Release v3.2.7

Also removed configuration option.

.idea/render.experimental.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="RenderSettings">
+    <option name="showDecorations" value="true" />
+  </component>
+</project>

README.md

@@ -30,6 +30,14 @@ To show your tracks on a map, a 3rd party application (e.g., [OsmAnd](https://pl
     <img alt="Donate using Liberapay" src="https://liberapay.com/assets/widgets/donate.svg" height="45">
 </a>
 
+## Screenshots
+<div>
+    <img width="20%" src="fastlane/metadata/android/en-US/phoneScreenshots/screenshot_1.png">
+    <img width="20%" src="fastlane/metadata/android/en-US/phoneScreenshots/screenshot_2.png">
+    <img width="20%" src="fastlane/metadata/android/en-US/phoneScreenshots/screenshot_3.png">
+    <img width="20%" src="fastlane/metadata/android/en-US/phoneScreenshots/screenshot_4.png">
+</div>
+
 ## Project history
 
 _OpenTracks_ is based upon Google _My Tracks app_ ([code](https://code.google.com/archive/p/mytracks/)).

build.gradle

@@ -6,7 +6,7 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.5.0'
+        classpath 'com.android.tools.build:gradle:3.5.2'
     }
 }
 
@@ -35,10 +35,14 @@ def getVersionName = { ->
     try {
         def stdout = new ByteArrayOutputStream()
         exec {
-            commandLine 'git', 'describe', '--tags', '--dirty'
+            commandLine 'git', 'describe', '--tags'
             standardOutput = stdout
         }
-        return stdout.toString().trim()
+        exec {
+            commandLine 'git', 'log', '--format="%h"', '-n 1'
+            standardOutput = stdout
+        }
+        return stdout.toString().replace('\n', '-').replace('"', '').trim()
     }
     catch (ignored) {
         return null
@@ -75,10 +79,6 @@ android {
     applicationVariants.all { variant ->
         variant.resValue "string", "applicationId", variant.applicationId
     }
-
-    lintOptions {
-        disable "AppCompatResource" // TODO Disable complaint to use androidx's SearchView as it is null.
-    }
 }
 
 dependencies {

fastlane/metadata/android/de-DE/full_description.txt

@@ -1,4 +1,4 @@
-Open Tracks – ein GPS-Tracker, der deine Daten für sich behält.
+OpenTracks – ein GPS-Tracker, der deine Daten für sich behält.
 Erfasst deine Kilometer, ohne dass es jemand anderes tut.
 
 Funktionen & Features:

fastlane/metadata/android/de-DE/short_description.txt

@@ -1 +1 @@
-Open Tracks – ein GPS-Tracker, der deine Daten für sich behält.
+OpenTracks – ein GPS-Tracker, der deine Daten für sich behält.

fastlane/metadata/android/en-US/changelogs/3137.txt

@@ -0,0 +1,8 @@
+v3.2.6: OpenTracks
+
+Changes:
+- Heart rate monitor: scan for available devices
+- Remove shortcut to Bluetooth settings
+
+Developer:
+- Preferences: moved default of preferences from code to xml

fastlane/metadata/android/en-US/changelogs/3149.txt

@@ -0,0 +1,10 @@
+v3.2.7: OpenTracks
+
+Changes:
+- Notification show GPS accuracy
+- Show heads-up notification if GPS accuracy drops beyond threshold
+- Always show chart by time as well as by distance
+- Added help (in Settings)
+
+Bugfix:
+- TrackDetailActivity: disabled non-working landscape mode (temporary)

fastlane/metadata/android/es-ES/full_description.txt

@@ -0,0 +1,8 @@
+OpenTracks es un tracker deportivo que respeta tu privacidad.
+
+Funciones:
+* Tracker deportivo: haz un seguimiento de tus actividades al aire libre
+* Marca lugares de interés, incluso agrega fotos a los marcadores
+* Pulsómetro (compatible con dispositivos Bluetooth LE)
+* Exporta tus rutas como KML o GPX
+* Completamente offline, no necesitas internet

fastlane/metadata/android/es-ES/short_description.txt

@@ -0,0 +1 @@
+OpenTracks es un tracker deportivo que respeta tu privacidad.

fastlane/metadata/android/es-ES/title.txt

@@ -0,0 +1 @@
+OpenTracks

src/androidTest/java/de/dennisguse/opentracks/fragments/ChartFragmentTest.java

@@ -46,8 +46,10 @@ public class ChartFragmentTest {
 
     @Before
     public void setUp() {
-        chartFragment = new ChartFragment();
-        chartFragment.setChartView(new ChartView(ApplicationProvider.getApplicationContext()));
+        boolean chartByDistance = false;
+        chartFragment = new ChartFragment(chartByDistance) {
+        };
+        chartFragment.setChartView(new ChartView(ApplicationProvider.getApplicationContext(), chartByDistance));
         chartFragment.setTripStatisticsUpdater(TrackStubUtils.INITIAL_TIME);
     }
 

src/androidTest/java/de/dennisguse/opentracks/services/TrackRecordingServiceNotificationManagerTest.java

@@ -0,0 +1,54 @@
+package de.dennisguse.opentracks.services;
+
+import android.app.NotificationManager;
+import android.content.Context;
+import android.location.Location;
+
+import androidx.core.app.NotificationCompat;
+import androidx.test.core.app.ApplicationProvider;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+
+import static org.mockito.ArgumentMatchers.anyBoolean;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+@RunWith(MockitoJUnitRunner.class)
+public class TrackRecordingServiceNotificationManagerTest {
+
+    private Context context = ApplicationProvider.getApplicationContext();
+
+    @Mock
+    private Location locationMock;
+
+    @Mock
+    private NotificationCompat.Builder notificationCompatBuilder;
+
+    @Mock
+    private NotificationManager notificationManager;
+
+    @Test
+    public void updateLocation_triggersAlertOnlyOnFirstInaccurateLocation() {
+        when(locationMock.hasAccuracy()).thenReturn(true);
+        when(locationMock.getAccuracy()).thenReturn(999f);
+        when(notificationCompatBuilder.setContentText(anyString())).thenReturn(notificationCompatBuilder);
+        when(notificationCompatBuilder.setOnlyAlertOnce(anyBoolean())).thenReturn(notificationCompatBuilder);
+
+        TrackRecordingServiceNotificationManager subject = new TrackRecordingServiceNotificationManager(notificationManager, notificationCompatBuilder);
+
+        // when
+        subject.updateLocation(context, locationMock, 100);
+        subject.updateLocation(context, locationMock, 100);
+        subject.updateLocation(context, locationMock, 1000);
+        subject.updateLocation(context, locationMock, 100);
+
+        // then
+        verify(notificationCompatBuilder, times(6)).setOnlyAlertOnce(true);
+        verify(notificationCompatBuilder, times(2)).setOnlyAlertOnce(false);
+    }
+}

src/androidTest/java/de/dennisguse/opentracks/services/TrackRecordingServiceTestLooper.java

@@ -139,7 +139,8 @@ public class TrackRecordingServiceTestLooper {
     @MediumTest
     @Test
     public void testWithProperties_minRecordingDistanceDefault() throws TimeoutException {
-        PreferencesUtils.setInt(context, R.string.recording_distance_interval_key, PreferencesUtils.RECORDING_DISTANCE_INTERVAL_DEFAULT);
+        int minRecordingIntervalDefault = Integer.parseInt(context.getResources().getString(R.string.min_recording_interval_default));
+        PreferencesUtils.setInt(context, R.string.recording_distance_interval_key, minRecordingIntervalDefault);
         fullRecordingSession();
     }
 
@@ -202,7 +203,8 @@ public class TrackRecordingServiceTestLooper {
     @MediumTest
     @Test
     public void testWithProperties_minRequiredAccuracyDefault() throws TimeoutException {
-        PreferencesUtils.setInt(context, R.string.recording_gps_accuracy_key, PreferencesUtils.RECORDING_GPS_ACCURACY_DEFAULT);
+        int recordingGPSAccuracyDefault = Integer.parseInt(context.getResources().getString(R.string.recording_gps_accuracy_default));
+        PreferencesUtils.setInt(context, R.string.recording_gps_accuracy_key, recordingGPSAccuracyDefault);
         fullRecordingSession();
     }
 

src/main/AndroidManifest.xml

@@ -16,8 +16,8 @@ limitations under the License.
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="de.dennisguse.opentracks"
     android:installLocation="auto"
-    android:versionCode="3123"
-    android:versionName="v3.2.5"> <!-- For FDroid. -->
+    android:versionCode="3149"
+    android:versionName="v3.2.7"> <!-- For FDroid. -->
     <!-- Permission to initialize services -->
     <application
         android:name=".Startup"
@@ -32,6 +32,10 @@ limitations under the License.
 
         <activity android:name=".DeleteActivity" />
 
+        <activity
+            android:name=".HelpActivity"
+            android:label="@string/menu_help" />
+
         <activity
             android:name=".io.file.importer.ImportActivity"
             android:theme="@style/ThemeCustomTransparent">
@@ -50,10 +54,10 @@ limitations under the License.
             </intent-filter>
         </activity>
 
-        <activity android:name=".MarkerEditActivity" />
-
         <activity android:name=".MarkerDetailActivity" />
 
+        <activity android:name=".MarkerEditActivity" />
+
         <activity
             android:name=".MarkerListActivity"
             android:label="@string/menu_markers">
@@ -79,7 +83,9 @@ limitations under the License.
 
         <activity android:name=".TrackEditActivity" />
 
-        <activity android:name=".TrackListActivity">
+        <activity
+            android:name=".TrackListActivity"
+            android:screenOrientation="userPortrait">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <category android:name="android.intent.category.LAUNCHER" />

src/main/java/de/dennisguse/opentracks/AbstractActivity.java

@@ -17,11 +17,12 @@
 package de.dennisguse.opentracks;
 
 import android.os.Bundle;
-import android.speech.tts.TextToSpeech;
 
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.appcompat.widget.Toolbar;
 
+import de.dennisguse.opentracks.util.TTSUtils;
+
 /**
  * @author Jimmy Shih
  */
@@ -32,7 +33,7 @@ public abstract class AbstractActivity extends AppCompatActivity {
         super.onCreate(savedInstanceState);
 
         // Set volume control stream for text to speech
-        setVolumeControlStream(TextToSpeech.Engine.DEFAULT_STREAM);
+        setVolumeControlStream(TTSUtils.getTTSStream());
 
         setContentView(getLayoutResId());
 

src/main/java/de/dennisguse/opentracks/ChartView.java

@@ -107,7 +107,7 @@ public class ChartView extends View {
     private int effectiveWidth = 0;
     private int effectiveHeight = 0;
 
-    private boolean chartByDistance = true;
+    private boolean chartByDistance;
     private boolean metricUnits = true;
     private boolean reportSpeed = true;
     private boolean showPointer = false;
@@ -117,8 +117,9 @@ public class ChartView extends View {
      *
      * @param context the context
      */
-    public ChartView(Context context) {
+    public ChartView(Context context, boolean chartByDistance) {
         super(context);
+        this.chartByDistance = chartByDistance;
 
         series[ELEVATION_SERIES] = new ChartValueSeries(context,
                 Integer.MIN_VALUE,

src/main/java/de/dennisguse/opentracks/HelpActivity.java

@@ -0,0 +1,9 @@
+package de.dennisguse.opentracks;
+
+public class HelpActivity extends AbstractActivity {
+
+    @Override
+    protected int getLayoutResId() {
+        return R.layout.help;
+    }
+}

src/main/java/de/dennisguse/opentracks/MarkerListActivity.java

@@ -69,7 +69,7 @@ public class MarkerListActivity extends AbstractActivity implements DeleteMarker
     private SharedPreferences sharedPreferences;
 
     private long recordingTrackId = PreferencesUtils.RECORDING_TRACK_ID_DEFAULT;
-    private boolean recordingTrackPaused = PreferencesUtils.RECORDING_TRACK_PAUSED_DEFAULT;
+    private boolean recordingTrackPaused;
     /*
      * Note that sharedPreferenceChangeListener cannot be an anonymous inner
      * class. Anonymous inner class will get garbage collected.
@@ -128,6 +128,8 @@ public class MarkerListActivity extends AbstractActivity implements DeleteMarker
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
 
+        recordingTrackPaused = PreferencesUtils.isRecordingTrackPausedDefault(this);
+
         contentProviderUtils = ContentProviderUtils.Factory.get(this);
         sharedPreferences = PreferencesUtils.getSharedPreferences(this);
 

src/main/java/de/dennisguse/opentracks/SearchListActivity.java

@@ -101,7 +101,7 @@ public class SearchListActivity extends AbstractListActivity implements DeleteMa
 
     private long recordingTrackId = PreferencesUtils.RECORDING_TRACK_ID_DEFAULT;
 
-    private boolean recordingTrackPaused = PreferencesUtils.RECORDING_TRACK_PAUSED_DEFAULT;
+    private boolean recordingTrackPaused;
 
     // Callback when an item is selected in the contextual action mode
     private ContextualActionModeCallback contextualActionModeCallback = new ContextualActionModeCallback() {
@@ -168,6 +168,8 @@ public class SearchListActivity extends AbstractListActivity implements DeleteMa
         super.onCreate(savedInstanceState);
         setDefaultKeyMode(DEFAULT_KEYS_SEARCH_LOCAL);
 
+        recordingTrackPaused = PreferencesUtils.isRecordingTrackPausedDefault(this);
+
         contentProviderUtils = ContentProviderUtils.Factory.get(this);
         sharedPreferences = PreferencesUtils.getSharedPreferences(this);
         trackRecordingServiceConnection = new TrackRecordingServiceConnection(this, null);

src/main/java/de/dennisguse/opentracks/TrackDetailActivity.java

@@ -45,7 +45,8 @@ import de.dennisguse.opentracks.content.TrackDataHub;
 import de.dennisguse.opentracks.content.Waypoint;
 import de.dennisguse.opentracks.content.Waypoint.WaypointType;
 import de.dennisguse.opentracks.content.WaypointCreationRequest;
-import de.dennisguse.opentracks.fragments.ChartFragment;
+import de.dennisguse.opentracks.fragments.ChartDistanceFragment;
+import de.dennisguse.opentracks.fragments.ChartTimeFragment;
 import de.dennisguse.opentracks.fragments.ChooseActivityTypeDialogFragment;
 import de.dennisguse.opentracks.fragments.ConfirmDeleteDialogFragment;
 import de.dennisguse.opentracks.fragments.StatsFragment;
@@ -54,6 +55,7 @@ import de.dennisguse.opentracks.settings.SettingsActivity;
 import de.dennisguse.opentracks.util.FileUtils;
 import de.dennisguse.opentracks.util.IntentUtils;
 import de.dennisguse.opentracks.util.PreferencesUtils;
+import de.dennisguse.opentracks.util.StatsUtils;
 import de.dennisguse.opentracks.util.TrackIconUtils;
 import de.dennisguse.opentracks.util.TrackUtils;
 
@@ -93,7 +95,7 @@ public class TrackDetailActivity extends AbstractListActivity implements ChooseA
 
     // Preferences
     private long recordingTrackId = PreferencesUtils.RECORDING_TRACK_ID_DEFAULT;
-    private boolean recordingTrackPaused = PreferencesUtils.RECORDING_TRACK_PAUSED_DEFAULT;
+    private boolean recordingTrackPaused;
 
     private final Runnable bindChangedCallback = new Runnable() {
         @Override
@@ -120,8 +122,7 @@ public class TrackDetailActivity extends AbstractListActivity implements ChooseA
      * Note that sharedPreferenceChangeListener cannot be an anonymous inner
      * class. Anonymous inner class will get garbage collected.
      */
-    private final OnSharedPreferenceChangeListener
-            sharedPreferenceChangeListener = new OnSharedPreferenceChangeListener() {
+    private final OnSharedPreferenceChangeListener sharedPreferenceChangeListener = new OnSharedPreferenceChangeListener() {
         @Override
         public void onSharedPreferenceChanged(SharedPreferences preferences, String key) {
             if (PreferencesUtils.isKey(TrackDetailActivity.this, R.string.recording_track_id_key, key)) {
@@ -182,6 +183,8 @@ public class TrackDetailActivity extends AbstractListActivity implements ChooseA
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
+        recordingTrackPaused = PreferencesUtils.isRecordingTrackPausedDefault(this);
+
         hasCamera = getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA);
         photoUri = savedInstanceState != null ? (Uri) savedInstanceState.getParcelable(PHOTO_URI_KEY) : null;
         hasPhoto = savedInstanceState != null && savedInstanceState.getBoolean(HAS_PHOTO_KEY, false);
@@ -203,8 +206,11 @@ public class TrackDetailActivity extends AbstractListActivity implements ChooseA
         TabSpec statsTabSpec = tabHost.newTabSpec(StatsFragment.STATS_FRAGMENT_TAG).setIndicator(getString(R.string.track_detail_stats_tab));
         tabsAdapter.addTab(statsTabSpec, StatsFragment.class, null);
 
-        TabSpec chartTabSpec = tabHost.newTabSpec(ChartFragment.CHART_FRAGMENT_TAG).setIndicator(getString(R.string.track_detail_chart_tab));
-        tabsAdapter.addTab(chartTabSpec, ChartFragment.class, null);
+        TabSpec chartTimeTabSpec = tabHost.newTabSpec(ChartTimeFragment.CHART_FRAGMENT_TAG).setIndicator(getString(R.string.settings_chart_by_time));
+        tabsAdapter.addTab(chartTimeTabSpec, ChartTimeFragment.class, null);
+
+        TabSpec chartDistanceTabSpec = tabHost.newTabSpec(ChartDistanceFragment.CHART_FRAGMENT_TAG).setIndicator(getString(R.string.settings_chart_by_distance));
+        tabsAdapter.addTab(chartDistanceTabSpec, ChartDistanceFragment.class, null);
 
         if (savedInstanceState != null) {
             tabHost.setCurrentTabByTag(savedInstanceState.getString(CURRENT_TAB_TAG_KEY));
@@ -410,10 +416,16 @@ public class TrackDetailActivity extends AbstractListActivity implements ChooseA
     /**
      * Gets the track id.
      */
+    // TODO Seems to be no used.
+    @Deprecated
     public long getTrackId() {
         return trackId;
     }
 
+    private void setBluetoothHeartRateSensorName(String sensorName) {
+        StatsUtils.setBluetoothHeartRateSensorName(this, sensorName, isRecording());
+    }
+
     /**
      * Handles the data in the intent.
      */

src/main/java/de/dennisguse/opentracks/TrackListActivity.java

@@ -125,7 +125,7 @@ public class TrackListActivity extends AbstractListActivity implements ConfirmDe
         }
     };
 
-    private boolean recordingTrackPaused = PreferencesUtils.RECORDING_TRACK_PAUSED_DEFAULT;
+    private boolean recordingTrackPaused;
 
     /*
      * Note that sharedPreferenceChangeListener cannot be an anonymous inner class.
@@ -225,8 +225,7 @@ public class TrackListActivity extends AbstractListActivity implements ConfirmDe
                 // Not recording -> Recording
                 updateMenuItems(false, true);
                 startRecording();
-            } else {
-                if (recordingTrackPaused) {
+            } else if (recordingTrackPaused) {
                     // Paused -> Resume
                     updateMenuItems(false, true);
                     trackRecordingServiceConnection.resumeTrack();
@@ -237,7 +236,6 @@ public class TrackListActivity extends AbstractListActivity implements ConfirmDe
                     trackRecordingServiceConnection.pauseTrack();
                     trackController.update(true, true);
                 }
-            }
         }
     };
 
@@ -245,6 +243,8 @@ public class TrackListActivity extends AbstractListActivity implements ConfirmDe
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
 
+        recordingTrackPaused = PreferencesUtils.isRecordingTrackPausedDefault(this);
+
         contentProviderUtils = ContentProviderUtils.Factory.get(this);
         sharedPreferences = PreferencesUtils.getSharedPreferences(this);
 

src/main/java/de/dennisguse/opentracks/fragments/ChartDistanceFragment.java

@@ -0,0 +1,10 @@
+package de.dennisguse.opentracks.fragments;
+
+public class ChartDistanceFragment extends ChartFragment {
+
+    public static final String CHART_FRAGMENT_TAG = ChartDistanceFragment.class.getSimpleName();
+
+    public ChartDistanceFragment() {
+        super(true);
+    }
+}

src/main/java/de/dennisguse/opentracks/fragments/ChartFragment.java

@@ -25,6 +25,7 @@ import android.view.ViewGroup.LayoutParams;
 import android.widget.ZoomControls;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import androidx.annotation.VisibleForTesting;
 import androidx.fragment.app.Fragment;
 import androidx.fragment.app.FragmentActivity;
@@ -54,9 +55,9 @@ import de.dennisguse.opentracks.util.UnitConversions;
  * @author Sandor Dornbush
  * @author Rodrigo Damazio
  */
-public class ChartFragment extends Fragment implements TrackDataListener {
+public abstract class ChartFragment extends Fragment implements TrackDataListener {
 
-    public static final String CHART_FRAGMENT_TAG = "chartFragment";
+    private static final String STATE_CHART_VIEW_BY_DISTANCE_KEY = "chartViewByDistance";
 
     private final ArrayList<double[]> pendingPoints = new ArrayList<>();
 
@@ -68,10 +69,10 @@ public class ChartFragment extends Fragment implements TrackDataListener {
 
     private boolean metricUnits = true;
     private boolean reportSpeed = true;
-    private int recordingDistanceInterval = PreferencesUtils.RECORDING_DISTANCE_INTERVAL_DEFAULT;
+    private int recordingDistanceInterval;
 
     // Modes of operation
-    private boolean chartByDistance = true;
+    private boolean chartByDistance;
     private boolean[] chartShow = new boolean[]{true, true, true, true, true, true};
 
     // UI elements
@@ -95,14 +96,18 @@ public class ChartFragment extends Fragment implements TrackDataListener {
         }
     };
 
+    public ChartFragment(boolean chartByDistance) {
+        this.chartByDistance = chartByDistance;
+    }
+
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
 
-        /*
-         * Create a chartView here to store data thus won't need to reload all the data on every onStart or onResume.
-         */
-        chartView = new ChartView(getActivity());
+        recordingDistanceInterval = PreferencesUtils.getRecordingDistanceIntervalDefault(getContext());
+
+        // Create a chartView here to store data thus won't need to reload all the data on every onStart or onResume.
+        chartView = new ChartView(getActivity(), chartByDistance);
     }
 
     @Override
@@ -127,7 +132,7 @@ public class ChartFragment extends Fragment implements TrackDataListener {
     @Override
     public void onStart() {
         super.onStart();
-        ViewGroup layout = getActivity().findViewById(R.id.chart_view_layout);
+        ViewGroup layout = getView().findViewById(R.id.chart_view_layout);
         LayoutParams layoutParams = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
         layout.addView(chartView, layoutParams);
     }
@@ -149,10 +154,24 @@ public class ChartFragment extends Fragment implements TrackDataListener {
     @Override
     public void onStop() {
         super.onStop();
-        ViewGroup layout = getActivity().findViewById(R.id.chart_view_layout);
+        ViewGroup layout = getView().findViewById(R.id.chart_view_layout);
         layout.removeView(chartView);
     }
 
+    @Override
+    public void onSaveInstanceState(@NonNull Bundle outState) {
+        super.onSaveInstanceState(outState);
+        outState.putBoolean(STATE_CHART_VIEW_BY_DISTANCE_KEY, chartByDistance);
+    }
+
+    @Override
+    public void onViewStateRestored(@Nullable Bundle savedInstanceState) {
+        super.onViewStateRestored(savedInstanceState);
+        if (savedInstanceState != null) {
+            chartByDistance = savedInstanceState.getBoolean(STATE_CHART_VIEW_BY_DISTANCE_KEY);
+        }
+    }
+
     @Override
     public void onTrackUpdated(Track track) {
         if (isResumed()) {
@@ -302,12 +321,6 @@ public class ChartFragment extends Fragment implements TrackDataListener {
      */
     private void checkChartSettings() {
         boolean needUpdate = false;
-        if (chartByDistance != PreferencesUtils.isChartByDistance(getActivity())) {
-            chartByDistance = !chartByDistance;
-            chartView.setChartByDistance(chartByDistance);
-            reloadTrackDataHub();
-            needUpdate = true;
-        }
         if (setSeriesEnabled(ChartView.ELEVATION_SERIES, PreferencesUtils.shouldChartShowElevation(getActivity()))) {
             needUpdate = true;
         }

src/main/java/de/dennisguse/opentracks/fragments/ChartTimeFragment.java

@@ -0,0 +1,10 @@
+package de.dennisguse.opentracks.fragments;
+
+public class ChartTimeFragment extends ChartFragment {
+
+    public static final String CHART_FRAGMENT_TAG = ChartTimeFragment.class.getSimpleName();
+
+    public ChartTimeFragment() {
+        super(false);
+    }
+}

src/main/java/de/dennisguse/opentracks/fragments/StatsFragment.java

@@ -45,7 +45,6 @@ import de.dennisguse.opentracks.services.ITrackRecordingService;
 import de.dennisguse.opentracks.services.TrackRecordingServiceConnection;
 import de.dennisguse.opentracks.stats.TripStatistics;
 import de.dennisguse.opentracks.util.LocationUtils;
-import de.dennisguse.opentracks.util.PreferencesUtils;
 import de.dennisguse.opentracks.util.StatsUtils;
 import de.dennisguse.opentracks.util.TrackIconUtils;
 import de.dennisguse.opentracks.util.UnitConversions;
@@ -81,7 +80,7 @@ public class StatsFragment extends Fragment implements TrackDataListener {
         }
     };
     private String category = "";
-    private int recordingGpsAccuracy = PreferencesUtils.RECORDING_GPS_ACCURACY_DEFAULT;
+    private int recordingGpsAccuracy;
 
     @Override
     public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
@@ -91,6 +90,9 @@ public class StatsFragment extends Fragment implements TrackDataListener {
     @Override
     public void onActivityCreated(Bundle savedInstanceState) {
         super.onActivityCreated(savedInstanceState);
+
+        recordingGpsAccuracy = Integer.parseInt(getContext().getResources().getString(R.string.recording_gps_accuracy_default));
+
         handlerUpdateUI = new Handler();
 
         Spinner activityTypeIcon = getView().findViewById(R.id.stats_activity_type_icon);

src/main/java/de/dennisguse/opentracks/services/LocationManagerConnector.java

@@ -33,10 +33,6 @@ public class LocationManagerConnector {
     private final Handler handler;
     private final LocationManager locationManager;
 
-    private LocationListener requestLocationUpdates;
-    private float requestLocationUpdatesDistance;
-    private long requestLocationUpdatesTime;
-
     public LocationManagerConnector(Context context, Looper looper) {
         this.handler = new Handler(looper);
 
@@ -55,10 +51,7 @@ public class LocationManagerConnector {
             @Override
             @SuppressLint("MissingPermission")
             public void run() {
-                requestLocationUpdatesTime = minTime;
-                requestLocationUpdatesDistance = minDistance;
-                requestLocationUpdates = locationListener;
-                locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, requestLocationUpdatesTime, requestLocationUpdatesDistance, locationListener);
+                locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, minTime, minDistance, locationListener);
             }
         });
     }
@@ -70,6 +63,5 @@ public class LocationManagerConnector {
      */
     public void removeLocationUpdates(final LocationListener locationListener) {
         locationManager.removeUpdates(locationListener);
-        requestLocationUpdates = null;
     }
 }

src/main/java/de/dennisguse/opentracks/services/TrackRecordingService.java

@@ -16,9 +16,6 @@
 
 package de.dennisguse.opentracks.services;
 
-import android.app.Notification;
-import android.app.NotificationChannel;
-import android.app.NotificationManager;
 import android.app.PendingIntent;
 import android.app.Service;
 import android.content.Context;
@@ -30,7 +27,6 @@ import android.location.Location;
 import android.location.LocationListener;
 import android.location.LocationManager;
 import android.net.Uri;
-import android.os.Build;
 import android.os.Bundle;
 import android.os.Handler;
 import android.os.IBinder;
@@ -38,7 +34,6 @@ import android.os.PowerManager.WakeLock;
 import android.util.Log;
 
 import androidx.annotation.VisibleForTesting;
-import androidx.core.app.NotificationCompat;
 import androidx.core.app.TaskStackBuilder;
 
 import java.util.concurrent.ExecutorService;
@@ -80,13 +75,13 @@ import de.dennisguse.opentracks.util.UnitConversions;
 public class TrackRecordingService extends Service {
 
     // The name of extra intent property to indicate whether we want to resume a previously recorded track.
-    public static final String RESUME_TRACK_EXTRA_NAME = "de.dennisguse.opentracks.RESUME_TRACK";
+    public static final String RESUME_TRACK_EXTRA_NAME = "RESUME_TRACK";
+    private static final int NOTIFICATION_ID = 123;
 
     public static final double PAUSE_LATITUDE = 100.0;
     public static final double RESUME_LATITUDE = 200.0;
 
     // Anything faster than that (in meters per second) will be considered moving.
-
     public static final double MAX_NO_MOVEMENT_SPEED = 0.224;
     @VisibleForTesting
     static final int MAX_AUTO_RESUME_TRACK_RETRY_ATTEMPTS = 3;
@@ -95,13 +90,13 @@ public class TrackRecordingService extends Service {
     private static final long ONE_MINUTE = (long) (UnitConversions.MIN_TO_S * UnitConversions.S_TO_MS);
     // The following variables are set in onCreate:
     private ExecutorService executorService;
-    private Context context;
     private ContentProviderUtils contentProviderUtils;
     private Handler handler;
     private LocationManagerConnector locationManagerConnector;
     private PeriodicTaskExecutor voiceExecutor;
     private PeriodicTaskExecutor splitExecutor;
     private SharedPreferences sharedPreferences;
+    private TrackRecordingServiceNotificationManager notificationManager;
     private long recordingTrackId;
     private boolean recordingTrackPaused;
     private LocationListenerPolicy locationListenerPolicy;
@@ -117,10 +112,11 @@ public class TrackRecordingService extends Service {
     private final OnSharedPreferenceChangeListener sharedPreferenceChangeListener = new OnSharedPreferenceChangeListener() {
         @Override
         public void onSharedPreferenceChanged(SharedPreferences preferences, String key) {
-            if (PreferencesUtils.isKey(context, R.string.recording_track_id_key, key)) {
+            Context context = TrackRecordingService.this;
+            if (PreferencesUtils.isKey(TrackRecordingService.this, R.string.recording_track_id_key, key)) {
                 // Only through the TrackRecordingService can one stop a recording and set the recordingTrackId to -1L.
-                if (PreferencesUtils.isRecording(context)) {
-                    recordingTrackId = PreferencesUtils.getRecordingTrackId(context);
+                if (PreferencesUtils.isRecording(TrackRecordingService.this)) {
+                    recordingTrackId = PreferencesUtils.getRecordingTrackId(TrackRecordingService.this);
                 }
             }
             if (PreferencesUtils.isKey(context, R.string.recording_track_paused_key, key)) {
@@ -139,17 +135,14 @@ public class TrackRecordingService extends Service {
             }
             if (PreferencesUtils.isKey(context, R.string.min_recording_interval_key, key)) {
                 int minRecordingInterval = PreferencesUtils.getMinRecordingInterval(context);
-                switch (minRecordingInterval) {
-                    case PreferencesUtils.MIN_RECORDING_INTERVAL_ADAPT_BATTERY_LIFE:
-                        // Choose battery life over moving time accuracy.
-                        locationListenerPolicy = new AdaptiveLocationListenerPolicy(30 * UnitConversions.ONE_SECOND, 5 * ONE_MINUTE, 5);
-                        break;
-                    case PreferencesUtils.MIN_RECORDING_INTERVAL_ADAPT_ACCURACY:
-                        // Get all the updates.
-                        locationListenerPolicy = new AdaptiveLocationListenerPolicy(UnitConversions.ONE_SECOND, 30 * UnitConversions.ONE_SECOND, 0);
-                        break;
-                    default:
-                        locationListenerPolicy = new AbsoluteLocationListenerPolicy(minRecordingInterval * UnitConversions.ONE_SECOND);
+                if (minRecordingInterval == PreferencesUtils.getMinRecordingIntervalAdaptBatteryLife(context)) {
+                    // Choose battery life over moving time accuracy.
+                    locationListenerPolicy = new AdaptiveLocationListenerPolicy(30 * UnitConversions.ONE_SECOND, 5 * ONE_MINUTE, 5);
+                } else if (minRecordingInterval == PreferencesUtils.getMinRecordingIntervalAdaptAccuracy(context)) {
+                    // Get all the updates.
+                    locationListenerPolicy = new AdaptiveLocationListenerPolicy(UnitConversions.ONE_SECOND, 30 * UnitConversions.ONE_SECOND, 0);
+                } else {
+                    locationListenerPolicy = new AbsoluteLocationListenerPolicy(minRecordingInterval * UnitConversions.ONE_SECOND);
                 }
             }
             if (PreferencesUtils.isKey(context, R.string.recording_distance_interval_key, key)) {
@@ -221,7 +214,6 @@ public class TrackRecordingService extends Service {
     public void onCreate() {
         super.onCreate();
         executorService = Executors.newSingleThreadExecutor();
-        context = this;
         contentProviderUtils = ContentProviderUtils.Factory.get(this);
         handler = new Handler();
         locationManagerConnector = new LocationManagerConnector(this, handler.getLooper());
@@ -229,6 +221,7 @@ public class TrackRecordingService extends Service {
         splitExecutor = new PeriodicTaskExecutor(this, new SplitPeriodicTaskFactory());
         sharedPreferences = PreferencesUtils.getSharedPreferences(this);
         sharedPreferences.registerOnSharedPreferenceChangeListener(sharedPreferenceChangeListener);
+        notificationManager = new TrackRecordingServiceNotificationManager(this);
 
         // onSharedPreferenceChanged might not set recordingTrackId.
         recordingTrackId = PreferencesUtils.RECORDING_TRACK_ID_DEFAULT;
@@ -270,7 +263,7 @@ public class TrackRecordingService extends Service {
         }
 
         // Reverse order from onCreate
-        showNotification(false);
+        showNotification(false); //TODO Why?
 
         handler.removeCallbacks(registerLocationRunnable);
         unregisterLocationListener();
@@ -403,40 +396,6 @@ public class TrackRecordingService extends Service {
         return Long.parseLong(uri.getLastPathSegment());
     }
 
-    /**
-     * Starts the service as a foreground service.
-     *
-     * @param pendingIntent the notification pending intent
-     * @param messageId     the notification message id
-     */
-    @VisibleForTesting
-    protected void startForegroundService(PendingIntent pendingIntent, int messageId) {
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
-            NotificationChannel notificationChannel = new NotificationChannel(getString(R.string.app_name), getString(R.string.app_name), NotificationManager.IMPORTANCE_DEFAULT);
-            NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
-            if (manager != null) {
-                manager.createNotificationChannel(notificationChannel);
-            }
-        }
-        NotificationCompat.Builder builder = new NotificationCompat.Builder(this, getString(R.string.app_name))
-                .setContentIntent(pendingIntent)
-                .setContentText(getString(messageId))
-                .setContentTitle(getString(R.string.app_name))
-                .setOngoing(true)
-                .setSmallIcon(R.drawable.ic_logo_color_24dp)
-                .setCategory(Notification.CATEGORY_SERVICE)
-                .setWhen(System.currentTimeMillis());
-        startForeground(1, builder.build());
-    }
-
-    /**
-     * Stops the service as a foreground service.
-     */
-    @VisibleForTesting
-    protected void stopForegroundService() {
-        stopForeground(true);
-    }
-
     /**
      * Handles start command.
      *
@@ -471,12 +430,12 @@ public class TrackRecordingService extends Service {
         }
         PreferencesUtils.incrementAutoResumeTrackCurrentRetryDefault(this);
 
-        if (autoResumeTrackTimeout == Integer.parseInt(context.getResources().getString(R.string.auto_resume_track_timeout_never))) {
+        if (autoResumeTrackTimeout == Integer.parseInt(getResources().getString(R.string.auto_resume_track_timeout_never))) {
             Log.d(TAG, "Not resuming. Auto-resume track timeout set to never.");
             return false;
         }
 
-        if (autoResumeTrackTimeout == Integer.parseInt(context.getResources().getString(R.string.auto_resume_track_timeout_always))) {
+        if (autoResumeTrackTimeout == Integer.parseInt(getResources().getString(R.string.auto_resume_track_timeout_always))) {
             Log.d(TAG, "Resuming. Auto-resume track timeout set to always.");
             return true;
         }
@@ -680,6 +639,8 @@ public class TrackRecordingService extends Service {
         }
 
         endRecording(false, recordingTrackId);
+
+        notificationManager.updateContent(getString(R.string.generic_paused));
     }
 
     /**
@@ -766,6 +727,8 @@ public class TrackRecordingService extends Service {
                 return;
             }
 
+            notificationManager.updateLocation(this, location, recordingGpsAccuracy);
+
             if (!location.hasAccuracy() || location.getAccuracy() >= recordingGpsAccuracy) {
                 Log.d(TAG, "Ignore onLocationChangedAsync. Poor accuracy.");
                 return;
@@ -801,10 +764,7 @@ public class TrackRecordingService extends Service {
             }
 
             if (!LocationUtils.isValidLocation(lastValidTrackPoint)) {
-                /*
-                 * Should not happen. The current segment should have a location. Just
-                 * insert the current location.
-                 */
+                // Should not happen. The current segment should have a location. Just insert the current location.
                 insertLocation(track, location, null);
                 lastLocation = location;
                 return;
@@ -951,33 +911,33 @@ public class TrackRecordingService extends Service {
         }
     }
 
-    /**
-     * Shows the notification.
-     *
-     * @param isGpsStarted true if GPS is started
-     */
     private void showNotification(boolean isGpsStarted) {
-        if (isRecording()) {
-            if (isPaused()) {
-                stopForegroundService();
-            } else {
-                Intent intent = IntentUtils.newIntent(this, TrackDetailActivity.class)
-                        .putExtra(TrackDetailActivity.EXTRA_TRACK_ID, recordingTrackId);
-                PendingIntent pendingIntent = TaskStackBuilder.create(this)
-                        .addParentStack(TrackDetailActivity.class).addNextIntent(intent)
-                        .getPendingIntent(0, PendingIntent.FLAG_UPDATE_CURRENT);
-                startForegroundService(pendingIntent, R.string.track_record_notification);
-            }
-        } else {
-            // Not recording
-            if (isGpsStarted) {
-                Intent intent = IntentUtils.newIntent(this, TrackListActivity.class);
-                PendingIntent pendingIntent = TaskStackBuilder.create(this)
-                        .addNextIntent(intent).getPendingIntent(0, 0);
-                startForegroundService(pendingIntent, R.string.gps_starting);
-            } else {
-                stopForegroundService();
-            }
+        if ((isRecording() && isPaused()) || (!isRecording() && !isGpsStarted)) {
+            stopForeground(true);
+        }
+
+        if (isRecording() && !isPaused()) {
+            Intent intent = IntentUtils.newIntent(this, TrackDetailActivity.class)
+                    .putExtra(TrackDetailActivity.EXTRA_TRACK_ID, recordingTrackId);
+            PendingIntent pendingIntent = TaskStackBuilder.create(this)
+                    .addParentStack(TrackDetailActivity.class)
+                    .addNextIntent(intent)
+                    .getPendingIntent(0, PendingIntent.FLAG_UPDATE_CURRENT);
+
+            notificationManager.updatePendingIntent(pendingIntent);
+            notificationManager.updateContent(getString(R.string.gps_starting));
+            startForeground(NOTIFICATION_ID, notificationManager.getNotification());
+        }
+        if (!isRecording() && isGpsStarted) {
+            Intent intent = IntentUtils.newIntent(this, TrackListActivity.class);
+            PendingIntent pendingIntent = TaskStackBuilder.create(this)
+                    .addNextIntent(intent)
+                    .getPendingIntent(0, 0);
+
+            notificationManager.updatePendingIntent(pendingIntent);
+            notificationManager.updateContent(getString(R.string.gps_starting));
+
+            startForeground(NOTIFICATION_ID, notificationManager.getNotification());
         }
     }
 

src/main/java/de/dennisguse/opentracks/services/TrackRecordingServiceNotificationManager.java

@@ -0,0 +1,94 @@
+package de.dennisguse.opentracks.services;
+
+import android.app.Notification;
+import android.app.NotificationChannel;
+import android.app.NotificationManager;
+import android.app.PendingIntent;
+import android.content.Context;
+import android.location.Location;
+import android.os.Build;
+
+import androidx.annotation.VisibleForTesting;
+import androidx.core.app.NotificationCompat;
+
+import de.dennisguse.opentracks.R;
+import de.dennisguse.opentracks.util.PreferencesUtils;
+import de.dennisguse.opentracks.util.StringUtils;
+
+/**
+ * Manages the content of the notification shown by {@link TrackRecordingService}.
+ */
+class TrackRecordingServiceNotificationManager {
+
+    private final static int NOTIFICATION_ID = 123;
+
+    private final static String CHANNEL_ID = TrackRecordingServiceNotificationManager.class.getSimpleName();
+
+    private NotificationCompat.Builder notificationBuilder;
+
+    private NotificationManager notificationManager;
+
+    private boolean previousLocationWasAccurate = true;
+
+    TrackRecordingServiceNotificationManager(Context context) {
+        notificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            NotificationChannel notificationChannel = new NotificationChannel(CHANNEL_ID, context.getString(R.string.app_name), NotificationManager.IMPORTANCE_HIGH);
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+                notificationChannel.setAllowBubbles(true);
+            }
+
+            notificationManager.createNotificationChannel(notificationChannel);
+        }
+
+        notificationBuilder = new NotificationCompat.Builder(context, CHANNEL_ID);
+        notificationBuilder
+                .setDefaults(NotificationCompat.DEFAULT_ALL)
+                .setPriority(NotificationCompat.PRIORITY_MAX)
+                .setOnlyAlertOnce(true)
+                .setOngoing(true)
+                .setCategory(NotificationCompat.CATEGORY_SERVICE)
+                .setContentTitle(context.getString(R.string.app_name))
+                .setSmallIcon(R.drawable.ic_logo_color_24dp);
+    }
+
+    @VisibleForTesting
+    TrackRecordingServiceNotificationManager(NotificationManager notificationManager, NotificationCompat.Builder notificationBuilder) {
+        this.notificationManager = notificationManager;
+        this.notificationBuilder = notificationBuilder;
+    }
+
+    void updateContent(String content) {
+        notificationBuilder.setContentText(content);
+        updateNotification();
+    }
+
+    void updateLocation(Context context, Location location, int recordingGpsAccuracy) {
+        String formattedAccuracy = context.getString(R.string.value_none);
+        if (location.hasAccuracy()) {
+            formattedAccuracy = StringUtils.formatDistance(context, location.getAccuracy(), PreferencesUtils.isMetricUnits(context));
+
+            boolean currentLocationWasAccurate = location.getAccuracy() < recordingGpsAccuracy;
+            boolean shouldAlert = !currentLocationWasAccurate && previousLocationWasAccurate;
+            notificationBuilder.setOnlyAlertOnce(!shouldAlert);
+            previousLocationWasAccurate = currentLocationWasAccurate;
+        }
+
+        notificationBuilder.setContentText(context.getString(R.string.track_recording_notification_accuracy, formattedAccuracy));
+        updateNotification();
+        notificationBuilder.setOnlyAlertOnce(true);
+    }
+
+    void updatePendingIntent(PendingIntent pendingIntent) {
+        notificationBuilder.setContentIntent(pendingIntent);
+        updateNotification();
+    }
+
+    Notification getNotification() {
+        return notificationBuilder.build();
+    }
+
+    private void updateNotification() {
+        notificationManager.notify(NOTIFICATION_ID, getNotification());
+    }
+}

src/main/java/de/dennisguse/opentracks/services/sensors/BluetoothConnectionManager.java

@@ -21,6 +21,7 @@ import android.bluetooth.BluetoothGatt;
 import android.bluetooth.BluetoothGattCallback;
 import android.bluetooth.BluetoothGattCharacteristic;
 import android.bluetooth.BluetoothGattDescriptor;
+import android.bluetooth.BluetoothGattService;
 import android.bluetooth.BluetoothProfile;
 import android.content.Context;
 import android.os.Handler;
@@ -45,7 +46,6 @@ public class BluetoothConnectionManager {
     static final int MESSAGE_READ = 3;
     static final int MESSAGE_DISCONNECTED = 4;
 
-    private static final UUID HEART_RATE_SERVICE_UUID = new UUID(0x180D00001000L, 0x800000805f9b34fbL);
     private static final UUID HEART_RATE_MEASUREMENT_CHAR_UUID = new UUID(0x2A3700001000L, 0x800000805f9b34fbL);
     private static final UUID CLIENT_CHARACTERISTIC_CONFIG_UUID = new UUID(0x290200001000L, 0x800000805f9b34fbL);
 
@@ -90,10 +90,18 @@ public class BluetoothConnectionManager {
 
         @Override
         public void onServicesDiscovered(@NonNull BluetoothGatt gatt, int status) {
-            BluetoothGattCharacteristic characteristic = gatt
-                    .getService(HEART_RATE_SERVICE_UUID)
-                    .getCharacteristic(HEART_RATE_MEASUREMENT_CHAR_UUID);
+            BluetoothGattService service = gatt.getService(BluetoothUtils.HEART_RATE_SERVICE_UUID);
+            if (service == null) {
+                Log.e(TAG, "Could not get heart rate service for " + gatt.getDevice().getAddress());
+                return;
+            }
 
+
+            BluetoothGattCharacteristic characteristic = service.getCharacteristic(HEART_RATE_MEASUREMENT_CHAR_UUID);
+            if (characteristic == null) {
+                Log.e(TAG, "Could not get BluetoothCharacteristic for " + gatt.getDevice().getAddress());
+                return;
+            }
             gatt.setCharacteristicNotification(characteristic, true);
 
             BluetoothGattDescriptor descriptor = characteristic.getDescriptor(CLIENT_CHARACTERISTIC_CONFIG_UUID);
@@ -131,8 +139,9 @@ public class BluetoothConnectionManager {
 
         Log.d(TAG, "Connecting to: " + bluetoothDevice);
 
-        setState(SensorState.CONNECTING);
         bluetoothGatt = bluetoothDevice.connectGatt(this.context, true, this.connectCallback);
+
+        setState(SensorState.CONNECTING);
     }
 
     public synchronized void disconnect() {

src/main/java/de/dennisguse/opentracks/services/sensors/BluetoothRemoteSensorManager.java

@@ -26,12 +26,10 @@ import android.os.Message;
 import android.util.Log;
 import android.widget.Toast;
 
-import java.util.ArrayList;
-
 import de.dennisguse.opentracks.R;
 import de.dennisguse.opentracks.content.sensor.SensorDataSet;
+import de.dennisguse.opentracks.util.BluetoothUtils;
 import de.dennisguse.opentracks.util.PreferencesUtils;
-import de.dennisguse.opentracks.util.UnitConversions;
 
 /**
  * Bluetooth LE sensor manager.
@@ -45,7 +43,7 @@ public class BluetoothRemoteSensorManager {
 
     private static final String TAG = BluetoothConnectionManager.class.getSimpleName();
 
-    private static final BluetoothAdapter bluetoothAdapter = getDefaultBluetoothAdapter();
+    private static final BluetoothAdapter bluetoothAdapter = BluetoothUtils.getDefaultBluetoothAdapter(TAG);
 
     private final Context context;
 
@@ -87,8 +85,8 @@ public class BluetoothRemoteSensorManager {
     private final SharedPreferences.OnSharedPreferenceChangeListener sharedPreferenceChangeListener = new SharedPreferences.OnSharedPreferenceChangeListener() {
         @Override
         public void onSharedPreferenceChanged(SharedPreferences preferences, String key) {
-            if (bluetoothConnectionManager != null && PreferencesUtils.isKey(context, R.string.settings_sensor_bluetooth_sensor_key, key)) {
-                String address = PreferencesUtils.getString(context, R.string.settings_sensor_bluetooth_sensor_key, PreferencesUtils.BLUETOOTH_SENSOR_DEFAULT);
+            if (bluetoothConnectionManager != null && PreferencesUtils.isKey(context, R.string.settings_sensor_bluetooth_heart_rate_key, key)) {
+                String address = PreferencesUtils.getBluetoothHeartRateSensorAddress(context);
                 if (address.equals(PreferencesUtils.BLUETOOTH_SENSOR_DEFAULT)) {
                     stop();
                     return;
@@ -114,43 +112,6 @@ public class BluetoothRemoteSensorManager {
         sharedPreferences = PreferencesUtils.getSharedPreferences(context);
     }
 
-    private static BluetoothAdapter getDefaultBluetoothAdapter() {
-        // If from the main application thread, return directly
-        if (Thread.currentThread().equals(Looper.getMainLooper().getThread())) {
-            return BluetoothAdapter.getDefaultAdapter();
-        }
-
-        // Get the default adapter from the main application thread
-        final ArrayList<BluetoothAdapter> adapters = new ArrayList<>(1);
-        final Object mutex = new Object();
-
-        Handler handler = new Handler(Looper.getMainLooper());
-        handler.post(new Runnable() {
-            @Override
-            public void run() {
-                adapters.add(BluetoothAdapter.getDefaultAdapter());
-                synchronized (mutex) {
-                    mutex.notify();
-                }
-            }
-        });
-
-        while (adapters.isEmpty()) {
-            synchronized (mutex) {
-                try {
-                    mutex.wait(UnitConversions.ONE_SECOND);
-                } catch (InterruptedException e) {
-                    Log.e(TAG, "Interrupted while waiting for default bluetooth adapter", e);
-                }
-            }
-        }
-
-        if (adapters.get(0) == null) {
-            Log.w(TAG, "No bluetooth adapter found.");
-        }
-        return adapters.get(0);
-    }
-
     public void start() {
         sharedPreferences.registerOnSharedPreferenceChangeListener(sharedPreferenceChangeListener);
         startCurrentSensor();
@@ -184,7 +145,8 @@ public class BluetoothRemoteSensorManager {
             return;
         }
 
-        String address = PreferencesUtils.getString(context, R.string.settings_sensor_bluetooth_sensor_key, PreferencesUtils.BLUETOOTH_SENSOR_DEFAULT);
+//        String address = PreferencesUtils.getString(context, R.string.settings_sensor_bluetooth_heart_rate_key, PreferencesUtils.BLUETOOTH_SENSOR_DEFAULT);
+        String address = PreferencesUtils.getBluetoothHeartRateSensorAddress(context);
         if (PreferencesUtils.BLUETOOTH_SENSOR_DEFAULT.equals(address)) {
             Log.w(TAG, "No bluetooth address.");
             return;

src/main/java/de/dennisguse/opentracks/services/tasks/AnnouncementPeriodicTask.java

@@ -34,6 +34,7 @@ import de.dennisguse.opentracks.services.TrackRecordingService;
 import de.dennisguse.opentracks.stats.TripStatistics;
 import de.dennisguse.opentracks.util.PreferencesUtils;
 import de.dennisguse.opentracks.util.StringUtils;
+import de.dennisguse.opentracks.util.TTSUtils;
 import de.dennisguse.opentracks.util.UnitConversions;
 
 /**
@@ -193,7 +194,7 @@ public class AnnouncementPeriodicTask implements PeriodicTask {
      * @param announcement the announcement
      */
     private void speakAnnouncement(String announcement) {
-        int result = audioManager.requestAudioFocus(null, TextToSpeech.Engine.DEFAULT_STREAM, AudioManager.AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK);
+        int result = audioManager.requestAudioFocus(null, TTSUtils.getTTSStream(), AudioManager.AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK);
         if (result == AudioManager.AUDIOFOCUS_REQUEST_FAILED) {
             Log.w(TAG, "Failed to request audio focus.");
         }

src/main/java/de/dennisguse/opentracks/services/tasks/PeriodicTaskExecutor.java

@@ -17,9 +17,9 @@ package de.dennisguse.opentracks.services.tasks;
 
 import android.util.Log;
 
+import de.dennisguse.opentracks.R;
 import de.dennisguse.opentracks.services.TrackRecordingService;
 import de.dennisguse.opentracks.stats.TripStatistics;
-import de.dennisguse.opentracks.util.PreferencesUtils;
 import de.dennisguse.opentracks.util.UnitConversions;
 
 /**
@@ -35,13 +35,14 @@ public class PeriodicTaskExecutor {
     private final TrackRecordingService trackRecordingService;
     private final PeriodicTaskFactory periodicTaskFactory;
 
+    private final int TASK_FREQUENCY_OFF;
     /**
      * The task frequency.
      * A positive value is a time frequency (minutes).
      * A negative value is a distance frequency (km or mi).
      * A zero value is to turn off periodic task.
      */
-    private int taskFrequency = PreferencesUtils.FREQUENCY_OFF;
+    private int taskFrequency;
 
     private PeriodicTask periodicTask;
 
@@ -56,6 +57,9 @@ public class PeriodicTaskExecutor {
     public PeriodicTaskExecutor(TrackRecordingService trackRecordingService, PeriodicTaskFactory periodicTaskFactory) {
         this.trackRecordingService = trackRecordingService;
         this.periodicTaskFactory = periodicTaskFactory;
+
+        TASK_FREQUENCY_OFF = Integer.parseInt(trackRecordingService.getBaseContext().getResources().getString(R.string.frequency_off));
+        taskFrequency = TASK_FREQUENCY_OFF;
     }
 
     /**
@@ -71,7 +75,7 @@ public class PeriodicTaskExecutor {
             timerTaskExecutor.shutdown();
             timerTaskExecutor = null;
         }
-        if (taskFrequency == PreferencesUtils.FREQUENCY_OFF) {
+        if (taskFrequency == TASK_FREQUENCY_OFF) {
             Log.d(TAG, "Task frequency is off.");
             return;
         }

src/main/java/de/dennisguse/opentracks/settings/ActivityTypePreference.java

@@ -43,14 +43,6 @@ import de.dennisguse.opentracks.util.TrackIconUtils;
  */
 public class ActivityTypePreference extends DialogPreference {
 
-    private SummaryProvider<DialogPreference> summaryProvider = new SummaryProvider<DialogPreference>() {
-        @Override
-        public CharSequence provideSummary(DialogPreference preference) {
-            String defaultActivity = PreferencesUtils.getDefaultActivity(ActivityTypePreference.this.getContext());
-            return defaultActivity != null && !defaultActivity.equals(PreferencesUtils.DEFAULT_ACTIVITY_DEFAULT) ? defaultActivity : getContext().getString(R.string.value_unknown);
-        }
-    };
-
     public ActivityTypePreference(Context context, AttributeSet attrs) {
         super(context, attrs);
         setDialogLayoutResource(R.layout.preference_activity_type);
@@ -58,6 +50,13 @@ public class ActivityTypePreference extends DialogPreference {
         setNegativeButtonText(android.R.string.cancel);
         setDialogIcon(null);
         setPersistent(true);
+
+        SummaryProvider<DialogPreference> summaryProvider = new SummaryProvider<DialogPreference>() {
+            @Override
+            public CharSequence provideSummary(DialogPreference preference) {
+                return PreferencesUtils.getDefaultActivity(ActivityTypePreference.this.getContext());
+            }
+        };
         setSummaryProvider(summaryProvider);
     }
 

src/main/java/de/dennisguse/opentracks/settings/BluetoothLeAdapter.java

@@ -0,0 +1,112 @@
+package de.dennisguse.opentracks.settings;
+
+import android.bluetooth.BluetoothDevice;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.BaseAdapter;
+import android.widget.TextView;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+
+public class BluetoothLeAdapter extends BaseAdapter {
+
+    /**
+     * Contains a unique list (by address) of devices.
+     */
+    private final List<Device> devices = new ArrayList<>();
+
+    @Override
+    public int getCount() {
+        return devices.size();
+    }
+
+    @Override
+    public Object getItem(int position) {
+        return devices.get(position);
+    }
+
+    @Override
+    public long getItemId(int position) {
+        return devices.get(position).hashCode();
+    }
+
+    @Override
+    public View getView(int position, View convertView, ViewGroup parent) {
+        View currentView = convertView;
+        if (convertView == null) {
+            LayoutInflater inflater = LayoutInflater.from(parent.getContext());
+            //TODO Check if there is a better way to achieve identical look and feel to ListPreference.
+            //Use material design single choice; for old style use: android.R.layout.select_dialog_singlechoice
+            currentView = inflater.inflate(androidx.appcompat.R.layout.select_dialog_singlechoice_material, null);
+        }
+
+        Device device = devices.get(position);
+        TextView textView = currentView.findViewById(android.R.id.text1);
+        textView.setText(device.getName());
+
+        return currentView;
+    }
+
+    public void add(String name, String address) {
+        Device device = new Device(name, address);
+        if (!devices.contains(device)) {
+            devices.add(new Device(name, address));
+        } else {
+            for (Device currentDevice : devices) {
+                if (currentDevice.getAddress().equals(address)) {
+                    currentDevice.setName(name);
+                }
+            }
+        }
+        notifyDataSetChanged();
+    }
+
+    public void add(BluetoothDevice bluetoothDevice) {
+        add(bluetoothDevice.getName(), bluetoothDevice.getAddress());
+    }
+
+    public Device get(int index) {
+        return devices.get(index);
+    }
+
+    public class Device {
+        private String name;
+        private String address;
+
+        public Device(String name, String address) {
+            this.name = name;
+            this.address = address;
+        }
+
+        public String getName() {
+            return name;
+        }
+
+        public void setName(String name) {
+            this.name = name;
+        }
+
+        public String getAddress() {
+            return address;
+        }
+
+        /**
+         * Check if the address is identical.
+         */
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (!(o instanceof Device)) return false;
+            Device device = (Device) o;
+            return address.equals(device.address);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(name, address);
+        }
+    }
+}

src/main/java/de/dennisguse/opentracks/settings/BluetoothLePreference.java

@@ -0,0 +1,199 @@
+package de.dennisguse.opentracks.settings;
+
+import android.bluetooth.BluetoothAdapter;
+import android.bluetooth.le.BluetoothLeScanner;
+import android.bluetooth.le.ScanCallback;
+import android.bluetooth.le.ScanFilter;
+import android.bluetooth.le.ScanResult;
+import android.bluetooth.le.ScanSettings;
+import android.content.Context;
+import android.content.DialogInterface;
+import android.os.Bundle;
+import android.os.ParcelUuid;
+import android.text.TextUtils;
+import android.util.AttributeSet;
+import android.util.Log;
+import android.widget.Toast;
+
+import androidx.appcompat.app.AlertDialog;
+import androidx.preference.DialogPreference;
+import androidx.preference.PreferenceDialogFragmentCompat;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import de.dennisguse.opentracks.R;
+import de.dennisguse.opentracks.util.BluetoothUtils;
+
+/**
+ * Preference to select a discoverable Bluetooth LE device.
+ * Based upon ListPreference.
+ */
+public class BluetoothLePreference extends DialogPreference {
+
+    private final static String TAG = BluetoothLePreference.class.getSimpleName();
+
+    public BluetoothLePreference(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
+        super(context, attrs, defStyleAttr, defStyleRes);
+    }
+
+    public BluetoothLePreference(Context context, AttributeSet attrs, int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+    }
+
+    public BluetoothLePreference(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    public BluetoothLePreference(Context context) {
+        super(context);
+    }
+
+    private String value;
+    private boolean valueSet = false;
+
+    public String getValue() {
+        return value;
+    }
+
+    public void setValue(String value) {
+        final boolean changed = !TextUtils.equals(this.value, value);
+        if (changed || !valueSet) {
+            this.value = value;
+            valueSet = true;
+            persistString(value);
+            if (changed) {
+                notifyChanged();
+            }
+        }
+    }
+
+    @Override
+    protected void onSetInitialValue(Object defaultValue) {
+        setValue(getPersistedString((String) defaultValue));
+    }
+
+    @Override
+    public CharSequence getSummary() {
+        return getValue();
+    }
+
+    public static class BluetoothLePreferenceDialog extends PreferenceDialogFragmentCompat {
+
+        private int selectedEntryIndex;
+        private BluetoothLeAdapter listAdapter = new BluetoothLeAdapter();
+
+        private BluetoothLeScanner scanner = null;
+        private ScanCallback scanCallback = new ScanCallback() {
+            @Override
+            public void onScanResult(int callbackType, ScanResult result) {
+                super.onScanResult(callbackType, result);
+                Log.d(TAG, "Found device " + result.getDevice().getName() + " " + result);
+
+                listAdapter.add(result.getDevice());
+            }
+
+            @Override
+            public void onBatchScanResults(List<ScanResult> results) {
+                for (ScanResult scanResult : results) {
+                    listAdapter.add(scanResult.getDevice());
+                }
+            }
+
+            @Override
+            public void onScanFailed(int errorCode) {
+                super.onScanFailed(errorCode);
+                Log.e(TAG, "Bluetooth scan failed with errorCode " + errorCode);
+                Toast.makeText(getContext(), R.string.sensor_could_not_scan, Toast.LENGTH_LONG).show();
+                dismiss();
+            }
+        };
+
+        static BluetoothLePreferenceDialog newInstance(String key) {
+            final BluetoothLePreferenceDialog fragment = new BluetoothLePreferenceDialog();
+            final Bundle b = new Bundle(1);
+            b.putString(ARG_KEY, key);
+            fragment.setArguments(b);
+            return fragment;
+        }
+
+        @Override
+        public void onCreate(Bundle savedInstanceState) {
+            super.onCreate(savedInstanceState);
+
+            BluetoothAdapter bluetoothAdapter = BluetoothUtils.getDefaultBluetoothAdapter(TAG);
+            if (bluetoothAdapter == null || !bluetoothAdapter.isEnabled()) {
+                Log.w(TAG, "Bluetooth adapter is present or not enabled.");
+                Toast.makeText(getContext(), R.string.bluetooth_disabled, Toast.LENGTH_SHORT).show();
+                dismiss();
+                return;
+            }
+
+            if (bluetoothAdapter.isDiscovering()) {
+                Log.i(TAG, "Cancelling ongoing bluetooth discovery.");
+                bluetoothAdapter.cancelDiscovery();
+            }
+
+            scanner = bluetoothAdapter.getBluetoothLeScanner();
+            if (scanner == null) {
+                Log.e(TAG, "BluetoothLeScanner is null.");
+                dismiss();
+                return;
+            }
+
+            String deviceNone = getContext().getString(R.string.sensor_type_value_none);
+            listAdapter.add(getContext().getString(R.string.value_none), deviceNone);
+            selectedEntryIndex = 0;
+
+            BluetoothLePreference preference = (BluetoothLePreference) getPreference();
+            String deviceSelected = preference.getValue();
+            if (!deviceNone.equals(deviceSelected)) {
+                listAdapter.add(preference.getValue(), preference.getValue());
+                selectedEntryIndex = 1;
+            }
+
+            ScanFilter.Builder scanFilterBuilder = new ScanFilter.Builder().setServiceUuid(new ParcelUuid(BluetoothUtils.HEART_RATE_SERVICE_UUID));
+            List<ScanFilter> scanFilter = new ArrayList<>();
+            scanFilter.add(scanFilterBuilder.build());
+
+            ScanSettings.Builder scanSettingsBuilder = new ScanSettings.Builder();
+            scanSettingsBuilder.setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY);
+
+            scanner.startScan(scanFilter, scanSettingsBuilder.build(), scanCallback);
+        }
+
+        //Behave like ListPreferenceDialogFragmentCompat, but uses a custom listAdapter.
+        @Override
+        protected void onPrepareDialogBuilder(AlertDialog.Builder builder) {
+            super.onPrepareDialogBuilder(builder);
+
+            builder.setSingleChoiceItems(listAdapter, selectedEntryIndex,
+                    new DialogInterface.OnClickListener() {
+                        @Override
+                        public void onClick(DialogInterface dialog, int which) {
+                            selectedEntryIndex = which;
+
+                            BluetoothLePreferenceDialog.this.onClick(dialog, DialogInterface.BUTTON_POSITIVE);
+                            dialog.dismiss();
+                        }
+                    });
+            builder.setIcon(android.R.drawable.stat_sys_data_bluetooth);
+            builder.setPositiveButton(null, null);
+        }
+
+        @Override
+        public void onDialogClosed(boolean positiveResult) {
+            if (scanner != null) {
+                scanner.stopScan(scanCallback);
+            }
+
+            if (positiveResult && selectedEntryIndex >= 0) {
+                String value = listAdapter.get(selectedEntryIndex).getAddress();
+                BluetoothLePreference preference = (BluetoothLePreference) getPreference();
+                if (preference.callChangeListener(value)) {
+                    preference.setValue(value);
+                }
+            }
+        }
+    }
+}

src/main/java/de/dennisguse/opentracks/settings/PreferenceHelper.java

@@ -1,210 +1,163 @@
 package de.dennisguse.opentracks.settings;
 
-import android.bluetooth.BluetoothAdapter;
 import android.content.Context;
 
-import androidx.preference.ListPreference;
-
-import java.util.ArrayList;
-import java.util.List;
-
 import de.dennisguse.opentracks.R;
-import de.dennisguse.opentracks.util.BluetoothUtils;
 import de.dennisguse.opentracks.util.PreferencesUtils;
 import de.dennisguse.opentracks.util.UnitConversions;
 
 final class PreferenceHelper {
 
-    /**
-     * Sets the min recording interval options.
-     *
-     * @param options the options
-     * @param values  the values
-     */
-    static void setMinRecordingIntervalOptions(Context context, String[] options, String[] values) {
-        for (int i = 0; i < values.length; i++) {
-            int value = Integer.parseInt(values[i]);
-            switch (value) {
-                case PreferencesUtils.MIN_RECORDING_INTERVAL_ADAPT_BATTERY_LIFE:
-                    options[i] = context.getString(R.string.value_adapt_battery_life);
-                    break;
-                case PreferencesUtils.MIN_RECORDING_INTERVAL_ADAPT_ACCURACY:
-                    options[i] = context.getString(R.string.value_adapt_accuracy);
-                    break;
-                case PreferencesUtils.MIN_RECORDING_INTERVAL_DEFAULT:
-                    options[i] = context.getString(R.string.value_smallest_recommended);
-                    break;
-                default:
-                    options[i] = value < 60 ? context.getString(R.string.value_integer_second, value) : context.getString(R.string.value_integer_minute, value / 60);
+    static String[] getMinRecordingIntervalEntries(Context context) {
+        String[] entryValues = context.getResources().getStringArray(R.array.min_recording_interval_values);
+        String[] entries = new String[entryValues.length];
+        for (int i = 0; i < entryValues.length; i++) {
+            int value = Integer.parseInt(entryValues[i]);
+
+            if (value == PreferencesUtils.getMinRecordingIntervalAdaptAccuracy(context)) {
+                entries[i] = context.getString(R.string.value_adapt_accuracy);
+            } else if (value == PreferencesUtils.getMinRecordingIntervalAdaptBatteryLife(context)) {
+                entries[i] = context.getString(R.string.value_adapt_battery_life);
+            } else if (value == PreferencesUtils.getMinRecordingIntervalDefault(context)) {
+                entries[i] = context.getString(R.string.value_smallest_recommended);
+            } else {
+                entries[i] = value < 60 ? context.getString(R.string.value_integer_second, value) : context.getString(R.string.value_integer_minute, value / 60);
             }
         }
+
+        return entries;
     }
 
-    /**
-     * Sets the recording distance interval options.
-     *
-     * @param options     the options
-     * @param values      the values
-     * @param metricUnits true for metric units
-     */
-    static void setRecordingDistanceIntervalOptions(Context context, String[] options, String[] values, boolean metricUnits) {
-        for (int i = 0; i < values.length; i++) {
-            int value = Integer.parseInt(values[i]);
+    static String[] getRecordingDistanceIntervalEntries(Context context, boolean metricUnits) {
+        String[] entryValues = context.getResources().getStringArray(R.array.recording_distance_interval_values);
+        String[] entries = new String[entryValues.length];
+
+        final int recordingDistanceIntervalDefault = PreferencesUtils.getRecordingDistanceIntervalDefault(context);
+
+        for (int i = 0; i < entryValues.length; i++) {
+            int value = Integer.parseInt(entryValues[i]);
             String displayValue;
             if (metricUnits) {
                 displayValue = context.getString(R.string.value_integer_meter, value);
-                if (value == PreferencesUtils.RECORDING_DISTANCE_INTERVAL_DEFAULT) {
-                    options[i] = context.getString(R.string.value_integer_meter_recommended, value);
+                if (value == recordingDistanceIntervalDefault) {
+                    entries[i] = context.getString(R.string.value_integer_meter_recommended, value);
                 } else {
-                    options[i] = displayValue;
+                    entries[i] = displayValue;
                 }
             } else {
                 int feet = (int) (value * UnitConversions.M_TO_FT);
                 displayValue = context.getString(R.string.value_integer_feet, feet);
-                if (value == PreferencesUtils.RECORDING_DISTANCE_INTERVAL_DEFAULT) {
-                    options[i] = context.getString(R.string.value_integer_feet_recommended, feet);
+                if (value == recordingDistanceIntervalDefault) {
+                    entries[i] = context.getString(R.string.value_integer_feet_recommended, feet);
                 } else {
-                    options[i] = displayValue;
+                    entries[i] = displayValue;
                 }
             }
         }
+
+        return entries;
     }
 
-    /**
-     * Sets the max recording distance options.
-     *
-     * @param options     the options
-     * @param values      the values
-     * @param metricUnits true for metric units
-     */
-    static void setMaxRecordingDistanceOptions(Context context, String[] options, String[] values, boolean metricUnits) {
-        for (int i = 0; i < values.length; i++) {
-            int value = Integer.parseInt(values[i]);
+    static String[] getMaxRecordingDistanceEntries(Context context, boolean metricUnits) {
+        String[] entryValues = context.getResources().getStringArray(R.array.max_recording_distance_values);
+        String[] entries = new String[entryValues.length];
+
+        final int maxRecordingDistanceDefault = Integer.parseInt(context.getResources().getString(R.string.max_recording_distance_default));
+
+        for (int i = 0; i < entryValues.length; i++) {
+            int value = Integer.parseInt(entryValues[i]);
             String displayValue;
             if (metricUnits) {
                 displayValue = context.getString(R.string.value_integer_meter, value);
-                if (value == PreferencesUtils.MAX_RECORDING_DISTANCE_DEFAULT) {
-                    options[i] = context.getString(R.string.value_integer_meter_recommended, value);
+                if (value == maxRecordingDistanceDefault) {
+                    entries[i] = context.getString(R.string.value_integer_meter_recommended, value);
                 } else {
-                    options[i] = displayValue;
+                    entries[i] = displayValue;
                 }
             } else {
                 int feet = (int) (value * UnitConversions.M_TO_FT);
                 if (feet < 2000) {
                     displayValue = context.getString(R.string.value_integer_feet, feet);
-                    if (value == PreferencesUtils.MAX_RECORDING_DISTANCE_DEFAULT) {
-                        options[i] = context.getString(R.string.value_integer_feet_recommended, feet);
+                    if (value == maxRecordingDistanceDefault) {
+                        entries[i] = context.getString(R.string.value_integer_feet_recommended, feet);
                     } else {
-                        options[i] = displayValue;
+                        entries[i] = displayValue;
                     }
                 } else {
                     double mile = feet * UnitConversions.FT_TO_MI;
                     displayValue = context.getString(R.string.value_float_mile, mile);
-                    options[i] = displayValue;
+                    entries[i] = displayValue;
                 }
             }
         }
+
+        return entries;
     }
 
-    /**
-     * Sets the recording gps accuracy options.
-     *
-     * @param options     the options
-     * @param values      the values
-     * @param metricUnits true for metric units
-     */
-    static void setRecordingGpsAccuracyOptions(Context context, String[] options, String[] values, boolean metricUnits) {
-        for (int i = 0; i < values.length; i++) {
-            int value = Integer.parseInt(values[i]);
+    static String[] getRecordingGpsAccuracyEntries(Context context, boolean metricUnits) {
+        String[] entryValues = context.getResources().getStringArray(R.array.recording_gps_accuracy_values);
+        String[] entries = new String[entryValues.length];
+
+        final int recordingGPSAccuracyDefault = Integer.parseInt(context.getResources().getString(R.string.recording_gps_accuracy_default));
+        final int recordingGPSAccuracyExcellent = Integer.parseInt(context.getResources().getString(R.string.recording_gps_accuracy_excellent));
+        final int recordingGPSAccuracyPoor = Integer.parseInt(context.getResources().getString(R.string.recording_gps_accuracy_poor));
+
+        for (int i = 0; i < entryValues.length; i++) {
+            int value = Integer.parseInt(entryValues[i]);
             String displayValue;
             if (metricUnits) {
                 displayValue = context.getString(R.string.value_integer_meter, value);
-                switch (value) {
-                    case PreferencesUtils.RECORDING_GPS_ACCURACY_DEFAULT:
-                        options[i] = context.getString(R.string.value_integer_meter_recommended, value);
-                        break;
-                    case PreferencesUtils.RECORDING_GPS_ACCURACY_EXCELLENT:
-                        options[i] = context.getString(R.string.value_integer_meter_excellent_gps, value);
-                        break;
-                    case PreferencesUtils.RECORDING_GPS_ACCURACY_POOR:
-                        options[i] = context.getString(R.string.value_integer_meter_poor_gps, value);
-                        break;
-                    default:
-                        options[i] = displayValue;
+                if (value == recordingGPSAccuracyDefault) {
+                    entries[i] = context.getString(R.string.value_integer_meter_recommended, value);
+                } else if (value == recordingGPSAccuracyExcellent) {
+                    entries[i] = context.getString(R.string.value_integer_meter_excellent_gps, value);
+                } else if (value == recordingGPSAccuracyPoor) {
+                    entries[i] = context.getString(R.string.value_integer_meter_poor_gps, value);
+                } else {
+                    entries[i] = displayValue;
                 }
             } else {
                 int feet = (int) (value * UnitConversions.M_TO_FT);
                 if (feet < 2000) {
                     displayValue = context.getString(R.string.value_integer_feet, feet);
-                    switch (value) {
-                        case PreferencesUtils.RECORDING_GPS_ACCURACY_DEFAULT:
-                            options[i] = context.getString(R.string.value_integer_feet_recommended, feet);
-                            break;
-                        case PreferencesUtils.RECORDING_GPS_ACCURACY_EXCELLENT:
-                            options[i] = context.getString(R.string.value_integer_feet_excellent_gps, feet);
-                            break;
-                        default:
-                            options[i] = displayValue;
+
+                    if (value == recordingGPSAccuracyDefault) {
+                        entries[i] = context.getString(R.string.value_integer_feet_recommended, feet);
+                    } else if (value == recordingGPSAccuracyExcellent) {
+                        entries[i] = context.getString(R.string.value_integer_feet_excellent_gps, feet);
+                    } else {
+                        entries[i] = displayValue;
                     }
                 } else {
                     double mile = feet * UnitConversions.FT_TO_MI;
                     displayValue = context.getString(R.string.value_float_mile, mile);
-                    if (value == PreferencesUtils.RECORDING_GPS_ACCURACY_POOR) {
-                        options[i] = context.getString(R.string.value_float_mile_poor_gps, mile);
+                    if (value == recordingGPSAccuracyPoor) {
+                        entries[i] = context.getString(R.string.value_float_mile_poor_gps, mile);
                     } else {
-                        options[i] = displayValue;
+                        entries[i] = displayValue;
                     }
                 }
             }
         }
+
+        return entries;
     }
 
-    /**
-     * Sets the auto resume track timeout options.
-     *
-     * @param options the options
-     * @param values  the values
-     */
-    static void setAutoResumeTrackTimeoutOptions(Context context, String[] options, String[] values) {
-        for (int i = 0; i < values.length; i++) {
-            int value = Integer.parseInt(values[i]);
+    static String[] getAutoResumeTrackTimeoutEntries(Context context) {
+        String[] entryValues = context.getResources().getStringArray(R.array.auto_resume_track_timeout_values);
+        String[] entries = new String[entryValues.length];
+
+        for (int i = 0; i < entryValues.length; i++) {
+            int value = Integer.parseInt(entryValues[i]);
             if (value == Integer.parseInt(context.getResources().getString(R.string.auto_resume_track_timeout_never))) {
-                options[i] = context.getString(R.string.value_never);
+                entries[i] = context.getString(R.string.value_never);
             } else if (value == Integer.parseInt(context.getResources().getString(R.string.auto_resume_track_timeout_always))) {
-                options[i] = context.getString(R.string.value_always);
+                entries[i] = context.getString(R.string.value_always);
             } else {
-                options[i] = context.getString(R.string.value_integer_minute, value);
+                entries[i] = context.getString(R.string.value_integer_minute, value);
             }
         }
-    }
 
-    /**
-     * Configures the bluetooth sensor.
-     */
-    static void configureBluetoothSensorList(ListPreference preference) {
-        Context context = preference.getContext();
-
-        String value = PreferencesUtils.getString(context, R.string.settings_sensor_bluetooth_sensor_key, PreferencesUtils.BLUETOOTH_SENSOR_DEFAULT);
-        List<String> devicesNameList = new ArrayList<>();
-        List<String> devicesAddressList = new ArrayList<>();
-        BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
-        if (bluetoothAdapter != null) {
-            BluetoothUtils.populateDeviceLists(bluetoothAdapter, devicesNameList, devicesAddressList);
-        }
-
-        // Was the previously configured device unpaired? Then forget it.
-        if (!devicesAddressList.contains(value)) {
-            value = PreferencesUtils.BLUETOOTH_SENSOR_DEFAULT;
-            PreferencesUtils.setString(context, R.string.settings_sensor_bluetooth_sensor_key, value);
-        }
-
-        devicesNameList.add(0, context.getString(R.string.value_none));
-        devicesAddressList.add(0, PreferencesUtils.BLUETOOTH_SENSOR_DEFAULT);
-
-        String[] values = devicesAddressList.toArray(new String[0]);
-        preference.setEntryValues(values);
-
-        String[] options = devicesNameList.toArray(new String[0]);
-        preference.setEntries(options);
+        return entries;
     }
 }

src/main/java/de/dennisguse/opentracks/settings/SettingsActivity.java

@@ -13,12 +13,15 @@ import androidx.preference.PreferenceFragmentCompat;
 
 import de.dennisguse.opentracks.R;
 import de.dennisguse.opentracks.fragments.ChooseActivityTypeDialogFragment;
+import de.dennisguse.opentracks.util.BluetoothUtils;
 import de.dennisguse.opentracks.util.HackUtils;
 import de.dennisguse.opentracks.util.PreferencesUtils;
 import de.dennisguse.opentracks.util.StringUtils;
 
 public class SettingsActivity extends AppCompatActivity implements ChooseActivityTypeDialogFragment.ChooseActivityTypeCaller, ResetDialogPreference.ResetCallback {
 
+    private static final String TAG = SettingsActivity.class.getSimpleName();
+
     private PrefsFragment prefsFragment;
 
     @Override
@@ -54,13 +57,14 @@ public class SettingsActivity extends AppCompatActivity implements ChooseActivit
         private final SharedPreferences.OnSharedPreferenceChangeListener sharedPreferenceChangeListener = new SharedPreferences.OnSharedPreferenceChangeListener() {
             @Override
             public void onSharedPreferenceChanged(SharedPreferences preferences, String key) {
-                getActivity().runOnUiThread(new Runnable() {
-                    @Override
-                    public void run() {
-                        updateUI();
-                    }
-                });
-
+                if (PreferencesUtils.isKey(getActivity(), R.string.recording_track_id_key, key)) {
+                    getActivity().runOnUiThread(new Runnable() {
+                        @Override
+                        public void run() {
+                            updateReset();
+                        }
+                    });
+                }
                 if (PreferencesUtils.isKey(getActivity(), R.string.stats_units_key, key)) {
                     getActivity().runOnUiThread(new Runnable() {
                         @Override
@@ -69,6 +73,14 @@ public class SettingsActivity extends AppCompatActivity implements ChooseActivit
                         }
                     });
                 }
+                if (PreferencesUtils.isKey(getActivity(), R.string.stats_rate_key, key)) {
+                    getActivity().runOnUiThread(new Runnable() {
+                        @Override
+                        public void run() {
+                            updateSpeed();
+                        }
+                    });
+                }
             }
         };
 
@@ -86,14 +98,16 @@ public class SettingsActivity extends AppCompatActivity implements ChooseActivit
 
                 setPreferencesFromResource(R.xml.settings, rootKey);
             }
-            updateUnits();
         }
 
         @Override
         public void onResume() {
             super.onResume();
             PreferencesUtils.getSharedPreferences(getActivity()).registerOnSharedPreferenceChangeListener(sharedPreferenceChangeListener);
-            updateUI();
+            updateSpeed();
+            updateUnits();
+            updateReset();
+            updateBluetooth();
         }
 
         @Override
@@ -102,40 +116,6 @@ public class SettingsActivity extends AppCompatActivity implements ChooseActivit
             PreferencesUtils.getSharedPreferences(getActivity()).unregisterOnSharedPreferenceChangeListener(sharedPreferenceChangeListener);
         }
 
-        private void configFrequencyPreference(int key, boolean metricUnits) {
-            ListPreference preference = findPreference(getString(key));
-
-            String[] options = StringUtils.getFrequencyOptions(getActivity(), metricUnits);
-            preference.setEntries(options);
-        }
-
-        private void configListPreference(int key, int valueArray, boolean metricUnits) {
-            String[] values = getResources().getStringArray(valueArray);
-            final String[] options = new String[values.length];
-            switch (key) {
-                case R.string.min_recording_interval_key:
-                    PreferenceHelper.setMinRecordingIntervalOptions(getActivity(), options, values);
-                    break;
-                case R.string.recording_distance_interval_key:
-                    PreferenceHelper.setRecordingDistanceIntervalOptions(getActivity(), options, values, metricUnits);
-                    break;
-                case R.string.max_recording_distance_key:
-                    PreferenceHelper.setMaxRecordingDistanceOptions(getActivity(), options, values, metricUnits);
-                    break;
-                case R.string.recording_gps_accuracy_key:
-                    PreferenceHelper.setRecordingGpsAccuracyOptions(getActivity(), options, values, metricUnits);
-                    break;
-                case R.string.auto_resume_track_timeout_key:
-                    PreferenceHelper.setAutoResumeTrackTimeoutOptions(getActivity(), options, values);
-                    break;
-                default:
-                    return;
-            }
-
-            final ListPreference listPreference = findPreference(getString(key));
-            listPreference.setEntries(options);
-        }
-
         @Override
         public void onDisplayPreferenceDialog(Preference preference) {
             DialogFragment dialogFragment = null;
@@ -144,6 +124,8 @@ public class SettingsActivity extends AppCompatActivity implements ChooseActivit
             } else if (preference instanceof ActivityTypePreference) {
                 activityPreferenceDialog = ActivityTypePreference.ActivityPreferenceDialog.newInstance(preference.getKey());
                 dialogFragment = activityPreferenceDialog;
+            } else if (preference instanceof BluetoothLePreference) {
+                dialogFragment = BluetoothLePreference.BluetoothLePreferenceDialog.newInstance(preference.getKey());
             }
 
             if (dialogFragment != null) {
@@ -161,35 +143,51 @@ public class SettingsActivity extends AppCompatActivity implements ChooseActivit
             }
         }
 
-        private void updateUI() {
+        private void updateReset() {
             final boolean isRecording = PreferencesUtils.isRecording(getActivity());
             Preference resetPreference = findPreference(getString(R.string.settings_reset_key));
             resetPreference.setSummary(isRecording ? getString(R.string.settings_not_while_recording) : "");
             resetPreference.setEnabled(!isRecording);
+        }
 
+        private void updateSpeed() {
             Preference speedCheckBoxPreference = findPreference(getString(R.string.chart_show_speed_key));
             speedCheckBoxPreference.setTitle(PreferencesUtils.isReportSpeed(getActivity()) ? R.string.stats_speed : R.string.stats_pace);
+        }
 
-            ListPreference bluetoothPreference = findPreference(getString(R.string.settings_sensor_bluetooth_sensor_key));
-            PreferenceHelper.configureBluetoothSensorList(bluetoothPreference);
+        private void updateBluetooth() {
+            // Disable Bluetooth preference if device does not have Bluetooth
+            BluetoothLePreference bluetoothPreference = findPreference(getString(R.string.settings_sensor_bluetooth_heart_rate_key));
+            bluetoothPreference.setVisible(BluetoothUtils.hasBluetooth(TAG));
         }
 
         private void updateUnits() {
             boolean metricUnits = PreferencesUtils.isMetricUnits(getActivity());
 
-            //TODO Refactor this!
-            configFrequencyPreference(R.string.voice_frequency_key, metricUnits);
-            configFrequencyPreference(R.string.split_frequency_key, metricUnits);
-            configListPreference(R.string.min_recording_interval_key, R.array.min_recording_interval_values, metricUnits);
-            configListPreference(R.string.recording_distance_interval_key, R.array.recording_distance_interval_values, metricUnits);
-            configListPreference(R.string.max_recording_distance_key, R.array.max_recording_distance_values, metricUnits);
-            configListPreference(R.string.recording_gps_accuracy_key, R.array.recording_gps_accuracy_values, metricUnits);
-            configListPreference(R.string.auto_resume_track_timeout_key, R.array.auto_resume_track_timeout_values, metricUnits);
-            configListPreference(R.string.auto_resume_track_timeout_key, R.array.auto_resume_track_timeout_values, metricUnits);
+            ListPreference voiceFrequency = findPreference(getString(R.string.voice_frequency_key));
+            voiceFrequency.setEntries(StringUtils.getFrequencyOptions(getActivity(), metricUnits));
 
-            final ListPreference statsRatePreferences = findPreference(getString(R.string.stats_rate_key));
-            String[] options = getResources().getStringArray(metricUnits ? R.array.stats_rate_metric_options : R.array.stats_rate_imperial_options);
-            statsRatePreferences.setEntries(options);
+            ListPreference splitFrequency = findPreference(getString(R.string.split_frequency_key));
+            splitFrequency.setEntries(StringUtils.getFrequencyOptions(getActivity(), metricUnits));
+
+            ListPreference minRecordingInterval = findPreference(getString(R.string.min_recording_interval_key));
+            minRecordingInterval.setEntries(PreferenceHelper.getMinRecordingIntervalEntries(getActivity()));
+
+            ListPreference recordingDistanceInterval = findPreference(getString(R.string.recording_distance_interval_key));
+            recordingDistanceInterval.setEntries(PreferenceHelper.getRecordingDistanceIntervalEntries(getActivity(), metricUnits));
+
+            ListPreference maxRecordingDistance = findPreference(getString(R.string.max_recording_distance_key));
+            maxRecordingDistance.setEntries(PreferenceHelper.getMaxRecordingDistanceEntries(getActivity(), metricUnits));
+
+            ListPreference recordingGpsAccuracy = findPreference(getString(R.string.recording_gps_accuracy_key));
+            recordingGpsAccuracy.setEntries(PreferenceHelper.getRecordingGpsAccuracyEntries(getActivity(), metricUnits));
+
+            ListPreference autoresumeTrack = findPreference(getString(R.string.auto_resume_track_timeout_key));
+            autoresumeTrack.setEntries(PreferenceHelper.getAutoResumeTrackTimeoutEntries(getActivity()));
+
+            ListPreference statsRatePreferences = findPreference(getString(R.string.stats_rate_key));
+            String[] entries = getResources().getStringArray(metricUnits ? R.array.stats_rate_metric_options : R.array.stats_rate_imperial_options);
+            statsRatePreferences.setEntries(entries);
 
             HackUtils.invalidatePreference(statsRatePreferences);
         }

src/main/java/de/dennisguse/opentracks/util/BluetoothUtils.java

@@ -16,12 +16,13 @@
 package de.dennisguse.opentracks.util;
 
 import android.bluetooth.BluetoothAdapter;
-import android.bluetooth.BluetoothClass;
-import android.bluetooth.BluetoothDevice;
 import android.bluetooth.BluetoothGattCharacteristic;
+import android.os.Handler;
+import android.os.Looper;
+import android.util.Log;
 
-import java.util.List;
-import java.util.Set;
+import java.util.ArrayList;
+import java.util.UUID;
 
 /**
  * Utilities for dealing with bluetooth devices.
@@ -30,29 +31,50 @@ import java.util.Set;
  */
 public class BluetoothUtils {
 
+    public static final UUID HEART_RATE_SERVICE_UUID = new UUID(0x180D00001000L, 0x800000805f9b34fbL);
+
     private BluetoothUtils() {
     }
 
-    /**
-     * Populates the device names and the device addresses with all the suitable
-     * bluetooth devices.
-     *
-     * @param bluetoothAdapter the bluetooth adapter
-     * @param deviceNames      list of device names
-     * @param deviceAddresses  list of device addresses
-     */
-    public static void populateDeviceLists(BluetoothAdapter bluetoothAdapter, List<String> deviceNames, List<String> deviceAddresses) {
-        // Ensure the bluetooth adapter is not in discovery mode.
-        bluetoothAdapter.cancelDiscovery();
+    public static BluetoothAdapter getDefaultBluetoothAdapter(final String TAG) {
+        // If from the main application thread, return directly
+        if (Thread.currentThread().equals(Looper.getMainLooper().getThread())) {
+            return BluetoothAdapter.getDefaultAdapter();
+        }
 
-        Set<BluetoothDevice> pairedDevices = bluetoothAdapter.getBondedDevices();
-        for (BluetoothDevice device : pairedDevices) {
-            BluetoothClass bluetoothClass = device.getBluetoothClass();
-            if (bluetoothClass != null && (bluetoothClass.getDeviceClass() & BluetoothClass.Device.HEALTH_PULSE_RATE) != 0) {
-                deviceAddresses.add(device.getAddress());
-                deviceNames.add(device.getName());
+        // Get the default adapter from the main application thread
+        final ArrayList<BluetoothAdapter> adapters = new ArrayList<>(1);
+        final Object mutex = new Object();
+
+        Handler handler = new Handler(Looper.getMainLooper());
+        handler.post(new Runnable() {
+            @Override
+            public void run() {
+                adapters.add(BluetoothAdapter.getDefaultAdapter());
+                synchronized (mutex) {
+                    mutex.notify();
+                }
+            }
+        });
+
+        while (adapters.isEmpty()) {
+            synchronized (mutex) {
+                try {
+                    mutex.wait(UnitConversions.ONE_SECOND);
+                } catch (InterruptedException e) {
+                    Log.e(TAG, "Interrupted while waiting for default bluetooth adapter", e);
+                }
             }
         }
+
+        if (adapters.get(0) == null) {
+            Log.w(TAG, "No bluetooth adapter found.");
+        }
+        return adapters.get(0);
+    }
+
+    public static boolean hasBluetooth(final String TAG) {
+        return BluetoothUtils.getDefaultBluetoothAdapter(TAG) != null;
     }
 
     public static int parseHeartRate(BluetoothGattCharacteristic characteristic) {

src/main/java/de/dennisguse/opentracks/util/LocationUtils.java

@@ -157,7 +157,7 @@ public class LocationUtils {
     }
 
     /**
-     * Checks if a given location is a valid (i.e. physically possible) locationon Earth.
+     * Checks if a given location is a valid (i.e. physically possible) location on Earth.
      * Note: The special separator locations (which have latitude = 100) will not qualify as valid.
      * Neither will locations with lat=0 and lng=0 as these are most likely "bad" measurements which often cause trouble.
      *

src/main/java/de/dennisguse/opentracks/util/PreferencesUtils.java

@@ -32,41 +32,8 @@ import de.dennisguse.opentracks.R;
  */
 public class PreferencesUtils {
 
-    /*
-     * Preferences values.
-     * The defaults need to match the defaults in the xml files.
-     */
-    @Deprecated
-    public static final boolean RECORDING_TRACK_PAUSED_DEFAULT = true;
-
     public static final String BLUETOOTH_SENSOR_DEFAULT = "";
 
-    // Value for split_frequency_key and voice_frequency_key
-    @Deprecated
-    public static final int FREQUENCY_OFF = 0;
-
-    @Deprecated
-    public static final int MAX_RECORDING_DISTANCE_DEFAULT = 200;
-
-    // Values for min_recording_interval_key
-    @Deprecated
-    public static final int MIN_RECORDING_INTERVAL_ADAPT_ACCURACY = -1;
-    @Deprecated
-    public static final int MIN_RECORDING_INTERVAL_ADAPT_BATTERY_LIFE = -2;
-    @Deprecated
-    public static final int MIN_RECORDING_INTERVAL_DEFAULT = 0;
-
-    @Deprecated
-    public static final int RECORDING_DISTANCE_INTERVAL_DEFAULT = 10;
-
-    // Values for recording_gps_accuracy
-    @Deprecated
-    public static final int RECORDING_GPS_ACCURACY_DEFAULT = 50;
-    @Deprecated
-    public static final int RECORDING_GPS_ACCURACY_EXCELLENT = 10;
-    @Deprecated
-    public static final int RECORDING_GPS_ACCURACY_POOR = 2000;
-
     private PreferencesUtils() {
     }
 
@@ -99,11 +66,8 @@ public class PreferencesUtils {
         PreferencesUtils.setInt(context, R.string.auto_resume_track_current_retry_key, getAutoResumeTrackCurrentRetryDefault(context) + 1);
     }
 
-
-    public static final String DEFAULT_ACTIVITY_DEFAULT = "";
-
     public static String getDefaultActivity(Context context) {
-        return PreferencesUtils.getString(context, R.string.default_activity_key, PreferencesUtils.DEFAULT_ACTIVITY_DEFAULT);
+        return PreferencesUtils.getString(context, R.string.default_activity_key, context.getString(R.string.default_activity_default));
     }
 
     public static void setDefaultActivity(Context context, String newDefaultActivity) {
@@ -273,9 +237,13 @@ public class PreferencesUtils {
         return PreferencesUtils.getInt(context, R.string.auto_resume_track_timeout_key, AUTO_RESUME_TRACK_TIMEOUT);
     }
 
+
     public static boolean isRecordingTrackPaused(Context context) {
-        final boolean RECORDING_TRACK_PAUSED = context.getResources().getBoolean(R.bool.recording_track_paused_default);
-        return PreferencesUtils.getBoolean(context, R.string.recording_track_paused_key, RECORDING_TRACK_PAUSED);
+        return PreferencesUtils.getBoolean(context, R.string.recording_track_paused_key, isRecordingTrackPausedDefault(context));
+    }
+
+    public static boolean isRecordingTrackPausedDefault(Context context) {
+        return context.getResources().getBoolean(R.bool.recording_track_paused_default);
     }
 
     public static void defaultRecordingTrackPaused(Context context) {
@@ -283,9 +251,12 @@ public class PreferencesUtils {
         PreferencesUtils.setBoolean(context, R.string.recording_track_paused_key, RECORDING_TRACK_PAUSED);
     }
 
-    public static boolean isChartByDistance(Context context) {
-        final String CHART_X_AXIS_DEFAULT = context.getString(R.string.chart_x_axis_default);
-        return CHART_X_AXIS_DEFAULT.equals(getString(context, R.string.chart_x_axis_key, CHART_X_AXIS_DEFAULT));
+    public static boolean isBluetoothHeartRateSensorAddressDefault(Context context) {
+        return PreferencesUtils.BLUETOOTH_SENSOR_DEFAULT.equals(getBluetoothHeartRateSensorAddress(context));
+    }
+
+    public static String getBluetoothHeartRateSensorAddress(Context context) {
+        return PreferencesUtils.getString(context, R.string.settings_sensor_bluetooth_heart_rate_key, PreferencesUtils.BLUETOOTH_SENSOR_DEFAULT);
     }
 
     public static boolean shouldChartShowCadence(Context context) {
@@ -340,7 +311,11 @@ public class PreferencesUtils {
 
     public static int getRecordingDistanceInterval(Context context) {
         final int RECORDING_DISTANCE_INTERVAL = Integer.parseInt(context.getResources().getString(R.string.recording_distance_interval_default));
-        return PreferencesUtils.getInt(context, R.string.recording_distance_interval_key, RECORDING_DISTANCE_INTERVAL);
+        return PreferencesUtils.getInt(context, R.string.recording_distance_interval_key, getRecordingDistanceIntervalDefault(context));
+    }
+
+    public static int getRecordingDistanceIntervalDefault(Context context) {
+        return Integer.parseInt(context.getResources().getString(R.string.recording_distance_interval_default));
     }
 
     public static int getMaxRecordingDistance(Context context) {
@@ -353,6 +328,22 @@ public class PreferencesUtils {
         return PreferencesUtils.getInt(context, R.string.min_recording_interval_key, MIN_RECORDING_INTERVAL);
     }
 
+    public static int getMinRecordingIntervalAdaptAccuracy(Context context) {
+        return Integer.parseInt(context.getResources().getString(R.string.min_recording_interval_adapt_accuracy));
+    }
+
+    public static int getMinRecordingIntervalAdaptBatteryLife(Context context) {
+        return Integer.parseInt(context.getResources().getString(R.string.min_recording_interval_adapt_battery_life));
+    }
+
+    public static int getMinRecordingIntervalDefault(Context context) {
+        return Integer.parseInt(context.getResources().getString(R.string.min_recording_interval_default));
+    }
+
+
+
+
+
     public static int getRecordingGPSAccuracy(Context context) {
         final int RECORDING_GPS_ACCURACY = Integer.parseInt(context.getResources().getString(R.string.recording_gps_accuracy_default));
         return PreferencesUtils.getInt(context, R.string.recording_gps_accuracy_key, RECORDING_GPS_ACCURACY);

src/main/java/de/dennisguse/opentracks/util/StatsUtils.java

@@ -108,7 +108,7 @@ public class StatsUtils {
     public static void setSensorData(Activity activity, SensorDataSet sensorDataSet, boolean isRecording) {
         // heart rate
         int isVisible = View.VISIBLE;
-        if (!isRecording || PreferencesUtils.BLUETOOTH_SENSOR_DEFAULT.equals(PreferencesUtils.getString(activity, R.string.settings_sensor_bluetooth_sensor_key, PreferencesUtils.BLUETOOTH_SENSOR_DEFAULT))) {
+        if (!isRecording || PreferencesUtils.isBluetoothHeartRateSensorAddressDefault(activity)) {
             isVisible = View.INVISIBLE;
         }
         activity.findViewById(R.id.stats_sensor_container).setVisibility(isVisible);
@@ -125,11 +125,18 @@ public class StatsUtils {
                 }
             }
 
-            heartRateValue.setText(heartRate);
+            setBluetoothHeartRateSensorName(activity, sensor, isRecording);
             heartRateSensor.setText(sensor);
         }
     }
 
+    public static void setBluetoothHeartRateSensorName(Activity activity, String sensorName, boolean isRecording) {
+        if (isRecording) {
+            TextView heartRateSensor = activity.findViewById(R.id.stats_sensor_heart_rate_sensor_value);
+            heartRateSensor.setText(sensorName);
+        }
+    }
+
     /**
      * Sets the total time value.
      *

src/main/java/de/dennisguse/opentracks/util/StringUtils.java

@@ -359,7 +359,7 @@ public class StringUtils {
         String[] options = new String[values.length];
         for (int i = 0; i < values.length; i++) {
             int value = Integer.parseInt(values[i]);
-            if (value == PreferencesUtils.FREQUENCY_OFF) {
+            if (context.getString(R.string.frequency_off).equals(values[i])) {
                 options[i] = context.getString(R.string.value_off);
             } else if (value < 0) {
                 options[i] = context.getString(metricUnits ? R.string.value_integer_kilometer : R.string.value_integer_mile, Math.abs(value));

src/main/java/de/dennisguse/opentracks/util/TTSUtils.java

@@ -0,0 +1,13 @@
+package de.dennisguse.opentracks.util;
+
+import android.speech.tts.TextToSpeech;
+
+public class TTSUtils {
+
+    private TTSUtils() {
+    }
+
+    public static int getTTSStream() {
+        return TextToSpeech.Engine.DEFAULT_STREAM;
+    }
+}

src/main/res/layout/help.xml

@@ -0,0 +1,188 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical">
+
+    <include layout="@layout/toolbar" />
+
+    <ScrollView
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content">
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="vertical"
+            android:padding="20dp">
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="@string/help_feature_title"
+                android:textStyle="bold" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="@string/help_feature_content" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="20dp"
+                android:text="@string/help_track_map_title"
+                android:textStyle="bold" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:linksClickable="true"
+                android:text="@string/help_track_map_content" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="20dp"
+                android:text="@string/help_data_statistics_customized_title"
+                android:textStyle="bold" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="@string/help_data_statistics_customized_content" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="20dp"
+                android:text="@string/help_recording_title"
+                android:textStyle="bold" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="@string/help_recording_content" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="20dp"
+                android:text="@string/help_gps_imprecise_title"
+                android:textStyle="bold" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="@string/help_gps_imprecise_content" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="20dp"
+                android:text="@string/help_heart_rate_sensors_title"
+                android:textStyle="bold" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="@string/help_heart_rate_sensors_content" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="20dp"
+                android:text="@string/help_storage_pictures_title"
+                android:textStyle="bold" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="@string/help_storage_pictures_content" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="20dp"
+                android:text="@string/help_track_export_title"
+                android:textStyle="bold" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="@string/help_track_export_content" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="20dp"
+                android:text="@string/help_data_upload_title"
+                android:textStyle="bold" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="@string/generic_no" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="@string/help_data_google_play_services_title"
+                android:textStyle="bold" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="@string/generic_no" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="20dp"
+                android:text="@string/help_data_online_title"
+                android:textStyle="bold" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="@string/generic_no" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="20dp"
+                android:text="@string/help_data_storage_title"
+                android:textStyle="bold" />
+
+            <TextView
+                style="@style/TextMedium"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="@string/help_data_storage_content" />
+        </LinearLayout>
+    </ScrollView>
+
+</LinearLayout>

src/main/res/menu/track_detail.xml

@@ -42,7 +42,7 @@ limitations under the License.
         android:id="@+id/track_detail_markers"
         android:icon="@drawable/ic_marker_show_24dp"
         android:orderInCategory="5"
-        android:showAsAction="ifRoom"
+        app:showAsAction="ifRoom"
         android:title="@string/menu_markers" />
     <item
         android:id="@+id/track_detail_edit"

src/main/res/values/settings.xml

@@ -27,12 +27,14 @@
 
     <string name="settings_reset_key" translatable="false">settingsReset</string>
 
-    <string name="settings_sensor_bluetooth_sensor_key" translatable="false">bluetoothSensor</string>
-    <string name="settings_sensor_bluetooth_pairing_key" translatable="false">settingsSensorBluetoothPairing</string>
+    <string name="settings_sensor_bluetooth_heart_rate_key" translatable="false">bluetoothSensor</string>
     <string name="sensor_type_value_none" translatable="false">NONE</string>
 
     <string name="default_activity_key" translatable="false">defaultActivity</string>
+    <string name="default_activity_default" translatable="false">@string/activity_type_unknown</string>
     <string-array name="activity_types">
+        <item>@string/default_activity_default</item>
+
         <item>@string/activity_type_airplane</item>
         <item>@string/activity_type_atv</item>
         <item>@string/activity_type_biking</item>
@@ -94,7 +96,6 @@
         <item>@string/activity_type_trail_running</item>
         <item>@string/activity_type_train</item>
         <item>@string/activity_type_ultimate_frisbee</item>
-        <item>@string/activity_type_unknown</item>
         <item>@string/activity_type_wakeboarding</item>
         <item>@string/activity_type_walking</item>
         <item>@string/activity_type_water_skiing</item>
@@ -113,26 +114,13 @@
         <item>@string/auto_resume_track_timeout_always</item>
     </string-array>
 
-    <string name="chart_x_axis_key" translatable="false">chartXAxis</string>
-    <string name="chart_x_axis_default" translatable="false">@string/chart_x_axis_distance</string>
-    <string-array name="chart_x_axis_values">
-        <item>@string/chart_x_axis_distance</item>
-        <item>@string/chart_x_axis_time</item>
-    </string-array>
-    <string name="chart_x_axis_time" translatable="false">TIME</string>
-    <string name="chart_x_axis_distance" translatable="false">DISTANCE</string>
-    <string-array name="chart_x_axis_options">
-        <item>@string/settings_chart_by_distance</item>
-        <item>@string/settings_chart_by_time</item>
-    </string-array>
-
     <string name="split_frequency_key" translatable="false">splitFrequency</string>
-    <string name="split_frequency_default" translatable="false">@string/frequency_default</string>
+    <string name="split_frequency_default" translatable="false">@string/frequency_off</string>
     <string name="voice_frequency_key" translatable="false">voiceFrequency</string>
-    <string name="voice_frequency_default" translatable="false">@string/frequency_default</string>
-    <string name="frequency_default" translatable="false">0</string>
+    <string name="voice_frequency_default" translatable="false">@string/frequency_off</string>
+    <string name="frequency_off" translatable="false">0</string>
     <string-array name="frequency_values">
-        <item>@string/frequency_default</item>
+        <item>@string/frequency_off</item>
         <item>1</item>
         <item>2</item>
         <item>5</item>

src/main/res/values/settings_deprecated.xml

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <!-- This file contains old and now unused settings. -->
+    <!-- It is recommended not to reuse the keys. -->
+
+    <string name="chart_x_axis_key" translatable="false">chartXAxis</string>
+    <string name="chart_x_axis_default" translatable="false">@string/chart_x_axis_distance</string>
+    <string-array name="chart_x_axis_values">
+        <item>@string/chart_x_axis_distance</item>
+        <item>@string/chart_x_axis_time</item>
+    </string-array>
+    <string name="chart_x_axis_time" translatable="false">TIME</string>
+    <string name="chart_x_axis_distance" translatable="false">DISTANCE</string>
+    <string-array name="chart_x_axis_options">
+        <item>@string/settings_chart_by_distance</item>
+        <item>@string/settings_chart_by_time</item>
+    </string-array>
+</resources>

src/main/res/values/strings.xml

@@ -38,6 +38,95 @@ limitations under the License.
     Libraries
   </string>
 
+  <!-- Help -->
+  <string name="help_feature_title">
+    OpenTracks has the following features:
+  </string>
+  <string name="help_feature_content">
+* Create markers (incl. pictures)\n
+* Heart rate sensor (Bluetooth LE)\n
+* Voice announcements by time or distance\n
+* While recording, show on lock screen\n
+* Share tracks
+  </string>
+
+  <string name="help_data_statistics_customized_title">
+    Can the statistics view be customized?
+  </string>
+  <string name="help_data_statistics_customized_content">
+    Yes, it can be customized in the Settings.
+  </string>
+
+  <string name="help_recording_title">
+    How does OpenTracks record data?
+  </string>
+  <string name="help_recording_content">
+    OpenTracks uses the GPS sensor of the device to record the location continuously.
+  </string>
+
+  <string name="help_gps_imprecise_title">
+    Statistics (e.g., speed) reported by OpenTracks are imprecise?
+  </string>
+  <string name="help_gps_imprecise_content">
+    OpenTracks directly uses the data provided by the GPS of the mobile device.
+    If the GPS device reports inaccurate locations, OpenTracks cannot do anything about it.
+  </string>
+
+  <string name="help_heart_rate_sensors_title">
+    Which heart rate sensors does OpenTracks support?
+  </string>
+  <string name="help_heart_rate_sensors_content">
+    OpenTracks should work with any Bluetooth LE heart sensor that support streaming the data in real-time.
+    Smartwatches that store the heart rate data are not supported.
+  </string>
+
+  <string name="help_track_map_title">
+    How to show a track on a map?
+  </string>
+  <string name="help_track_map_content">
+    This requires a 3rd party application to be installed that can consume KMZ-encoded geo data.
+    This works well with <a href="http://osmand.net/">OsmAnd~</a> and <a href="https://maps.me/">Maps.ME</a>.
+    In fact, an App needs to support <i>ACTION_VIEW</i> with MIME <i>application/vnd.google-earth.kmz</i>.
+    At the moment, the recorded locations as well as the timestamps are send to an App while pictures and sensor data are not shared.
+  </string>
+
+  <string name="help_storage_pictures_title">
+    How does OpenTracks store pictures that were taken as markers?
+  </string>
+  <string name="help_storage_pictures_content">
+    These are stored directly on the file system.
+  </string>
+
+  <string name="help_track_export_title">
+    How can I export/share recorded tracks?
+  </string>
+  <string name="help_track_export_content">
+    Tracks can be exported from the Settings as KMZ, KML, or GPX.
+    KMZ contains all data incl. images, while KML contains only the sensor data, and GPX only the location.
+    Tracks shared via the <i>share icon</i> are shared as KMZ and any App can be used to send the data.
+  </string>
+
+  <string name="help_data_upload_title">
+    Can OpenTracks upload the data automatically?
+  </string>
+
+  <string name="help_data_google_play_services_title">
+    Does OpenTracks require/use Google Play Service?
+  </string>
+
+  <string name="help_data_online_title">
+    Does OpenTracks use online services?
+  </string>
+
+  <string name="help_data_storage_title">
+    How does OpenTracks store sensor data?
+  </string>
+  <string name="help_data_storage_content">
+    OpenTracks stores sensor data per recorded location.
+    In terms of a heart rate sensor this means that only <i>one</i> heart rate measurement is stored per location.
+    If you are standing still or are indoors, no sensor data will be recorded (but it will be shown).
+  </string>
+
   <!-- Activity Type -->
     <string name="activity_type_airplane" translation_description="When entering an 'Activity type', in the auto-complete text box, the
       completion suggestion for airplane.">
@@ -1055,7 +1144,13 @@ limitations under the License.
     Sending
   </string>
   <string name="sensor_not_known" translation_description="Error message if sensor is not available in Android (e.g., pairing was removed in Bluetooth Settings).">
-    Sensor %1$s is not known. Please check the settings.
+    Sensor %1$s is unknown. Please check the settings.
+  </string>
+    <string name="sensor_could_not_scan">
+    Could not scan for Bluetooth devices (error %1$i).
+  </string>
+  <string name="bluetooth_disabled">
+    Please enable Bluetooth.
   </string>
     <!-- Settings -->
     <string name="settings_not_while_recording" translation_description="In settings, the summary for an option that is not available during a
@@ -1220,7 +1315,7 @@ limitations under the License.
   </string>
 
   <string name="settings_error_initial_values_restored" translation_description="If the ">
-    Sorry, but an error occurred: and the all settings were reset to there default values.
+    Sorry, but an error occurred. All settings have been reverted to the default values.
   </string>
 
   <!-- Settings Sensor -->
@@ -1419,6 +1514,9 @@ limitations under the License.
     <string name="track_record_notification" translation_description="When recording a track, the message on the OpenTracks notification
       informing the user that OpenTracks is actively recording his track.">
     Recording your track&#8230;
+  </string>
+  <string name="track_recording_notification_accuracy">
+      Location accuracy: %1$s
   </string>
     <string name="track_markers" translation_description="Title indicating a particular track's markers.
 

src/main/res/xml/settings.xml

@@ -17,6 +17,14 @@ limitations under the License.
     xmlns:app="http://schemas.android.com/apk/res-auto"
     android:title="@string/menu_settings">
 
+    <PreferenceCategory android:title="@string/menu_help">
+        <Preference android:title="@string/menu_help">
+            <intent
+                android:targetClass="de.dennisguse.opentracks.HelpActivity"
+                android:targetPackage="@string/applicationId" />
+        </Preference>
+    </PreferenceCategory>
+
     <PreferenceCategory android:title="@string/track_detail_stats_tab">
         <ListPreference
             android:defaultValue="@string/stats_units_default"
@@ -46,13 +54,6 @@ limitations under the License.
     </PreferenceCategory>
 
     <PreferenceCategory android:title="@string/track_detail_chart_tab">
-        <ListPreference
-            android:defaultValue="@string/chart_x_axis_default"
-            android:entries="@array/chart_x_axis_options"
-            android:entryValues="@array/chart_x_axis_values"
-            android:key="@string/chart_x_axis_key"
-            android:title="@string/settings_chart_x_axis"
-            app:useSimpleSummaryProvider="true" />
         <CheckBoxPreference
             android:defaultValue="true"
             android:key="@string/chart_show_elevation_key"
@@ -93,7 +94,7 @@ limitations under the License.
             android:title="@string/settings_recording_track_name_title"
             app:useSimpleSummaryProvider="true" />
         <ListPreference
-            android:defaultValue="0"
+            android:defaultValue="@string/min_recording_interval_default"
             android:entryValues="@array/min_recording_interval_values"
             android:key="@string/min_recording_interval_key"
             android:title="@string/settings_recording_min_recording_interval_title"
@@ -111,37 +112,29 @@ limitations under the License.
             android:title="@string/settings_recording_max_recording_distance_title"
             app:useSimpleSummaryProvider="true" />
         <ListPreference
-            android:defaultValue="50"
+            android:defaultValue="@string/recording_gps_accuracy_default"
             android:entryValues="@array/recording_gps_accuracy_values"
             android:key="@string/recording_gps_accuracy_key"
             android:title="@string/settings_recording_min_required_accuracy_title"
             app:useSimpleSummaryProvider="true" />
         <ListPreference
-            android:defaultValue="10"
+            android:defaultValue="@string/auto_resume_track_timeout_default"
             android:entries="@array/auto_resume_track_timeout_values"
             android:entryValues="@array/auto_resume_track_timeout_values"
             android:key="@string/auto_resume_track_timeout_key"
             android:title="@string/settings_recording_auto_resume_track_timeout_title"
             app:useSimpleSummaryProvider="true" />
         <de.dennisguse.opentracks.settings.ActivityTypePreference
-            android:defaultValue="@string/activity_type_running"
+            android:defaultValue="@string/default_activity_default"
             android:key="@string/default_activity_key"
             android:title="@string/settings_recording_default_activity_title" />
     </PreferenceCategory>
 
-    <PreferenceCategory android:title="@string/settings_sensor">
-        <ListPreference
+    <PreferenceCategory android:title="@string/settings_sensor_bluetooth">
+        <de.dennisguse.opentracks.settings.BluetoothLePreference
             android:defaultValue="@string/sensor_type_value_none"
-            android:key="@string/settings_sensor_bluetooth_sensor_key"
-            android:title="@string/settings_sensor_bluetooth_sensor"
-            app:useSimpleSummaryProvider="true" />
-        <Preference
-            android:key="@string/settings_sensor_bluetooth_pairing_key"
-            android:persistent="false"
-            android:summary="@string/settings_sensor_bluetooth_pairing_summary"
-            android:title="@string/settings_sensor_bluetooth_pairing">
-            <intent android:action="android.settings.BLUETOOTH_SETTINGS" />
-        </Preference>
+            android:key="@string/settings_sensor_bluetooth_heart_rate_key"
+            android:title="@string/sensor_state_heart_rate" />
     </PreferenceCategory>
 
     <PreferenceCategory android:title="@string/generic_tracks">