The Tor Browser / file revision

 /* -*- Mode: Java; c-basic-offset: 4; tab-width: 4; indent-tabs-mode: nil; -*-

  * This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this

  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

 package org.mozilla.gecko;

 import android.content.BroadcastReceiver;

 import android.content.Context;

 import android.content.Intent;

 import android.content.IntentFilter;

 import android.os.BatteryManager;

 import android.os.Build;

 import android.os.SystemClock;

 import android.util.Log;

 public class GeckoBatteryManager extends BroadcastReceiver {

     private static final String LOGTAG = "GeckoBatteryManager";

     // Those constants should be keep in sync with the ones in:

     // dom/battery/Constants.h

     private final static double  kDefaultLevel         = 1.0;

     private final static boolean kDefaultCharging      = true;

     private final static double  kDefaultRemainingTime = 0.0;

     private final static double  kUnknownRemainingTime = -1.0;

     private static long    sLastLevelChange            = 0;

     private static boolean sNotificationsEnabled       = false;

     private static double  sLevel                      = kDefaultLevel;

     private static boolean sCharging                   = kDefaultCharging;

     private static double  sRemainingTime              = kDefaultRemainingTime;

     private static GeckoBatteryManager sInstance = new GeckoBatteryManager();

     private final IntentFilter mFilter;

     private Context mApplicationContext;

     private boolean mIsEnabled;

     public static GeckoBatteryManager getInstance() {

         return sInstance;

     }

     private GeckoBatteryManager() {

         mFilter = new IntentFilter();

         mFilter.addAction(Intent.ACTION_BATTERY_CHANGED);

     }

     public synchronized void start(final Context context) {

         if (mIsEnabled) {

             Log.w(LOGTAG, "Already started!");

             return;

         }

         mApplicationContext = context.getApplicationContext();

         // registerReceiver will return null if registering fails.

         if (mApplicationContext.registerReceiver(this, mFilter) == null) {

             Log.e(LOGTAG, "Registering receiver failed");

         } else {

             mIsEnabled = true;

         }

     }

     public synchronized void stop() {

         if (!mIsEnabled) {

             Log.w(LOGTAG, "Already stopped!");

             return;

         }

         mApplicationContext.unregisterReceiver(this);

         mApplicationContext = null;

         mIsEnabled = false;

     }

     @Override

     public void onReceive(Context context, Intent intent) {

         if (!intent.getAction().equals(Intent.ACTION_BATTERY_CHANGED)) {

             Log.e(LOGTAG, "Got an unexpected intent!");

             return;

         }

         boolean previousCharging = isCharging();

         double previousLevel = getLevel();

         // NOTE: it might not be common (in 2012) but technically, Android can run

         // on a device that has no battery so we want to make sure it's not the case

         // before bothering checking for battery state.

         // However, the Galaxy Nexus phone advertizes itself as battery-less which

         // force us to special-case the logic.

         // See the Google bug: https://code.google.com/p/android/issues/detail?id=22035

         if (intent.getBooleanExtra(BatteryManager.EXTRA_PRESENT, false) ||

                 Build.MODEL.equals("Galaxy Nexus")) {

             int plugged = intent.getIntExtra(BatteryManager.EXTRA_PLUGGED, -1);

             if (plugged == -1) {

                 sCharging = kDefaultCharging;

                 Log.e(LOGTAG, "Failed to get the plugged status!");

             } else {

                 // Likely, if plugged > 0, it's likely plugged and charging but the doc

                 // isn't clear about that.

                 sCharging = plugged != 0;

             }

             if (sCharging != previousCharging) {

                 sRemainingTime = kUnknownRemainingTime;

                 // The new remaining time is going to take some time to show up but

                 // it's the best way to show a not too wrong value.

                 sLastLevelChange = 0;

             }

             // We need two doubles because sLevel is a double.

             double current =  (double)intent.getIntExtra(BatteryManager.EXTRA_LEVEL, -1);

             double max = (double)intent.getIntExtra(BatteryManager.EXTRA_SCALE, -1);

             if (current == -1 || max == -1) {

                 Log.e(LOGTAG, "Failed to get battery level!");

                 sLevel = kDefaultLevel;

             } else {

                 sLevel = current / max;

             }

             if (sLevel == 1.0 && sCharging) {

                 sRemainingTime = kDefaultRemainingTime;

             } else if (sLevel != previousLevel) {

                 // Estimate remaining time.

                 if (sLastLevelChange != 0) {

                     // Use elapsedRealtime() because we want to track time across device sleeps.

                     long currentTime = SystemClock.elapsedRealtime();

                     long dt = (currentTime - sLastLevelChange) / 1000;

                     double dLevel = sLevel - previousLevel;

                     if (sCharging) {

                         if (dLevel < 0) {

                             Log.w(LOGTAG, "When charging, level should increase!");

                             sRemainingTime = kUnknownRemainingTime;

                         } else {

                             sRemainingTime = Math.round(dt / dLevel * (1.0 - sLevel));

                         }

                     } else {

                         if (dLevel > 0) {

                             Log.w(LOGTAG, "When discharging, level should decrease!");

                             sRemainingTime = kUnknownRemainingTime;

                         } else {

                             sRemainingTime = Math.round(dt / -dLevel * sLevel);

                         }

                     }

                     sLastLevelChange = currentTime;

                 } else {

                     // That's the first time we got an update, we can't do anything.

                     sLastLevelChange = SystemClock.elapsedRealtime();

                 }

             }

         } else {

             sLevel = kDefaultLevel;

             sCharging = kDefaultCharging;

             sRemainingTime = kDefaultRemainingTime;

         }

         /*

          * We want to inform listeners if the following conditions are fulfilled:

          *  - we have at least one observer;

          *  - the charging state or the level has changed.

          *

          * Note: no need to check for a remaining time change given that it's only

          * updated if there is a level change or a charging change.

          *

          * The idea is to prevent doing all the way to the DOM code in the child

          * process to finally not send an event.

          */

         if (sNotificationsEnabled &&

                 (previousCharging != isCharging() || previousLevel != getLevel())) {

             GeckoAppShell.notifyBatteryChange(getLevel(), isCharging(), getRemainingTime());

         }

     }

     public static boolean isCharging() {

         return sCharging;

     }

     public static double getLevel() {

         return sLevel;

     }

     public static double getRemainingTime() {

         return sRemainingTime;

     }

     public static void enableNotifications() {

         sNotificationsEnabled = true;

     }

     public static void disableNotifications() {

         sNotificationsEnabled = false;

     }

     public static double[] getCurrentInformation() {

         return new double[] { getLevel(), isCharging() ? 1.0 : 0.0, getRemainingTime() };

     }

 }