CONFIG_BRIGHTNESS,
                                 mUserTracker.getCurrentUserId()));
             }
         });
     }

     private void setBrightness(float brightness) {
         mDisplayManager.setTemporaryBrightness(mDisplayId, brightness);
     }

     private void updateVrMode(boolean isEnabled) {
         if (mIsVrModeEnabled != isEnabled) {
             mIsVrModeEnabled = isEnabled;
             mBackgroundHandler.post(mUpdateSliderRunnable);
         }
     }

     private void updateSlider(float brightnessValue, boolean inVrMode) {
         final float min;
         final float max;
         if (inVrMode) {
             min = mMinimumBacklightForVr;
             max = mMaximumBacklightForVr;
         } else {
             min = mBrightnessMin;
             max = mBrightnessMax;
         }
         // convertGammaToLinearFloat returns 0-1
         if (BrightnessSynchronizer.floatEquals(brightnessValue,
                 convertGammaToLinearFloat(mControl.getValue(), min, max))) {
             // If the value in the slider is equal to the value on the current brightness
             // then the slider does not need to animate, since the brightness will not change.
             return;
         }
         // Returns GAMMA_SPACE_MIN - GAMMA_SPACE_MAX
         final int sliderVal = convertLinearToGammaFloat(brightnessValue, min, max);
         animateSliderTo(sliderVal);
     }

     private void animateSliderTo(int target) {
         if (!mControlValueInitialized) {
             // Don't animate the first value since its default state isn't meaningful to users.
             mControl.setValue(target);
             mControlValueInitialized = true;
         }
         if (mSliderAnimator != null && mSliderAnimator.isStarted()) {
             mSliderAnimator.cancel();
         }
         mSliderAnimator = ValueAnimator.ofInt(mControl.getValue(), target);
         mSliderAnimator.addUpdateListener((ValueAnimator animation) -> {
             mExternalChange = true;
             mControl.setValue((int) animation.getAnimatedValue());
             mExternalChange = false;
         });
         final long animationDuration = SLIDER_ANIMATION_DURATION * Math.abs(
                 mControl.getValue() - target) / GAMMA_SPACE_MAX;
         mSliderAnimator.setDuration(animationDuration);
         mSliderAnimator.start();
     }

     private void notifyCallbacks() {
         final int size = mChangeCallbacks.size();
         for (int i = 0; i < size; i++) {
             mChangeCallbacks.get(i).onBrightnessLevelChanged();
         }
     }

     /** Factory for creating a {@link BrightnessController}. */
     public static class Factory {
         private final Context mContext;
         private final BroadcastDispatcher mBroadcastDispatcher;

         @Inject
         public Factory(Context context, BroadcastDispatcher broadcastDispatcher) {
             mContext = context;
             mBroadcastDispatcher = broadcastDispatcher;
         }

         /** Create a {@link BrightnessController} */
         public BrightnessController create(ToggleSlider toggleSlider) {
             return new BrightnessController(mContext, toggleSlider, mBroadcastDispatcher);
         }
     }

 }
	/*
	* Copyright (C) 2020 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.systemui.settings.brightness;

	import static com.android.settingslib.display.BrightnessUtils.GAMMA_SPACE_MAX;
	import static com.android.settingslib.display.BrightnessUtils.convertGammaToLinearFloat;
	import static com.android.settingslib.display.BrightnessUtils.convertLinearToGammaFloat;

	import android.animation.ValueAnimator;
	import android.content.ContentResolver;
	import android.content.Context;
	import android.database.ContentObserver;
	import android.hardware.display.BrightnessInfo;
	import android.hardware.display.DisplayManager;
	import android.hardware.display.DisplayManager.DisplayListener;
	import android.net.Uri;
	import android.os.AsyncTask;
	import android.os.Handler;
	import android.os.Looper;
	import android.os.Message;
	import android.os.PowerManager;
	import android.os.RemoteException;
	import android.os.ServiceManager;
	import android.os.UserHandle;
	import android.os.UserManager;
	import android.provider.Settings;
	import android.service.vr.IVrManager;
	import android.service.vr.IVrStateCallbacks;
	import android.util.Log;
	import android.util.MathUtils;

	import com.android.internal.display.BrightnessSynchronizer;
	import com.android.internal.logging.MetricsLogger;
	import com.android.internal.logging.nano.MetricsProto.MetricsEvent;
	import com.android.settingslib.RestrictedLockUtilsInternal;
	import com.android.systemui.Dependency;
	import com.android.systemui.broadcast.BroadcastDispatcher;
	import com.android.systemui.settings.CurrentUserTracker;

	import java.util.ArrayList;

	import javax.inject.Inject;

	public class BrightnessController implements ToggleSlider.Listener {
	private static final String TAG = "StatusBar.BrightnessController";
	private static final int SLIDER_ANIMATION_DURATION = 3000;

	private static final int MSG_UPDATE_SLIDER = 1;
	private static final int MSG_ATTACH_LISTENER = 2;
	private static final int MSG_DETACH_LISTENER = 3;
	private static final int MSG_VR_MODE_CHANGED = 4;

	private static final Uri BRIGHTNESS_MODE_URI =
	Settings.System.getUriFor(Settings.System.SCREEN_BRIGHTNESS_MODE);
	private static final Uri BRIGHTNESS_FOR_VR_FLOAT_URI =
	Settings.System.getUriFor(Settings.System.SCREEN_BRIGHTNESS_FOR_VR_FLOAT);

	private final float mMinimumBacklightForVr;
	private final float mMaximumBacklightForVr;

	private final int mDisplayId;
	private final Context mContext;
	private final ToggleSlider mControl;
	private final DisplayManager mDisplayManager;
	private final CurrentUserTracker mUserTracker;
	private final IVrManager mVrManager;

	private final Handler mBackgroundHandler;
	private final BrightnessObserver mBrightnessObserver;

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

	@Override
	public void onDisplayRemoved(int displayId) {}

	@Override
	public void onDisplayChanged(int displayId) {
	mBackgroundHandler.post(mUpdateSliderRunnable);
	notifyCallbacks();
	}
	};

	private ArrayList<BrightnessStateChangeCallback> mChangeCallbacks =
	new ArrayList<BrightnessStateChangeCallback>();

	private volatile boolean mAutomatic; // Brightness adjusted automatically using ambient light.
	private volatile boolean mIsVrModeEnabled;
	private boolean mListening;
	private boolean mExternalChange;
	private boolean mControlValueInitialized;
	private float mBrightnessMin = PowerManager.BRIGHTNESS_MIN;
	private float mBrightnessMax = PowerManager.BRIGHTNESS_MAX;

	private ValueAnimator mSliderAnimator;

	public interface BrightnessStateChangeCallback {
	/** Indicates that some of the brightness settings have changed */
	void onBrightnessLevelChanged();
	}

	/** ContentObserver to watch brightness */
	private class BrightnessObserver extends ContentObserver {

	BrightnessObserver(Handler handler) {
	super(handler);
	}

	@Override
	public void onChange(boolean selfChange, Uri uri) {
	if (selfChange) return;

	if (BRIGHTNESS_MODE_URI.equals(uri)) {
	mBackgroundHandler.post(mUpdateModeRunnable);
	mBackgroundHandler.post(mUpdateSliderRunnable);
	} else if (BRIGHTNESS_FOR_VR_FLOAT_URI.equals(uri)) {
	mBackgroundHandler.post(mUpdateSliderRunnable);
	} else {
	mBackgroundHandler.post(mUpdateModeRunnable);
	mBackgroundHandler.post(mUpdateSliderRunnable);
	}
	notifyCallbacks();
	}

	public void startObserving() {
	final ContentResolver cr = mContext.getContentResolver();
	cr.unregisterContentObserver(this);
	cr.registerContentObserver(
	BRIGHTNESS_MODE_URI,
	false, this, UserHandle.USER_ALL);
	cr.registerContentObserver(
	BRIGHTNESS_FOR_VR_FLOAT_URI,
	false, this, UserHandle.USER_ALL);
	mDisplayManager.registerDisplayListener(mDisplayListener, mHandler,
	DisplayManager.EVENT_FLAG_DISPLAY_BRIGHTNESS);
	}

	public void stopObserving() {
	final ContentResolver cr = mContext.getContentResolver();
	cr.unregisterContentObserver(this);
	mDisplayManager.unregisterDisplayListener(mDisplayListener);
	}

	}

	private final Runnable mStartListeningRunnable = new Runnable() {
	@Override
	public void run() {
	if (mListening) {
	return;
	}
	mListening = true;

	if (mVrManager != null) {
	try {
	mVrManager.registerListener(mVrStateCallbacks);
	mIsVrModeEnabled = mVrManager.getVrModeState();
	} catch (RemoteException e) {
	Log.e(TAG, "Failed to register VR mode state listener: ", e);
	}
	}

	mBrightnessObserver.startObserving();
	mUserTracker.startTracking();

	// Update the slider and mode before attaching the listener so we don't
	// receive the onChanged notifications for the initial values.
	mUpdateModeRunnable.run();
	mUpdateSliderRunnable.run();

	mHandler.sendEmptyMessage(MSG_ATTACH_LISTENER);
	}
	};

	private final Runnable mStopListeningRunnable = new Runnable() {
	@Override
	public void run() {
	if (!mListening) {
	return;
	}
	mListening = false;

	if (mVrManager != null) {
	try {
	mVrManager.unregisterListener(mVrStateCallbacks);
	} catch (RemoteException e) {
	Log.e(TAG, "Failed to unregister VR mode state listener: ", e);
	}
	}

	mBrightnessObserver.stopObserving();
	mUserTracker.stopTracking();

	mHandler.sendEmptyMessage(MSG_DETACH_LISTENER);
	}
	};

	/**
	* Fetch the brightness mode from the system settings and update the icon. Should be called from
	* background thread.
	*/
	private final Runnable mUpdateModeRunnable = new Runnable() {
	@Override
	public void run() {
	int automatic;
	automatic = Settings.System.getIntForUser(mContext.getContentResolver(),
	Settings.System.SCREEN_BRIGHTNESS_MODE,
	Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL,
	UserHandle.USER_CURRENT);
	mAutomatic = automatic != Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL;
	}
	};

	/**
	* Fetch the brightness from the system settings and update the slider. Should be called from
	* background thread.
	*/
	private final Runnable mUpdateSliderRunnable = new Runnable() {
	@Override
	public void run() {
	final boolean inVrMode = mIsVrModeEnabled;
	final BrightnessInfo info = mContext.getDisplay().getBrightnessInfo();
	if (info == null) {
	return;
	}
	mBrightnessMax = info.brightnessMaximum;
	mBrightnessMin = info.brightnessMinimum;
	// Value is passed as intbits, since this is what the message takes.
	final int valueAsIntBits = Float.floatToIntBits(info.brightness);
	mHandler.obtainMessage(MSG_UPDATE_SLIDER, valueAsIntBits,
	inVrMode ? 1 : 0).sendToTarget();
	}
	};

	private final IVrStateCallbacks mVrStateCallbacks = new IVrStateCallbacks.Stub() {
	@Override
	public void onVrStateChanged(boolean enabled) {
	mHandler.obtainMessage(MSG_VR_MODE_CHANGED, enabled ? 1 : 0, 0)
	.sendToTarget();
	}
	};

	private final Handler mHandler = new Handler() {
	@Override
	public void handleMessage(Message msg) {
	mExternalChange = true;
	try {
	switch (msg.what) {
	case MSG_UPDATE_SLIDER:
	updateSlider(Float.intBitsToFloat(msg.arg1), msg.arg2 != 0);
	break;
	case MSG_ATTACH_LISTENER:
	mControl.setOnChangedListener(BrightnessController.this);
	break;
	case MSG_DETACH_LISTENER:
	mControl.setOnChangedListener(null);
	break;
	case MSG_VR_MODE_CHANGED:
	updateVrMode(msg.arg1 != 0);
	break;
	default:
	super.handleMessage(msg);
	}
	} finally {
	mExternalChange = false;
	}
	}
	};

	public BrightnessController(Context context, ToggleSlider control,
	BroadcastDispatcher broadcastDispatcher) {
	mContext = context;
	mControl = control;
	mControl.setMax(GAMMA_SPACE_MAX);
	mBackgroundHandler = new Handler((Looper) Dependency.get(Dependency.BG_LOOPER));
	mUserTracker = new CurrentUserTracker(broadcastDispatcher) {
	@Override
	public void onUserSwitched(int newUserId) {
	mBackgroundHandler.post(mUpdateModeRunnable);
	mBackgroundHandler.post(mUpdateSliderRunnable);
	}
	};
	mBrightnessObserver = new BrightnessObserver(mHandler);

	mDisplayId = mContext.getDisplayId();
	PowerManager pm = context.getSystemService(PowerManager.class);
	mMinimumBacklightForVr = pm.getBrightnessConstraint(
	PowerManager.BRIGHTNESS_CONSTRAINT_TYPE_MINIMUM_VR);
	mMaximumBacklightForVr = pm.getBrightnessConstraint(
	PowerManager.BRIGHTNESS_CONSTRAINT_TYPE_MAXIMUM_VR);

	mDisplayManager = context.getSystemService(DisplayManager.class);
	mVrManager = IVrManager.Stub.asInterface(ServiceManager.getService(
	Context.VR_SERVICE));
	}

	public void addStateChangedCallback(BrightnessStateChangeCallback cb) {
	mChangeCallbacks.add(cb);
	}

	public boolean removeStateChangedCallback(BrightnessStateChangeCallback cb) {
	return mChangeCallbacks.remove(cb);
	}

	public void registerCallbacks() {
	mBackgroundHandler.post(mStartListeningRunnable);
	}

	/** Unregister all call backs, both to and from the controller */
	public void unregisterCallbacks() {
	mBackgroundHandler.post(mStopListeningRunnable);
	mControlValueInitialized = false;
	}

	@Override
	public void onChanged(boolean tracking, int value, boolean stopTracking) {
	if (mExternalChange) return;

	if (mSliderAnimator != null) {
	mSliderAnimator.cancel();
	}

	final float minBacklight;
	final float maxBacklight;
	final int metric;

	if (mIsVrModeEnabled) {
	metric = MetricsEvent.ACTION_BRIGHTNESS_FOR_VR;
	minBacklight = mMinimumBacklightForVr;
	maxBacklight = mMaximumBacklightForVr;
	} else {
	metric = mAutomatic
	? MetricsEvent.ACTION_BRIGHTNESS_AUTO
	: MetricsEvent.ACTION_BRIGHTNESS;
	minBacklight = mBrightnessMin;
	maxBacklight = mBrightnessMax;
	}
	final float valFloat = MathUtils.min(
	convertGammaToLinearFloat(value, minBacklight, maxBacklight),
	maxBacklight);
	if (stopTracking) {
	// TODO(brightnessfloat): change to use float value instead.
	MetricsLogger.action(mContext, metric,
	BrightnessSynchronizer.brightnessFloatToInt(valFloat));

	}
	setBrightness(valFloat);
	if (!tracking) {
	AsyncTask.execute(new Runnable() {
	public void run() {
	mDisplayManager.setBrightness(mDisplayId, valFloat);
	}
	});
	}

	for (BrightnessStateChangeCallback cb : mChangeCallbacks) {
	cb.onBrightnessLevelChanged();
	}
	}

	public void checkRestrictionAndSetEnabled() {
	mBackgroundHandler.post(new Runnable() {
	@Override
	public void run() {
	mControl.setEnforcedAdmin(
	RestrictedLockUtilsInternal.checkIfRestrictionEnforced(mContext,
	UserManager.DISALLOW_CONFIG_BRIGHTNESS,
	mUserTracker.getCurrentUserId()));
	}
	});
	}

	private void setBrightness(float brightness) {
	mDisplayManager.setTemporaryBrightness(mDisplayId, brightness);
	}

	private void updateVrMode(boolean isEnabled) {
	if (mIsVrModeEnabled != isEnabled) {
	mIsVrModeEnabled = isEnabled;
	mBackgroundHandler.post(mUpdateSliderRunnable);
	}
	}

	private void updateSlider(float brightnessValue, boolean inVrMode) {
	final float min;
	final float max;
	if (inVrMode) {
	min = mMinimumBacklightForVr;
	max = mMaximumBacklightForVr;
	} else {
	min = mBrightnessMin;
	max = mBrightnessMax;
	}
	// convertGammaToLinearFloat returns 0-1
	if (BrightnessSynchronizer.floatEquals(brightnessValue,
	convertGammaToLinearFloat(mControl.getValue(), min, max))) {
	// If the value in the slider is equal to the value on the current brightness
	// then the slider does not need to animate, since the brightness will not change.
	return;
	}
	// Returns GAMMA_SPACE_MIN - GAMMA_SPACE_MAX
	final int sliderVal = convertLinearToGammaFloat(brightnessValue, min, max);
	animateSliderTo(sliderVal);
	}

	private void animateSliderTo(int target) {
	if (!mControlValueInitialized) {
	// Don't animate the first value since its default state isn't meaningful to users.
	mControl.setValue(target);
	mControlValueInitialized = true;
	}
	if (mSliderAnimator != null && mSliderAnimator.isStarted()) {
	mSliderAnimator.cancel();
	}
	mSliderAnimator = ValueAnimator.ofInt(mControl.getValue(), target);
	mSliderAnimator.addUpdateListener((ValueAnimator animation) -> {
	mExternalChange = true;
	mControl.setValue((int) animation.getAnimatedValue());
	mExternalChange = false;
	});
	final long animationDuration = SLIDER_ANIMATION_DURATION * Math.abs(
	mControl.getValue() - target) / GAMMA_SPACE_MAX;
	mSliderAnimator.setDuration(animationDuration);
	mSliderAnimator.start();
	}

	private void notifyCallbacks() {
	final int size = mChangeCallbacks.size();
	for (int i = 0; i < size; i++) {
	mChangeCallbacks.get(i).onBrightnessLevelChanged();
	}
	}

	/** Factory for creating a {@link BrightnessController}. */
	public static class Factory {
	private final Context mContext;
	private final BroadcastDispatcher mBroadcastDispatcher;

	@Inject
	public Factory(Context context, BroadcastDispatcher broadcastDispatcher) {
	mContext = context;
	mBroadcastDispatcher = broadcastDispatcher;
	}

	/** Create a {@link BrightnessController} */
	public BrightnessController create(ToggleSlider toggleSlider) {
	return new BrightnessController(mContext, toggleSlider, mBroadcastDispatcher);
	}
	}

	}