Kotlin Rewrite - everything is new

.gitignore

@@ -1,8 +1,68 @@
+# Built application files
+*.apk
+*.ap_
+
+# Files for the ART/Dalvik VM
+*.dex
+
+# Java class files
+*.class
+
+# Generated files
+bin/
+gen/
+out/
+
+# Gradle files
+.gradle/
+build/
+
+# Local configuration file (sdk path, etc)
+local.properties
+
+# Proguard folder generated by Eclipse
+proguard/
+
+# Log Files
+*.log
+
+# Android Studio Navigation editor temp files
+.navigation/
+
+# Android Studio captures folder
+captures/
+
+# IntelliJ
 *.iml
-.gradle
-/local.properties
-/.idea
-.DS_Store
-/build
-/captures
-/projectFilesBackup
+.idea/
+#.idea/workspace.xml
+#.idea/tasks.xml
+#.idea/gradle.xml
+#.idea/assetWizardSettings.xml
+#.idea/dictionaries
+#.idea/libraries
+#.idea/caches
+
+# Keystore files
+*.jks
+
+# External native build folder generated in Android Studio 2.2 and later
+.externalNativeBuild
+
+# Google Services (e.g. APIs or Firebase)
+google-services.json
+
+# Freeline
+freeline.py
+freeline/
+freeline_project_description.json
+
+# fastlane
+fastlane/report.xml
+fastlane/Preview.html
+fastlane/screenshots
+fastlane/test_output
+fastlane/readme.md
+
+# Misc
+.DS_Store

LICENSE.md

@@ -1,7 +1,7 @@
 The MIT License (MIT)
 =====================
 
-Copyright (c) 2016-19 - Y20K.org
+Copyright (c) 2016-20 - Y20K.org
 --------------------------------
 
 Permission is hereby granted, free of charge, to any person obtaining a copy

README.md

@@ -4,7 +4,9 @@ README
 Trackbook - Movement Recorder for Android
 -----------------------------------------
 
-**Version 1.2.x ("San Tropez")**
+**Version 2.0.x ("Echoes")**
+
+**Please note: Trackbook is currently being completely re-written in Kotlin. No line of code is left unchanged. The process is not finished yet.**
 
 Trackbook is a bare bones app for recording your movements. Trackbook is great for hiking, vacation or workout. Once started it traces your movements on a map. The map data is provided by [OpenStreetMap (OSM)](https://www.openstreetmap.org/).
 

app/build.gradle

@@ -1,48 +1,89 @@
 apply plugin: 'com.android.application'
+apply plugin: 'kotlin-android'
+apply plugin: 'kotlin-android-extensions'
+apply plugin: 'androidx.navigation.safeargs.kotlin'
 
 android {
-
-    compileSdkVersion project.ext.compileSdkVersion
+    compileSdkVersion 29
     // buildToolsVersion is optional because the plugin uses a recommended version by default
 
     defaultConfig {
-        applicationId project.ext.applicationId
-        minSdkVersion project.ext.minSdkVersion
-        targetSdkVersion project.ext.targetSdkVersion
-        versionCode project.ext.versionCode
-        versionName project.ext.versionName
+        applicationId 'org.y20k.trackbook'
+        minSdkVersion 25
+        targetSdkVersion 27
+        versionCode 27
+        versionName '2.0.0'
+        resConfigs "en"
+    }
 
-        vectorDrawables.useSupportLibrary = true
-        resConfigs "en", "da", "de", "fr", "id", "it", "ja", "nb-rNO", "nl", "sv", "zh-rCN"
+    kotlinOptions {
+        jvmTarget = '1.8'
+    }
+
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+
+    lintOptions{
+        disable 'MissingTranslation'
     }
 
     buildTypes {
-
         release {
+            // Enables code shrinking, obfuscation, and optimization for only
+            // your project's release build type.
             minifyEnabled true
+
+            // Enables resource shrinking, which is performed by the
+            // Android Gradle plugin.
             shrinkResources true
-            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+
+            // Includes the default ProGuard rules files that are packaged with
+            // the Android Gradle plugin. To learn more, go to the section about
+            // R8 configuration files.
+            proguardFiles getDefaultProguardFile(
+                    'proguard-android-optimize.txt'),
+                    'proguard-rules.pro'
         }
 
-    }
+        debug {
+            // Comment out the below lines if you do not need to test resource shrinking
+            //minifyEnabled true
+            //shrinkResources true
+            //proguardFiles getDefaultProguardFile(
+            //        'proguard-android-optimize.txt'),
+            //        'proguard-rules.pro'
+        }
 
-    lintOptions {
-        warning 'MissingTranslation'
     }
 
 }
 
 dependencies {
+    implementation fileTree(dir: 'libs', include: ['*.jar'])
 
-    implementation fileTree(include: ['*.jar'], dir: 'libs')
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
+    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.2.2"
+    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:1.2.2"
 
-    implementation "androidx.appcompat:appcompat:$appcompatVersion"
-    implementation "androidx.constraintlayout:constraintlayout:$constraintlayoutVersion"
-    implementation "androidx.cardview:cardview:$cardviewVersion"
+    implementation 'androidx.appcompat:appcompat:1.1.0'
+    implementation "androidx.core:core-ktx:1.1.0"
+    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
+    implementation 'androidx.swiperefreshlayout:swiperefreshlayout:1.0.0'
+    implementation 'androidx.coordinatorlayout:coordinatorlayout:1.1.0'
+    implementation "androidx.preference:preference-ktx:1.1.0"
 
-    implementation "com.google.android.material:material:$materialVersion"
+    implementation 'androidx.navigation:navigation-fragment-ktx:2.1.0'
+    implementation 'androidx.navigation:navigation-ui-ktx:2.1.0'
 
-    implementation "org.osmdroid:osmdroid-android:$osmdroidVersion"
-    implementation "com.google.code.gson:gson:$gsonVersion"
 
+    implementation "com.google.android.material:material:1.1.0-beta01"
+    implementation "com.google.code.gson:gson:2.8.6"
+
+    implementation "org.osmdroid:osmdroid-android:6.1.5"
+}
+
+androidExtensions {
+    experimental = true
 }

app/proguard-rules.pro

@@ -1,14 +1,10 @@
 # Add project specific ProGuard rules here.
-# By default, the flags in this file are appended to flags specified
-# in /Users/solaris/Library/Android/sdk/tools/proguard/proguard-android.txt
-# You can edit the include path and order by changing the proguardFiles
-# directive in build.gradle.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
 #
 # For more details, see
 #   http://developer.android.com/guide/developing/tools/proguard.html
 
-# Add any project specific keep options here:
-
 # If your project uses WebView with JS, uncomment the following
 # and specify the fully qualified class name to the JavaScript interface
 # class:
@@ -16,6 +12,10 @@
 #   public *;
 #}
 
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
 
-# stop re-ordering of gson elements
--dontshrink
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

app/src/main/AndroidManifest.xml

@@ -1,10 +1,11 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:tools="http://schemas.android.com/tools"
-    package="org.y20k.trackbook">
+        xmlns:tools="http://schemas.android.com/tools"
+        package="org.y20k.trackbook">
 
-    <!-- EXCLUDE NON-GPS DEVICES -->
+    <!-- USE GPS AND NETWORK - EXCLUDE NON-GPS DEVICES -->
     <uses-feature android:name="android.hardware.location.gps" android:required="true" />
+    <uses-feature android:name="android.hardware.location.network" />
 
     <!-- NORMAL PERMISSIONS, automatically granted -->
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
@@ -18,27 +19,19 @@
     <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
 
     <application
-        android:name=".Trackbook"
-        android:allowBackup="true"
-        android:fullBackupContent="@xml/backupscheme"
-        android:icon="@mipmap/ic_launcher"
-        android:label="@string/app_name"
-        android:supportsRtl="true"
-        android:theme="@style/TrackbookAppTheme"
-        tools:ignore="GoogleAppIndexingWarning">
-
-        <!-- MAIN ACTIVITY -->
-        <activity
-            android:name=".MainActivity"
+            android:name=".Trackbook"
+            android:allowBackup="true"
+            android:icon="@mipmap/ic_launcher"
             android:label="@string/app_name"
-            android:theme="@style/TrackbookAppTheme"
-            android:resizeableActivity="true"
-            android:launchMode="singleTop">
+            android:supportsRtl="true"
+            android:theme="@style/AppTheme"
+            tools:ignore="GoogleAppIndexingWarning">
+
+        <activity android:name=".MainActivity">
             <intent-filter>
-                <action android:name="android.intent.action.MAIN" />
-                <category android:name="android.intent.category.LAUNCHER" />
+                <action android:name="android.intent.action.MAIN"/>
+                <category android:name="android.intent.category.LAUNCHER"/>
             </intent-filter>
-            <!-- TODO App is not indexable by Google Search; consider adding at least one Activity with an ACTION-VIEW intent filter. See issue explanation for more details. -->
         </activity>
 
         <!-- TRACKER SERVICE -->
@@ -53,17 +46,20 @@
             </intent-filter>
         </service>
 
-        <!-- EXPORT HELPER (FILE PROVIDER) -->
+
         <provider
-            android:name=".helpers.ExportHelper"
-            android:authorities="org.y20k.trackbook.exporthelper.provider"
-            android:exported="false"
-            android:grantUriPermissions="true">
+                android:name="androidx.core.content.FileProvider"
+                android:authorities="${applicationId}.provider"
+                android:exported="false"
+                android:grantUriPermissions="true">
             <meta-data
-                android:name="android.support.FILE_PROVIDER_PATHS"
-                android:resource="@xml/provider_paths"/>
+                    android:name="android.support.FILE_PROVIDER_PATHS"
+                    android:resource="@xml/provider_paths"/>
         </provider>
 
     </application>
 
-</manifest>
+
+
+
+</manifest>

app/src/main/java/org/y20k/trackbook/Keys.kt

@@ -0,0 +1,134 @@
+/*
+ * Keys.kt
+ * Implements the keys used throughout the app
+ * This object hosts all keys used to control Trackbook's state
+ *
+ * This file is part of
+ * TRACKBOOK - Movement Recorder for Android
+ *
+ * Copyright (c) 2016-20 - Y20K.org
+ * Licensed under the MIT-License
+ * http://opensource.org/licenses/MIT
+ *
+ * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
+ * https://github.com/osmdroid/osmdroid
+ */
+
+
+package org.y20k.trackbook
+
+import java.util.*
+
+
+/*
+ * Keys object
+ */
+object Keys {
+
+    // application name
+    const val APPLICATION_NAME: String = "Trackbook"
+
+    // version numbers
+    const val CURRENT_TRACK_FORMAT_VERSION: Int = 4
+    const val CURRENT_TRACKLIST_FORMAT_VERSION: Int = 0
+
+    // other values
+    const val MAXIMUM_TRACK_FILES: Int = 25
+    const val FIFTY_METER_RADIUS: Int = 50
+    const val UNIT_METRIC: Int = 1
+    const val UNIT_IMPERIAL: Int = -1
+
+    // intent actions
+    const val ACTION_START: String = "org.y20k.trackbooks.action.START"
+    const val ACTION_STOP: String = "org.y20k.trackbooks.action.STOP"
+    const val ACTION_RESUME: String = "org.y20k.transistors.action.RESUME"
+
+    // args
+    const val ARG_TRACK_TITLE: String = "ArgTrackTitle"
+    const val ARG_TRACK_FILE_URI: String = "ArgTrackFileUri"
+    const val ARG_GPX_FILE_URI: String = "ArgGpxFileUri"
+    const val ARG_TRACK_ID: String = "ArgTrackId"
+
+    // preferences
+    const val PREF_ONE_TIME_HOUSEKEEPING_NECESSARY = "ONE_TIME_HOUSEKEEPING_NECESSARY_VERSIONCODE_37" // increment to current app version code to trigger housekeeping that runs only once
+    const val PREF_NIGHT_MODE_STATE: String= "prefNightModeState"
+    const val PREF_CURRENT_BEST_LOCATION_PROVIDER: String = "prefCurrentBestLocationProvider"
+    const val PREF_CURRENT_BEST_LOCATION_LATITUDE: String = "prefCurrentBestLocationLatitude"
+    const val PREF_CURRENT_BEST_LOCATION_LONGITUDE: String = "prefCurrentBestLocationLongitude"
+    const val PREF_CURRENT_BEST_LOCATION_ACCURACY: String = "prefCurrentBestLocationAccuracy"
+    const val PREF_CURRENT_BEST_LOCATION_ALTITUDE: String = "prefCurrentBestLocationAltitude"
+    const val PREF_CURRENT_BEST_LOCATION_TIME: String = "prefCurrentBestLocationTime"
+    const val PREF_MAP_ZOOM_LEVEL: String = "prefMapZoomLevel"
+    const val PREF_TRACKING_STATE: String = "prefTrackingState"
+    const val PREF_USE_IMPERIAL_UNITS: String = "prefUseImperialUnits"
+    const val PREF_GPS_ONLY: String = "prefGpsOnly"
+    const val PREF_LOCATION_ACCURACY_THRESHOLD: String = "prefLocationAccuracyThreshold"
+    const val PREF_LOCATION_AGE_THRESHOLD: String = "prefLocationAgeThreshold"
+
+    // states
+    const val STATE_NOT_TRACKING: Int = 0
+    const val STATE_TRACKING_ACTIVE: Int = 1
+    const val STATE_TRACKING_STOPPED: Int = 2
+
+    // dialog types
+    const val DIALOG_EMPTY_RECORDING: Int = 0
+    const val DIALOG_REMOVE_TRACK: Int = 1
+
+    // dialog results
+    const val DIALOG_RESULT_DEFAULT: Int = -1
+    const val DIALOG_EMPTY_PAYLOAD_STRING: String = ""
+    const val DIALOG_EMPTY_PAYLOAD_INT: Int = -1
+    const val DIALOG_RESULT_SAVE_DIALOG: Int = 1
+    const val DIALOG_RESULT_CLEAR_DIALOG: Int = 2
+    const val DIALOG_RESULT_DELETE_DIALOG: Int = 3
+    const val DIALOG_RESULT_EXPORT_DIALOG: Int = 4
+    const val DIALOG_RESULT_EMPTY_RECORDING_DIALOG: Int = 5
+
+    // folder names
+    const val FOLDER_TEMP: String  = "temp"
+    const val FOLDER_TRACKS: String = "tracks"
+    const val FOLDER_GPX: String = "gpx"
+
+    // file names and extensions
+    const val GPX_FILE_EXTENSION: String = ".gpx"
+    const val TRACKBOOK_LEGACY_FILE_EXTENSION: String = ".trackbook"
+    const val TRACKBOOK_FILE_EXTENSION: String = ".json"
+    const val TEMP_FILE: String = "temp.json"
+    const val TRACKLIST_FILE: String = "tracklist.json"
+    const val PODCAST_COVER_FILE: String = "cover.jpg"
+    const val PODCAST_SMALL_COVER_FILE: String = "cover-small.jpg"
+    const val DEBUG_LOG_FILE: String = "log-can-be-deleted.txt"
+    const val FILE_TYPE_TEMP: Int = 0
+    const val FILE_TYPE_TRACK: Int = 1
+
+
+    // default values
+    val DEFAULT_DATE: Date = Date(0L)
+    const val DEFAULT_RFC2822_DATE: String = "Thu, 01 Jan 1970 01:00:00 +0100"  // --> Date(0)
+    const val ONE_HOUR_IN_MILLISECONDS: Int = 3600000
+    const val EMPTY_STRING_RESOURCE: Int = 0
+    const val REQUEST_CURRENT_LOCATION_INTERVAL: Long = 1000L                   // 1 second in milliseconds
+    const val ADD_WAYPOINT_TO_TRACK_INTERVAL: Long = 15000L                     // 15 seconds in milliseconds
+    const val SIGNIFICANT_TIME_DIFFERENCE: Long = 120000L                       // 2 minutes in milliseconds
+    const val STOP_OVER_THRESHOLD: Long = 300000L                               // 5 minutes in milliseconds
+    const val DEFAULT_LATITUDE: Double = 71.172500                              // latitude Nordkapp, Norway
+    const val DEFAULT_LONGITUDE: Double = 25.784444                             // longitude Nordkapp, Norway
+    const val DEFAULT_ACCURACY: Float = 300f                                    // in meters
+    const val DEFAULT_ALTITUDE: Double = 0.0
+    const val DEFAULT_TIME: Long = 0L
+    const val DEFAULT_THRESHOLD_LOCATION_ACCURACY: Int = 30                     // 30 meters
+    const val DEFAULT_THRESHOLD_LOCATION_AGE: Long = 60000000000L               // one minute in nanoseconds
+    const val DEFAULT_THRESHOLD_DISTANCE: Float = 15f                           // 15 meters
+    const val DEFAULT_ZOOM_LEVEL: Double = 16.0
+    const val ALTITUDE_MEASUREMENT_ERROR_THRESHOLD = 10 // altitude changes of 10 meter or more (per 15 seconds) are being discarded
+    const val REQUEST_CODE_FOREGROUND = 42
+
+    // requests
+
+    // results
+
+    // notification
+    const val TRACKER_SERVICE_NOTIFICATION_ID: Int = 1
+    const val NOTIFICATION_CHANNEL_RECORDING: String = "notificationChannelIdRecordingChannel"
+
+}

app/src/main/java/org/y20k/trackbook/MainActivity.java

@@ -1,925 +0,0 @@
-/**
- * MainActivity.java
- * Implements the app's main activity
- * The main activity sets up the main view
- *
- * This file is part of
- * TRACKBOOK - Movement Recorder for Android
- *
- * Copyright (c) 2016-19 - Y20K.org
- * Licensed under the MIT-License
- * http://opensource.org/licenses/MIT
- *
- * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
- * https://github.com/osmdroid/osmdroid
- */
-
-package org.y20k.trackbook;
-
-import android.Manifest;
-import android.annotation.TargetApi;
-import android.app.Activity;
-import android.content.BroadcastReceiver;
-import android.content.ComponentName;
-import android.content.Context;
-import android.content.Intent;
-import android.content.IntentFilter;
-import android.content.ServiceConnection;
-import android.content.SharedPreferences;
-import android.content.pm.PackageManager;
-import android.location.Location;
-import android.os.Build;
-import android.os.Bundle;
-import android.os.Environment;
-import android.os.IBinder;
-import android.os.Vibrator;
-import android.preference.PreferenceManager;
-import android.util.SparseArray;
-import android.view.MenuItem;
-import android.view.View;
-import android.view.ViewGroup;
-import android.widget.Button;
-import android.widget.Toast;
-
-import androidx.annotation.NonNull;
-import androidx.annotation.Nullable;
-import androidx.appcompat.app.AppCompatActivity;
-import androidx.cardview.widget.CardView;
-import androidx.core.content.ContextCompat;
-import androidx.fragment.app.DialogFragment;
-import androidx.fragment.app.Fragment;
-import androidx.fragment.app.FragmentManager;
-import androidx.fragment.app.FragmentStatePagerAdapter;
-import androidx.localbroadcastmanager.content.LocalBroadcastManager;
-
-import com.google.android.material.bottomnavigation.BottomNavigationView;
-import com.google.android.material.floatingactionbutton.FloatingActionButton;
-import com.google.android.material.snackbar.Snackbar;
-
-import org.osmdroid.config.Configuration;
-import org.y20k.trackbook.helpers.DialogHelper;
-import org.y20k.trackbook.helpers.ExportHelper;
-import org.y20k.trackbook.helpers.LogHelper;
-import org.y20k.trackbook.helpers.NightModeHelper;
-import org.y20k.trackbook.helpers.TrackbookKeys;
-import org.y20k.trackbook.layout.NonSwipeableViewPager;
-
-import java.lang.ref.WeakReference;
-import java.util.ArrayList;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-
-
-/**
- * MainActivity class
- */
-public class MainActivity extends AppCompatActivity implements TrackbookKeys {
-
-    /* Define log tag */
-    private static final String LOG_TAG = MainActivity.class.getSimpleName();
-
-
-    /* Main class variables */
-    private TrackerService mTrackerService;
-    private BottomNavigationView mBottomNavigationView;
-    private NonSwipeableViewPager mViewPager;
-    private SectionsPagerAdapter mSectionsPagerAdapter;
-    private boolean mTrackerServiceRunning;
-    private boolean mPermissionsGranted;
-    private boolean mFloatingActionButtonSubMenuVisible;
-    private List<String> mMissingPermissions;
-    private FloatingActionButton mFloatingActionButtonMain;
-    private FloatingActionButton mFloatingActionButtonSubSave;
-    private FloatingActionButton mFloatingActionButtonSubClear;
-    private FloatingActionButton mFloatingActionButtonSubResume;
-    private FloatingActionButton mFloatingActionButtonLocation;
-    private CardView mFloatingActionButtonSubSaveLabel;
-    private CardView mFloatingActionButtonSubClearLabel;
-    private CardView mFloatingActionButtonSubResumeLabel;
-    private BroadcastReceiver mTrackingChangedReceiver;
-    private int mFloatingActionButtonState;
-    private int mSelectedTab;
-
-    private boolean mBound = false;
-
-
-    @Override
-    protected void onCreate(Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-
-        // check state of External Storage
-        checkExternalStorageState();
-
-        // empty cache
-        ExportHelper.emptyCacheDirectory(this);
-
-        // load saved state of app
-        loadFloatingActionButtonState(this);
-
-        // check permissions on Android 6 and higher
-        mPermissionsGranted = false;
-        if (Build.VERSION.SDK_INT >= 23) {
-            // check permissions
-            mMissingPermissions = checkPermissions();
-            mPermissionsGranted = mMissingPermissions.size() == 0;
-        } else {
-            mPermissionsGranted = true;
-        }
-
-        // initialize state
-        if (savedInstanceState != null) {
-            // restore if saved instance is available
-            mTrackerServiceRunning = savedInstanceState.getBoolean(INSTANCE_TRACKING_STATE, false);
-            mSelectedTab = savedInstanceState.getInt(INSTANCE_SELECTED_TAB, FRAGMENT_ID_MAP);
-            mFloatingActionButtonSubMenuVisible = savedInstanceState.getBoolean(INSTANCE_FAB_SUB_MENU_VISIBLE, false);
-        } else {
-            // use default values
-            mTrackerServiceRunning = false;
-            mSelectedTab = FRAGMENT_ID_MAP;
-            mFloatingActionButtonSubMenuVisible = false;
-        }
-
-        // set user agent to prevent getting banned from the osm servers
-        Configuration.getInstance().setUserAgentValue(BuildConfig.APPLICATION_ID);
-        // set the path for osmdroid's files (e.g. tile cache)
-        Configuration.getInstance().setOsmdroidBasePath(this.getExternalFilesDir(null));
-
-        // set up main layout
-        setupLayout();
-    }
-
-
-    @Override
-    protected void onStart() {
-        super.onStart();
-
-        // bind to TrackerService
-        Intent intent = new Intent(this, TrackerService.class);
-        bindService(intent, mConnection, Context.BIND_AUTO_CREATE);
-
-        // register broadcast receiver for changed tracking state
-        mTrackingChangedReceiver = createTrackingChangedReceiver();
-        IntentFilter trackingStoppedIntentFilter = new IntentFilter(ACTION_TRACKING_STATE_CHANGED);
-        LocalBroadcastManager.getInstance(this).registerReceiver(mTrackingChangedReceiver, trackingStoppedIntentFilter);
-    }
-
-
-    @Override
-    protected void onResume() {
-        super.onResume();
-
-        // load state of Floating Action Button
-        loadFloatingActionButtonState(this);
-
-        // handle incoming intent (from notification)
-        handleIncomingIntent();
-
-        // if not in onboarding mode: set state of FloatingActionButton
-        if (mFloatingActionButtonMain != null) {
-            setFloatingActionButtonState();
-        }
-    }
-
-
-    @Override
-    protected void onPause() {
-        super.onPause();
-
-    }
-
-
-    @Override
-    protected void onStop() {
-        super.onStop();
-        // unbind from TrackerService
-        unbindService(mConnection);
-    }
-
-
-    @Override
-    public void onDestroy() {
-        super.onDestroy();
-        LogHelper.v(LOG_TAG, "onDestroy called.");
-
-        // reset selected tab
-        mSelectedTab = FRAGMENT_ID_MAP;
-
-        // disable  broadcast receiver
-        LocalBroadcastManager.getInstance(this).unregisterReceiver(mTrackingChangedReceiver);
-    }
-
-
-    @Override
-    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
-        switch (requestCode) {
-            case REQUEST_CODE_ASK_MULTIPLE_PERMISSIONS:	{
-                Map<String, Integer> perms = new HashMap<>();
-                perms.put(Manifest.permission.ACCESS_FINE_LOCATION, PackageManager.PERMISSION_GRANTED);
-                perms.put(Manifest.permission.WRITE_EXTERNAL_STORAGE, PackageManager.PERMISSION_GRANTED);
-                for (int i = 0; i < permissions.length; i++)
-                    perms.put(permissions[i], grantResults[i]);
-
-                // check for ACCESS_FINE_LOCATION and WRITE_EXTERNAL_STORAGE
-                Boolean location = perms.get(Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED;
-                // Boolean storage = perms.get(Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED;
-
-                if (location) {
-                    // permissions granted - notify user
-                    Toast.makeText(this, R.string.toast_message_permissions_granted, Toast.LENGTH_SHORT).show();
-                    mPermissionsGranted = true;
-                    // switch to main map layout
-                    setupLayout();
-                } else {
-                    // permissions denied - notify user
-                    Toast.makeText(this, R.string.toast_message_unable_to_start_app, Toast.LENGTH_SHORT).show();
-                    mPermissionsGranted = false;
-                }
-            }
-            break;
-            default:
-                super.onRequestPermissionsResult(requestCode, permissions, grantResults);
-        }
-    }
-
-
-    @Override
-    protected void onSaveInstanceState(Bundle outState) {
-        outState.putBoolean(INSTANCE_TRACKING_STATE, mTrackerServiceRunning);
-        outState.putInt(INSTANCE_SELECTED_TAB, mSelectedTab);
-        outState.putBoolean(INSTANCE_FAB_SUB_MENU_VISIBLE, mFloatingActionButtonSubMenuVisible);
-        super.onSaveInstanceState(outState);
-    }
-
-
-    /* Handles FloatingActionButton dialog results - called by MainActivityMapFragment after Saving and/or clearing the map */
-    public void onFloatingActionButtonResult(int requestCode, int resultCode) {
-        switch(requestCode) {
-            case RESULT_SAVE_DIALOG:
-                if (resultCode == Activity.RESULT_OK) {
-                    // user chose SAVE
-                    handleStateAfterSave();
-                    LogHelper.v(LOG_TAG, "Save dialog result: SAVE");
-                } else if (resultCode == Activity.RESULT_CANCELED){
-                    LogHelper.v(LOG_TAG, "Save dialog result: CANCEL");
-                }
-                break;
-            case RESULT_CLEAR_DIALOG:
-                if (resultCode == Activity.RESULT_OK) {
-                    // user chose CLEAR
-                    handleStateAfterClear();
-                    LogHelper.v(LOG_TAG, "Clear map dialog result: CLEAR");
-                } else if (resultCode == Activity.RESULT_CANCELED){
-                    LogHelper.v(LOG_TAG, "Clear map dialog result: User chose CANCEL.");
-                }
-                break;
-            case RESULT_EMPTY_RECORDING_DIALOG:
-                if (resultCode == Activity.RESULT_OK) {
-                    // User chose RESUME RECORDING
-                    handleResumeButtonClick((View)mFloatingActionButtonMain);
-                    LogHelper.v(LOG_TAG, "Empty recording dialog result: RESUME");
-                } else if (resultCode == Activity.RESULT_CANCELED){
-                    // User chose CANCEL - do nothing just hide the sub menu
-                    showFloatingActionButtonMenu(false);
-                    LogHelper.v(LOG_TAG, "Empty recording dialog result: CANCEL");
-                }
-                break;
-        }
-    }
-
-
-    /* Handles the visual state after a save action */
-    private void handleStateAfterSave() {
-        // display and update tracks tab
-        mBottomNavigationView.setSelectedItemId(R.id.navigation_last_tracks);
-
-        // dismiss notification
-        dismissNotification();
-
-        // hide Floating Action Button sub menu
-        showFloatingActionButtonMenu(false);
-
-        // update Floating Action Button icon
-        mFloatingActionButtonState = FAB_STATE_DEFAULT;
-        setFloatingActionButtonState();
-    }
-
-
-    /* Start tracker service */
-    private void startTrackerService() {
-        // start service so that it keeps running after unbind
-        Intent intent = new Intent(this, TrackerService.class);
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
-            // ... start service in foreground to prevent it being killed on Oreo
-            startForegroundService(intent);
-        } else {
-            startService(intent);
-        }
-    }
-
-
-    /* Start recording movements */
-    private void startRecording(Location lastLocation) {
-        startTrackerService();
-        if (mBound) {
-            mTrackerService.startTracking(lastLocation);
-        }
-    }
-
-
-    /* Resume recording movements */
-    private void resumeRecording(Location lastLocation) {
-        startTrackerService();
-        if (mBound) {
-            mTrackerService.resumeTracking(lastLocation);
-        }
-    }
-
-
-    /* Stop recording movements */
-    private void stopRecording() {
-        if (mBound) {
-            mTrackerService.stopTracking();
-        }
-    }
-
-
-    /* Dismiss notification */
-    private void dismissNotification() {
-        if (mBound) {
-            mTrackerService.dismissNotification();
-        }
-    }
-
-
-    /* Handles the visual state after a save action */
-    private void handleStateAfterClear() {
-        // dismiss notification
-        dismissNotification();
-
-        // hide Floating Action Button sub menu
-        showFloatingActionButtonMenu(false);
-
-        // update Floating Action Button icon
-        mFloatingActionButtonState = FAB_STATE_DEFAULT;
-        setFloatingActionButtonState();
-    }
-
-
-    /* Handles tap on the button "save" */
-    private void handleSaveButtonClick() {
-        // save button click is handled by onActivityResult in MainActivityMapFragment
-        MainActivityMapFragment mainActivityMapFragment = (MainActivityMapFragment) mSectionsPagerAdapter.getFragment(FRAGMENT_ID_MAP);
-        mainActivityMapFragment.onActivityResult(RESULT_SAVE_DIALOG, Activity.RESULT_OK, getIntent());
-    }
-
-
-    /* Handles tap on the button "clear" */
-    private void handleClearButtonClick() {
-        // prepare delete dialog
-        int dialogTitle = -1;
-        String dialogMessage = getString(R.string.dialog_clear_content);
-        int dialogPositiveButton = R.string.dialog_clear_action_clear;
-        int dialogNegativeButton = R.string.dialog_default_action_cancel;
-        // show delete dialog
-        MainActivityMapFragment mainActivityMapFragment = (MainActivityMapFragment) mSectionsPagerAdapter.getFragment(FRAGMENT_ID_MAP);
-        DialogFragment dialogFragment = DialogHelper.newInstance(dialogTitle, dialogMessage, dialogPositiveButton, dialogNegativeButton);
-        dialogFragment.setTargetFragment(mainActivityMapFragment, RESULT_CLEAR_DIALOG);
-        dialogFragment.show(getSupportFragmentManager(), "ClearDialog");
-        // results of dialog are handled by onActivityResult in MainActivityMapFragment
-    }
-
-
-    /* Handles tap on the button "resume" */
-    private void handleResumeButtonClick(View view) {
-
-        // get last location from MainActivity Fragment // todo check -> may produce NullPointerException
-        MainActivityMapFragment mainActivityMapFragment = (MainActivityMapFragment) mSectionsPagerAdapter.getFragment(FRAGMENT_ID_MAP);
-        Location lastLocation = mainActivityMapFragment.getCurrentBestLocation();
-
-        if (lastLocation != null) {
-            // show snackbar
-            Snackbar.make(view, R.string.snackbar_message_tracking_resumed, Snackbar.LENGTH_SHORT).setAction("Action", null).show();
-            // resume tracking
-            resumeRecording(lastLocation);
-            // hide sub menu
-            showFloatingActionButtonMenu(false);
-        } else {
-            Toast.makeText(this, getString(R.string.toast_message_location_services_not_ready), Toast.LENGTH_LONG).show();
-        }
-    }
-
-
-    /* Loads state of Floating Action Button from preferences */
-    private void loadFloatingActionButtonState(Context context) {
-        SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(context);
-        mFloatingActionButtonState = settings.getInt(PREFS_FAB_STATE, FAB_STATE_DEFAULT);
-    }
-
-
-    /* Set up main layout */
-    private void setupLayout() {
-        if (mPermissionsGranted) {
-            // point to the main map layout
-            setContentView(R.layout.activity_main);
-
-            // create adapter that returns fragments for the maim map and the last track display
-            mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
-
-            // set up the ViewPager with the sections adapter.
-            mViewPager = (NonSwipeableViewPager) findViewById(R.id.fragmentContainer);
-            mViewPager.setAdapter(mSectionsPagerAdapter);
-
-            // setup bottom navigation
-            mBottomNavigationView = findViewById(R.id.navigation);
-            mBottomNavigationView.setOnNavigationItemSelectedListener(getOnNavigationItemSelectedListener());
-
-            // get references to the record button and show/hide its sub menu
-            mFloatingActionButtonMain = findViewById(R.id.fabMainButton);
-            mFloatingActionButtonLocation = findViewById(R.id.fabLocationButton);
-            mFloatingActionButtonSubSave = findViewById(R.id.fabSubMenuButtonSave);
-            mFloatingActionButtonSubSaveLabel = findViewById(R.id.fabSubMenuLabelSave);
-            mFloatingActionButtonSubClear = findViewById(R.id.fabSubMenuButtonClear);
-            mFloatingActionButtonSubClearLabel = findViewById(R.id.fabSubMenuLabelClear);
-            mFloatingActionButtonSubResume = findViewById(R.id.fabSubMenuButtonResume);
-            mFloatingActionButtonSubResumeLabel = findViewById(R.id.fabSubMenuLabelResume);
-            if (mFloatingActionButtonSubMenuVisible) {
-                showFloatingActionButtonMenu(true);
-            } else {
-                showFloatingActionButtonMenu(false);
-            }
-
-            // restore selected tab
-            if (mSelectedTab == FRAGMENT_ID_TRACKS) {
-                mBottomNavigationView.setSelectedItemId(R.id.navigation_last_tracks);
-            } else {
-                mBottomNavigationView.setSelectedItemId(R.id.navigation_map);
-            }
-
-            // add listeners to buttons
-            addListenersToViews();
-
-        } else {
-            // point to the on main onboarding layout
-            setContentView(R.layout.main_onboarding);
-
-            // show the okay button and attach listener
-            Button okayButton = (Button) findViewById(R.id.button_okay);
-            okayButton.setOnClickListener(new View.OnClickListener() {
-                @TargetApi(Build.VERSION_CODES.M)
-                @Override
-                public void onClick(View view) {
-                    if (mMissingPermissions != null && !mMissingPermissions.isEmpty()) {
-                        // request permissions
-                        String[] params = mMissingPermissions.toArray(new String[mMissingPermissions.size()]);
-                        requestPermissions(params, REQUEST_CODE_ASK_MULTIPLE_PERMISSIONS);
-                    }
-                }
-            });
-
-        }
-
-    }
-
-
-    /* Add listeners to ui buttons */
-    private void addListenersToViews() {
-
-        mFloatingActionButtonMain.setOnClickListener(new View.OnClickListener() {
-            @Override
-            public void onClick(View view) {
-                handleFloatingActionButtonClick(view);
-            }
-        });
-        mFloatingActionButtonSubSave.setOnClickListener(new View.OnClickListener() {
-            @Override
-            public void onClick(View view) {
-                handleSaveButtonClick();
-            }
-        });
-        mFloatingActionButtonSubSaveLabel.setOnClickListener(new View.OnClickListener() {
-            @Override
-            public void onClick(View view) {
-                handleSaveButtonClick();
-            }
-        });
-        mFloatingActionButtonSubClear.setOnClickListener(new View.OnClickListener() {
-            @Override
-            public void onClick(View view) {
-                handleClearButtonClick();
-            }
-        });
-        mFloatingActionButtonSubClearLabel.setOnClickListener(new View.OnClickListener() {
-            @Override
-            public void onClick(View view) {
-                handleClearButtonClick();
-            }
-        });
-        mFloatingActionButtonSubResume.setOnClickListener(new View.OnClickListener() {
-            @Override
-            public void onClick(View view) {
-                handleResumeButtonClick(view);
-            }
-        });
-        mFloatingActionButtonSubResumeLabel.setOnClickListener(new View.OnClickListener() {
-            @Override
-            public void onClick(View view) {
-                handleResumeButtonClick(view);
-            }
-        });
-
-
-        mFloatingActionButtonLocation.setOnClickListener(new View.OnClickListener() {
-            @Override
-            public void onClick(View view) {
-                MainActivityMapFragment mainActivityMapFragment = (MainActivityMapFragment) mSectionsPagerAdapter.getFragment(FRAGMENT_ID_MAP);
-                mainActivityMapFragment.handleShowMyLocation();
-            }
-        });
-
-        // secret night mode switch
-        mFloatingActionButtonLocation.setOnLongClickListener(new View.OnLongClickListener() {
-            @Override
-            public boolean onLongClick(View v) {
-                NightModeHelper.switchMode(MainActivity.this);
-                // vibrate 50 milliseconds
-                Vibrator vibrator = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
-                vibrator.vibrate(50);
-                // recreate activity
-                recreate();
-                return true;
-            }
-        });
-    }
-
-
-    /* Handles tap on the record button */
-    private void handleFloatingActionButtonClick(View view) {
-
-        switch (mFloatingActionButtonState) {
-            case FAB_STATE_DEFAULT:
-
-                // get last location from MainActivity Fragment // todo check -> may produce NullPointerException
-                MainActivityMapFragment mainActivityMapFragment = (MainActivityMapFragment) mSectionsPagerAdapter.getFragment(FRAGMENT_ID_MAP);
-                Location lastLocation = mainActivityMapFragment.getCurrentBestLocation();
-
-                if (lastLocation != null) {
-                    // show snackbar
-                    Snackbar.make(view, R.string.snackbar_message_tracking_started, Snackbar.LENGTH_SHORT).setAction("Action", null).show();
-                    // start recording
-                    startRecording(lastLocation);
-                } else {
-                    Toast.makeText(this, getString(R.string.toast_message_location_services_not_ready), Toast.LENGTH_LONG).show();
-                }
-
-                break;
-
-            case FAB_STATE_RECORDING:
-                // show snackbar
-                Snackbar.make(view, R.string.snackbar_message_tracking_stopped, Snackbar.LENGTH_SHORT).setAction("Action", null).show();
-                // stop tracker service
-                stopRecording();
-
-                break;
-
-            case FAB_STATE_SAVE:
-                // toggle visibility floating action button sub menu
-                showFloatingActionButtonMenu(!mFloatingActionButtonSubMenuVisible);
-
-                break;
-
-        }
-
-        // update tracking state in MainActivityMapFragment // todo check -> may produce NullPointerException
-        MainActivityMapFragment mainActivityMapFragment = (MainActivityMapFragment) mSectionsPagerAdapter.getFragment(FRAGMENT_ID_MAP);
-        mainActivityMapFragment.setTrackingState(mTrackerServiceRunning);
-    }
-
-
-    /* Set state of FloatingActionButton */
-    private void setFloatingActionButtonState() {
-
-        switch (mFloatingActionButtonState) {
-            case FAB_STATE_DEFAULT:
-                mFloatingActionButtonMain.hide(); // workaround todo remove asap
-                mFloatingActionButtonMain.setImageResource(R.drawable.ic_fiber_manual_record_white_24dp);
-                mFloatingActionButtonMain.setContentDescription(getString(R.string.descr_fab_main_start));
-                if (mSelectedTab == FRAGMENT_ID_MAP) mFloatingActionButtonMain.show(); // workaround todo remove asap
-                break;
-            case FAB_STATE_RECORDING:
-                mFloatingActionButtonMain.hide(); // workaround todo remove asap
-                mFloatingActionButtonMain.setImageResource(R.drawable.ic_fiber_manual_record_red_24dp);
-                mFloatingActionButtonMain.setContentDescription(getString(R.string.descr_fab_main_stop));
-                if (mSelectedTab == FRAGMENT_ID_MAP) mFloatingActionButtonMain.show(); // workaround todo remove asap
-                break;
-            case FAB_STATE_SAVE:
-                mFloatingActionButtonMain.hide(); // workaround todo remove asap
-                mFloatingActionButtonMain.setImageResource(R.drawable.ic_save_white_24dp);
-                mFloatingActionButtonMain.setContentDescription(getString(R.string.descr_fab_main_options));
-                if (mSelectedTab == FRAGMENT_ID_MAP) mFloatingActionButtonMain.show(); // workaround todo remove asap
-                break;
-            default:
-                mFloatingActionButtonMain.hide(); // workaround todo remove asap
-                mFloatingActionButtonMain.setImageResource(R.drawable.ic_fiber_manual_record_white_24dp);
-                mFloatingActionButtonMain.setContentDescription(getString(R.string.descr_fab_main_start));
-                if (mSelectedTab == FRAGMENT_ID_MAP) mFloatingActionButtonMain.show(); // workaround todo remove asap
-                break;
-        }
-    }
-
-
-    /* Shows (and hides) the sub menu of the floating action button */
-    private void showFloatingActionButtonMenu(boolean visible) {
-        if (visible) {
-            mFloatingActionButtonSubResume.show();
-            mFloatingActionButtonSubResumeLabel.setVisibility(View.VISIBLE);
-            mFloatingActionButtonSubClear.show();
-            mFloatingActionButtonSubClearLabel.setVisibility(View.VISIBLE);
-            mFloatingActionButtonSubSave.show();
-            mFloatingActionButtonSubSaveLabel.setVisibility(View.VISIBLE);
-            mFloatingActionButtonSubMenuVisible = true;
-        } else {
-            mFloatingActionButtonSubResume.hide();
-            mFloatingActionButtonSubResumeLabel.setVisibility(View.INVISIBLE);
-            mFloatingActionButtonSubClear.hide();
-            mFloatingActionButtonSubClearLabel.setVisibility(View.INVISIBLE);
-            mFloatingActionButtonSubSave.hide();
-            mFloatingActionButtonSubSaveLabel.setVisibility(View.INVISIBLE);
-            mFloatingActionButtonSubMenuVisible = false;
-        }
-    }
-
-
-    /* Handles taps on the bottom navigation */
-    private BottomNavigationView.OnNavigationItemSelectedListener getOnNavigationItemSelectedListener() {
-        return new BottomNavigationView.OnNavigationItemSelectedListener() {
-            @Override
-            public boolean onNavigationItemSelected(@NonNull MenuItem item) {
-                switch (item.getItemId()) {
-                    case R.id.navigation_map:
-                        // show the Floating Action Button
-                        mFloatingActionButtonMain.show();
-
-                        // show the my location button
-                        mFloatingActionButtonLocation.show();
-
-                        // show map fragment
-                        mSelectedTab = FRAGMENT_ID_MAP;
-                        mViewPager.setCurrentItem(mSelectedTab);
-
-                        return true;
-
-                    case R.id.navigation_last_tracks:
-                        // hide the Floating Action Button - and its sub menu
-                        mFloatingActionButtonMain.hide();
-                        showFloatingActionButtonMenu(false);
-
-                        // hide the my location button
-                        mFloatingActionButtonLocation.hide();
-
-                        // show tracks fragment
-                        mSelectedTab = FRAGMENT_ID_TRACKS;
-                        mViewPager.setCurrentItem(mSelectedTab);
-
-                        return true;
-
-                    default:
-                        // show the Floating Action Button
-                        mFloatingActionButtonMain.show();
-                        return false;
-                }
-            }
-        };
-    }
-
-
-    /* Handles new incoming intents */
-    private void handleIncomingIntent() {
-        Intent intent = getIntent();
-        LogHelper.v(LOG_TAG, "Main Activity received intent. Content: " + intent.toString());
-        String intentAction = intent.getAction();
-        switch (intentAction) {
-            case ACTION_SHOW_MAP:
-                // show map fragment
-                mBottomNavigationView.setSelectedItemId(R.id.navigation_map);
-
-                // clear intent
-                intent.setAction(ACTION_DEFAULT);
-
-                break;
-
-            case ACTION_CLEAR:
-                // show map fragment
-                mBottomNavigationView.setSelectedItemId(R.id.navigation_map);
-
-                // show clear dialog
-                handleClearButtonClick();
-
-                // clear intent
-                intent.setAction(ACTION_DEFAULT);
-
-                break;
-
-            default:
-                break;
-        }
-    }
-
-
-    /* Inform user and give haptic feedback (vibration) */
-    private void longPressFeedback(int stringResource) {
-        // inform user
-        Toast.makeText(this, stringResource, Toast.LENGTH_LONG).show();
-        // vibrate 50 milliseconds
-        Vibrator v = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
-        if (v != null) {
-            v.vibrate(50);
-//            v.vibrate(VibrationEffect.createOneShot(50, DEFAULT_AMPLITUDE)); // todo check if there is a support library vibrator
-        }
-    }
-
-
-
-    /* Check which permissions have been granted */
-    private List<String> checkPermissions() {
-        List<String> permissions = new ArrayList<>();
-
-        // check for location permission
-        if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
-            // add missing permission
-            permissions.add(Manifest.permission.ACCESS_FINE_LOCATION);
-        }
-
-//        // check for storage permission
-//        if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
-//            // add missing permission
-//            permissions.add(Manifest.permission.WRITE_EXTERNAL_STORAGE);
-//        }
-
-        return permissions;
-    }
-
-
-    /* Creates receiver for stopped tracking */
-    private BroadcastReceiver createTrackingChangedReceiver() {
-        return new BroadcastReceiver() {
-            @Override
-            public void onReceive(Context context, Intent intent) {
-
-                // change state
-                mTrackerServiceRunning = intent.getBooleanExtra(EXTRA_TRACKING_STATE, false);
-                if (mTrackerServiceRunning) {
-                    mFloatingActionButtonState = FAB_STATE_RECORDING;
-                } else {
-                    mFloatingActionButtonState = FAB_STATE_SAVE;
-                }
-                setFloatingActionButtonState();
-
-                // pass tracking state to MainActivityMapFragment // todo check -> may produce NullPointerException
-                MainActivityMapFragment mainActivityMapFragment = (MainActivityMapFragment) mSectionsPagerAdapter.getFragment(FRAGMENT_ID_MAP);
-                mainActivityMapFragment.setTrackingState(mTrackerServiceRunning);
-            }
-        };
-    }
-
-
-    /* Checks the state of External Storage */
-    private void checkExternalStorageState() {
-
-        String state = Environment.getExternalStorageState();
-        if (!state.equals(Environment.MEDIA_MOUNTED)) {
-            LogHelper.e(LOG_TAG, "Error: Unable to mount External Storage. Current state: " + state);
-
-            // move MainActivity to back
-            moveTaskToBack(true);
-
-            // shutting down app
-            android.os.Process.killProcess(android.os.Process.myPid());
-            System.exit(1);
-        }
-    }
-
-
-//    public class SectionsPagerAdapter extends FragmentPagerAdapter {
-//
-//        public SectionsPagerAdapter(FragmentManager fm) {
-//            super(fm);
-//        }
-//
-//        @Override
-//        public Fragment getItem(int position) {
-//            // getItem is called to instantiate the fragment for the given page.
-//            switch (position) {
-//                case FRAGMENT_ID_MAP:
-//                    return new MainActivityMapFragment();
-//                case FRAGMENT_ID_TRACKS:
-//                    return new MainActivityTrackFragment();
-//            }
-//            return null;
-//        }
-//
-//        @Override
-//        public int getCount() {
-//            return 2;
-//        }
-//
-//        public Fragment getFragment(int pos) {
-//            return getItem(pos);
-//        }
-//
-//    }
-
-
-    /**
-     * Defines callbacks for service binding, passed to bindService()
-     */
-    private ServiceConnection mConnection = new ServiceConnection() {
-
-        @Override
-        public void onServiceConnected(ComponentName className, IBinder service) {
-            // We've bound to LocalService, cast the IBinder and get LocalService instance
-            TrackerService.LocalBinder binder = (TrackerService.LocalBinder) service;
-            mTrackerService = binder.getService();
-            mBound = true;
-        }
-
-        @Override
-        public void onServiceDisconnected(ComponentName arg0) {
-            mBound = false;
-        }
-    };
-
-
-    /**
-     * Inner class: SectionsPagerAdapter that returns a fragment corresponding to one of the tabs.
-     * see also: https://developer.android.com/reference/android/support/v4/app/FragmentPagerAdapter.html
-     * and: http://www.truiton.com/2015/12/android-activity-fragment-communication/
-     */
-    public class SectionsPagerAdapter extends FragmentStatePagerAdapter {
-
-        private final SparseArray<WeakReference<Fragment>> instantiatedFragments = new SparseArray<>();
-
-        public SectionsPagerAdapter(FragmentManager fm) {
-            super(fm);
-        }
-
-        @Override
-        public Fragment getItem(int position) {
-            // getItem is called to instantiate the fragment for the given page.
-            switch (position) {
-                case FRAGMENT_ID_MAP:
-                    return new MainActivityMapFragment();
-                case FRAGMENT_ID_TRACKS:
-                    return new MainActivityTrackFragment();
-            }
-            return null;
-        }
-
-        @Override
-        public int getCount() {
-            // show 2 total pages.
-            return 2;
-        }
-
-        @Override
-        public CharSequence getPageTitle(int position) {
-            switch (position) {
-                case FRAGMENT_ID_MAP:
-                    return getString(R.string.tab_map);
-                case FRAGMENT_ID_TRACKS:
-                    return getString(R.string.tab_last_tracks);
-            }
-            return null;
-        }
-
-        @NonNull
-        @Override
-        public Object instantiateItem(final ViewGroup container, final int position) {
-            final Fragment fragment = (Fragment) super.instantiateItem(container, position);
-            instantiatedFragments.put(position, new WeakReference<>(fragment));
-            return fragment;
-        }
-
-        @Override
-        public void destroyItem(final ViewGroup container, final int position, final Object object) {
-            instantiatedFragments.remove(position);
-            super.destroyItem(container, position, object);
-        }
-
-        @Nullable
-        public Fragment getFragment(final int position) {
-            final WeakReference<Fragment> wr = instantiatedFragments.get(position);
-            if (wr != null) {
-                return wr.get();
-            } else {
-                return null;
-            }
-        }
-
-    }
-    /**
-     * End of inner class
-     */
-
-
-}

app/src/main/java/org/y20k/trackbook/MainActivity.kt

@@ -0,0 +1,85 @@
+/*
+ * MainActivity.kt
+ * Implements the main activity of the app
+ * The MainActivity hosts fragments for: current map, track list,  settings
+ *
+ * This file is part of
+ * TRACKBOOK - Movement Recorder for Android
+ *
+ * Copyright (c) 2016-20 - Y20K.org
+ * Licensed under the MIT-License
+ * http://opensource.org/licenses/MIT
+ *
+ * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
+ * https://github.com/osmdroid/osmdroid
+ */
+
+
+package org.y20k.trackbook
+
+import android.os.Bundle
+import androidx.appcompat.app.AppCompatActivity
+import androidx.navigation.fragment.NavHostFragment
+import androidx.navigation.ui.setupWithNavController
+import com.google.android.material.bottomnavigation.BottomNavigationView
+import org.osmdroid.config.Configuration
+import org.y20k.trackbook.helpers.ImportHelper
+import org.y20k.trackbook.helpers.LogHelper
+import org.y20k.trackbook.helpers.PreferencesHelper
+
+
+/*
+ * MainActivity class
+ */
+class MainActivity : AppCompatActivity() {
+
+    /* Define log tag */
+    private val TAG: String = LogHelper.makeLogTag(MainActivity::class.java)
+
+
+    /* Main class variables */
+    private lateinit var navHostFragment: NavHostFragment
+    private lateinit var bottomNavigationView: BottomNavigationView
+
+
+    /* Overrides onCreate from AppCompatActivity */
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        // set user agent to prevent getting banned from the osm servers
+        Configuration.getInstance().userAgentValue = BuildConfig.APPLICATION_ID
+        // set the path for osmdroid's files (e.g. tile cache)
+        Configuration.getInstance().osmdroidBasePath = this.getExternalFilesDir(null)
+
+        // set up views
+        setContentView(R.layout.activity_main)
+        navHostFragment  = supportFragmentManager.findFragmentById(R.id.main_container) as NavHostFragment
+        bottomNavigationView = findViewById<BottomNavigationView>(R.id.bottom_navigation_view)
+        bottomNavigationView.setupWithNavController(navController = navHostFragment.navController)
+
+        // listen for navigation changes
+        navHostFragment.navController.addOnDestinationChangedListener { _, destination, _ ->
+            when (destination.id) {
+                R.id.fragment_track -> {
+                    runOnUiThread( Runnable() {
+                        run(){
+                            // mark menu item "Tracks" as checked
+                            bottomNavigationView.menu.findItem(R.id.tracklist_fragment).setChecked(true)
+                        }
+                    })
+                }
+                else -> {
+                    // do nothing
+                }
+            }
+        }
+
+        // convert old tracks (one-time import)
+        if (PreferencesHelper.isHouseKeepingNecessary(this)) {
+            ImportHelper.convertOldTracks(this)
+            PreferencesHelper.saveHouseKeepingNecessaryState(this)
+        }
+
+    }
+
+}

app/src/main/java/org/y20k/trackbook/MainActivityMapFragment.java

@@ -1,741 +0,0 @@
-/**
- * MainActivityMapFragment.java
- * Implements the map fragment used in the map tab of the main activity
- * This fragment displays a map using osmdroid
- *
- * This file is part of
- * TRACKBOOK - Movement Recorder for Android
- *
- * Copyright (c) 2016-19 - Y20K.org
- * Licensed under the MIT-License
- * http://opensource.org/licenses/MIT
- *
- * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
- * https://github.com/osmdroid/osmdroid
- */
-
-package org.y20k.trackbook;
-
-import android.app.Activity;
-import android.content.BroadcastReceiver;
-import android.content.Context;
-import android.content.Intent;
-import android.content.IntentFilter;
-import android.content.SharedPreferences;
-import android.database.ContentObserver;
-import android.location.Location;
-import android.location.LocationListener;
-import android.location.LocationManager;
-import android.os.AsyncTask;
-import android.os.Bundle;
-import android.os.Handler;
-import android.os.SystemClock;
-import android.preference.PreferenceManager;
-import android.view.LayoutInflater;
-import android.view.View;
-import android.view.ViewGroup;
-import android.widget.Toast;
-
-import androidx.annotation.NonNull;
-import androidx.appcompat.app.AppCompatActivity;
-import androidx.fragment.app.DialogFragment;
-import androidx.fragment.app.Fragment;
-import androidx.localbroadcastmanager.content.LocalBroadcastManager;
-
-import com.google.android.material.snackbar.Snackbar;
-
-import org.osmdroid.api.IMapController;
-import org.osmdroid.tileprovider.tilesource.TileSourceFactory;
-import org.osmdroid.util.GeoPoint;
-import org.osmdroid.views.MapView;
-import org.osmdroid.views.overlay.ItemizedIconOverlay;
-import org.osmdroid.views.overlay.TilesOverlay;
-import org.osmdroid.views.overlay.compass.CompassOverlay;
-import org.osmdroid.views.overlay.compass.InternalCompassOrientationProvider;
-import org.y20k.trackbook.core.Track;
-import org.y20k.trackbook.helpers.DialogHelper;
-import org.y20k.trackbook.helpers.LocationHelper;
-import org.y20k.trackbook.helpers.LogHelper;
-import org.y20k.trackbook.helpers.MapHelper;
-import org.y20k.trackbook.helpers.NightModeHelper;
-import org.y20k.trackbook.helpers.StorageHelper;
-import org.y20k.trackbook.helpers.TrackbookKeys;
-
-import java.util.List;
-
-
-/**
- * MainActivityMapFragment class
- */
-public class MainActivityMapFragment extends Fragment implements TrackbookKeys {
-
-    /* Define log tag */
-    private static final String LOG_TAG = MainActivityMapFragment.class.getSimpleName();
-
-
-    /* Main class variables */
-    private Activity mActivity;
-    private Track mTrack;
-    private boolean mFirstStart;
-    private Snackbar mLocationOffBar;
-    private BroadcastReceiver mTrackUpdatedReceiver;
-    private SettingsContentObserver mSettingsContentObserver;
-    private MapView mMapView;
-    private IMapController mController;
-    private StorageHelper mStorageHelper;
-    private LocationManager mLocationManager;
-    private LocationListener mGPSListener;
-    private LocationListener mNetworkListener;
-    private ItemizedIconOverlay mMyLocationOverlay;
-    private ItemizedIconOverlay mTrackOverlay;
-    private Location mCurrentBestLocation;
-    private boolean mTrackerServiceRunning;
-    private boolean mLocalTrackerRunning;
-    private boolean mLocationSystemSetting;
-    private boolean mFragmentVisible;
-
-
-    /* Constructor (default) */
-    public MainActivityMapFragment() {
-    }
-
-
-    /* Return a new Instance of MainActivityMapFragment */
-    public static MainActivityMapFragment newInstance() {
-        return new MainActivityMapFragment();
-    }
-
-
-    @Override
-    public void onCreate(Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-
-        // get activity
-        mActivity = getActivity();
-
-        // restore first start state and tracking state
-        mFirstStart = true;
-        mTrackerServiceRunning = false;
-        loadTrackerServiceState(mActivity);
-        if (savedInstanceState != null) {
-            mFirstStart = savedInstanceState.getBoolean(INSTANCE_FIRST_START, true);
-        }
-
-        // create storage helper
-        mStorageHelper = new StorageHelper(mActivity);
-
-        // acquire reference to Location Manager
-        mLocationManager = (LocationManager) mActivity.getSystemService(Context.LOCATION_SERVICE);
-
-        // CASE 1: get saved location if possible
-        if (savedInstanceState != null) {
-            Location savedLocation = savedInstanceState.getParcelable(INSTANCE_CURRENT_LOCATION);
-            // check if saved location is still current
-            if (LocationHelper.isCurrent(savedLocation)) {
-                mCurrentBestLocation = savedLocation;
-            } else {
-                mCurrentBestLocation = null;
-            }
-        }
-
-        // CASE 2: get last known location if no saved location or saved location is too old
-        if (mCurrentBestLocation == null && mLocationManager.getProviders(true).size() > 0) {
-            mCurrentBestLocation = LocationHelper.determineLastKnownLocation(mLocationManager);
-        }
-
-        // CASE 3: location services are available but unable to get location - this should not happen
-        if (mCurrentBestLocation == null) {
-            mCurrentBestLocation = new Location(LocationManager.NETWORK_PROVIDER);
-            mCurrentBestLocation.setLatitude(DEFAULT_LATITUDE);
-            mCurrentBestLocation.setLongitude(DEFAULT_LONGITUDE);
-        }
-
-        // get state of location system setting
-        mLocationSystemSetting = LocationHelper.checkLocationSystemSetting(mActivity);
-
-        // create content observer for changes in System Settings
-        mSettingsContentObserver = new SettingsContentObserver( new Handler());
-
-        // register broadcast receiver for new WayPoints
-        mTrackUpdatedReceiver = createTrackUpdatedReceiver();
-        IntentFilter trackUpdatedIntentFilter = new IntentFilter(ACTION_TRACK_UPDATED);
-        LocalBroadcastManager.getInstance(mActivity).registerReceiver(mTrackUpdatedReceiver, trackUpdatedIntentFilter);
-    }
-
-
-    @Override
-    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
-        // create basic map
-        mMapView = new MapView(inflater.getContext());
-
-        // get map controller
-        mController = mMapView.getController();
-
-        // basic map setup
-        mMapView.setTileSource(TileSourceFactory.MAPNIK);
-        mMapView.setTilesScaledToDpi(true);
-
-        // set dark map tiles, if necessary
-        if (NightModeHelper.getNightMode(mActivity)) {
-            mMapView.getOverlayManager().getTilesOverlay().setColorFilter(TilesOverlay.INVERT_COLORS);
-        }
-
-        // add multi-touch capability
-        mMapView.setMultiTouchControls(true);
-
-        // disable default zoom controls
-        mMapView.getZoomController().setVisibility(org.osmdroid.views.CustomZoomButtonsController.Visibility.NEVER);
-
-        // add compass to map
-        CompassOverlay compassOverlay = new CompassOverlay(mActivity, new InternalCompassOrientationProvider(mActivity), mMapView);
-        compassOverlay.enableCompass();
-        mMapView.getOverlays().add(compassOverlay);
-
-        // initiate map state
-        if (savedInstanceState != null) {
-            // restore saved instance of map
-            GeoPoint position = new GeoPoint(savedInstanceState.getDouble(INSTANCE_LATITUDE_MAIN_MAP, DEFAULT_LATITUDE), savedInstanceState.getDouble(INSTANCE_LONGITUDE_MAIN_MAP, DEFAULT_LONGITUDE));
-            mController.setCenter(position);
-            mController.setZoom(savedInstanceState.getDouble(INSTANCE_ZOOM_LEVEL_MAIN_MAP, 16f));
-            // restore current location
-            mCurrentBestLocation = savedInstanceState.getParcelable(INSTANCE_CURRENT_LOCATION);
-        } else if (mCurrentBestLocation != null) {
-            // fallback or first run: set map to current position
-            GeoPoint position = convertToGeoPoint(mCurrentBestLocation);
-            mController.setCenter(position);
-            mController.setZoom(16f);
-        }
-
-        // inform user that new/better location is on its way
-        if (mFirstStart && !mTrackerServiceRunning) {
-            Toast.makeText(mActivity, mActivity.getString(R.string.toast_message_acquiring_location), Toast.LENGTH_LONG).show();
-            mFirstStart = false;
-        }
-
-//        // load track from saved instance
-//        if (savedInstanceState != null) {
-//            mTrack = savedInstanceState.getParcelable(INSTANCE_TRACK_MAIN_MAP);
-//        }
-
-        // mark user's location on map
-        if (mCurrentBestLocation != null && !mTrackerServiceRunning) {
-            mMyLocationOverlay = MapHelper.createMyLocationOverlay(mActivity, mCurrentBestLocation, LocationHelper.isCurrent(mCurrentBestLocation), false);
-            mMapView.getOverlays().add(mMyLocationOverlay);
-        }
-
-        return mMapView;
-    }
-
-
-    @Override
-    public void onResume() {
-        super.onResume();
-
-        // set visibility
-        mFragmentVisible = true;
-
-        // load state of tracker service - see if anything changed
-        loadTrackerServiceState(mActivity);
-
-        // load track from temp file if it exists
-        if (mStorageHelper.tempFileExists()) {
-            LoadTempTrackAsyncHelper loadTempTrackAsyncHelper = new LoadTempTrackAsyncHelper();
-            loadTempTrackAsyncHelper.execute();
-        }
-
-//        // CASE 1: recording active
-//        if (mTrackerServiceRunning) {
-//            // request an updated track recording from service
-//            ((MainActivity)mActivity).requestTrack();
-//        }
-//
-//        // CASE 2: recording stopped - temp file exists
-//        else if (mStorageHelper.tempFileExists()) {
-//            // load track from temp file if it exists
-//            LoadTempTrackAsyncHelper loadTempTrackAsyncHelper = new LoadTempTrackAsyncHelper();
-//            loadTempTrackAsyncHelper.execute();
-//        }
-
-//        // CASE 3: not recording and no temp file
-//        else if (mTrack != null) {
-//            // just draw existing track data (from saved instance)
-//            drawTrackOverlay(mTrack);
-//        }
-
-        // show/hide the location off notification bar
-        toggleLocationOffBar();
-
-        // start preliminary tracking - if no TrackerService is running
-        if (!mTrackerServiceRunning && mFragmentVisible) {
-            startPreliminaryTracking();
-        }
-
-        // register content observer for changes in System Settings
-        mActivity.getContentResolver().registerContentObserver(android.provider.Settings.Secure.CONTENT_URI, true, mSettingsContentObserver );
-    }
-
-
-    @Override
-    public void onPause() {
-        super.onPause();
-
-        // set visibility
-        mFragmentVisible = false;
-
-        // disable preliminary location listeners
-        stopPreliminaryTracking();
-
-        // disable content observer for changes in System Settings
-        mActivity.getContentResolver().unregisterContentObserver(mSettingsContentObserver);
-    }
-
-
-    @Override
-    public void onDestroyView(){
-        super.onDestroyView();
-
-        // deactivate map
-        mMapView.onDetach();
-    }
-
-
-    @Override
-    public void onDestroy() {
-        LogHelper.v(LOG_TAG, "onDestroy called.");
-
-        // reset first start state
-        mFirstStart = true;
-
-        // disable  broadcast receivers
-        LocalBroadcastManager.getInstance(mActivity).unregisterReceiver(mTrackUpdatedReceiver);
-
-        super.onDestroy();
-    }
-
-
-    @Override
-    public void onActivityResult(int requestCode, int resultCode, Intent data) {
-        super.onActivityResult(requestCode, resultCode, data);
-        switch(requestCode) {
-            case RESULT_SAVE_DIALOG:
-                if (resultCode == Activity.RESULT_OK) {
-                    // user chose SAVE
-                    if (mTrack.getSize() > 0) {
-                        // Track is not empty - clear map AND save track
-                        clearMap(true);
-                        // FloatingActionButton state is already being handled in MainActivity
-                        ((MainActivity)mActivity).onFloatingActionButtonResult(requestCode, resultCode);
-                        LogHelper.v(LOG_TAG, "Save dialog result: SAVE");
-                    } else {
-                        // track is empty
-                        handleEmptyRecordingSaveRequest();
-                    }
-                } else if (resultCode == Activity.RESULT_CANCELED){
-                    LogHelper.v(LOG_TAG, "Save dialog result: CANCEL");
-                }
-                break;
-            case RESULT_CLEAR_DIALOG:
-                if (resultCode == Activity.RESULT_OK) {
-                    // User chose CLEAR
-                    if (mTrack.getSize() > 0) {
-                        // Track is not empty - notify user
-                        Toast.makeText(mActivity, getString(R.string.toast_message_track_clear), Toast.LENGTH_LONG).show();
-                    }
-                    // clear map, DO NOT save track
-                    clearMap(false);
-                    // handle FloatingActionButton state in MainActivity
-                    ((MainActivity)mActivity).onFloatingActionButtonResult(requestCode, resultCode);
-                } else if (resultCode == Activity.RESULT_CANCELED){
-                    LogHelper.v(LOG_TAG, "Clear dialog result: CANCEL");
-                }
-                break;
-            case RESULT_EMPTY_RECORDING_DIALOG:
-                // handle FloatingActionButton state and possible Resume-Action in MainActivity
-                ((MainActivity)mActivity).onFloatingActionButtonResult(requestCode, resultCode);
-                break;
-        }
-    }
-
-
-    @Override
-    public void onSaveInstanceState(@NonNull Bundle outState) {
-        outState.putBoolean(INSTANCE_FIRST_START, mFirstStart);
-        outState.putBoolean(INSTANCE_TRACKING_STATE, mTrackerServiceRunning);
-        outState.putParcelable(INSTANCE_CURRENT_LOCATION, mCurrentBestLocation);
-        outState.putDouble(INSTANCE_LATITUDE_MAIN_MAP, mMapView.getMapCenter().getLatitude());
-        outState.putDouble(INSTANCE_LONGITUDE_MAIN_MAP, mMapView.getMapCenter().getLongitude());
-        outState.putDouble(INSTANCE_ZOOM_LEVEL_MAIN_MAP, mMapView.getZoomLevelDouble());
-//        outState.putParcelable(INSTANCE_TRACK_MAIN_MAP, mTrack);
-        super.onSaveInstanceState(outState);
-    }
-
-
-    /* Setter for tracking state */
-    public void setTrackingState(boolean trackingState) {
-        mTrackerServiceRunning = trackingState;
-
-        // turn on/off tracking for MainActivity Fragment - prevent double tracking
-        if (mTrackerServiceRunning) {
-            stopPreliminaryTracking();
-        } else if (!mLocalTrackerRunning && mFragmentVisible) {
-            startPreliminaryTracking();
-        }
-
-        if (mTrack != null) {
-            drawTrackOverlay(mTrack); // TODO check if redundant
-        }
-
-        // update marker
-        updateMyLocationMarker();
-        LogHelper.v(LOG_TAG, "TrackingState: " + trackingState);
-    }
-
-
-    /* Getter for current best location */
-    public Location getCurrentBestLocation() {
-        if (mLocationSystemSetting) {
-            return mCurrentBestLocation;
-        } else {
-            return null;
-        }
-    }
-
-
-    /* Handles tap on the my location button */
-    public boolean handleShowMyLocation() {
-
-        // do nothing if location setting is off
-        if (toggleLocationOffBar()) {
-            stopPreliminaryTracking();
-            return false;
-        }
-
-        GeoPoint position;
-
-        // get current position
-        if (mTrackerServiceRunning && mTrack != null && mTrack.getSize() > 0) {
-            // get current Location from tracker service
-            mCurrentBestLocation = mTrack.getWayPointLocation(mTrack.getSize() - 1);
-        } else if (mCurrentBestLocation == null) {
-            // app does not have any location fix
-            mCurrentBestLocation = LocationHelper.determineLastKnownLocation(mLocationManager);
-        }
-
-        // check if really got a position
-        if (mCurrentBestLocation != null) {
-            position = convertToGeoPoint(mCurrentBestLocation);
-
-            // center map on current position
-            mController.setCenter(position);
-
-            // mark user's new location on map and remove last marker
-            updateMyLocationMarker();
-
-            // inform user about location quality
-            String locationInfo;
-            long locationAge =  (SystemClock.elapsedRealtimeNanos() - mCurrentBestLocation.getElapsedRealtimeNanos()) / 1000000;
-            String locationAgeString = LocationHelper.convertToReadableTime(locationAge, false);
-            if (locationAgeString == null) {
-                locationAgeString = mActivity.getString(R.string.toast_message_last_location_age_one_hour);
-            }
-            locationInfo = " " + locationAgeString + " | " + mCurrentBestLocation.getProvider();
-            Toast.makeText(mActivity, mActivity.getString(R.string.toast_message_last_location) + locationInfo, Toast.LENGTH_LONG).show();
-            return true;
-        } else {
-            Toast.makeText(mActivity, mActivity.getString(R.string.toast_message_location_services_not_ready), Toast.LENGTH_LONG).show();
-            return false;
-        }
-    }
-
-
-    /* Removes track crumbs from map */
-    private void clearMap(boolean saveTrack) {
-
-        // clear map
-        if (mTrackOverlay != null) {
-            mMapView.getOverlays().remove(mTrackOverlay);
-            mTrackOverlay = null;
-        }
-
-        if (saveTrack) {
-            // save track object if requested
-            SaveTrackAsyncHelper saveTrackAsyncHelper = new SaveTrackAsyncHelper();
-            saveTrackAsyncHelper.execute();
-            Toast.makeText(mActivity, mActivity.getString(R.string.toast_message_save_track), Toast.LENGTH_LONG).show();
-        } else {
-            // clear track object and delete temp file
-            mTrack = null;
-            mStorageHelper.deleteTempFile();
-        }
-
-    }
-
-
-    /* Handles case when user chose to save recording with zero waypoints */ // todo implement
-    private void handleEmptyRecordingSaveRequest() {
-        // prepare empty recording dialog ("Unable to save")
-        int dialogTitle = R.string.dialog_error_empty_recording_title;
-        String dialogMessage = getString(R.string.dialog_error_empty_recording_content);
-        int dialogPositiveButton = R.string.dialog_error_empty_recording_action_resume;
-        int dialogNegativeButton = R.string.dialog_default_action_cancel;
-        // show  empty recording dialog
-        DialogFragment dialogFragment = DialogHelper.newInstance(dialogTitle, dialogMessage, dialogPositiveButton, dialogNegativeButton);
-        dialogFragment.setTargetFragment(this, RESULT_EMPTY_RECORDING_DIALOG);
-        dialogFragment.show(((AppCompatActivity)mActivity).getSupportFragmentManager(), "EmptyRecordingDialog");
-        // results of dialog are handled by onActivityResult
-    }
-
-
-    /* Start preliminary tracking for map */
-    private void startPreliminaryTracking() {
-        if (mLocationSystemSetting && !mLocalTrackerRunning) {
-            // create location listeners
-            List locationProviders = mLocationManager.getAllProviders();
-            if (locationProviders.contains(LocationManager.GPS_PROVIDER)) {
-                mGPSListener = createLocationListener();
-                mLocalTrackerRunning = true;
-            }
-            if (locationProviders.contains(LocationManager.NETWORK_PROVIDER)) {
-                mNetworkListener = createLocationListener();
-                mLocalTrackerRunning = true;
-            }
-            // register listeners
-            LocationHelper.registerLocationListeners(mLocationManager, mGPSListener, mNetworkListener);
-            LogHelper.v(LOG_TAG, "Starting preliminary tracking.");
-        }
-    }
-
-
-    /* Removes gps and network location listeners */
-    private void stopPreliminaryTracking() {
-        if (mLocalTrackerRunning) {
-            mLocalTrackerRunning = false;
-            // remove listeners
-            LocationHelper.removeLocationListeners(mLocationManager, mGPSListener, mNetworkListener);
-            LogHelper.v(LOG_TAG, "Stopping preliminary tracking.");
-        }
-    }
-
-
-    /* Creates listener for changes in location status */
-    private LocationListener createLocationListener() {
-        return new LocationListener() {
-            public void onLocationChanged(Location location) {
-                // check if the new location is better
-                if (mCurrentBestLocation == null || LocationHelper.isBetterLocation(location, mCurrentBestLocation)) {
-                    // save location
-                    mCurrentBestLocation = location;
-                    // mark user's new location on map and remove last marker
-                    updateMyLocationMarker();
-                }
-            }
-
-            public void onStatusChanged(String provider, int status, Bundle extras) {
-                LogHelper.v(LOG_TAG, "Location provider status change: " +  provider + " | " + status);
-            }
-
-            public void onProviderEnabled(String provider) {
-                LogHelper.v(LOG_TAG, "Location provider enabled: " +  provider);
-            }
-
-            public void onProviderDisabled(String provider) {
-                LogHelper.v(LOG_TAG, "Location provider disabled: " +  provider);
-            }
-        };
-    }
-
-
-    /* Updates marker for current user location  */
-    private void updateMyLocationMarker() {
-        mMapView.getOverlays().remove(mMyLocationOverlay);
-        // only update while not tracking
-        if (!mTrackerServiceRunning) {
-            mMyLocationOverlay = MapHelper.createMyLocationOverlay(mActivity, mCurrentBestLocation, LocationHelper.isCurrent(mCurrentBestLocation), false);
-            mMapView.getOverlays().add(mMyLocationOverlay);
-        }
-    }
-
-
-    /* Draws track onto overlay */
-    private void drawTrackOverlay(Track track) {
-        mMapView.getOverlays().remove(mTrackOverlay);
-        mTrackOverlay = null;
-        if (track == null || track.getSize() == 0) {
-            LogHelper.i(LOG_TAG, "Waiting for a track. Showing preliminary location.");
-            mTrackOverlay = MapHelper.createMyLocationOverlay(mActivity, mCurrentBestLocation, false, mTrackerServiceRunning);
-            Toast.makeText(mActivity, mActivity.getString(R.string.toast_message_acquiring_location), Toast.LENGTH_LONG).show();
-        } else {
-            LogHelper.v(LOG_TAG, "Drawing track overlay.");
-            mTrackOverlay = MapHelper.createTrackOverlay(mActivity, track, mTrackerServiceRunning);
-        }
-        mMapView.getOverlays().add(mTrackOverlay);
-
-    }
-
-
-    /* Toggles snackbar indicating that location setting is off */
-    private boolean toggleLocationOffBar() {
-        // create snackbar indicator for location setting off
-        if (mLocationOffBar == null) {
-            mLocationOffBar = Snackbar.make(mMapView, R.string.snackbar_message_location_offline, Snackbar.LENGTH_INDEFINITE).setAction("Action", null);
-        }
-
-        // get state of location system setting
-        mLocationSystemSetting = LocationHelper.checkLocationSystemSetting(mActivity);
-
-        // show snackbar if necessary
-        if (!mLocationSystemSetting)  {
-            // show snackbar
-            mLocationOffBar.show();
-            return true;
-
-        } else {
-            // hide snackbar
-            mLocationOffBar.dismiss();
-            return false;
-        }
-
-    }
-
-
-    /* Creates receiver for new WayPoints */
-    private BroadcastReceiver createTrackUpdatedReceiver() {
-        return new BroadcastReceiver() {
-            @Override
-            public void onReceive(Context context, Intent intent) {
-                if (intent.hasExtra(EXTRA_TRACK) && intent.hasExtra(EXTRA_LAST_LOCATION)) {
-                    // draw track on map
-                    mTrack = intent.getParcelableExtra(EXTRA_TRACK);
-                    drawTrackOverlay(mTrack);
-                    // center map over last location
-                    mCurrentBestLocation = intent.getParcelableExtra(EXTRA_LAST_LOCATION);
-                    mController.setCenter(convertToGeoPoint(mCurrentBestLocation));
-                    // clear intent
-                    intent.setAction(ACTION_DEFAULT);
-                }
-            }
-        };
-    }
-
-
-    /* Converts Location to GeoPoint */
-    private GeoPoint convertToGeoPoint (Location location) {
-        if (location != null) {
-            return new GeoPoint(location.getLatitude(), location.getLongitude());
-        } else {
-            return new GeoPoint(DEFAULT_LATITUDE, DEFAULT_LONGITUDE);
-        }
-    }
-
-
-    /* Loads state tracker service from preferences */
-    private void loadTrackerServiceState(Context context) {
-        // TODO: get state directly from service, create a ServiceConnection.
-        // see: https://github.com/ena1106/FragmentBoundServiceExample/blob/master/app/src/main/java/it/ena1106/fragmentboundservice/BoundFragment.java
-        SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(context);
-        mTrackerServiceRunning = settings.getBoolean(PREFS_TRACKER_SERVICE_RUNNING, false);
-    }
-
-
-    /**
-     * Inner class: SettingsContentObserver is a custom ContentObserver for changes in Android Settings
-     */
-    private class SettingsContentObserver extends ContentObserver {
-
-        SettingsContentObserver(Handler handler) {
-            super(handler);
-        }
-
-        @Override
-        public boolean deliverSelfNotifications() {
-            return super.deliverSelfNotifications();
-        }
-
-        @Override
-        public void onChange(boolean selfChange) {
-            super.onChange(selfChange);
-            LogHelper.v(LOG_TAG, "System Setting change detected.");
-
-            // check if location setting was changed
-            boolean previousLocationSystemSetting = mLocationSystemSetting;
-            mLocationSystemSetting = LocationHelper.checkLocationSystemSetting(mActivity);
-            if (previousLocationSystemSetting != mLocationSystemSetting) {
-                LogHelper.v(LOG_TAG, "Location Setting change detected.");
-                toggleLocationOffBar();
-            }
-
-            // start / stop preliminary tracking
-            if (!mLocationSystemSetting) {
-                stopPreliminaryTracking();
-            } else if (!mTrackerServiceRunning && mFragmentVisible) {
-                startPreliminaryTracking();
-            }
-        }
-
-    }
-
-
-    /**
-     * Inner class: Saves track to external storage using AsyncTask
-     */
-    private class SaveTrackAsyncHelper extends AsyncTask<Void, Void, Void> {
-
-        @Override
-        protected Void doInBackground(Void... voids) {
-            LogHelper.v(LOG_TAG, "Saving track object in background.");
-            // save track object
-            mStorageHelper.saveTrack(mTrack, FILE_MOST_CURRENT_TRACK);
-            return null;
-        }
-
-        @Override
-        protected void onPostExecute(Void aVoid) {
-            super.onPostExecute(aVoid);
-            // clear track object
-            LogHelper.v(LOG_TAG, "Saving finished.");
-            mTrack = null;
-
-            // notify track fragment that save is finished
-            Intent i = new Intent();
-            i.setAction(ACTION_TRACK_SAVE);
-            i.putExtra(EXTRA_SAVE_FINISHED, true);
-            LocalBroadcastManager.getInstance(mActivity).sendBroadcast(i);
-        }
-    }
-    /**
-     * End of inner class
-     */
-
-
-    /**
-     * Inner class: Loads track from external storage using AsyncTask
-     */
-    private class LoadTempTrackAsyncHelper extends AsyncTask<Void, Void, Void> {
-
-        @Override
-        protected Void doInBackground(Void... voids) {
-            LogHelper.v(LOG_TAG, "Loading temporary track object in background.");
-            // load track object
-            mTrack = mStorageHelper.loadTrack(FILE_TEMP_TRACK);
-            return null;
-        }
-
-        @Override
-        protected void onPostExecute(Void aVoid) {
-            super.onPostExecute(aVoid);
-            LogHelper.v(LOG_TAG, "Loading finished.");
-
-            // draw track on map
-            if (mTrack != null) {
-                drawTrackOverlay(mTrack);
-            }
-
-            // delete temp file
-//            mStorageHelper.deleteTempFile(); // todo check if necessary
-        }
-    }
-    /**
-     * End of inner class
-     */
-
-}

app/src/main/java/org/y20k/trackbook/MainActivityTrackFragment.java

@@ -1,729 +0,0 @@
-/**
- * MainActivityTrackFragment.java
- * Implements the track fragment used in the track tab of the main activity
- * This fragment displays a saved track
- *
- * This file is part of
- * TRACKBOOK - Movement Recorder for Android
- *
- * Copyright (c) 2016-19 - Y20K.org
- * Licensed under the MIT-License
- * http://opensource.org/licenses/MIT
- *
- * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
- * https://github.com/osmdroid/osmdroid
- */
-
-package org.y20k.trackbook;
-
-import android.app.Activity;
-import android.content.BroadcastReceiver;
-import android.content.Context;
-import android.content.Intent;
-import android.content.IntentFilter;
-import android.location.Location;
-import android.os.AsyncTask;
-import android.os.Bundle;
-import android.os.Vibrator;
-import android.view.GestureDetector;
-import android.view.LayoutInflater;
-import android.view.MotionEvent;
-import android.view.View;
-import android.view.ViewGroup;
-import android.widget.AdapterView;
-import android.widget.ImageButton;
-import android.widget.LinearLayout;
-import android.widget.Spinner;
-import android.widget.TextView;
-import android.widget.Toast;
-
-import androidx.annotation.NonNull;
-import androidx.annotation.Nullable;
-import androidx.constraintlayout.widget.ConstraintLayout;
-import androidx.constraintlayout.widget.Group;
-import androidx.core.content.ContextCompat;
-import androidx.fragment.app.DialogFragment;
-import androidx.fragment.app.Fragment;
-import androidx.fragment.app.FragmentActivity;
-import androidx.localbroadcastmanager.content.LocalBroadcastManager;
-
-import com.google.android.material.bottomsheet.BottomSheetBehavior;
-
-import org.osmdroid.api.IMapController;
-import org.osmdroid.events.MapEventsReceiver;
-import org.osmdroid.tileprovider.tilesource.TileSourceFactory;
-import org.osmdroid.util.GeoPoint;
-import org.osmdroid.views.MapView;
-import org.osmdroid.views.overlay.ItemizedIconOverlay;
-import org.osmdroid.views.overlay.MapEventsOverlay;
-import org.osmdroid.views.overlay.TilesOverlay;
-import org.osmdroid.views.overlay.compass.CompassOverlay;
-import org.osmdroid.views.overlay.compass.InternalCompassOrientationProvider;
-import org.y20k.trackbook.core.Track;
-import org.y20k.trackbook.helpers.DialogHelper;
-import org.y20k.trackbook.helpers.DropdownAdapter;
-import org.y20k.trackbook.helpers.ExportHelper;
-import org.y20k.trackbook.helpers.LengthUnitHelper;
-import org.y20k.trackbook.helpers.LocationHelper;
-import org.y20k.trackbook.helpers.LogHelper;
-import org.y20k.trackbook.helpers.MapHelper;
-import org.y20k.trackbook.helpers.NightModeHelper;
-import org.y20k.trackbook.helpers.StorageHelper;
-import org.y20k.trackbook.helpers.TrackbookKeys;
-
-import java.io.File;
-import java.text.DateFormat;
-import java.util.Locale;
-
-
-/**
- * MainActivityTrackFragment class
- */
-public class MainActivityTrackFragment extends Fragment implements AdapterView.OnItemSelectedListener, MapEventsReceiver, TrackbookKeys {
-
-    /* Define log tag */
-    private static final String LOG_TAG = MainActivityTrackFragment.class.getSimpleName();
-
-
-    /* Main class variables */
-    private FragmentActivity mActivity;
-    private View mRootView;
-    private MapView mMapView;
-    private LinearLayout mOnboardingView;
-    private IMapController mController;
-    private ItemizedIconOverlay mTrackOverlay;
-    private DropdownAdapter mDropdownAdapter;
-    private ConstraintLayout mTrackManagementLayout;
-    private Spinner mDropdown;
-    private View mStatisticsSheet;
-    private View mStatisticsView;
-    private TextView mDistanceView;
-    private TextView mStepsView;
-    private TextView mWaypointsView;
-    private TextView mDurationView;
-    private TextView mRecordingStartView;
-    private TextView mRecordingStopView;
-    private TextView mMaxAltitudeView;
-    private TextView mMinAltitudeView;
-    private TextView mPositiveElevationView;
-    private TextView mNegativeElevationView;
-    private Group mElevationDataViews;
-    private Group mStatisticsHeaderViews;
-    private BottomSheetBehavior mStatisticsSheetBehavior;
-    private int mCurrentTrack;
-    private Track mTrack;
-    private BroadcastReceiver mTrackSavedReceiver;
-
-
-    /* Return a new Instance of MainActivityTrackFragment */
-    public static MainActivityTrackFragment newInstance() {
-        return new MainActivityTrackFragment();
-    }
-
-
-    @Override
-    public void onCreate(Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-
-        // action bar has options menu
-        setHasOptionsMenu(true);
-
-        // store activity
-        mActivity = getActivity();
-
-        // get current track
-        if (savedInstanceState != null) {
-            mCurrentTrack = savedInstanceState.getInt(INSTANCE_CURRENT_TRACK, 0);
-        } else {
-            mCurrentTrack = 0;
-        }
-
-        // create drop-down adapter
-        mDropdownAdapter = new DropdownAdapter(mActivity);
-
-        // listen for finished save operation
-        mTrackSavedReceiver = new BroadcastReceiver() {
-            @Override
-            public void onReceive(Context context, Intent intent) {
-                if (intent.hasExtra(EXTRA_SAVE_FINISHED) && intent.getBooleanExtra(EXTRA_SAVE_FINISHED, false)) {
-                    LogHelper.v(LOG_TAG, "Save operation detected. Start loading the new track.");
-
-                    // update dropdown menu (and load track in onItemSelected)
-                    mDropdownAdapter.refresh();
-                    mDropdownAdapter.notifyDataSetChanged();
-                    mDropdown.setAdapter(mDropdownAdapter);
-                    mDropdown.setSelection(0, true);
-
-                    // remove onboarding if necessary
-                    switchOnboardingLayout();
-                }
-            }
-        };
-        IntentFilter trackSavedReceiverIntentFilter = new IntentFilter(ACTION_TRACK_SAVE);
-        LocalBroadcastManager.getInstance(mActivity).registerReceiver(mTrackSavedReceiver, trackSavedReceiverIntentFilter);
-
-    }
-
-
-    @Nullable
-    @Override
-    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
-
-        // inflate root view from xml
-        mRootView = inflater.inflate(R.layout.fragment_main_track, container, false);
-
-        // get reference to onboarding layout
-        mOnboardingView = (LinearLayout) mRootView.findViewById(R.id.track_tab_onboarding);
-
-        // get reference to basic map
-        mMapView = (MapView) mRootView.findViewById(R.id.track_map);
-
-        // get map controller
-        mController = mMapView.getController();
-
-        // basic map setup
-        mMapView.setTileSource(TileSourceFactory.MAPNIK);
-        mMapView.setTilesScaledToDpi(true);
-
-        // set dark map tiles, if necessary
-        if (NightModeHelper.getNightMode(mActivity)) {
-            mMapView.getOverlayManager().getTilesOverlay().setColorFilter(TilesOverlay.INVERT_COLORS);
-        }
-
-        // add multi-touch capability
-        mMapView.setMultiTouchControls(true);
-
-        // disable default zoom controls
-        mMapView.getZoomController().setVisibility(org.osmdroid.views.CustomZoomButtonsController.Visibility.NEVER);
-
-        // add compass to map
-        CompassOverlay compassOverlay = new CompassOverlay(mActivity, new InternalCompassOrientationProvider(mActivity), mMapView);
-        compassOverlay.enableCompass();
-        // move the compass overlay down a bit
-        compassOverlay.setCompassCenter(35.0f, 96.0f);
-        mMapView.getOverlays().add(compassOverlay);
-
-        // initiate map state
-        if (savedInstanceState != null) {
-            // restore saved instance of map
-            GeoPoint position = new GeoPoint(savedInstanceState.getDouble(INSTANCE_LATITUDE_TRACK_MAP, DEFAULT_LATITUDE), savedInstanceState.getDouble(INSTANCE_LONGITUDE_TRACK_MAP, DEFAULT_LONGITUDE));
-            mController.setCenter(position);
-            mController.setZoom(savedInstanceState.getDouble(INSTANCE_ZOOM_LEVEL_MAIN_MAP, 16f));
-        } else {
-            mController.setZoom(16f);
-        }
-
-        // get views for track selector
-        mTrackManagementLayout = (ConstraintLayout) mRootView.findViewById(R.id.track_management_layout);
-        mDropdown = (Spinner) mRootView.findViewById(R.id.track_selector);
-
-        // attach listeners to export and delete buttons
-        ImageButton shareButton = (ImageButton) mRootView.findViewById(R.id.share_button);
-        ImageButton exportButton = (ImageButton) mRootView.findViewById(R.id.export_button);
-        ImageButton deleteButton = (ImageButton) mRootView.findViewById(R.id.delete_button);
-        shareButton.setOnClickListener(getShareButtonListener());
-        exportButton.setOnClickListener(getExportButtonListener());
-        deleteButton.setOnClickListener(getDeleteButtonListener());
-
-        // get views for statistics sheet
-        mStatisticsView = mRootView.findViewById(R.id.statistics_view);
-        mStatisticsSheet = mRootView.findViewById(R.id.statistics_sheet);
-        mDistanceView = (TextView) mRootView.findViewById(R.id.statistics_data_distance);
-        mStepsView = (TextView) mRootView.findViewById(R.id.statistics_data_steps);
-        mWaypointsView = (TextView) mRootView.findViewById(R.id.statistics_data_waypoints);
-        mDurationView = (TextView) mRootView.findViewById(R.id.statistics_data_duration);
-        mRecordingStartView = (TextView) mRootView.findViewById(R.id.statistics_data_recording_start);
-        mRecordingStopView = (TextView) mRootView.findViewById(R.id.statistics_data_recording_stop);
-        mMaxAltitudeView = (TextView) mRootView.findViewById(R.id.statistics_data_max_altitude);
-        mMinAltitudeView = (TextView) mRootView.findViewById(R.id.statistics_data_min_altitude);
-        mPositiveElevationView = (TextView) mRootView.findViewById(R.id.statistics_data_positive_elevation);
-        mNegativeElevationView = (TextView) mRootView.findViewById(R.id.statistics_data_negative_elevation);
-        mElevationDataViews = (Group) mRootView.findViewById(R.id.elevation_data);
-        mStatisticsHeaderViews = (Group) mRootView.findViewById(R.id.statistics_header);
-
-
-        // display map and statistics
-        if (savedInstanceState != null) {
-            // get track from saved instance and display map and statistics
-            mTrack = savedInstanceState.getParcelable(INSTANCE_TRACK_TRACK_MAP);
-            displayTrack();
-        } else if (mTrack == null) {
-            // load track and display map and statistics
-            LoadTrackAsyncHelper loadTrackAsyncHelper = new LoadTrackAsyncHelper();
-            loadTrackAsyncHelper.execute();
-        } else {
-            // just display map and statistics
-            displayTrack();
-        }
-
-        // set up and show statistics sheet
-        mStatisticsSheetBehavior = BottomSheetBehavior.from(mStatisticsSheet);
-        mStatisticsSheetBehavior.setState(BottomSheetBehavior.STATE_COLLAPSED);
-        mStatisticsSheetBehavior.setBottomSheetCallback(getStatisticsSheetCallback());
-
-        // attach listener for taps on elevation views
-        attachTapListenerToElevationViews();
-
-        // attach listener for taps on statistics sheet header
-        attachTapListenerToStatisticHeaderViews();
-
-        // attach listener for taps on statistics - for US and other states plagued by Imperial units
-        if (LengthUnitHelper.getUnitSystem() == IMPERIAL || Locale.getDefault().getCountry().equals("GB")) {
-            attachTapListenerToStatisticsSheet();
-        }
-
-        // enable additional gestures
-        MapEventsOverlay OverlayEventos = new MapEventsOverlay(this);
-        mMapView.getOverlays().add(OverlayEventos);
-
-        return mRootView;
-    }
-
-
-    @Override
-    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
-        super.onViewCreated(view, savedInstanceState);
-        mDropdown.setAdapter(mDropdownAdapter);
-        mDropdown.setOnItemSelectedListener(this);
-    }
-
-
-    @Override
-    public void onResume() {
-        super.onResume();
-        // show / hide the onboarding layout
-        switchOnboardingLayout();
-    }
-
-
-    @Override
-    public void onPause() {
-        super.onPause();
-    }
-
-
-    @Override
-    public void onDestroyView(){
-        super.onDestroyView();
-
-        // deactivate map
-        mMapView.onDetach();
-    }
-
-
-    @Override
-    public void onDestroy() {
-        LogHelper.v(LOG_TAG, "onDestroy called.");
-
-        // remove listener
-        LocalBroadcastManager.getInstance(mActivity).unregisterReceiver(mTrackSavedReceiver);
-
-        super.onDestroy();
-    }
-
-
-    @Override
-    public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
-        // update current track
-        mCurrentTrack = i;
-
-        // load track and display map and statistics
-        LoadTrackAsyncHelper loadTrackAsyncHelper = new LoadTrackAsyncHelper();
-        loadTrackAsyncHelper.execute(i);
-    }
-
-    @Override
-    public void onNothingSelected(AdapterView<?> adapterView) {
-
-    }
-
-
-    @Override
-    public void onSaveInstanceState(@NonNull Bundle outState) {
-        outState.putDouble(INSTANCE_LATITUDE_TRACK_MAP, mMapView.getMapCenter().getLatitude());
-        outState.putDouble(INSTANCE_LONGITUDE_TRACK_MAP, mMapView.getMapCenter().getLongitude());
-        outState.putDouble(INSTANCE_ZOOM_LEVEL_TRACK_MAP, mMapView.getZoomLevelDouble());
-        outState.putParcelable(INSTANCE_TRACK_TRACK_MAP, mTrack);
-        outState.putInt(INSTANCE_CURRENT_TRACK, mCurrentTrack);
-        super.onSaveInstanceState(outState);
-    }
-
-
-    @Override
-    public void onActivityResult(int requestCode, int resultCode, Intent data) {
-        super.onActivityResult(requestCode, resultCode, data);
-        switch(requestCode) {
-            case RESULT_DELETE_DIALOG:
-                if (resultCode == Activity.RESULT_OK) {
-                    deleteCurrentTrack();
-                } else if (resultCode == Activity.RESULT_CANCELED){
-                    LogHelper.v(LOG_TAG, "Delete dialog result: CANCEL");
-                }
-                break;
-            case RESULT_EXPORT_DIALOG:
-                if (resultCode == Activity.RESULT_OK) {
-                    // user chose EXPORT
-                    ExportHelper.exportToGpx(mActivity, mTrack);
-                } else if (resultCode == Activity.RESULT_CANCELED){
-                    // User chose CANCEL
-                    LogHelper.v(LOG_TAG, "Export to GPX: User chose CANCEL.");
-                }
-                break;
-        }
-    }
-
-
-    @Override
-    public boolean singleTapConfirmedHelper(GeoPoint p) {
-        return false;
-    }
-
-
-    @Override
-    public boolean longPressHelper(GeoPoint p) {
-        if (mTrack != null) {
-            // vibrate 50 milliseconds
-            Vibrator vibrator = (Vibrator) mActivity.getSystemService(Context.VIBRATOR_SERVICE);
-            vibrator.vibrate(50);
-            // zoom to bounding box (= edge coordinates of map)
-            mMapView.zoomToBoundingBox(mTrack.getBoundingBox(), true);
-        }
-        return true;
-    }
-
-
-    /* Displays map and statistics for track */
-    private void displayTrack() {
-        GeoPoint position;
-
-        if (mTrack != null && mTrack.getSize() > 0) {
-            // set end of track as position
-            Location lastLocation = mTrack.getWayPointLocation(mTrack.getSize() -1);
-            position = new GeoPoint(lastLocation.getLatitude(), lastLocation.getLongitude());
-
-            String recordingStart = DateFormat.getDateInstance(DateFormat.SHORT, Locale.getDefault()).format(mTrack.getRecordingStart()) + " " +
-                    DateFormat.getTimeInstance(DateFormat.SHORT, Locale.getDefault()).format(mTrack.getRecordingStart());
-            String recordingStop = DateFormat.getDateInstance(DateFormat.SHORT, Locale.getDefault()).format(mTrack.getRecordingStop()) + " " +
-                    DateFormat.getTimeInstance(DateFormat.SHORT, Locale.getDefault()).format(mTrack.getRecordingStop());
-            String stepsTaken;
-            if (mTrack.getStepCount() == -1) {
-                stepsTaken = getString(R.string.statistics_sheet_p_steps_no_pedometer);
-            } else {
-                stepsTaken = String.valueOf(Math.round(mTrack.getStepCount()));
-            }
-
-            // populate length views
-            displayCurrentLengthUnits();
-            // populate other views
-            mStepsView.setText(stepsTaken);
-            mWaypointsView.setText(String.valueOf(mTrack.getWayPoints().size()));
-            mDurationView.setText(LocationHelper.convertToReadableTime(mTrack.getTrackDuration(), true));
-            mRecordingStartView.setText(recordingStart);
-            mRecordingStopView.setText(recordingStop);
-
-            // show/hide elevation views depending on file format version
-            if (mTrack.getTrackFormatVersion() > 1 && mTrack.getMinAltitude() > 0) {
-                // show elevation views
-                mElevationDataViews.setVisibility(View.VISIBLE);
-            } else {
-                // hide elevation views
-                mElevationDataViews.setVisibility(View.GONE);
-            }
-
-            // draw track on map
-            drawTrackOverlay(mTrack);
-        } else {
-            position = new GeoPoint(DEFAULT_LATITUDE, DEFAULT_LONGITUDE);
-        }
-
-        // center map over position
-        mController.setCenter(position);
-
-    }
-
-
-    /* Draws track onto overlay */
-    private void drawTrackOverlay(Track track) {
-        mMapView.getOverlays().remove(mTrackOverlay);
-        mTrackOverlay = MapHelper.createTrackOverlay(mActivity, track, false);
-        mMapView.getOverlays().add(mTrackOverlay);
-    }
-
-
-    /* show the onboarding layout, if no track has been recorded yet */
-    private void switchOnboardingLayout() {
-        if (mDropdownAdapter.isEmpty()){
-            // show onboarding layout
-            mMapView.setVisibility(View.GONE);
-            mOnboardingView.setVisibility(View.VISIBLE);
-            mTrackManagementLayout.setVisibility(View.GONE);
-            mStatisticsSheetBehavior.setState(BottomSheetBehavior.STATE_COLLAPSED);
-            mStatisticsSheet.setVisibility(View.GONE);
-        } else {
-            // show normal layout
-            mOnboardingView.setVisibility(View.GONE);
-            mMapView.setVisibility(View.VISIBLE);
-            mTrackManagementLayout.setVisibility(View.VISIBLE);
-            mStatisticsSheetBehavior.setState(BottomSheetBehavior.STATE_COLLAPSED);
-            mStatisticsSheet.setVisibility(View.VISIBLE);
-        }
-    }
-
-
-    /* Displays views in statistic sheet according to current locale */
-    private void displayCurrentLengthUnits() {
-        mDistanceView.setText(LengthUnitHelper.convertDistanceToString(mTrack.getTrackDistance()));
-        mPositiveElevationView.setText(LengthUnitHelper.convertDistanceToString(mTrack.getPositiveElevation()));
-        mNegativeElevationView.setText(LengthUnitHelper.convertDistanceToString(mTrack.getNegativeElevation()));
-        mMaxAltitudeView.setText(LengthUnitHelper.convertDistanceToString(mTrack.getMaxAltitude()));
-        mMinAltitudeView.setText(LengthUnitHelper.convertDistanceToString(mTrack.getMinAltitude()));
-    }
-
-
-    /* Switches views in statistic sheet between Metric and Imperial */
-    private void displayOppositeLengthUnits() {
-        int oppositeLengthUnit = LengthUnitHelper.getUnitSystem() * -1;
-        mDistanceView.setText(LengthUnitHelper.convertDistanceToString(mTrack.getTrackDistance(), oppositeLengthUnit));
-        mPositiveElevationView.setText(LengthUnitHelper.convertDistanceToString(mTrack.getPositiveElevation(), oppositeLengthUnit));
-        mNegativeElevationView.setText(LengthUnitHelper.convertDistanceToString(mTrack.getNegativeElevation(), oppositeLengthUnit));
-        mMaxAltitudeView.setText(LengthUnitHelper.convertDistanceToString(mTrack.getMaxAltitude(), oppositeLengthUnit));
-        mMinAltitudeView.setText(LengthUnitHelper.convertDistanceToString(mTrack.getMinAltitude(), oppositeLengthUnit));
-    }
-
-
-    /* Deletes currently visible track */
-    private void deleteCurrentTrack() {
-
-        // delete track file and refresh dropdown adapter
-        if (mDropdownAdapter.getItem(mCurrentTrack).getTrackFile().delete()) {
-            mDropdownAdapter.refresh();
-            mDropdownAdapter.notifyDataSetChanged();
-            mDropdown.setAdapter(mDropdownAdapter);
-        } else {
-            LogHelper.e(LOG_TAG, "Unable to delete recording.");
-            return;
-        }
-
-        if (mDropdownAdapter.isEmpty()) {
-            // show onboarding
-            switchOnboardingLayout();
-        } else {
-            // show next track
-            mDropdown.setSelection(0, true);
-            mCurrentTrack = 0;
-        }
-
-    }
-
-
-    /* Creates BottomSheetCallback for the statistics sheet - needed in onCreateView */
-    private BottomSheetBehavior.BottomSheetCallback getStatisticsSheetCallback() {
-        return new BottomSheetBehavior.BottomSheetCallback() {
-            @Override
-            public void onStateChanged(@NonNull View bottomSheet, int newState) {
-                // react to state change
-                switch (newState) {
-                    case BottomSheetBehavior.STATE_EXPANDED:
-                        // statistics sheet expanded
-                        mTrackManagementLayout.setVisibility(View.INVISIBLE);
-                        mStatisticsSheet.setBackgroundColor(ContextCompat.getColor(mActivity, R.color.statistic_sheet_background_expanded));
-                        break;
-                    case BottomSheetBehavior.STATE_COLLAPSED:
-                        // statistics sheet collapsed
-                        mTrackManagementLayout.setVisibility(View.VISIBLE);
-                        mStatisticsSheet.setBackgroundColor(ContextCompat.getColor(mActivity, R.color.statistic_sheet_background_collapsed));
-                        mStatisticsSheetBehavior.setState(BottomSheetBehavior.STATE_COLLAPSED);
-                        break;
-                    case BottomSheetBehavior.STATE_HIDDEN:
-                        // statistics sheet hidden
-                        mStatisticsSheetBehavior.setState(BottomSheetBehavior.STATE_COLLAPSED);
-                        break;
-                    default:
-                        break;
-                }
-            }
-            @Override
-            public void onSlide(@NonNull View bottomSheet, float slideOffset) {
-                // reset length unit displays
-                displayCurrentLengthUnits();
-                // react to dragging events
-                if (slideOffset < 0.5f) {
-                    mTrackManagementLayout.setVisibility(View.VISIBLE);
-                } else {
-                    mTrackManagementLayout.setVisibility(View.INVISIBLE);
-                }
-                if (slideOffset < 0.125f) {
-                    mStatisticsSheet.setBackgroundColor(ContextCompat.getColor(mActivity, R.color.statistic_sheet_background_collapsed));
-                } else {
-                    mStatisticsSheet.setBackgroundColor(ContextCompat.getColor(mActivity, R.color.statistic_sheet_background_expanded));
-                }
-            }
-        };
-    }
-
-
-    /* Creates OnClickListener for the export button - needed in onCreateView */
-    private View.OnClickListener getShareButtonListener() {
-        return new View.OnClickListener() {
-            @Override
-            public void onClick(View view) {
-                Intent intent = ExportHelper.getGpxFileIntent(mActivity, mTrack);
-                // create intent to show chooser
-                String title = getString(R.string.dialog_share_gpx);
-//                String title = getResources().getString(R.string.chooser_title);
-                Intent chooser = Intent.createChooser(intent, title);
-                if (intent.resolveActivity(mActivity.getPackageManager()) != null) {
-                    startActivity(chooser);
-                } else {
-                    Toast.makeText(mActivity, R.string.toast_message_install_file_helper, Toast.LENGTH_LONG).show();
-                }
-            }
-        };
-    }
-
-
-    /* Creates OnClickListener for the export button - needed in onCreateView */
-    private View.OnClickListener getExportButtonListener() {
-        return new View.OnClickListener() {
-            @Override
-            public void onClick(View view) {
-                // dialog text components
-                int dialogTitle;
-                int dialogPositiveButton;
-                int dialogNegativeButton;
-                DateFormat df = DateFormat.getDateInstance(DateFormat.MEDIUM, Locale.getDefault());
-                String recordingStartDate = df.format(mTrack.getRecordingStart());
-                String dialogMessage;
-
-                // get text elements for delete dialog
-                if (ExportHelper.gpxFileExists(mTrack)) {
-                    // CASE: OVERWRITE - GPX file exists
-                    dialogTitle = R.string.dialog_export_title_overwrite;
-                    dialogMessage = getString(R.string.dialog_export_content_overwrite) + " (" + recordingStartDate + " | " + LengthUnitHelper.convertDistanceToString(mTrack.getTrackDistance()) + ")";
-                    dialogPositiveButton = R.string.dialog_export_action_overwrite;
-                    dialogNegativeButton = R.string.dialog_default_action_cancel;
-                } else {
-                    // CASE: EXPORT - GPX file does NOT yet exits
-                    dialogTitle = R.string.dialog_export_title_export;
-                    dialogMessage = getString(R.string.dialog_export_content_export) + " (" + recordingStartDate + " | " + LengthUnitHelper.convertDistanceToString(mTrack.getTrackDistance()) + ")";
-                    dialogPositiveButton = R.string.dialog_export_action_export;
-                    dialogNegativeButton = R.string.dialog_default_action_cancel;
-                }
-
-                // show delete dialog - results are handles by onActivityResult
-                DialogFragment dialogFragment = DialogHelper.newInstance(dialogTitle, dialogMessage, dialogPositiveButton, dialogNegativeButton);
-                dialogFragment.setTargetFragment(MainActivityTrackFragment.this, RESULT_EXPORT_DIALOG);
-                dialogFragment.show(mActivity.getSupportFragmentManager(), "ExportDialog");
-            }
-        };
-    }
-
-
-    /* Creates OnClickListener for the delete button - needed in onCreateView */
-    private View.OnClickListener getDeleteButtonListener() {
-        return new View.OnClickListener() {
-            @Override
-            public void onClick(View view) {
-                // get text elements for delete dialog
-                int dialogTitle = R.string.dialog_delete_title;
-                int dialogPositiveButton = R.string.dialog_delete_action_delete;
-                int dialogNegativeButton = R.string.dialog_default_action_cancel;
-                DateFormat df = DateFormat.getDateInstance(DateFormat.MEDIUM, Locale.getDefault());
-                String recordingStartDate = df.format(mTrack.getRecordingStart());
-                String dialogMessage = getString(R.string.dialog_delete_content) + " " + recordingStartDate + " | " + LengthUnitHelper.convertDistanceToString(mTrack.getTrackDistance());
-
-                // show delete dialog - results are handles by onActivityResult
-                DialogFragment dialogFragment = DialogHelper.newInstance(dialogTitle, dialogMessage, dialogPositiveButton, dialogNegativeButton);
-                dialogFragment.setTargetFragment(MainActivityTrackFragment.this, RESULT_DELETE_DIALOG);
-                dialogFragment.show(mActivity.getSupportFragmentManager(), "DeleteDialog");
-            }
-        };
-    }
-
-
-    /* Add tap listener to elevation data views */
-    private void attachTapListenerToElevationViews() {
-        int referencedIds[] = mElevationDataViews.getReferencedIds();
-        for (int id : referencedIds) {
-            mRootView.findViewById(id).setOnClickListener(new View.OnClickListener() {
-                @Override
-                public void onClick(View view) {
-                    // inform user about possible issues with altitude measurements
-                    Toast.makeText(mActivity, R.string.toast_message_elevation_info, Toast.LENGTH_LONG).show();
-                }
-            });
-        }
-    }
-
-
-    /* Add tap listener to statistic header views */
-    private void attachTapListenerToStatisticHeaderViews() {
-        int referencedIds[] = mStatisticsHeaderViews.getReferencedIds();
-        for (int id : referencedIds) {
-            mRootView.findViewById(id).setOnClickListener(new View.OnClickListener() {
-                @Override
-                public void onClick(View view) {
-                    if (mStatisticsSheetBehavior.getState() == BottomSheetBehavior.STATE_EXPANDED) {
-                        mStatisticsSheetBehavior.setState(BottomSheetBehavior.STATE_COLLAPSED);
-                    } else {
-                        mStatisticsSheetBehavior.setState(BottomSheetBehavior.STATE_EXPANDED);
-                    }
-                }
-            });
-        }
-    }
-
-
-    /* Add tap listener to statistics sheet */
-    private void attachTapListenerToStatisticsSheet() {
-        mStatisticsView.setOnTouchListener(new View.OnTouchListener() {
-            @Override
-            public boolean onTouch(View v, MotionEvent event) {
-                if(event.getAction() == MotionEvent.ACTION_DOWN) {
-                    displayOppositeLengthUnits();
-                } else if (event.getAction() == MotionEvent.ACTION_UP) {
-                    displayCurrentLengthUnits();
-                }
-                return true;
-            }
-        });
-    }
-
-
-    /**
-     * Inner class: Loads track from external storage using AsyncTask
-     */
-    private class LoadTrackAsyncHelper extends AsyncTask<Integer, Void, Void> {
-
-        @Override
-        protected Void doInBackground(Integer... ints) {
-            LogHelper.v(LOG_TAG, "Loading track object in background.");
-
-            StorageHelper storageHelper = new StorageHelper(mActivity);
-            if (ints.length > 0) {
-                // get track file from dropdown adapter
-                int item = ints[0];
-                File trackFile = mDropdownAdapter.getItem(item).getTrackFile();
-                LogHelper.v(LOG_TAG, "Loading track number " + item);
-                mTrack = storageHelper.loadTrack(trackFile);
-            } else {
-                // load track object from most current file
-                LogHelper.v(LOG_TAG, "No specific track specified. Loading most current one.");
-                mTrack = storageHelper.loadTrack(FILE_MOST_CURRENT_TRACK);
-            }
-            return null;
-        }
-
-        @Override
-        protected void onPostExecute(Void aVoid) {
-            super.onPostExecute(aVoid);
-
-            // display track on map
-            displayTrack();
-        }
-    }
-    /**
-     * End of inner class
-     */
-
-}

app/src/main/java/org/y20k/trackbook/MapFragment.kt

@@ -0,0 +1,289 @@
+/*
+ * MapFragment.kt
+ * Implements the MapFragment fragment
+ * A MapFragment displays a map using osmdroid as well as the controls to start / stop a recording
+ *
+ * This file is part of
+ * TRACKBOOK - Movement Recorder for Android
+ *
+ * Copyright (c) 2016-20 - Y20K.org
+ * Licensed under the MIT-License
+ * http://opensource.org/licenses/MIT
+ *
+ * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
+ * https://github.com/osmdroid/osmdroid
+ */
+
+
+package org.y20k.trackbook
+
+import YesNoDialog
+import android.Manifest
+import android.content.ComponentName
+import android.content.Context
+import android.content.Intent
+import android.content.ServiceConnection
+import android.content.pm.PackageManager
+import android.location.Location
+import android.os.Build
+import android.os.Bundle
+import android.os.Handler
+import android.os.IBinder
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.core.content.ContextCompat
+import androidx.fragment.app.Fragment
+import androidx.navigation.fragment.findNavController
+import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.launch
+import org.y20k.trackbook.core.Track
+import org.y20k.trackbook.core.TracklistElement
+import org.y20k.trackbook.helpers.*
+import org.y20k.trackbook.ui.MapFragmentLayoutHolder
+
+
+/*
+ * MapFragment class
+ */
+class MapFragment : Fragment(), YesNoDialog.YesNoDialogListener {
+
+    /* Define log tag */
+    private val TAG: String = LogHelper.makeLogTag(MapFragment::class.java)
+
+
+    /* Main class variables */
+    private var bound: Boolean = false
+    private val handler: Handler = Handler()
+    private var trackingState: Int = Keys.STATE_NOT_TRACKING
+    private var gpsProviderActive: Boolean = false
+    private var networkProviderActive: Boolean = false
+    private var track: Track = Track()
+    private lateinit var currentBestLocation: Location
+    private lateinit var layout: MapFragmentLayoutHolder
+    private lateinit var trackerService: TrackerService
+
+
+    /* Overrides onCreate from Fragment */
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        // get current best location
+        currentBestLocation = LocationHelper.getLastKnownLocation(activity as Context)
+        // get saved tracking state
+        trackingState = PreferencesHelper.loadTrackingState(activity as Context)
+    }
+
+
+    /* Overrides onStop from Fragment */
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
+        // initialize layout
+        layout = MapFragmentLayoutHolder(activity as Context, inflater, container, currentBestLocation, trackingState)
+
+        // set up buttons
+        layout.currentLocationButton.setOnClickListener {
+            layout.centerMap(currentBestLocation, animated = true)
+        }
+        layout.recordingButton.setOnClickListener {
+            handleTrackingManagementMenu()
+        }
+        layout.saveButton.setOnClickListener {
+            saveTrack()
+        }
+        layout.clearButton.setOnClickListener {
+            trackerService.clearTrack()
+        }
+        layout.resumeButton.setOnClickListener {
+            // start service via intent so that it keeps running after unbind
+            startTrackerService()
+            trackerService.resumeTracking()
+        }
+
+        return layout.rootView
+    }
+
+
+    /* Overrides onStart from Fragment */
+    override fun onStart() {
+        super.onStart()
+        // request location permission if denied
+        if (ContextCompat.checkSelfPermission(activity as Context, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_DENIED) {
+            this.requestPermissions(arrayOf(Manifest.permission.ACCESS_FINE_LOCATION), Keys.REQUEST_CODE_FOREGROUND)
+        }
+        // bind to TrackerService
+        activity?.bindService(Intent(activity, TrackerService::class.java), connection, Context.BIND_AUTO_CREATE)
+    }
+
+
+    /* Overrides onResume from Fragment */
+    override fun onResume() {
+        super.onResume()
+        // show hide the location error snackbar
+        layout.toggleLocationErrorBar(gpsProviderActive, networkProviderActive)
+        // set map center
+        layout.centerMap(currentBestLocation)
+    }
+
+
+    /* Overrides onPause from Fragment */
+    override fun onPause() {
+        super.onPause()
+        layout.saveState(currentBestLocation)
+    }
+
+
+    /* Overrides onStop from Fragment */
+    override fun onStop() {
+        super.onStop()
+        // unbind from TrackerService
+        activity?.unbindService(connection)
+    }
+
+
+    /* Overrides onRequestPermissionsResult from Fragment */
+    override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<String>, grantResults: IntArray) {
+        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
+        when (requestCode) {
+            Keys.REQUEST_CODE_FOREGROUND -> {
+                if ((grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED)) {
+                    // permission was granted - re-bind service
+                    activity?.unbindService(connection)
+                    activity?.bindService(Intent(activity, TrackerService::class.java), connection, Context.BIND_AUTO_CREATE)
+                    LogHelper.i(TAG, "Request result: Location permission has been granted.")
+                } else {
+                    // permission denied - unbind service
+                    activity?.unbindService(connection)
+                }
+                layout.toggleLocationErrorBar(gpsProviderActive, networkProviderActive)
+                return
+            }
+        }
+    }
+
+
+    /* Overrides onYesNoDialog from YesNoDialogListener */
+    override fun onYesNoDialog(type: Int, dialogResult: Boolean, payload: Int, payloadString: String) {
+        super.onYesNoDialog(type, dialogResult, payload, payloadString)
+        when (type) {
+            Keys.DIALOG_EMPTY_RECORDING -> {
+                when (dialogResult) {
+                    // user tapped resume
+                    true -> {
+                        trackerService.resumeTracking()
+                    }
+                }
+            }
+        }
+    }
+
+
+    /* Start tracker service */
+    private fun startTrackerService() {
+        val intent = Intent(activity, TrackerService::class.java)
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            // ... start service in foreground to prevent it being killed on Oreo
+            activity?.startForegroundService(intent)
+        } else {
+            activity?.startService(intent)
+        }
+    }
+
+
+    /* Starts / pauses tracking and toggles the recording sub menu_bottom_navigation */
+    private fun handleTrackingManagementMenu() {
+        when (trackingState) {
+            Keys.STATE_TRACKING_STOPPED -> layout.toggleRecordingButtonSubMenu()
+            Keys.STATE_TRACKING_ACTIVE -> trackerService.stopTracking()
+            Keys.STATE_NOT_TRACKING -> {
+                // start service via intent so that it keeps running after unbind
+                startTrackerService()
+                trackerService.startTracking()
+            }
+        }
+    }
+
+
+    /* Saves track - shows dialog, if recording is still empty */
+    private fun saveTrack() {
+        if (track.wayPoints.isEmpty()) {
+            YesNoDialog(this as YesNoDialog.YesNoDialogListener).show(activity as Context, type = Keys.DIALOG_EMPTY_RECORDING, title = R.string.dialog_error_empty_recording_title, message = R.string.dialog_error_empty_recording_message, yesButton = R.string.dialog_error_empty_recording_action_resume)
+        } else {
+            GlobalScope.launch {
+                // step 1: create and store filenames for json and gpx files
+                track.trackUriString = FileHelper.getTrackFileUri(activity as Context, track).toString()
+                track.gpxUriString = FileHelper.getGpxFileUri(activity as Context, track).toString()
+                // step 2: save track
+                FileHelper.saveTrackSuspended(track, saveGpxToo = true)
+                // step 3: save tracklist - suspended
+                FileHelper.addTrackAndSaveTracklistSuspended(activity as Context, track)
+                // step 3: clear track
+                trackerService.clearTrack()
+                // step 4: open track in TrackFragement
+                openTrack(track.toTracklistElement(activity as Context))
+            }
+        }
+    }
+
+
+    /* Opens a track in TrackFragment */
+    private fun openTrack(tracklistElement: TracklistElement) {
+        val bundle: Bundle = Bundle()
+        bundle.putString(Keys.ARG_TRACK_TITLE, tracklistElement.name)
+        bundle.putString(Keys.ARG_TRACK_FILE_URI, tracklistElement.trackUriString)
+        bundle.putString(Keys.ARG_GPX_FILE_URI, tracklistElement.gpxUriString)
+        bundle.putLong(Keys.ARG_TRACK_ID, TrackHelper.getTrackId(tracklistElement))
+        findNavController().navigate(R.id.fragment_track, bundle)
+    }
+
+
+    /*
+     * Defines callbacks for service binding, passed to bindService()
+     */
+    private val connection = object : ServiceConnection {
+        override fun onServiceConnected(className: ComponentName, service: IBinder) {
+            // We've bound to LocalService, cast the IBinder and get LocalService instance
+            val binder = service as TrackerService.LocalBinder
+            trackerService = binder.service
+            bound = true
+            // start listening for location updates
+            handler.removeCallbacks(periodicLocationRequestRunnable)
+            handler.postDelayed(periodicLocationRequestRunnable, 0)
+        }
+        override fun onServiceDisconnected(arg0: ComponentName) {
+            bound = false
+            // stop receiving location updates
+            handler.removeCallbacks(periodicLocationRequestRunnable)
+        }
+    }
+    /*
+     * End of declaration
+     */
+
+
+    /*
+     * Runnable: Periodically requests location
+     */
+    private val periodicLocationRequestRunnable: Runnable = object : Runnable {
+        override fun run() {
+            // pull values from service
+            currentBestLocation = trackerService.currentBestLocation
+            track = trackerService.track
+            gpsProviderActive = trackerService.gpsProviderActive
+            networkProviderActive = trackerService.networkProviderActive
+            trackingState = trackerService.trackingState
+            // update location and track
+            layout.markCurrentPosition(currentBestLocation, trackingState)
+            layout.overlayCurrentTrack(track, trackingState)
+            layout.updateRecordingButton(trackingState)
+            // center map, if it had not been dragged/zoomed before
+            if (!layout.userInteraction) { layout.centerMap(currentBestLocation, true)}
+            // show error snackbar if necessary
+            layout.toggleLocationErrorBar(gpsProviderActive, networkProviderActive)
+            // use the handler to start runnable again after specified delay
+            handler.postDelayed(this, Keys.REQUEST_CURRENT_LOCATION_INTERVAL)
+        }
+    }
+    /*
+     * End of declaration
+     */
+
+}

app/src/main/java/org/y20k/trackbook/SettingsFragment.kt

@@ -0,0 +1,109 @@
+/*
+ * SettingsFragment.kt
+ * Implements the SettingsFragment fragment
+ * A SettingsFragment displays the user accessible settings of the app
+ *
+ * This file is part of
+ * TRACKBOOK - Movement Recorder for Android
+ *
+ * Copyright (c) 2016-20 - Y20K.org
+ * Licensed under the MIT-License
+ * http://opensource.org/licenses/MIT
+ *
+ * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
+ * https://github.com/osmdroid/osmdroid
+ */
+
+
+package org.y20k.trackbook
+
+
+import android.content.Context
+import android.os.Bundle
+import android.view.View
+import androidx.preference.*
+import org.y20k.trackbook.helpers.LengthUnitHelper
+import org.y20k.trackbook.helpers.LogHelper
+
+
+/*
+ * SettingsFragment class
+ */
+class SettingsFragment : PreferenceFragmentCompat() {
+
+    /* Define log tag */
+    private val TAG: String = LogHelper.makeLogTag(SettingsFragment::class.java)
+
+
+    /* Overrides onViewCreated from PreferenceFragmentCompat */
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+        // set the background color
+        view.setBackgroundColor(resources.getColor(R.color.app_window_background, null))
+        // add padding - necessary because translucent status bar is used
+        val topPadding = this.resources.displayMetrics.density * 24 // 24 dp * display density
+        view.setPadding(0, topPadding.toInt(), 0, 0)
+    }
+
+
+    /* Overrides onCreatePreferences from PreferenceFragmentCompat */
+    override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
+
+        val context = preferenceManager.context
+        val screen = preferenceManager.createPreferenceScreen(context)
+
+        // set up "Enable Imperial Measurements" preference
+        val preferenceImperialMeasurementUnits: SwitchPreferenceCompat = SwitchPreferenceCompat(activity as Context)
+        preferenceImperialMeasurementUnits.title = getString(R.string.pref_imperial_measurement_units_title)
+        preferenceImperialMeasurementUnits.key = Keys.PREF_USE_IMPERIAL_UNITS
+        preferenceImperialMeasurementUnits.summaryOn = getString(R.string.pref_imperial_measurement_units_summary_imperial)
+        preferenceImperialMeasurementUnits.summaryOff = getString(R.string.pref_imperial_measurement_units_summary_metric)
+        preferenceImperialMeasurementUnits.setDefaultValue(LengthUnitHelper.useImperialUnits())
+
+        // set up "Restrict to GPS" preference
+        val preferenceGpsOnly: SwitchPreferenceCompat = SwitchPreferenceCompat(activity as Context)
+        preferenceGpsOnly.title = getString(R.string.pref_gps_only_title)
+        preferenceGpsOnly.key = Keys.PREF_GPS_ONLY
+        preferenceGpsOnly.summaryOn = getString(R.string.pref_gps_only_summary_gps_only)
+        preferenceGpsOnly.summaryOff = getString(R.string.pref_gps_only_summary_gps_and_network)
+        preferenceGpsOnly.setDefaultValue(false)
+
+        // set up "Accuracy Threshold" preference
+        val preferenceAccuracyThreshold: SeekBarPreference = SeekBarPreference(activity as Context)
+        preferenceAccuracyThreshold.title = getString(R.string.pref_accuracy_threshold_title)
+        preferenceAccuracyThreshold.key = Keys.PREF_LOCATION_ACCURACY_THRESHOLD
+        preferenceAccuracyThreshold.summary = getString(R.string.pref_accuracy_threshold_summary)
+        preferenceAccuracyThreshold.showSeekBarValue = true
+        preferenceAccuracyThreshold.max = 50
+        preferenceAccuracyThreshold.setDefaultValue(Keys.DEFAULT_THRESHOLD_LOCATION_ACCURACY)
+
+        // set up "Reset" preference
+        val preferenceResetAdvanced: Preference = Preference(activity as Context)
+        preferenceResetAdvanced.title = getString(R.string.pref_reset_advanced_title)
+        preferenceResetAdvanced.summary = getString(R.string.pref_reset_advanced_summary)
+        preferenceResetAdvanced.setOnPreferenceClickListener{
+            preferenceAccuracyThreshold.value = Keys.DEFAULT_THRESHOLD_LOCATION_ACCURACY
+            return@setOnPreferenceClickListener true
+        }
+
+        // set preference categories
+        val preferenceCategoryGeneral: PreferenceCategory = PreferenceCategory(activity as Context)
+        preferenceCategoryGeneral.title = getString(R.string.pref_general_title)
+        preferenceCategoryGeneral.contains(preferenceImperialMeasurementUnits)
+        preferenceCategoryGeneral.contains(preferenceGpsOnly)
+        val preferenceCategoryAdvanced: PreferenceCategory = PreferenceCategory(activity as Context)
+        preferenceCategoryAdvanced.title = getString(R.string.pref_advanced_title)
+        preferenceCategoryAdvanced.contains(preferenceAccuracyThreshold)
+        preferenceCategoryAdvanced.contains(preferenceResetAdvanced)
+
+        // setup preference screen
+        screen.addPreference(preferenceCategoryGeneral)
+        screen.addPreference(preferenceImperialMeasurementUnits)
+        screen.addPreference(preferenceGpsOnly)
+        screen.addPreference(preferenceCategoryAdvanced)
+        screen.addPreference(preferenceAccuracyThreshold)
+        screen.addPreference(preferenceResetAdvanced)
+        preferenceScreen = screen
+    }
+
+}

app/src/main/java/org/y20k/trackbook/TrackFragment.kt

@@ -0,0 +1,143 @@
+/*
+ * TrackFragment.kt
+ * Implements the TrackFragment fragment
+ * A TrackFragment displays a previously recorded track
+ *
+ * This file is part of
+ * TRACKBOOK - Movement Recorder for Android
+ *
+ * Copyright (c) 2016-20 - Y20K.org
+ * Licensed under the MIT-License
+ * http://opensource.org/licenses/MIT
+ *
+ * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
+ * https://github.com/osmdroid/osmdroid
+ */
+
+
+package org.y20k.trackbook
+
+
+import YesNoDialog
+import android.content.Context
+import android.content.Intent
+import android.content.pm.PackageManager
+import android.net.Uri
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import android.widget.Toast
+import androidx.core.content.FileProvider
+import androidx.core.net.toFile
+import androidx.core.os.bundleOf
+import androidx.fragment.app.Fragment
+import androidx.navigation.fragment.findNavController
+import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.launch
+import org.y20k.trackbook.Keys.ARG_TRACK_ID
+import org.y20k.trackbook.dialogs.RenameTrackDialog
+import org.y20k.trackbook.helpers.FileHelper
+import org.y20k.trackbook.helpers.LogHelper
+import org.y20k.trackbook.ui.TrackFragmentLayoutHolder
+
+class TrackFragment : Fragment(), RenameTrackDialog.RenameTrackListener, YesNoDialog.YesNoDialogListener {
+
+    /* Define log tag */
+    private val TAG: String = LogHelper.makeLogTag(TrackFragment::class.java)
+
+
+    /* Main class variables */
+    private lateinit var layout:TrackFragmentLayoutHolder
+
+
+    /* Overrides onCreateView from Fragment */
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
+        // initialize layout
+        layout = TrackFragmentLayoutHolder(activity as Context, inflater, container, arguments)
+
+        // set up share button
+        layout.shareButton.setOnClickListener {
+            shareGpXTrack()
+        }
+        // set up delete button
+        layout.deleteButton.setOnClickListener {
+            val dialogMessage: String = "${getString(R.string.dialog_yes_no_message_remove_recording)}\n\n- ${layout.trackNameView.text}"
+            YesNoDialog(this@TrackFragment as YesNoDialog.YesNoDialogListener).show(context = activity as Context, type = Keys.DIALOG_REMOVE_TRACK, messageString = dialogMessage, yesButton = R.string.dialog_yes_no_positive_button_remove_recording)
+        }
+        // set up rename button
+        layout.editButton.setOnClickListener {
+            RenameTrackDialog(this as RenameTrackDialog.RenameTrackListener).show(activity as Context, layout.trackNameView.text.toString())
+        }
+
+        return layout.rootView
+    }
+
+
+    /* Overrides onResume from Fragment */
+    override fun onResume() {
+        super.onResume()
+        // update zoom level and map center
+        layout.updateMapView()
+    }
+
+
+    /* Overrides onPause from Fragment */
+    override fun onPause() {
+        super.onPause()
+        // save zoom level and map center
+        layout.saveViewStateToTrack()
+    }
+
+
+    /* Overrides onRenameTrackDialog from RenameTrackDialog */
+    override fun onRenameTrackDialog(textInput: String) {
+        // rename track async (= fire & forget - no return value needed)
+        GlobalScope.launch { FileHelper.renameTrackSuspended(activity as Context, layout.track, textInput) }
+        // update name in layout
+        layout.track.name = textInput
+        layout.trackNameView.text = textInput
+    }
+
+
+    /* Overrides onYesNoDialog from YesNoDialogListener */
+    override fun onYesNoDialog(type: Int, dialogResult: Boolean, payload: Int, payloadString: String) {
+        when (type) {
+            Keys.DIALOG_REMOVE_TRACK -> {
+                when (dialogResult) {
+                    // user tapped remove track
+                    true -> {
+                        // switch to TracklistFragment and remove track there
+                        val trackId: Long = arguments?.getLong(ARG_TRACK_ID, -1L) ?: -1L
+                        val bundle: Bundle = bundleOf(Keys.ARG_TRACK_ID to trackId)
+                        findNavController().navigate(R.id.tracklist_fragment, bundle)
+                    }
+                }
+            }
+        }
+    }
+
+
+    /* Share track as GPX via share sheet */
+    private fun shareGpXTrack() {
+        val gpxFile = Uri.parse(layout.track.gpxUriString).toFile()
+        val gpxShareUri = FileProvider.getUriForFile(this.activity as Context, "${activity!!.applicationContext.packageName}.provider", gpxFile)
+        val shareIntent: Intent = Intent.createChooser(Intent().apply {
+            action = Intent.ACTION_SEND
+            data = gpxShareUri
+            type = "application/gpx+xml"
+            flags = Intent.FLAG_GRANT_READ_URI_PERMISSION
+            putExtra(Intent.EXTRA_STREAM, gpxShareUri)
+            putExtra(Intent.EXTRA_TITLE, getString(R.string.dialog_share_gpx))
+        }, null)
+
+        // show share sheet - if file helper is available
+        val packageManager: PackageManager? = activity?.packageManager
+        if (packageManager != null && shareIntent.resolveActivity(packageManager) != null) {
+            startActivity(shareIntent)
+        } else {
+            Toast.makeText(activity, R.string.toast_message_install_file_helper, Toast.LENGTH_LONG).show()
+        }
+    }
+
+}

app/src/main/java/org/y20k/trackbook/Trackbook.java

@@ -1,59 +0,0 @@
-/**
- * Trackbook.java
- * Implements the Trackbook class
- * Trackbook starts up the app and sets up the basic theme (Day / Night)
- *
- * This file is part of
- * TRACKBOOK - Movement Recorder for Android
- *
- * Copyright (c) 2016-19 - Y20K.org
- * Licensed under the MIT-License
- * http://opensource.org/licenses/MIT
- *
- * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
- * https://github.com/osmdroid/osmdroid
- */
-
-package org.y20k.trackbook;
-
-import android.app.Application;
-
-import org.y20k.trackbook.helpers.LogHelper;
-import org.y20k.trackbook.helpers.NightModeHelper;
-
-
-/**
- * Trackbook.class
- */
-public class Trackbook extends Application {
-
-    /* Define log tag */
-    private static final String LOG_TAG = Trackbook.class.getSimpleName();
-
-
-    @Override
-    public void onCreate() {
-        super.onCreate();
-
-        // set Day / Night theme state
-        NightModeHelper.restoreSavedState(this);
-
-// todo remove
-//        if (Build.VERSION.SDK_INT >= 28) {
-//            // Android P might introduce a system wide theme option - in that case: follow system (28 = Build.VERSION_CODES.P)
-//            AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM);
-//        } else {
-//            // try to get last state the user chose
-//            NightModeHelper.restoreSavedState(this);
-//        }
-
-    }
-
-
-    @Override
-    public void onTerminate() {
-        super.onTerminate();
-        LogHelper.v(LOG_TAG, "Trackbook application terminated.");
-    }
-
-}

app/src/main/java/org/y20k/trackbook/Trackbook2.kt

@@ -0,0 +1,51 @@
+/*
+ * Trackbook.kt
+ * Implements the Trackbook class
+ * Trackbook is the base Application class that sets up day and night theme
+ *
+ * This file is part of
+ * TRACKBOOK - Movement Recorder for Android
+ *
+ * Copyright (c) 2016-20 - Y20K.org
+ * Licensed under the MIT-License
+ * http://opensource.org/licenses/MIT
+ *
+ * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
+ * https://github.com/osmdroid/osmdroid
+ */
+
+
+
+package org.y20k.trackbook
+
+import android.app.Application
+import org.y20k.trackbook.helpers.LogHelper
+import org.y20k.trackbook.helpers.NightModeHelper
+
+
+/*
+ * Trackbook.class
+ */
+class Trackbook: Application() {
+
+
+    /* Define log tag */
+    private val TAG: String = LogHelper.makeLogTag(Trackbook::class.java)
+
+
+    /* Implements onCreate */
+    override fun onCreate() {
+        super.onCreate()
+        LogHelper.v(TAG, "Trackbook application started.")
+        // set Day / Night theme state
+        NightModeHelper.restoreSavedState(this)
+    }
+
+
+    /* Implements onTerminate */
+    override fun onTerminate() {
+        super.onTerminate()
+        LogHelper.v(TAG, "Trackbook application terminated.")
+    }
+
+}

app/src/main/java/org/y20k/trackbook/TrackerService.java

@@ -1,618 +0,0 @@
-/**
- * TrackerService.java
- * Implements the app's movement tracker service
- * The TrackerService creates a Track object and displays a notification
- *
- * This file is part of
- * TRACKBOOK - Movement Recorder for Android
- *
- * Copyright (c) 2016-19 - Y20K.org
- * Licensed under the MIT-License
- * http://opensource.org/licenses/MIT
- *
- * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
- * https://github.com/osmdroid/osmdroid
- */
-
-package org.y20k.trackbook;
-
-import android.app.Notification;
-import android.app.NotificationManager;
-import android.app.Service;
-import android.content.Context;
-import android.content.Intent;
-import android.content.SharedPreferences;
-import android.database.ContentObserver;
-import android.hardware.Sensor;
-import android.hardware.SensorEvent;
-import android.hardware.SensorEventListener;
-import android.hardware.SensorManager;
-import android.location.Location;
-import android.location.LocationListener;
-import android.location.LocationManager;
-import android.os.AsyncTask;
-import android.os.Binder;
-import android.os.Bundle;
-import android.os.CountDownTimer;
-import android.os.Handler;
-import android.os.IBinder;
-import android.preference.PreferenceManager;
-import android.widget.Toast;
-
-import androidx.core.app.NotificationCompat;
-import androidx.localbroadcastmanager.content.LocalBroadcastManager;
-
-import org.y20k.trackbook.core.Track;
-import org.y20k.trackbook.helpers.LocationHelper;
-import org.y20k.trackbook.helpers.LogHelper;
-import org.y20k.trackbook.helpers.NotificationHelper;
-import org.y20k.trackbook.helpers.StorageHelper;
-import org.y20k.trackbook.helpers.TrackbookKeys;
-
-import java.util.List;
-
-import static android.hardware.Sensor.TYPE_STEP_COUNTER;
-
-
-/**
- * TrackerService class
- */
-public class TrackerService extends Service implements TrackbookKeys, SensorEventListener {
-
-    /* Define log tag */
-    private static final String LOG_TAG = TrackerService.class.getSimpleName();
-
-
-    /* Main class variables */
-    private Track mTrack;
-    private CountDownTimer mTimer;
-    private LocationManager mLocationManager;
-    private SensorManager mSensorManager;
-    private float mStepCountOffset;
-    private LocationListener mGPSListener = null;
-    private LocationListener mNetworkListener = null;
-    private SettingsContentObserver mSettingsContentObserver;
-    private Location mCurrentBestLocation;
-    private Notification mNotification;
-    private NotificationCompat.Builder mNotificationBuilder;
-    private NotificationManager mNotificationManager;
-    private boolean mTrackerServiceRunning;
-    private boolean mLocationSystemSetting;
-    private boolean mResumedFlag;
-
-    private final IBinder mBinder = new LocalBinder(); // todo move to onCreate
-
-
-    @Override
-    public void onCreate() {
-        super.onCreate();
-
-        // prepare notification channel and get NotificationManager
-        mNotificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
-        NotificationHelper.createNotificationChannel(this);
-
-        // acquire reference to Location Manager
-        mLocationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
-
-        // acquire reference to Sensor Manager
-        mSensorManager = (SensorManager) this.getSystemService(Context.SENSOR_SERVICE);
-
-        // get state of location system setting
-        mLocationSystemSetting = LocationHelper.checkLocationSystemSetting(getApplicationContext());
-
-        // create content observer for changes in System Settings
-        mSettingsContentObserver = new SettingsContentObserver(new Handler());
-
-        // initialize the resume flag
-        mResumedFlag = false;
-    }
-
-
-    @Override
-    public IBinder onBind(Intent intent) {
-        // a client is binding to the service with bindService()
-        return mBinder;
-    }
-
-
-    @Override
-    public boolean onUnbind(Intent intent) {
-        // return true if you would like to have the service's onRebind(Intent) method later called when new clients bind to it.
-        return true;
-    }
-
-
-    @Override
-    public void onRebind(Intent intent) {
-        // a client is binding to the service with bindService(), after onUnbind() has already been called
-    }
-
-
-    @Override
-    public int onStartCommand(Intent intent, int flags, int startId) {
-
-        // SERVICE RESTART (via START_STICKY)
-        if (intent == null) {
-            if (PreferenceManager.getDefaultSharedPreferences(this).getBoolean(PREFS_TRACKER_SERVICE_RUNNING, false)) {
-                LogHelper.w(LOG_TAG, "Trackbook has been killed by the operating system. Trying to resume recording.");
-                resumeTracking(LocationHelper.determineLastKnownLocation(mLocationManager));
-            }
-        }
-        // ACTION STOP
-        else if (ACTION_STOP.equals(intent.getAction())) {
-            stopTracking();
-        }
-        // ACTION RESUME
-        else if (ACTION_RESUME.equals(intent.getAction())) {
-            resumeTracking(LocationHelper.determineLastKnownLocation(mLocationManager));
-        }
-
-        // START_STICKY is used for services that are explicitly started and stopped as needed
-        return START_STICKY;
-    }
-
-
-    @Override
-    public void onTaskRemoved(Intent rootIntent) {
-        super.onTaskRemoved(rootIntent);
-        LogHelper.v(LOG_TAG, "onTaskRemoved called.");
-    }
-
-
-    @Override
-    public void onDestroy() {
-        LogHelper.v(LOG_TAG, "onDestroy called.");
-
-        if (mTrackerServiceRunning) {
-            stopTracking();
-        }
-
-        // remove TrackerService from foreground state
-        stopForeground(true);
-
-        super.onDestroy();
-    }
-
-
-    @Override
-    public void onSensorChanged(SensorEvent sensorEvent) {
-        // save the step count offset (steps previously recorded by the system) and subtract any steps recorded during this session in case the app was killed
-        if (mStepCountOffset == 0) {
-            mStepCountOffset = (sensorEvent.values[0] - 1) - mTrack.getStepCount();
-        }
-
-        // calculate step count
-        float stepCount = sensorEvent.values[0] - mStepCountOffset;
-
-        // set step count in track
-        mTrack.setStepCount(stepCount);
-    }
-
-
-    @Override
-    public void onAccuracyChanged(Sensor sensor, int i) {
-
-    }
-
-
-    /* Start tracking location */
-    public void startTracking(Location lastLocation) {
-        if (mLocationSystemSetting) {
-            LogHelper.v(LOG_TAG, "Start tracking");
-
-            // create a new track - if requested
-            mTrack = new Track();
-
-            // get last location
-            if (lastLocation != null) {
-                mCurrentBestLocation = lastLocation;
-            } else {
-                mCurrentBestLocation = LocationHelper.determineLastKnownLocation(mLocationManager);
-            }
-
-            // begin recording
-            startMovementRecording();
-
-        } else {
-            LogHelper.i(LOG_TAG, "Location Setting is turned off.");
-            Toast.makeText(getApplicationContext(), R.string.toast_message_location_offline, Toast.LENGTH_LONG).show();
-        }
-    }
-
-
-    /* Resume tracking after stop/pause */
-    public void resumeTracking(Location lastLocation) {
-        if (mLocationSystemSetting) {
-            LogHelper.v(LOG_TAG, "Recording resumed");
-
-            // switch the resume flag
-            mResumedFlag = true;
-
-            // create a new track - if requested
-            StorageHelper storageHelper = new StorageHelper(this);
-            if (storageHelper.tempFileExists()) {
-                // load temp track file
-                mTrack = storageHelper.loadTrack(FILE_TEMP_TRACK);
-                // try to mark last waypoint as stopover
-                int lastWayPoint = mTrack.getSize() - 1;
-                if (lastWayPoint >= 0) {
-                    mTrack.getWayPoints().get(lastWayPoint).setIsStopOver(true);
-                }
-            } else {
-                // fallback, if tempfile did not exist
-                LogHelper.e(LOG_TAG, "Unable to find previously saved track temp file.");
-                mTrack = new Track();
-            }
-
-            // get last location
-            mCurrentBestLocation = lastLocation;
-            // FALLBACK: use last recorded location
-            if (mCurrentBestLocation == null && mTrack.getSize() > 0) {
-                mCurrentBestLocation = mTrack.getWayPointLocation(mTrack.getSize() -1);
-            }
-
-            // begin recording
-            startMovementRecording();
-
-        } else {
-            LogHelper.i(LOG_TAG, "Location Setting is turned off.");
-            Toast.makeText(getApplicationContext(), R.string.toast_message_location_offline, Toast.LENGTH_LONG).show();
-        }
-    }
-
-
-    /* Stop tracking location */
-    public void stopTracking() {
-        LogHelper.v(LOG_TAG, "Recording stopped");
-
-        // catches a bug that leaves the ui in a incorrect state after a crash
-        if (!mTrackerServiceRunning) {
-            saveTrackerServiceState(mTrackerServiceRunning, FAB_STATE_SAVE);
-            broadcastTrackingStateChange();
-            return;
-        }
-
-        // store current date and time
-        mTrack.setRecordingEnd();
-
-        // stop timer
-        mTimer.cancel();
-
-        // broadcast an updated track
-        broadcastTrackUpdate();
-
-        // save a temp file in case the activity has been killed
-        SaveTempTrackAsyncHelper saveTempTrackAsyncHelper = new SaveTempTrackAsyncHelper();
-        saveTempTrackAsyncHelper.execute();
-
-        // change notification
-        displayNotification(false);
-
-        // reset resume flag
-        mResumedFlag = false;
-
-        // remove listeners
-        stopFindingLocation();
-        mSensorManager.unregisterListener(this);
-
-        // disable content observer for changes in System Settings
-        this.getContentResolver().unregisterContentObserver(mSettingsContentObserver);
-
-        // remove TrackerService from foreground state
-        stopForeground(false);
-    }
-
-
-    /* Dismiss notification */
-    public void dismissNotification() {
-        // save state
-        saveTrackerServiceState(mTrackerServiceRunning, FAB_STATE_DEFAULT);
-        // cancel notification
-        mNotificationManager.cancel(TRACKER_SERVICE_NOTIFICATION_ID); // todo check if necessary?
-        stopForeground(true);
-    }
-
-
-    /* Starts to record movements */
-    private void startMovementRecording() {
-        // initialize step counter
-        mStepCountOffset = 0;
-
-        // add last location as WayPoint to track
-        addWayPointToTrack();
-
-        // put up notification
-        displayNotification(true);
-
-        // create gps and network location listeners
-        startFindingLocation();
-
-        // start timer that periodically request a location update
-        startRequestingLocationChanges();
-
-        // start counting steps
-        startStepCounter();
-
-        // register content observer for changes in System Settings
-        this.getContentResolver().registerContentObserver(android.provider.Settings.Secure.CONTENT_URI, true, mSettingsContentObserver);
-
-        // start service in foreground
-        startForeground(TRACKER_SERVICE_NOTIFICATION_ID, mNotification);
-    }
-
-
-    /* Registers a step counter listener */
-    private void startStepCounter() {
-        boolean stepCounterAvailable = mSensorManager.registerListener(this, mSensorManager.getDefaultSensor(TYPE_STEP_COUNTER), SensorManager.SENSOR_DELAY_UI);
-        if (stepCounterAvailable) {
-            LogHelper.v(LOG_TAG, "Pedometer sensor available: Registering listener.");
-        } else {
-            LogHelper.i(LOG_TAG, "Pedometer sensor not available.");
-            mTrack.setStepCount(-1);
-        }
-    }
-
-
-    /* Set timer to periodically retrieve new locations and to prevent endless tracking */
-    private void startRequestingLocationChanges() {
-        final long previouslyRecordedDuration = mTrack.getTrackDuration();
-        mTimer = new CountDownTimer(EIGHT_HOURS_IN_MILLISECONDS, FIFTEEN_SECONDS_IN_MILLISECONDS) {
-            @Override
-            public void onTick(long millisUntilFinished) {
-                // update track duration - and add duration from previously interrupted / paused session
-                long duration = EIGHT_HOURS_IN_MILLISECONDS - millisUntilFinished + previouslyRecordedDuration;
-                mTrack.setDuration(duration);
-                // try to add WayPoint to Track
-                addWayPointToTrack();
-                // update notification
-                mNotification = NotificationHelper.getUpdatedNotification(TrackerService.this, mNotificationBuilder, mTrack);
-                mNotificationManager.notify(TRACKER_SERVICE_NOTIFICATION_ID, mNotification);
-                // save a temp file in case the service has been killed by the system
-                SaveTempTrackAsyncHelper saveTempTrackAsyncHelper = new SaveTempTrackAsyncHelper();
-                saveTempTrackAsyncHelper.execute();
-            }
-
-            @Override
-            public void onFinish() {
-                // stop tracking after eight hours
-                stopTracking();
-            }
-        };
-        mTimer.start();
-    }
-
-
-    /* Display notification */
-    private void displayNotification(boolean trackingState) {
-        mNotificationBuilder = new NotificationCompat.Builder(this, NOTIFICATION_CHANEL_ID_RECORDING_CHANNEL);
-        mNotification = NotificationHelper.getNotification(this, mNotificationBuilder, mTrack, trackingState);
-        mNotificationManager.notify(TRACKER_SERVICE_NOTIFICATION_ID, mNotification); // todo check if necessary in pre Android O
-    }
-
-
-    /* Adds a new WayPoint to current track */
-    private void addWayPointToTrack() {
-
-        boolean success = false;
-        Location previousLocation = null;
-        int trackSize = mTrack.getSize();
-
-        if (trackSize == 0) {
-            // if accurate AND current
-            if (LocationHelper.isAccurate(mCurrentBestLocation) && LocationHelper.isCurrent(mCurrentBestLocation)) {
-                // add first location to track
-                success = mTrack.addWayPoint(previousLocation, mCurrentBestLocation);
-            } else {
-                // just send a broadcast indicating that current location fix not not suited
-                broadcastTrackUpdate();
-            }
-        } else {
-            // get location of previous WayPoint
-            previousLocation = mTrack.getWayPointLocation(trackSize - 1);
-
-            // default value for average speed
-            float averageSpeed = 0f;
-
-            // compute average speed if new location came from network provider
-            if (trackSize > 1 && LocationManager.NETWORK_PROVIDER.equals(mCurrentBestLocation.getProvider())) {
-                Location firstWayPoint = mTrack.getWayPointLocation(0);
-                float distance = firstWayPoint.distanceTo(previousLocation);
-                long timeDifference = previousLocation.getElapsedRealtimeNanos() - firstWayPoint.getElapsedRealtimeNanos();
-                averageSpeed = distance / ((float) timeDifference / ONE_SECOND_IN_NANOSECOND);
-            }
-
-            // if accurate AND new
-            if (LocationHelper.isAccurate(mCurrentBestLocation) && LocationHelper.isNewWayPoint(previousLocation, mCurrentBestLocation, averageSpeed)) {
-                // add current best location to track
-                success = mTrack.addWayPoint(previousLocation, mCurrentBestLocation);
-            }
-        }
-
-        if (success) {
-            if (mResumedFlag) {
-                int lastWayPoint = mTrack.getSize() - 2;
-                if (lastWayPoint >= 0) {
-                    // mark last location as stop over
-                    mTrack.getWayPoints().get(lastWayPoint).setIsStopOver(true);
-                }
-                mResumedFlag = false;
-            } else {
-                // update distance, if not resumed
-                mTrack.updateDistance(previousLocation, mCurrentBestLocation);
-            }
-
-            // send local broadcast if new WayPoint was added
-            broadcastTrackUpdate();
-        }
-
-    }
-
-
-    /* Broadcasts a track update */
-    private void broadcastTrackUpdate() {
-        if (mTrack != null) {
-            Intent i = new Intent();
-            i.setAction(ACTION_TRACK_UPDATED);
-            i.putExtra(EXTRA_TRACK, mTrack);
-            i.putExtra(EXTRA_LAST_LOCATION, mCurrentBestLocation);
-            LocalBroadcastManager.getInstance(getApplicationContext()).sendBroadcast(i);
-        }
-    }
-
-
-    /* Creates a location listener */
-    private LocationListener createLocationListener() {
-        return new LocationListener() {
-            public void onLocationChanged(Location location) {
-                // check if the new location is better
-                if (LocationHelper.isBetterLocation(location, mCurrentBestLocation)) {
-                    // save location
-                    mCurrentBestLocation = location;
-                }
-            }
-
-            public void onStatusChanged(String provider, int status, Bundle extras) {
-                LogHelper.v(LOG_TAG, "Location provider status change: " + provider + " | " + status);
-            }
-
-            public void onProviderEnabled(String provider) {
-                LogHelper.v(LOG_TAG, "Location provider enabled: " + provider);
-            }
-
-            public void onProviderDisabled(String provider) {
-                LogHelper.v(LOG_TAG, "Location provider disabled: " + provider);
-            }
-        };
-    }
-
-
-    /* Creates gps and network location listeners */
-    private void startFindingLocation() {
-
-        // register location listeners and request updates
-        List locationProviders = mLocationManager.getAllProviders();
-        if (locationProviders.contains(LocationManager.GPS_PROVIDER)) {
-            mGPSListener = createLocationListener();
-            mTrackerServiceRunning = true;
-        }
-        if (locationProviders.contains(LocationManager.NETWORK_PROVIDER)) {
-            mNetworkListener = createLocationListener();
-            mTrackerServiceRunning = true;
-        }
-        LocationHelper.registerLocationListeners(mLocationManager, mGPSListener, mNetworkListener);
-        saveTrackerServiceState(mTrackerServiceRunning, FAB_STATE_RECORDING);
-
-        // notify MainActivity
-        broadcastTrackingStateChange();
-    }
-
-
-    /* Removes gps and network location listeners */
-    private void stopFindingLocation() {
-        // remove listeners
-        LocationHelper.removeLocationListeners(mLocationManager, mGPSListener, mNetworkListener);
-        mTrackerServiceRunning = false;
-        saveTrackerServiceState(mTrackerServiceRunning, FAB_STATE_SAVE);
-
-        // notify MainActivity
-        broadcastTrackingStateChange();
-    }
-
-
-    /* Sends a broadcast with tracking changed */
-    private void broadcastTrackingStateChange() {
-        Intent i = new Intent();
-        i.setAction(ACTION_TRACKING_STATE_CHANGED);
-        i.putExtra(EXTRA_TRACK, mTrack);
-        i.putExtra(EXTRA_LAST_LOCATION, mCurrentBestLocation);
-        i.putExtra(EXTRA_TRACKING_STATE, mTrackerServiceRunning);
-        LocalBroadcastManager.getInstance(getApplicationContext()).sendBroadcast(i);
-    }
-
-
-    /* Saves state of Tracker Service and floating Action Button */
-    private void saveTrackerServiceState(boolean trackerServiceRunning, int fabState) {
-        SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(this);
-        SharedPreferences.Editor editor = settings.edit();
-        editor.putBoolean(PREFS_TRACKER_SERVICE_RUNNING, trackerServiceRunning);
-        editor.putInt(PREFS_FAB_STATE, fabState);
-        editor.apply();
-    }
-
-
-    /**
-     * Inner class: Local Binder that returns this service
-     */
-    public class LocalBinder extends Binder {
-        TrackerService getService() {
-            // return this instance of TrackerService so clients can call public methods
-            return TrackerService.this;
-        }
-    }
-    /**
-     * End of inner class
-     */
-
-
-    /**
-     * Inner class: SettingsContentObserver is a custom ContentObserver for changes in Android Settings
-     */
-    public class SettingsContentObserver extends ContentObserver {
-
-        public SettingsContentObserver(Handler handler) {
-            super(handler);
-        }
-
-        @Override
-        public boolean deliverSelfNotifications() {
-            return super.deliverSelfNotifications();
-        }
-
-        @Override
-        public void onChange(boolean selfChange) {
-            super.onChange(selfChange);
-            LogHelper.v(LOG_TAG, "System Setting change detected.");
-
-            // check if location setting was changed
-            boolean previousLocationSystemSetting = mLocationSystemSetting;
-            mLocationSystemSetting = LocationHelper.checkLocationSystemSetting(getApplicationContext());
-            if (previousLocationSystemSetting != mLocationSystemSetting && !mLocationSystemSetting && mTrackerServiceRunning) {
-                LogHelper.v(LOG_TAG, "Location Setting turned off while tracking service running.");
-                if (mTrack != null) {
-                    stopTracking();
-                }
-                stopForeground(true);
-            }
-        }
-
-    }
-    /**
-     * End of inner class
-     */
-
-
-    /**
-     * Inner class: Saves track to external storage using AsyncTask
-     */
-    private class SaveTempTrackAsyncHelper extends AsyncTask<Void, Void, Void> {
-
-        @Override
-        protected Void doInBackground(Void... voids) {
-            LogHelper.v(LOG_TAG, "Saving temporary track object in background.");
-            // save track object
-            StorageHelper storageHelper = new StorageHelper(TrackerService.this);
-            storageHelper.saveTrack(mTrack, FILE_TEMP_TRACK);
-            return null;
-        }
-
-        @Override
-        protected void onPostExecute(Void aVoid) {
-            super.onPostExecute(aVoid);
-            LogHelper.v(LOG_TAG, "Saving finished.");
-        }
-    }
-    /**
-     * End of inner class
-     */
-
-}

app/src/main/java/org/y20k/trackbook/TrackerService.kt

@@ -0,0 +1,356 @@
+/*
+ * TrackerService.kt
+ * Implements the app's movement tracker service
+ * The TrackerService keeps track of the current location
+ *
+ * This file is part of
+ * TRACKBOOK - Movement Recorder for Android
+ *
+ * Copyright (c) 2016-20 - Y20K.org
+ * Licensed under the MIT-License
+ * http://opensource.org/licenses/MIT
+ *
+ * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
+ * https://github.com/osmdroid/osmdroid
+ */
+
+
+package org.y20k.trackbook
+
+import android.Manifest
+import android.app.Notification
+import android.app.NotificationManager
+import android.app.Service
+import android.content.Context
+import android.content.Intent
+import android.content.SharedPreferences
+import android.content.pm.PackageManager
+import android.hardware.Sensor
+import android.hardware.SensorEvent
+import android.hardware.SensorEventListener
+import android.hardware.SensorManager
+import android.location.Location
+import android.location.LocationListener
+import android.location.LocationManager
+import android.os.Binder
+import android.os.Bundle
+import android.os.Handler
+import android.os.IBinder
+import androidx.core.content.ContextCompat
+import androidx.preference.PreferenceManager
+import kotlinx.coroutines.*
+import org.y20k.trackbook.core.Track
+import org.y20k.trackbook.helpers.*
+import java.util.*
+import kotlin.coroutines.CoroutineContext
+
+
+/*
+ * TrackerService class
+ */
+class TrackerService(): Service(), CoroutineScope, SensorEventListener {
+
+    /* Define log tag */
+    private val TAG: String = LogHelper.makeLogTag(TrackerService::class.java)
+
+
+    /* Main class variables */
+    var trackingState: Int = Keys.STATE_NOT_TRACKING
+    var gpsProviderActive: Boolean = false
+    var networkProviderActive: Boolean = false
+    var useImperial: Boolean = false
+    var gpsOnly: Boolean = false
+    var locationAccuracyThreshold: Int = Keys.DEFAULT_THRESHOLD_LOCATION_ACCURACY
+    var currentBestLocation: Location = LocationHelper.getDefaultLocation()
+    var stepCountOffset: Float = 0f
+    var track: Track = Track()
+    private val binder = LocalBinder()
+    private val handler: Handler = Handler()
+    private lateinit var locationManager: LocationManager
+    private lateinit var sensorManager: SensorManager
+    private lateinit var notificationManager: NotificationManager
+    private lateinit var notificationHelper: NotificationHelper
+    private lateinit var gpsLocationListener: LocationListener
+    private lateinit var networkLocationListener: LocationListener
+    private lateinit var backgroundJob: Job
+
+
+    /* Overrides coroutineContext variable */
+    override val coroutineContext: CoroutineContext get() = backgroundJob + Dispatchers.Main
+
+
+    /* Overrides onCreate from Service */
+    override fun onCreate() {
+        super.onCreate()
+        locationManager = getSystemService(Context.LOCATION_SERVICE) as LocationManager
+        sensorManager = this.getSystemService(Context.SENSOR_SERVICE) as SensorManager
+        notificationManager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+        notificationHelper = NotificationHelper(this)
+        gpsProviderActive = LocationHelper.isGpsEnabled(locationManager)
+        networkProviderActive = LocationHelper.isNetworkEnabled(locationManager)
+        gpsLocationListener = createLocationListener()
+        networkLocationListener = createLocationListener()
+        useImperial = PreferencesHelper.loadUseImperialUnits(this)
+        locationAccuracyThreshold = PreferencesHelper.loadAccuracyThreshold(this)
+        trackingState = PreferencesHelper.loadTrackingState(this)
+        currentBestLocation = LocationHelper.getLastKnownLocation(this)
+        track = FileHelper.readTrack(this, FileHelper.getTempFileUri(this))
+        backgroundJob = Job()
+        PreferenceManager.getDefaultSharedPreferences(this).registerOnSharedPreferenceChangeListener(sharedPreferenceChangeListener)
+    }
+
+
+    /* Overrides onStartCommand from Service */
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+
+        // SERVICE RESTART (via START_STICKY)
+        if (intent == null) {
+            if (trackingState == Keys.STATE_TRACKING_ACTIVE) {
+                LogHelper.w(TAG, "Trackbook has been killed by the operating system. Trying to resume recording.")
+                resumeTracking()
+            }
+        // ACTION STOP
+        } else if (Keys.ACTION_STOP == intent.action) {
+            stopTracking()
+        // ACTION START
+        } else if (Keys.ACTION_START == intent.action) {
+            startTracking()
+        // ACTION RESUME
+        } else if (Keys.ACTION_RESUME == intent.action) {
+            resumeTracking()
+        }
+
+        // START_STICKY is used for services that are explicitly started and stopped as needed
+        return Service.START_STICKY
+    }
+
+
+    /* Overrides onBind from Service */
+    override fun onBind(p0: Intent?): IBinder? {
+        addLocationListeners()
+        return binder
+    }
+
+
+    /* Overrides onDestroy from Service */
+    override fun onDestroy() {
+        super.onDestroy()
+        LogHelper.i(TAG, "onDestroy called.")
+        if (trackingState == Keys.STATE_TRACKING_ACTIVE) stopTracking()
+        stopForeground(true)
+        PreferenceManager.getDefaultSharedPreferences(this).unregisterOnSharedPreferenceChangeListener(sharedPreferenceChangeListener)
+        removeLocationListeners()
+        backgroundJob.cancel()
+    }
+
+
+    /* Overrides onAccuracyChanged from SensorEventListener */
+    override fun onAccuracyChanged(sensor: Sensor?, accuracy: Int) {
+        LogHelper.v(TAG, "Accuracy changed: $accuracy")
+    }
+
+
+    /* Overrides onSensorChanged from SensorEventListener */
+    override fun onSensorChanged(sensorEvent: SensorEvent?) {
+        var steps: Float = 0f
+        if (sensorEvent != null) {
+            if (stepCountOffset == 0f) {
+                // store steps previously recorded by the system
+                stepCountOffset = (sensorEvent.values[0] - 1) - track.stepCount // subtract any steps recorded during this session in case the app was killed
+            }
+            // calculate step count - subtract steps previously recorded
+            steps = sensorEvent.values[0] - stepCountOffset
+        }
+        // update step count in track
+        track.stepCount = steps
+    }
+
+
+    /* Resume tracking after stop/pause */
+    fun resumeTracking() {
+        // load temp track - returns an empty track if not available
+        track = FileHelper.readTrack(this, FileHelper.getTempFileUri(this))
+        // try to mark last waypoint as stopover
+        if (track.wayPoints.size > 0) {
+            val lastWayPointIndex = track.wayPoints.size - 1
+            track.wayPoints.get(lastWayPointIndex).isStopOver = true
+        }
+        // start tracking
+        startTracking(newTrack = false)
+    }
+
+
+    /* Start tracking location */
+    fun startTracking(newTrack: Boolean = true) {
+        if (newTrack) {
+            track.recordingStart = GregorianCalendar.getInstance().time
+            track.recordingStop = track.recordingStart
+            track.name = DateTimeHelper.convertToReadableDate(track.recordingStart)
+            stepCountOffset = 0f
+        }
+        trackingState = Keys.STATE_TRACKING_ACTIVE
+        PreferencesHelper.saveTrackingState(this, trackingState)
+        startStepCounter()
+        handler.postDelayed(periodicTrackUpdate, 0)
+        startForeground(Keys.TRACKER_SERVICE_NOTIFICATION_ID, displayNotification())
+    }
+
+
+    /* Stop tracking location */
+    fun stopTracking() {
+        track.recordingStop = GregorianCalendar.getInstance().time
+        trackingState = Keys.STATE_TRACKING_STOPPED
+        PreferencesHelper.saveTrackingState(this, trackingState)
+        sensorManager.unregisterListener(this)
+        handler.removeCallbacks(periodicTrackUpdate)
+        displayNotification()
+        stopForeground(false)
+    }
+
+
+    /* Clear track recording */
+    fun clearTrack() {
+        track = Track()
+        FileHelper.deleteTempFile(this)
+        trackingState = Keys.STATE_NOT_TRACKING
+        PreferencesHelper.saveTrackingState(this, trackingState)
+        stopForeground(true)
+    }
+
+
+    /* Saves track recording to storage */
+    fun saveTrack() {
+        // save track using "deferred await"
+        launch {
+            // step 1: create and store filenames for json and gpx files
+            track.trackUriString = FileHelper.getTrackFileUri(this@TrackerService, track).toString()
+            track.gpxUriString = FileHelper.getGpxFileUri(this@TrackerService, track).toString()
+            // step 2: save track
+            FileHelper.saveTrackSuspended(track, saveGpxToo = true)
+            // step 3: save tracklist
+            FileHelper.addTrackAndSaveTracklistSuspended(this@TrackerService, track)
+            // step 3: clear track
+            clearTrack()
+        }
+    }
+
+
+    /* Creates location listener */
+    private fun createLocationListener(): LocationListener {
+        return object : LocationListener {
+            override fun onLocationChanged(location: Location) {
+                // update currentBestLocation if a better location is available
+                if (LocationHelper.isBetterLocation(location, currentBestLocation)) {
+                    currentBestLocation = location
+                }
+            }
+            override fun onProviderEnabled(provider: String) {
+                LogHelper.v(TAG, "onProviderEnabled $provider")
+                when (provider) {
+                    LocationManager.GPS_PROVIDER -> gpsProviderActive = LocationHelper.isGpsEnabled(locationManager)
+                    LocationManager.NETWORK_PROVIDER -> networkProviderActive = LocationHelper.isNetworkEnabled(locationManager)
+                }
+            }
+            override fun onProviderDisabled(provider: String) {
+                LogHelper.v(TAG, "onProviderDisabled $provider")
+                when (provider) {
+                    LocationManager.GPS_PROVIDER -> gpsProviderActive = LocationHelper.isGpsEnabled(locationManager)
+                    LocationManager.NETWORK_PROVIDER -> networkProviderActive = LocationHelper.isNetworkEnabled(locationManager)
+                }
+            }
+            override fun onStatusChanged(p0: String?, p1: Int, p2: Bundle?) {
+                // deprecated method
+            }
+        }
+    }
+
+
+    /* Adds location listeners to location manager */
+    private fun addLocationListeners() {
+        if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
+            if (gpsProviderActive) {
+                locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0f,gpsLocationListener)
+            }
+            if (networkProviderActive) {
+                locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0f,networkLocationListener)
+            }
+        } else {
+            LogHelper.w(TAG, "Unable to request device location. Permission is not granted.")
+        }
+    }
+
+
+    /* Removes location listeners from location manager */
+    private fun removeLocationListeners() {
+        locationManager.removeUpdates(gpsLocationListener)
+        locationManager.removeUpdates(networkLocationListener)
+    }
+
+
+    /* Registers a step counter listener */
+    private fun startStepCounter() {
+        val stepCounterAvailable = sensorManager.registerListener(this, sensorManager.getDefaultSensor(Sensor.TYPE_STEP_COUNTER), SensorManager.SENSOR_DELAY_UI)
+        if (!stepCounterAvailable) {
+            LogHelper.w(TAG, "Pedometer sensor not available.")
+            track.stepCount = -1f
+        }
+    }
+
+
+    /* Displays / updates notification */
+    private fun displayNotification(): Notification {
+        val notification: Notification = notificationHelper.createNotification(trackingState, track.length, track.duration, useImperial)
+        notificationManager.notify(Keys.TRACKER_SERVICE_NOTIFICATION_ID, notification)
+        return notification
+    }
+
+
+    /*
+     * Defines the listener for changes in shared preferences
+     */
+    val sharedPreferenceChangeListener = object : SharedPreferences.OnSharedPreferenceChangeListener {
+        override fun onSharedPreferenceChanged(sharedPreferences: SharedPreferences?, key: String?) {
+            when (key) {
+                Keys.PREF_GPS_ONLY -> gpsOnly = PreferencesHelper.loadGpsOnly(this@TrackerService)
+                Keys.PREF_USE_IMPERIAL_UNITS -> useImperial = PreferencesHelper.loadUseImperialUnits(this@TrackerService)
+                Keys.PREF_LOCATION_ACCURACY_THRESHOLD -> locationAccuracyThreshold = PreferencesHelper.loadAccuracyThreshold(this@TrackerService)
+            }
+        }
+    }
+    /*
+     * End of declaration
+     */
+
+
+    /*
+     * Inner class: Local Binder that returns this service
+     */
+    inner class LocalBinder : Binder() {
+        val service: TrackerService = this@TrackerService
+    }
+    /*
+     * End of inner class
+     */
+
+
+    /*
+     * Runnable: Periodically track updates (if recording active)
+     */
+    private val periodicTrackUpdate: Runnable = object : Runnable {
+        override fun run() {
+            // add waypoint to track - step count is continuously updated in onSensorChanged
+            track = TrackHelper.addWayPointToTrack(track, currentBestLocation, locationAccuracyThreshold)
+            // update notification
+            displayNotification()
+            // save temp track using GlobalScope.launch = fire & forget (no return value from save)
+            GlobalScope.launch { FileHelper.saveTempTrackSuspended(this@TrackerService, track) }
+            // re-run this in 10 seconds
+            handler.postDelayed(this, Keys.ADD_WAYPOINT_TO_TRACK_INTERVAL)
+        }
+    }
+    /*
+     * End of declaration
+     */
+
+
+}

app/src/main/java/org/y20k/trackbook/TracklistFragment.kt

@@ -0,0 +1,161 @@
+/*
+ * TracklistFragment.kt
+ * Implements the TracklistFragment fragment
+ * A TracklistFragment displays a list recorded tracks
+ *
+ * This file is part of
+ * TRACKBOOK - Movement Recorder for Android
+ *
+ * Copyright (c) 2016-20 - Y20K.org
+ * Licensed under the MIT-License
+ * http://opensource.org/licenses/MIT
+ *
+ * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
+ * https://github.com/osmdroid/osmdroid
+ */
+
+
+package org.y20k.trackbook
+
+import YesNoDialog
+import android.content.Context
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.constraintlayout.widget.ConstraintLayout
+import androidx.fragment.app.Fragment
+import androidx.navigation.fragment.findNavController
+import androidx.recyclerview.widget.DefaultItemAnimator
+import androidx.recyclerview.widget.ItemTouchHelper
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView
+import org.y20k.escapepod.helpers.UiHelper
+import org.y20k.trackbook.core.TracklistElement
+import org.y20k.trackbook.helpers.LogHelper
+import org.y20k.trackbook.helpers.TrackHelper
+import org.y20k.trackbook.tracklist.TracklistAdapter
+
+
+/*
+ * TracklistFragment class
+ */
+class TracklistFragment : Fragment(), TracklistAdapter.TracklistAdapterListener, YesNoDialog.YesNoDialogListener {
+
+    /* Define log tag */
+    private val TAG: String = LogHelper.makeLogTag(TracklistFragment::class.java)
+
+
+    /* Main class variables */
+    private lateinit var tracklistAdapter: TracklistAdapter
+    private lateinit var trackElementList: RecyclerView
+    private lateinit var tracklistOnboarding: ConstraintLayout
+
+
+    /* Overrides onCreateView from Fragment */
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        // create tracklist adapter
+        tracklistAdapter = TracklistAdapter(this)
+    }
+
+
+    /* Overrides onCreateView from Fragment */
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
+        // find views
+        val rootView = inflater.inflate(R.layout.fragment_tracklist, container, false)
+        trackElementList = rootView.findViewById(R.id.track_element_list)
+        tracklistOnboarding = rootView.findViewById(R.id.track_list_onboarding)
+
+        // set up recycler view
+        trackElementList.layoutManager = CustomLinearLayoutManager(activity as Context)
+        trackElementList.itemAnimator = DefaultItemAnimator()
+        trackElementList.adapter = tracklistAdapter
+
+        // enable swipe to delete
+        val swipeHandler = object : UiHelper.SwipeToDeleteCallback(activity as Context) {
+            override fun onSwiped(viewHolder: RecyclerView.ViewHolder, direction: Int) {
+                // ask user
+                val adapterPosition: Int = viewHolder.adapterPosition
+                val dialogMessage: String = "${getString(R.string.dialog_yes_no_message_remove_recording)}\n\n- ${tracklistAdapter.getTrackName(adapterPosition)}"
+                YesNoDialog(this@TracklistFragment as YesNoDialog.YesNoDialogListener).show(context = activity as Context, type = Keys.DIALOG_REMOVE_TRACK, messageString = dialogMessage, yesButton = R.string.dialog_yes_no_positive_button_remove_recording, payload = adapterPosition)
+            }
+        }
+        val itemTouchHelper = ItemTouchHelper(swipeHandler)
+        itemTouchHelper.attachToRecyclerView(rootView.findViewById(R.id.track_element_list))
+
+        // toggle onboarding layout
+        toggleOnboardingLayout(tracklistAdapter.itemCount)
+
+        return rootView
+    }
+
+
+    /* Overrides onTrackElementTapped from TracklistElementAdapterListener */
+    override fun onTrackElementTapped(tracklistElement: TracklistElement) {
+        val bundle: Bundle = Bundle()
+        bundle.putString(Keys.ARG_TRACK_TITLE, tracklistElement.name)
+        bundle.putString(Keys.ARG_TRACK_FILE_URI, tracklistElement.trackUriString)
+        bundle.putString(Keys.ARG_GPX_FILE_URI, tracklistElement.gpxUriString)
+        bundle.putLong(Keys.ARG_TRACK_ID, TrackHelper.getTrackId(tracklistElement))
+        findNavController().navigate(R.id.fragment_track, bundle)
+    }
+
+
+    /* Overrides onYesNoDialog from YesNoDialogListener */
+    override fun onYesNoDialog(type: Int, dialogResult: Boolean, payload: Int, payloadString: String) {
+        when (type) {
+            Keys.DIALOG_REMOVE_TRACK -> {
+                when (dialogResult) {
+                    // user tapped remove track
+                    true -> {
+                        toggleOnboardingLayout(tracklistAdapter.itemCount -1)
+                        tracklistAdapter.removeTrack(activity as Context, payload)
+                    }
+                    // user tapped cancel
+                    false -> {
+                        tracklistAdapter.notifyItemChanged(payload)
+                    }
+                }
+            }
+        }
+    }
+
+
+    // toggle onboarding layout
+    private fun toggleOnboardingLayout(trackCount: Int) {
+        when (trackCount == 0) {
+            true -> tracklistOnboarding.visibility = View.VISIBLE // show onboarding layout
+            false -> tracklistOnboarding.visibility = View.GONE // hide onboarding layout
+        }
+    }
+
+
+
+    /*
+     * Inner class: custom LinearLayoutManager that overrides onLayoutCompleted
+     */
+    inner class CustomLinearLayoutManager(context: Context): LinearLayoutManager(context, VERTICAL, false) {
+
+        override fun supportsPredictiveItemAnimations(): Boolean {
+            return true
+        }
+
+        override fun onLayoutCompleted(state: RecyclerView.State?) {
+            super.onLayoutCompleted(state)
+            // handle delete request from TrackFragment - after layout calculations are complete
+            val deleteTrackId: Long = arguments?.getLong(Keys.ARG_TRACK_ID, -1L) ?: -1L
+            arguments?.putLong(Keys.ARG_TRACK_ID, -1L)
+            if (deleteTrackId != -1L) {
+                val position: Int = tracklistAdapter.findPosition(deleteTrackId)
+                tracklistAdapter.removeTrack(this@TracklistFragment.activity as Context, position)
+                toggleOnboardingLayout(tracklistAdapter.itemCount -1)
+            }
+        }
+
+    }
+    /*
+     * End of inner class
+     */
+
+}

app/src/main/java/org/y20k/trackbook/core/Track.java

@@ -1,337 +0,0 @@
-/**
- * Track.java
- * Implements the Track class
- * A Track stores a list of WayPoints
- *
- * This file is part of
- * TRACKBOOK - Movement Recorder for Android
- *
- * Copyright (c) 2016-19 - Y20K.org
- * Licensed under the MIT-License
- * http://opensource.org/licenses/MIT
- *
- * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
- * https://github.com/osmdroid/osmdroid
- */
-
-package org.y20k.trackbook.core;
-
-import android.location.Location;
-import android.os.Parcel;
-import android.os.Parcelable;
-
-import androidx.annotation.Nullable;
-
-import org.osmdroid.util.BoundingBox;
-import org.y20k.trackbook.helpers.LocationHelper;
-import org.y20k.trackbook.helpers.TrackbookKeys;
-
-import java.util.ArrayList;
-import java.util.Date;
-import java.util.GregorianCalendar;
-import java.util.List;
-
-
-/**
- * Track class
- */
-public class Track implements TrackbookKeys, Parcelable {
-
-    /* Define log tag */
-    private static final String LOG_TAG = Track.class.getSimpleName();
-
-
-    /* Main class variables */
-    private final int mTrackFormatVersion;
-    private final List<WayPoint> mWayPoints;
-    private float mTrackLength;
-    private long mDuration;
-    private float mStepCount;
-    private final Date mRecordingStart;
-    private Date mRecordingStop;
-    private double mMaxAltitude;
-    private double mMinAltitude;
-    private double mPositiveElevation;
-    private double mNegativeElevation;
-    private BoundingBox mBoundingBox;
-
-
-    /* Generic Constructor */
-    public Track(int trackFormatVersion, List<WayPoint> wayPoints, float trackLength, long duration, float stepCount, Date recordingStart, Date recordingStop, double maxAltitude, double minAltitude, double positiveElevation, double negativeElevation, BoundingBox boundingBox) {
-        mTrackFormatVersion = trackFormatVersion;
-        mWayPoints = wayPoints;
-        mTrackLength = trackLength;
-        mDuration = duration;
-        mStepCount = stepCount;
-        mRecordingStart = recordingStart;
-        mRecordingStop = recordingStop;
-        mMaxAltitude = maxAltitude;
-        mMinAltitude = minAltitude;
-        mPositiveElevation = positiveElevation;
-        mNegativeElevation = negativeElevation;
-        mBoundingBox = boundingBox;
-    }
-
-
-    /* Copy Constructor */
-    public Track(Track track) {
-        this(track.getTrackFormatVersion(), track.getWayPoints(), track.getTrackLength(), track.getTrackDuration(), track.getStepCount(), track.getRecordingStart(), track.getRecordingStop(), track.getMaxAltitude(), track.getMinAltitude(), track.getPositiveElevation(), track.getNegativeElevation(), track.getBoundingBox());
-    }
-
-
-    /* Constructor */
-    public Track() {
-        mTrackFormatVersion = CURRENT_TRACK_FORMAT_VERSION;
-        mWayPoints = new ArrayList<WayPoint>();
-        mTrackLength = 0f;
-        mDuration = 0;
-        mStepCount = 0f;
-        mRecordingStart = GregorianCalendar.getInstance().getTime();
-        mRecordingStop = mRecordingStart;
-        mMaxAltitude = 0f;
-        mMinAltitude = 0f;
-        mPositiveElevation = 0f;
-        mNegativeElevation = 0f;
-        mBoundingBox = new BoundingBox();
-    }
-
-
-    /* Constructor used by CREATOR */
-    protected Track(Parcel in) {
-        mTrackFormatVersion = in.readInt();
-        mWayPoints = in.createTypedArrayList(WayPoint.CREATOR);
-        mTrackLength = in.readFloat();
-        mDuration = in.readLong();
-        mStepCount = in.readFloat();
-        mRecordingStart = new Date(in.readLong());
-        mRecordingStop = new Date(in.readLong());
-        mMaxAltitude = in.readDouble();
-        mMinAltitude = in.readDouble();
-        mPositiveElevation = in.readDouble();
-        mNegativeElevation = in.readDouble();
-        mBoundingBox = new BoundingBox(in.readDouble(), in.readDouble(),in.readDouble(),in.readDouble());
-        // BoundingBox(double north, double east, double south, double west)
-    }
-
-
-    /* CREATOR for Track object used to do parcel related operations */
-    public static final Creator<Track> CREATOR = new Creator<Track>() {
-        @Override
-        public Track createFromParcel(Parcel in) {
-            return new Track(in);
-        }
-
-        @Override
-        public Track[] newArray(int size) {
-            return new Track[size];
-        }
-    };
-
-
-    /* Adds new WayPoint */
-    public boolean addWayPoint(@Nullable Location previousLocation, Location newLocation) {
-
-        // toggle stop over status, if necessary
-        boolean isStopOver = LocationHelper.isStopOver(previousLocation, newLocation);
-        if (isStopOver) {
-            int wayPointCount = mWayPoints.size();
-            mWayPoints.get(wayPointCount-1).setIsStopOver(isStopOver);
-        }
-
-        // create new WayPoint
-        WayPoint wayPoint = new WayPoint(newLocation, false, mTrackLength);
-
-        // add new WayPoint to track
-        return mWayPoints.add(wayPoint);
-    }
-
-
-    /* Updates distance */
-    public boolean updateDistance(@Nullable Location previousLocation, Location newLocation){
-        // two data points needed to calculate distance
-        if (previousLocation != null) {
-            // add up distance
-            mTrackLength = mTrackLength + previousLocation.distanceTo(newLocation);
-            return true;
-        } else {
-            // this was the first waypoint
-            return false;
-        }
-    }
-
-
-    /* Toggles stop over status of last waypoint */
-    public void toggleLastWayPointStopOverStatus(boolean stopOver) {
-        int wayPointCount = mWayPoints.size();
-        mWayPoints.get(wayPointCount-1).setIsStopOver(stopOver);
-    }
-
-
-    /* Sets end time and date of recording */
-    public void setRecordingEnd() {
-        mRecordingStop = GregorianCalendar.getInstance().getTime();
-    }
-
-
-    /* Setter for duration of track */
-    public void setDuration(long duration) {
-        mDuration = duration;
-    }
-
-
-    /* Setter for step count of track */
-    public void setStepCount(float stepCount) {
-        mStepCount = stepCount;
-    }
-
-
-    /* Setter for maximum altitude of recording */
-    public void setMaxAltitude(double maxAltitude) {
-        mMaxAltitude = maxAltitude;
-    }
-
-
-    /* Setter for lowest altitude of recording */
-    public void setMinAltitude(double minAltitude) {
-        mMinAltitude = minAltitude;
-    }
-
-
-    /* Setter for positive elevation of recording (cumulative altitude difference) */
-    public void setPositiveElevation(double positiveElevation) {
-        mPositiveElevation = positiveElevation;
-    }
-
-
-    /* Setter for negative elevation of recording (cumulative altitude difference) */
-    public void setNegativeElevation(double negativeElevation) {
-        mNegativeElevation = negativeElevation;
-    }
-
-
-    /* Setter for this track's BoundingBox - a data structure describing the edge coordinates of a track */
-    public void setBoundingBox(BoundingBox boundingBox) {
-        mBoundingBox = boundingBox;
-    }
-
-
-    /* Getter for file/track format version */
-    public int getTrackFormatVersion() {
-        return mTrackFormatVersion;
-    }
-
-
-    /* Getter for mWayPoints */
-    public List<WayPoint> getWayPoints() {
-        return mWayPoints;
-    }
-
-
-    /* Getter size of Track / number of WayPoints */
-    public int getSize() {
-        return mWayPoints.size();
-    }
-
-
-    /* Getter for track length */
-    public float getTrackLength() {
-        return mTrackLength;
-    }
-
-
-    /* Getter for duration of track */
-    public long getTrackDuration() {
-        return mDuration;
-    }
-
-    /* Getter for start date of recording */
-    public Date getRecordingStart() {
-        return mRecordingStart;
-    }
-
-
-    /* Getter for stop date of recording */
-    public Date getRecordingStop() {
-        return mRecordingStop;
-    }
-
-
-    /* Getter for step count of recording */
-    public float getStepCount() {
-        return mStepCount;
-    }
-
-
-    /* Getter for maximum altitude of recording */
-    public double getMaxAltitude() {
-        return mMaxAltitude;
-    }
-
-
-    /* Getter for lowest altitude of recording */
-    public double getMinAltitude() {
-        return mMinAltitude;
-    }
-
-
-    /* Getter for positive elevation of recording (cumulative altitude difference) */
-    public double getPositiveElevation() {
-        return mPositiveElevation;
-    }
-
-
-    /* Getter for negative elevation of recording (cumulative altitude difference) */
-    public double getNegativeElevation() {
-        return mNegativeElevation;
-    }
-
-
-    /* Getter for this track's BoundingBox - a data structure describing the edge coordinates of a track */
-    public BoundingBox getBoundingBox() { return mBoundingBox; }
-
-
-    /* Getter recorded distance */
-    public Double getTrackDistance() {
-        int size = mWayPoints.size();
-        if (size > 0) {
-            return (double)mWayPoints.get(size - 1).getDistanceToStartingPoint();
-        } else {
-            return (double)0f;
-        }
-    }
-
-
-    /* Getter for location of specific WayPoint */
-    public Location getWayPointLocation(int index) {
-        return mWayPoints.get(index).getLocation();
-    }
-
-
-    @Override
-    public int describeContents() {
-        return 0;
-    }
-
-
-    @Override
-    public void writeToParcel(Parcel parcel, int flags) {
-        parcel.writeInt(mTrackFormatVersion);
-        parcel.writeTypedList(mWayPoints);
-        parcel.writeFloat(mTrackLength);
-        parcel.writeLong(mDuration);
-        parcel.writeFloat(mStepCount);
-        parcel.writeLong(mRecordingStart.getTime());
-        parcel.writeLong(mRecordingStop.getTime());
-        parcel.writeDouble(mMaxAltitude);
-        parcel.writeDouble(mMinAltitude);
-        parcel.writeDouble(mPositiveElevation);
-        parcel.writeDouble(mNegativeElevation);
-        parcel.writeDouble(mBoundingBox.getLatNorth());
-        parcel.writeDouble(mBoundingBox.getLonEast());
-        parcel.writeDouble(mBoundingBox.getLatSouth());
-        parcel.writeDouble(mBoundingBox.getLonWest());
-        // BoundingBox(double north, double east, double south, double west)
-    }
-
-
-}

app/src/main/java/org/y20k/trackbook/core/Track.kt

@@ -0,0 +1,77 @@
+/*
+ * Track.kt
+ * Implements the Track data class
+ * A Track stores a list of WayPoints
+ *
+ * This file is part of
+ * TRACKBOOK - Movement Recorder for Android
+ *
+ * Copyright (c) 2016-20 - Y20K.org
+ * Licensed under the MIT-License
+ * http://opensource.org/licenses/MIT
+ *
+ * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
+ * https://github.com/osmdroid/osmdroid
+ */
+
+
+package org.y20k.trackbook.core
+
+import android.content.Context
+import android.os.Parcelable
+import androidx.annotation.Keep
+import com.google.gson.annotations.Expose
+import kotlinx.android.parcel.Parcelize
+import org.y20k.trackbook.Keys
+import org.y20k.trackbook.helpers.DateTimeHelper
+import java.util.*
+
+
+/*
+ * Track data class
+ */
+@Keep
+@Parcelize
+data class Track (@Expose var trackFormatVersion: Int = Keys.CURRENT_TRACK_FORMAT_VERSION,
+                  @Expose val wayPoints: MutableList<WayPoint> = mutableListOf<WayPoint>(),
+                  @Expose var length: Float = 0f,
+                  @Expose var duration: Long = 0L,
+                  @Expose var stepCount: Float = 0f,
+                  @Expose var recordingStart: Date = GregorianCalendar.getInstance().time,
+                  @Expose var recordingStop: Date = recordingStart,
+                  @Expose var maxAltitude: Double = 0.0,
+                  @Expose var minAltitude: Double = 0.0,
+                  @Expose var positiveElevation: Double = 0.0,
+                  @Expose var negativeElevation: Double = 0.0,
+                  @Expose var trackUriString: String = String(),
+                  @Expose var gpxUriString: String = String(),
+                  @Expose var latitude: Double = Keys.DEFAULT_LATITUDE,
+                  @Expose var longitude: Double = Keys.DEFAULT_LONGITUDE,
+                  @Expose var zoomLevel: Double = Keys.DEFAULT_ZOOM_LEVEL,
+                  @Expose var name: String = String()): Parcelable {
+
+
+    /* Creates a TracklistElement */
+    fun toTracklistElement(context: Context): TracklistElement {
+        val readableDateString: String = DateTimeHelper.convertToReadableDate(recordingStart)
+        val readableDurationString: String = DateTimeHelper.convertToReadableTime(context, duration)
+        return TracklistElement(
+            name = name,
+            date = recordingStart,
+            dateString = readableDateString,
+            length = length,
+            durationString = readableDurationString,
+            trackUriString = trackUriString,
+            gpxUriString = gpxUriString,
+            starred = false
+        )
+    }
+
+
+    /* Returns unique ID for Track - currently the start date */
+    fun getTrackId(): Long {
+        return recordingStart.time
+    }
+
+
+}

app/src/main/java/org/y20k/trackbook/core/TrackBuilder.java

@@ -1,87 +0,0 @@
-/**
- * TrackBuilder.java
- * Implements a builder for the Track class
- * A TrackBuilder can build a track object depending on the version of its file format
- *
- * This file is part of
- * TRACKBOOK - Movement Recorder for Android
- *
- * Copyright (c) 2016-19 - Y20K.org
- * Licensed under the MIT-License
- * http://opensource.org/licenses/MIT
- *
- * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
- * https://github.com/osmdroid/osmdroid
- */
-
-
-package org.y20k.trackbook.core;
-
-import org.osmdroid.util.BoundingBox;
-import org.y20k.trackbook.helpers.LogHelper;
-import org.y20k.trackbook.helpers.MapHelper;
-
-import java.util.Date;
-import java.util.List;
-
-
-/**
- * TrackBuilder class
- */
-public class TrackBuilder {
-
-    /* Define log tag */
-    private static final String LOG_TAG = TrackBuilder.class.getSimpleName();
-
-
-    /* Main class variables */
-    private final int mTrackFormatVersion;
-    private final List<WayPoint> mWayPoints;
-    private final float mTrackLength;
-    private final long mDuration;
-    private final float mStepCount;
-    private final Date mRecordingStart;
-    private final Date mRecordingStop;
-    private final double mMaxAltitude;
-    private final double mMinAltitude;
-    private final double mPositiveElevation;
-    private final double mNegativeElevation;
-    private BoundingBox mBoundingBox;
-
-
-    /* Generic Constructor */
-    public TrackBuilder(int trackFormatVersion, List<WayPoint> wayPoints, float trackLength, long duration, float stepCount, Date recordingStart, Date recordingStop, double maxAltitude, double minAltitude, double positiveElevation, double negativeElevation, BoundingBox boundingBox) {
-        mTrackFormatVersion = trackFormatVersion;
-        mWayPoints = wayPoints;
-        mTrackLength = trackLength;
-        mDuration = duration;
-        mStepCount = stepCount;
-        mRecordingStart = recordingStart;
-        mRecordingStop = recordingStop;
-        mMaxAltitude = maxAltitude;
-        mMinAltitude = minAltitude;
-        mPositiveElevation = positiveElevation;
-        mNegativeElevation = negativeElevation;
-        mBoundingBox = boundingBox;
-    }
-
-
-    /* Builds and return a Track object */
-    public Track toTrack() {
-        switch (mTrackFormatVersion) {
-            case 1:
-                // file format version 1 - does not have elevation data stored
-                return new Track(mTrackFormatVersion, mWayPoints, mTrackLength, mDuration, mStepCount, mRecordingStart, mRecordingStop, 0f, 0f, 0f, 0f, new BoundingBox());
-            case 2:
-                // file format version 2 - does not have edge coordinates stored
-                return new Track(mTrackFormatVersion, mWayPoints, mTrackLength, mDuration, mStepCount, mRecordingStart, mRecordingStop, mMaxAltitude, mMinAltitude, mPositiveElevation, mNegativeElevation, MapHelper.calculateBoundingBox(mWayPoints));
-            case 3:
-                // file format version 3 (current version)
-                return new Track(mTrackFormatVersion, mWayPoints, mTrackLength, mDuration, mStepCount, mRecordingStart, mRecordingStop, mMaxAltitude, mMinAltitude, mPositiveElevation, mNegativeElevation, new BoundingBox());
-            default:
-                LogHelper.e(LOG_TAG, "Unknown file format version: " + mTrackFormatVersion);
-                return null;
-        }
-    }
-
-}

app/src/main/java/org/y20k/trackbook/core/TrackBundle.java

@@ -1,85 +0,0 @@
-/**
- * TrackBundle.java
- * Implements a TrackBundle
- * TrackBundle is a container for file and corresponding name of a track
- *
- * This file is part of
- * TRACKBOOK - Movement Recorder for Android
- *
- * Copyright (c) 2016-19 - Y20K.org
- * Licensed under the MIT-License
- * http://opensource.org/licenses/MIT
- *
- * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
- * https://github.com/osmdroid/osmdroid
- */
-
-
-package org.y20k.trackbook.core;
-
-import org.y20k.trackbook.helpers.LogHelper;
-
-import java.io.File;
-import java.text.DateFormat;
-import java.text.ParseException;
-import java.text.SimpleDateFormat;
-import java.util.Date;
-import java.util.Locale;
-
-
-/**
- * TrackBundle class
- */
-public class TrackBundle {
-
-    /* Define log tag */
-    private static final String LOG_TAG = TrackBundle.class.getSimpleName();
-
-    /* Main class variables */
-    private final File mTrackFile;
-    private final String mTrackName;
-
-
-    /* Constructor */
-    public TrackBundle(File file) {
-        mTrackFile = file;
-        mTrackName = buildTrackName(file);
-    }
-
-
-    /* Getter for track file */
-    public File getTrackFile() {
-        return mTrackFile;
-    }
-
-
-    /* Getter for track name */
-    public String getTrackName() {
-        return mTrackName;
-    }
-
-
-    /* Builds a readable track name from the track's file name */
-    private String buildTrackName(File file) {
-
-        // get file name without extension
-        String readableTrackName = file.getName();
-        readableTrackName = readableTrackName.substring(0, readableTrackName.indexOf(".trackbook"));
-
-        try {
-            // convert file name to date
-            DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss", Locale.US);
-            Date trackDate = dateFormat.parse(readableTrackName);
-
-            // convert date to track name string according to current locale
-            readableTrackName = DateFormat.getDateInstance(DateFormat.LONG, Locale.getDefault()).format(trackDate) + " - " +
-                    DateFormat.getTimeInstance(DateFormat.SHORT, Locale.getDefault()).format(trackDate);
-
-        } catch (ParseException e) {
-            LogHelper.w(LOG_TAG, "Unable to parse file name into date object (yyyy-MM-dd-HH-mm-ss): " + e);
-        }
-
-        return readableTrackName;
-    }
-
-}

app/src/main/java/org/y20k/trackbook/core/Tracklist.kt

@@ -0,0 +1,53 @@
+/*
+ * Tracklist.kt
+ * Implements the Tracklist data class
+ * A Tracklist stores a list of Tracks
+ *
+ * This file is part of
+ * TRACKBOOK - Movement Recorder for Android
+ *
+ * Copyright (c) 2016-20 - Y20K.org
+ * Licensed under the MIT-License
+ * http://opensource.org/licenses/MIT
+ *
+ * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
+ * https://github.com/osmdroid/osmdroid
+ */
+
+
+package org.y20k.trackbook.core
+
+import android.os.Parcelable
+import androidx.annotation.Keep
+import com.google.gson.annotations.Expose
+import kotlinx.android.parcel.Parcelize
+import org.y20k.trackbook.Keys
+import org.y20k.trackbook.helpers.TrackHelper
+import java.util.*
+
+
+/*
+ * Tracklist data class
+ */
+@Keep
+@Parcelize
+data class Tracklist (@Expose val tracklistFormatVersion: Int = Keys.CURRENT_TRACKLIST_FORMAT_VERSION,
+                      @Expose val tracklistElements: MutableList<TracklistElement> = mutableListOf<TracklistElement>(),
+                      @Expose var modificationDate: Date = Date()): Parcelable {
+
+    /* Return trackelement for given track id */
+    fun getTrackElement(trackId: Long): TracklistElement? {
+        tracklistElements.forEach { tracklistElement ->
+            if (TrackHelper.getTrackId(tracklistElement) == trackId) {
+                return tracklistElement
+            }
+        }
+        return null
+    }
+
+    /* Create a deep copy */
+    fun deepCopy(): Tracklist {
+        return Tracklist(tracklistFormatVersion, mutableListOf<TracklistElement>().apply { addAll(tracklistElements) }, modificationDate)
+    }
+
+}

app/src/main/java/org/y20k/trackbook/core/TracklistElement.kt

@@ -0,0 +1,46 @@
+/*
+ * TracklistElement.kt
+ * Implements the TracklistElement data class
+ * A TracklistElement data about a Track
+ *
+ * This file is part of
+ * TRACKBOOK - Movement Recorder for Android
+ *
+ * Copyright (c) 2016-20 - Y20K.org
+ * Licensed under the MIT-License
+ * http://opensource.org/licenses/MIT
+ *
+ * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
+ * https://github.com/osmdroid/osmdroid
+ */
+
+
+package org.y20k.trackbook.core
+
+import android.os.Parcelable
+import androidx.annotation.Keep
+import com.google.gson.annotations.Expose
+import kotlinx.android.parcel.Parcelize
+import java.util.*
+
+
+/*
+ * TracklistElement data class
+ */
+@Keep
+@Parcelize
+data class TracklistElement(@Expose var name: String,
+                            @Expose val date: Date,
+                            @Expose val dateString: String,
+                            @Expose val durationString: String,
+                            @Expose val length: Float,
+                            @Expose val trackUriString: String,
+                            @Expose val gpxUriString: String,
+                            @Expose var starred: Boolean = false): Parcelable {
+
+    /* Returns unique ID for TracklistElement - currently the start date */
+    fun getTrackId(): Long {
+        return date.time
+    }
+
+}

app/src/main/java/org/y20k/trackbook/core/WayPoint.java

@@ -1,124 +0,0 @@
-/**
- * WayPoint.java
- * Implements the WayPoint class
- * A WayPoint stores a location plus additional metadata
- *
- * This file is part of
- * TRACKBOOK - Movement Recorder for Android
- *
- * Copyright (c) 2016-19 - Y20K.org
- * Licensed under the MIT-License
- * http://opensource.org/licenses/MIT
- *
- * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
- * https://github.com/osmdroid/osmdroid
- */
-
-package org.y20k.trackbook.core;
-
-import android.location.Location;
-import android.os.Bundle;
-import android.os.Parcel;
-import android.os.Parcelable;
-
-
-/**
- * WayPoint class
- */
-public class WayPoint implements Parcelable {
-
-    private Location mLocation;
-    private boolean mIsStopOver;
-    private float mDistanceToStartingPoint;
-    private final int mNumberSatellites;
-
-    /* Constructor */
-    public WayPoint(Location location, boolean isStopOver, float distanceToStartingPoint) {
-        mLocation = location;
-        mIsStopOver = isStopOver;
-        mDistanceToStartingPoint = distanceToStartingPoint;
-
-        // save number of satellites
-        Bundle extras = location.getExtras();
-        if (extras != null && extras.containsKey("satellites")) {
-            mNumberSatellites = extras.getInt("satellites", 0);
-            mLocation.setExtras(null); // necessary because Location Extras cause cannot be serialized properly by GSON
-        } else {
-            mNumberSatellites = 0;
-        }
-
-    }
-
-    /* Constructor used by CREATOR */
-    protected WayPoint(Parcel in) {
-        mLocation = Location.CREATOR.createFromParcel(in);
-        mIsStopOver = in.readByte() != 0;
-        mDistanceToStartingPoint = in.readFloat();
-        mNumberSatellites = in.readInt();
-    }
-
-
-    /* CREATOR for WayPoint object used to do parcel related operations */
-    public static final Creator<WayPoint> CREATOR = new Creator<WayPoint>() {
-        @Override
-        public WayPoint createFromParcel(Parcel in) {
-            return new WayPoint(in);
-        }
-
-        @Override
-        public WayPoint[] newArray(int size) {
-            return new WayPoint[size];
-        }
-    };
-
-
-    /* Getter for mLocation */
-    public Location getLocation() {
-        return mLocation;
-    }
-
-
-    /* Getter for mIsStopOver */
-    public boolean getIsStopOver() {
-        return mIsStopOver;
-    }
-
-
-    /* Getter for mDistanceToStartingPoint */
-    public float getDistanceToStartingPoint() {
-        return mDistanceToStartingPoint;
-    }
-
-
-    /* Setter for mLocation */
-    public void setLocation(Location location) {
-        mLocation = location;
-    }
-
-
-    /* Setter for mIsStopOver */
-    public void setIsStopOver(boolean isStopOver) {
-        mIsStopOver = isStopOver;
-    }
-
-
-    /* Setter for mDistanceToStartingPoint */
-    public void setDistanceToStartingPoint(float distanceToStartingPoint) {
-        mDistanceToStartingPoint = distanceToStartingPoint;
-    }
-
-    @Override
-    public int describeContents() {
-        return 0;
-    }
-
-
-    @Override
-    public void writeToParcel(Parcel parcel, int flags) {
-        mLocation.setExtras(null); // necessary because Location Extras cause cannot be serialized properly by GSON
-        mLocation.writeToParcel(parcel, flags);
-        parcel.writeByte((byte) (mIsStopOver ? 1 : 0));
-        parcel.writeFloat(mDistanceToStartingPoint);
-        parcel.writeInt(mNumberSatellites);
-    }
-}

app/src/main/java/org/y20k/trackbook/core/WayPoint.kt

@@ -0,0 +1,54 @@
+/*
+ * WayPoint.kt
+ * Implements the WayPoint data class
+ * A WayPoint stores a location plus additional metadata
+ *
+ * This file is part of
+ * TRACKBOOK - Movement Recorder for Android
+ *
+ * Copyright (c) 2016-20 - Y20K.org
+ * Licensed under the MIT-License
+ * http://opensource.org/licenses/MIT
+ *
+ * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
+ * https://github.com/osmdroid/osmdroid
+ */
+
+
+package org.y20k.trackbook.core
+
+import android.location.Location
+import android.os.Parcelable
+import androidx.annotation.Keep
+import com.google.gson.annotations.Expose
+import kotlinx.android.parcel.Parcelize
+
+
+/*
+ * WayPoint data class
+ */
+@Keep
+@Parcelize
+data class WayPoint(@Expose val provider: String,
+                    @Expose val latitude: Double,
+                    @Expose val longitude: Double,
+                    @Expose val altitude: Double,
+                    @Expose val accuracy: Float,
+                    @Expose val time: Long,
+                    @Expose val distanceToStartingPoint: Float = 0f,
+                    @Expose val numberSatellites: Int = 0,
+                    @Expose var isStopOver: Boolean = false): Parcelable {
+
+
+    /* Converts WayPoint into Location */
+    fun toLocation(): Location {
+        val location: Location = Location(provider)
+        location.latitude = latitude
+        location.longitude = longitude
+        location.altitude = altitude
+        location.accuracy = accuracy
+        location.time = time
+        return location
+    }
+
+}

app/src/main/java/org/y20k/trackbook/dialogs/ErrorDialog.kt

@@ -0,0 +1,92 @@
+/*
+ * ErrorDialog.kt
+ * Implements the ErrorDialog object
+ * A ErrorDialog shows an error dialog with details
+ *
+ * This file is part of
+ * TRACKBOOK - Movement Recorder for Android
+ *
+ * Copyright (c) 2016-20 - Y20K.org
+ * Licensed under the MIT-License
+ * http://opensource.org/licenses/MIT
+ *
+ * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
+ * https://github.com/osmdroid/osmdroid
+ */
+
+
+package org.y20k.trackbook.dialogs
+
+import android.content.Context
+import android.content.DialogInterface
+import android.text.method.ScrollingMovementMethod
+import android.view.LayoutInflater
+import android.view.View
+import android.widget.TextView
+import com.google.android.material.dialog.MaterialAlertDialogBuilder
+import org.y20k.trackbook.R
+import org.y20k.trackbook.helpers.LogHelper
+
+
+/*
+ * ErrorDialog object
+ */
+object ErrorDialog {
+
+    /* Define log tag */
+    private val TAG: String = LogHelper.makeLogTag(ErrorDialog::class.java)
+
+
+    /* Construct and show dialog */
+    fun show(context: Context, errorTitle: Int, errorMessage: Int, errorDetails: String = String()) {
+        // prepare dialog builder
+        val builder: MaterialAlertDialogBuilder = MaterialAlertDialogBuilder(context, R.style.AlertDialogTheme)
+
+        // set title
+        builder.setTitle(context.getString(errorTitle))
+
+        // get views
+        val inflater: LayoutInflater = LayoutInflater.from(context)
+        val view: View = inflater.inflate(R.layout.dialog_generic_with_details, null)
+        val errorMessageView: TextView = view.findViewById(R.id.dialog_message) as TextView
+        val errorDetailsLinkView: TextView = view.findViewById(R.id.dialog_details_link) as TextView
+        val errorDetailsView: TextView = view.findViewById(R.id.dialog_details) as TextView
+
+        // set dialog view
+        builder.setView(view)
+
+        // set detail view
+        if (errorDetails.isNotEmpty()) {
+            // show details link
+            errorDetailsLinkView.visibility = View.VISIBLE
+
+            // allow scrolling on details view
+            errorDetailsView.movementMethod = ScrollingMovementMethod()
+
+            // show and hide details on click
+            errorDetailsLinkView.setOnClickListener {
+                when (errorDetailsView.visibility) {
+                    View.GONE -> errorDetailsView.visibility = View.VISIBLE
+                    View.VISIBLE -> errorDetailsView.visibility = View.GONE
+                }
+            }
+            // set details text view
+            errorDetailsView.text = errorDetails
+        } else {
+            // hide details link
+            errorDetailsLinkView.visibility = View.GONE
+        }
+
+        // set text views
+        errorMessageView.text = context.getString(errorMessage)
+
+        // add okay button
+        builder.setPositiveButton(R.string.dialog_generic_button_okay, DialogInterface.OnClickListener { _, _ ->
+            // listen for click on okay button
+            // do nothing
+        })
+
+        // display error dialog
+        builder.show()
+    }
+}

app/src/main/java/org/y20k/trackbook/dialogs/RenameTrackDialog.kt

@@ -0,0 +1,82 @@
+/*
+ * RenameTrackDialog.kt
+ * Implements the RenameTrackDialog class
+ * A RenameTrackDialog offers user to change name of track
+ *
+ * This file is part of
+ * TRACKBOOK - Movement Recorder for Android
+ *
+ * Copyright (c) 2016-20 - Y20K.org
+ * Licensed under the MIT-License
+ * http://opensource.org/licenses/MIT
+ *
+ * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
+ * https://github.com/osmdroid/osmdroid
+ */
+
+
+package org.y20k.trackbook.dialogs
+
+import android.content.Context
+import android.text.InputType
+import android.view.LayoutInflater
+import android.view.View
+import android.widget.EditText
+import android.widget.TextView
+import com.google.android.material.dialog.MaterialAlertDialogBuilder
+import org.y20k.trackbook.R
+import org.y20k.trackbook.helpers.LogHelper
+
+
+/*
+ * RenameTrackDialog class
+ */
+class RenameTrackDialog (private var renameTrackListener: RenameTrackListener) {
+
+    /* Interface used to communicate back to activity */
+    interface RenameTrackListener {
+        fun onRenameTrackDialog(textInput: String) {
+        }
+    }
+
+    /* Define log tag */
+    private val TAG = LogHelper.makeLogTag(RenameTrackDialog::class.java.simpleName)
+
+
+    /* Construct and show dialog */
+    fun show(context: Context, trackName: String) {
+        // prepare dialog builder
+        val builder: MaterialAlertDialogBuilder = MaterialAlertDialogBuilder(context)
+
+        // get input field
+        val inflater = LayoutInflater.from(context)
+        val view = inflater.inflate(R.layout.dialog_rename_track, null)
+        val inputField = view.findViewById<View>(R.id.dialog_rename_track_input_edit_text) as EditText
+
+        // pre-fill with current track name
+        inputField.setText(trackName, TextView.BufferType.EDITABLE)
+        inputField.setSelection(trackName.length)
+        inputField.inputType = InputType.TYPE_CLASS_TEXT
+
+        // set dialog view
+        builder.setView(view)
+
+        // add "add" button
+        builder.setPositiveButton(R.string.dialog_rename_track_button) { _, _ ->
+            // hand text over to initiating activity
+            inputField.text?.let {
+                renameTrackListener.onRenameTrackDialog(it.toString())
+            }
+        }
+
+        // add cancel button
+        builder.setNegativeButton(R.string.dialog_generic_button_cancel) { _, _ ->
+            // listen for click on cancel button
+            // do nothing
+        }
+
+        // display add dialog
+        builder.show()
+    }
+
+}

app/src/main/java/org/y20k/trackbook/dialogs/YesNoDialog.kt

@@ -0,0 +1,97 @@
+/*
+ * YesNoDialog
+ * Implements the YesNoDialog class
+ * A YesNoDialog asks the user if he/she wants to do something or notpackage org.y20k.trackbook.dialogs
+ *
+ * This file is part of
+ * TRACKBOOK - Movement Recorder for Android
+ *
+ * Copyright (c) 2016-20 - Y20K.org
+ * Licensed under the MIT-License
+ * http://opensource.org/licenses/MIT
+ *
+ * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
+ * https://github.com/osmdroid/osmdroid
+ */
+
+
+import android.content.Context
+import com.google.android.material.dialog.MaterialAlertDialogBuilder
+import org.y20k.trackbook.Keys
+import org.y20k.trackbook.R
+import org.y20k.trackbook.helpers.LogHelper
+
+/*
+ * YesNoDialog class
+ */
+class YesNoDialog (private var yesNoDialogListener: YesNoDialogListener) {
+
+    /* Interface used to communicate back to activity */
+    interface YesNoDialogListener {
+        fun onYesNoDialog(type: Int, dialogResult: Boolean, payload: Int, payloadString: String) {
+        }
+    }
+
+
+    /* Define log tag */
+    private val TAG = LogHelper.makeLogTag(YesNoDialog::class.java.simpleName)
+
+
+
+
+
+    /* Construct and show dialog - variant: message from string  */
+    fun show(context: Context,
+             type: Int,
+             title: Int = Keys.EMPTY_STRING_RESOURCE,
+             message: Int,
+             yesButton: Int = R.string.dialog_yes_no_positive_button_default,
+             noButton: Int = R.string.dialog_generic_button_cancel,
+             payload: Int = Keys.DIALOG_EMPTY_PAYLOAD_INT,
+             payloadString: String = Keys.DIALOG_EMPTY_PAYLOAD_STRING) {
+        // extract string from message resource and feed into main show method
+        show(context, type, title, context.getString(message), yesButton, noButton, payload, payloadString)
+    }
+
+
+    /* Construct and show dialog */
+    fun show(context: Context,
+             type: Int,
+             title: Int = Keys.EMPTY_STRING_RESOURCE,
+             messageString: String,
+             yesButton: Int = R.string.dialog_yes_no_positive_button_default,
+             noButton: Int = R.string.dialog_generic_button_cancel,
+             payload: Int = Keys.DIALOG_EMPTY_PAYLOAD_INT,
+             payloadString: String = Keys.DIALOG_EMPTY_PAYLOAD_STRING) {
+
+        // prepare dialog builder
+        val builder: MaterialAlertDialogBuilder = MaterialAlertDialogBuilder(context, R.style.AlertDialogTheme)
+
+        // set title and message
+        builder.setMessage(messageString)
+        if (title != Keys.EMPTY_STRING_RESOURCE) {
+            builder.setTitle(context.getString(title))
+        }
+
+
+        // add yes button
+        builder.setPositiveButton(yesButton) { _, _ ->
+            // listen for click on yes button
+            yesNoDialogListener.onYesNoDialog(type, true, payload, payloadString)
+        }
+
+        // add no button
+        builder.setNegativeButton(noButton) { _, _ ->
+            // listen for click on no button
+            yesNoDialogListener.onYesNoDialog(type, false, payload, payloadString)
+        }
+
+        // handle outside-click as "no"
+        builder.setOnCancelListener(){
+            yesNoDialogListener.onYesNoDialog(type, false, payload, payloadString)
+        }
+
+        // display dialog
+        builder.show()
+    }
+}

app/src/main/java/org/y20k/trackbook/extensions/SharedPreferencesExt.kt

@@ -0,0 +1,29 @@
+/*
+ * SharedPreferencesExt.kt
+ * Implements the SharedPreferencesExt extension functions
+ * SharedPreferencesExt displays provides additional functions for dealing with shared preferences
+ *
+ * This file is part of
+ * TRACKBOOK - Movement Recorder for Android
+ *
+ * Copyright (c) 2016-20 - Y20K.org
+ * Licensed under the MIT-License
+ * http://opensource.org/licenses/MIT
+ *
+ * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
+ * https://github.com/osmdroid/osmdroid
+ */
+
+
+package org.y20k.trackbook.extensions
+
+
+import android.content.SharedPreferences
+
+
+/* Puts a Double value in SharedPreferences */
+fun SharedPreferences.Editor.putDouble(key: String, double: Double) = putLong(key, java.lang.Double.doubleToRawLongBits(double))
+
+
+/* gets a Double value from SharedPreferences */
+fun SharedPreferences.getDouble(key: String, default: Double) = java.lang.Double.longBitsToDouble(getLong(key, java.lang.Double.doubleToRawLongBits(default)))

app/src/main/java/org/y20k/trackbook/helpers/DateTimeHelper.kt

@@ -0,0 +1,84 @@
+/*
+ * DateTimeHelper.kt
+ * Implements the DateTimeHelper object
+ * A DateTimeHelper provides helper methods for converting Date and Time objects
+ *
+ * This file is part of
+ * TRACKBOOK - Movement Recorder for Android
+ *
+ * Copyright (c) 2016-20 - Y20K.org
+ * Licensed under the MIT-License
+ * http://opensource.org/licenses/MIT
+ *
+ * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
+ * https://github.com/osmdroid/osmdroid
+ */
+
+
+package org.y20k.trackbook.helpers
+
+import android.content.Context
+import android.location.Location
+import org.y20k.trackbook.Keys
+import org.y20k.trackbook.R
+import java.text.DateFormat
+import java.text.SimpleDateFormat
+import java.util.*
+import java.util.concurrent.TimeUnit
+
+
+/*
+ * DateTimeHelper object
+ */
+object DateTimeHelper {
+
+    /* Converts milliseconds to mm:ss or hh:mm:ss */
+    fun convertToReadableTime(context: Context, milliseconds: Long): String {
+        var timeString: String = String()
+        val hours: Long = TimeUnit.MILLISECONDS.toHours(milliseconds)
+        val minutes: Long = TimeUnit.MILLISECONDS.toMinutes(milliseconds) % TimeUnit.HOURS.toMinutes(1)
+        val seconds: Long = TimeUnit.MILLISECONDS.toSeconds(milliseconds) % TimeUnit.MINUTES.toSeconds(1)
+        val h: String = context.getString(R.string.abbreviation_hours)
+        val m: String = context.getString(R.string.abbreviation_minutes)
+        val s: String = context.getString(R.string.abbreviation_seconds)
+
+        when (milliseconds >= Keys.ONE_HOUR_IN_MILLISECONDS) {
+            // CASE: format hh:mm:ss
+            true -> {
+                timeString = "$hours $h $minutes $m $seconds $s"
+            }
+            // CASE: format mm:ss
+            false -> {
+                timeString = "$minutes $m $seconds $s"
+            }
+        }
+        return timeString
+    }
+
+
+    /* Create sortable string from date - used for filenames  */
+    fun convertToSortableDateString(date: Date): String {
+        val dateFormat: SimpleDateFormat = SimpleDateFormat("yyyy-MM-dd-HH-mm-ss", Locale.US)
+        return dateFormat.format(date)
+    }
+
+
+    /* Creates a readable string from date - used in the UI */
+    fun convertToReadableDate(date: Date, dateStyle: Int = DateFormat.LONG): String {
+        return DateFormat.getDateInstance(dateStyle, Locale.getDefault()).format(date)
+    }
+
+
+    /* Calculates time difference between two locations */
+    fun calculateTimeDistance(previousLocation: Location?, location: Location): Long  {
+        var timeDifference: Long = 0L
+        // two data points needed to calculate time difference
+        if (previousLocation != null) {
+            // get time difference
+            timeDifference = location.time - previousLocation.time
+        }
+        return timeDifference
+    }
+
+
+}

app/src/main/java/org/y20k/trackbook/helpers/DialogHelper.java

@@ -1,87 +0,0 @@
-/**
- * DialogHelper.java
- * Implements the DialogHelper class
- * A DialogHelper creates a customizable alert dialog
- *
- * This file is part of
- * TRACKBOOK - Movement Recorder for Android
- *
- * Copyright (c) 2016-19 - Y20K.org
- * Licensed under the MIT-License
- * http://opensource.org/licenses/MIT
- *
- * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
- * https://github.com/osmdroid/osmdroid
- */
-
-package org.y20k.trackbook.helpers;
-
-import android.app.Activity;
-import android.app.AlertDialog;
-import android.app.Dialog;
-import android.content.DialogInterface;
-import android.os.Bundle;
-
-import androidx.annotation.NonNull;
-import androidx.fragment.app.DialogFragment;
-import androidx.fragment.app.Fragment;
-
-
-/**
- * DialogHelper class
- */
-public class DialogHelper extends DialogFragment implements TrackbookKeys {
-
-    /* Constructs a new instance */
-    public static DialogHelper newInstance(int title, String message, int positiveButton, int negativeButton) {
-        DialogHelper fragment = new DialogHelper();
-        Bundle args = new Bundle();
-        args.putInt(ARG_DIALOG_TITLE, title);
-        args.putString(ARG_DIALOG_MESSAGE, message);
-        args.putInt(ARG_DIALOG_BUTTON_POSITIVE, positiveButton);
-        args.putInt(ARG_DIALOG_BUTTON_NEGATIVE, negativeButton);
-        fragment.setArguments(args);
-        return fragment;
-    }
-
-
-    @NonNull
-    @Override
-    public Dialog onCreateDialog(Bundle savedInstanceState) {
-        Bundle args = getArguments();
-
-        // get text elements
-        int title = args.getInt(ARG_DIALOG_TITLE);
-        String message = args.getString(ARG_DIALOG_MESSAGE);
-        int positiveButton = args.getInt(ARG_DIALOG_BUTTON_POSITIVE);
-        int negativeButton = args.getInt(ARG_DIALOG_BUTTON_NEGATIVE);
-
-        // build dialog
-        AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(getActivity());
-        if (title != -1) {
-            dialogBuilder.setTitle(title);
-        }
-        dialogBuilder.setMessage(message);
-        dialogBuilder.setPositiveButton(positiveButton,
-                new DialogInterface.OnClickListener() {
-                    public void onClick(DialogInterface dialog, int whichButton) {
-                        Fragment target = getTargetFragment();
-                        if (target != null) {
-                            target.onActivityResult(getTargetRequestCode(), Activity.RESULT_OK, getActivity().getIntent());
-                        }
-                    }
-                }
-        );        dialogBuilder.setNegativeButton(negativeButton,
-                new DialogInterface.OnClickListener() {
-                    public void onClick(DialogInterface dialog, int whichButton) {
-                        Fragment target = getTargetFragment();
-                        if (target != null) {
-                            target.onActivityResult(getTargetRequestCode(), Activity.RESULT_CANCELED, getActivity().getIntent());
-                        }
-                    }
-                }
-        );
-
-        return dialogBuilder.create();
-    }
-}

app/src/main/java/org/y20k/trackbook/helpers/DropdownAdapter.java

@@ -1,187 +0,0 @@
-/**
- * DropdownHelper.java
- * Implements a dropdown menu
- * The dropdown menu used to select tracks
- *
- * This file is part of
- * TRACKBOOK - Movement Recorder for Android
- *
- * Copyright (c) 2016-19 - Y20K.org
- * Licensed under the MIT-License
- * http://opensource.org/licenses/MIT
- *
- * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
- * https://github.com/osmdroid/osmdroid
- */
-
-
-package org.y20k.trackbook.helpers;
-
-import android.app.Activity;
-import android.content.res.Resources;
-import android.database.DataSetObserver;
-import android.view.LayoutInflater;
-import android.view.View;
-import android.view.ViewGroup;
-import android.widget.BaseAdapter;
-import android.widget.TextView;
-
-import org.y20k.trackbook.R;
-import org.y20k.trackbook.core.TrackBundle;
-
-import java.io.File;
-import java.util.ArrayList;
-import java.util.List;
-
-import androidx.annotation.Nullable;
-import androidx.appcompat.widget.ThemedSpinnerAdapter;
-
-
-/**
- * DropdownHelper class
- */
-public class DropdownAdapter extends BaseAdapter implements ThemedSpinnerAdapter, TrackbookKeys {
-
-    /* Define log tag */
-    private static final String LOG_TAG = DropdownAdapter.class.getSimpleName();
-
-
-    /* Main class variables */
-    private final Activity mActivity;
-    private final ThemedSpinnerAdapter.Helper mDropdownAdapterHelper;
-    private List<TrackBundle> mTrackBundleList;
-
-
-    /* Constructor */
-    public DropdownAdapter(Activity activity) {
-        // store activity
-        mActivity = activity;
-
-        // fill list with track bundles
-        initializeTrackBundleList();
-
-        // create an adapter helper
-        mDropdownAdapterHelper = new ThemedSpinnerAdapter.Helper(activity);
-    }
-
-
-    @Override
-    public void setDropDownViewTheme(@Nullable Resources.Theme theme) {
-        mDropdownAdapterHelper.setDropDownViewTheme(theme);
-    }
-
-
-    @Nullable
-    @Override
-    public Resources.Theme getDropDownViewTheme() {
-        return mDropdownAdapterHelper.getDropDownViewTheme();
-    }
-
-
-    @Override
-    public View getView(int position, View convertView, ViewGroup parent) {
-        // getView -> collapsed view of dropdown
-        View view = convertView;
-        if (view == null) {
-            LayoutInflater inflater = mDropdownAdapterHelper.getDropDownViewInflater();
-            view = inflater.inflate(R.layout.custom_dropdown_item_collapsed, parent, false);
-        }
-        ((TextView) view).setText(getItem(position).getTrackName());
-        return view;
-    }
-
-
-    @Override
-    public View getDropDownView(int position, View convertView, ViewGroup parent) {
-        // getDropDownView -> expanded view of dropdown
-        View view = convertView;
-        if (view == null) {
-            LayoutInflater inflater = mDropdownAdapterHelper.getDropDownViewInflater();
-//            view = inflater.inflate(R.layout.custom_dropdown_item_expanded, parent, false);
-            view = inflater.inflate(R.layout.support_simple_spinner_dropdown_item, parent, false);
-        }
-        ((TextView) view).setText(getItem(position).getTrackName());
-        return view;
-    }
-
-
-    @Override
-    public void registerDataSetObserver(DataSetObserver dataSetObserver) {
-
-    }
-
-
-    @Override
-    public void unregisterDataSetObserver(DataSetObserver dataSetObserver) {
-
-    }
-
-
-    @Override
-    public int getCount() {
-        return mTrackBundleList.size();
-    }
-
-
-    @Override
-    public TrackBundle getItem(int i) {
-        return mTrackBundleList.get(i);
-    }
-
-
-    @Override
-    public long getItemId(int i) {
-        return 0;
-    }
-
-
-    @Override
-    public boolean hasStableIds() {
-        return false;
-    }
-
-
-    @Override
-    public int getItemViewType(int i) {
-        return 0;
-    }
-
-
-    @Override
-    public int getViewTypeCount() {
-        return 1;
-    }
-
-
-    @Override
-    public boolean isEmpty() {
-        return mTrackBundleList.size() == 0;
-    }
-
-
-    /* Refreshes the adapter data */
-    public void refresh() {
-        // re-initialize the adapter's array list
-        initializeTrackBundleList();
-    }
-
-
-    /* Initializes list of track bundles */
-    private void initializeTrackBundleList() {
-
-        // get list of files from storage
-        StorageHelper storageHelper = new StorageHelper(mActivity);
-        File files[] = storageHelper.getListOfTrackbookFiles();
-
-        // fill list with track bundles
-        mTrackBundleList = new ArrayList<>();
-        for (File file : files) {
-            String fileName = file.getName();
-            if (fileName.endsWith(FILE_TYPE_TRACKBOOK_EXTENSION) && !fileName.startsWith(FILE_NAME_TEMP)) {
-                mTrackBundleList.add(new TrackBundle(file));
-            }
-        }
-
-    }
-
-}

app/src/main/java/org/y20k/trackbook/helpers/ExportHelper.java

@@ -1,224 +0,0 @@
-/**
- * ExportHelper.java
- * Implements the ExportHelper class
- * A ExportHelper can convert Track object into a GPX string
- *
- * This file is part of
- * TRACKBOOK - Movement Recorder for Android
- *
- * Copyright (c) 2016-19 - Y20K.org
- * Licensed under the MIT-License
- * http://opensource.org/licenses/MIT
- *
- * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
- * https://github.com/osmdroid/osmdroid
- */
-
-package org.y20k.trackbook.helpers;
-
-import android.content.Context;
-import android.content.Intent;
-import android.location.Location;
-import android.os.Environment;
-import android.widget.Toast;
-
-import org.y20k.trackbook.R;
-import org.y20k.trackbook.core.Track;
-import org.y20k.trackbook.core.WayPoint;
-
-import java.io.BufferedWriter;
-import java.io.File;
-import java.io.FileWriter;
-import java.io.IOException;
-import java.text.DateFormat;
-import java.text.SimpleDateFormat;
-import java.util.Date;
-import java.util.Locale;
-import java.util.TimeZone;
-
-import androidx.core.content.FileProvider;
-
-/**
- * ExportHelper class
- */
-public final class ExportHelper extends FileProvider implements TrackbookKeys {
-
-    /* Define log tag */
-    private static final String LOG_TAG = ExportHelper.class.getSimpleName();
-
-
-    /* Checks if a GPX file for given track is already present */
-    public static boolean gpxFileExists(Track track) {
-        File folder = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
-        return createFile(track, folder).exists();
-    }
-
-
-    /* Exports given track to GPX */
-    public static boolean exportToGpx(Context context, Track track) {
-        // get file for given track
-        File gpxFile = createFile(track, getDownloadFolder());
-
-        // get GPX string representation for given track
-        String gpxString = createGpxString(track);
-
-        // write GPX file
-        if (writeGpxToFile(gpxString, gpxFile)) {
-            String toastMessage = context.getResources().getString(R.string.toast_message_export_success) + " " + gpxFile.toString();
-            Toast.makeText(context, toastMessage, Toast.LENGTH_LONG).show();
-            return true;
-        } else {
-            String toastMessage = context.getResources().getString(R.string.toast_message_export_fail) + " " + gpxFile.toString();
-            Toast.makeText(context, toastMessage, Toast.LENGTH_LONG).show();
-            return false;
-        }
-    }
-
-
-    /* Creates Intent used to bring up an Android share sheet */
-    public static Intent getGpxFileIntent(Context context, Track track) {
-
-        // create file in Cache directory for given track
-        File gpxFile = createFile(track, context.getCacheDir());
-
-        // get GPX string representation for given track
-        String gpxString = createGpxString(track);
-
-        // write GPX file
-        if (writeGpxToFile(gpxString, gpxFile)) {
-            String toastMessage = context.getResources().getString(R.string.toast_message_export_success) + " " + gpxFile.toString();
-            Toast.makeText(context, toastMessage, Toast.LENGTH_LONG).show();
-        } else {
-            String toastMessage = context.getResources().getString(R.string.toast_message_export_fail) + " " + gpxFile.toString();
-            Toast.makeText(context, toastMessage, Toast.LENGTH_LONG).show();
-        }
-
-        // create intent
-        String authority = "org.y20k.trackbook.exporthelper.provider";
-        Intent intent = new Intent();
-        intent.setAction(Intent.ACTION_SEND);
-        intent.setDataAndType(FileProvider.getUriForFile(context, authority, gpxFile), "application/gpx+xml");
-        intent.setType("application/gpx+xml");
-        intent.putExtra(Intent.EXTRA_STREAM, FileProvider.getUriForFile(context, authority, gpxFile));
-
-        return intent;
-    }
-
-
-    /* Empties the internal chache directory */
-    public static void emptyCacheDirectory(Context context) {
-        // todo implement a date check - delete only stuff that is a week old
-        File[] cacheFiles = context.getCacheDir().listFiles();
-        for (File file: cacheFiles) {
-            file.delete();
-        }
-    }
-
-
-    /* Get "Download" folder */
-    private static File getDownloadFolder() {
-        File folder = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
-        if (folder != null && !folder.exists()) {
-            LogHelper.v(LOG_TAG, "Creating new folder: " + folder.toString());
-            folder.mkdirs();
-        }
-        return folder;
-    }
-
-
-    /* Return a GPX filepath for a given track */
-    private static File createFile(Track track, File folder) {
-        Date recordingStart = track.getRecordingStart();
-        DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss", Locale.US);
-
-        return new File(folder, dateFormat.format(recordingStart) + FILE_TYPE_GPX_EXTENSION);
-    }
-
-
-    /* Writes given GPX string to given file */
-    private static boolean writeGpxToFile (String gpxString, File gpxFile) {
-        // write track
-        try (BufferedWriter bw = new BufferedWriter(new FileWriter(gpxFile))) {
-            LogHelper.v(LOG_TAG, "Saving track to external storage: " + gpxFile.toString());
-            bw.write(gpxString);
-            return true;
-        } catch (IOException e) {
-            LogHelper.e(LOG_TAG, "Unable to saving track to external storage (IOException): " + gpxFile.toString());
-            return false;
-        }
-    }
-
-
-    /* Creates GPX formatted string */
-    private static String createGpxString(Track track) {
-        String gpxString;
-
-        // add header
-        gpxString = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"no\" ?>\n" +
-                    "<gpx version=\"1.1\" creator=\"Transistor App (Android)\"\n" +
-                    "     xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"\n" +
-                    "     xsi:schemaLocation=\"http://www.topografix.com/GPX/1/1 http://www.topografix.com/GPX/1/1/gpx.xsd\">\n";
-
-        // add track
-        gpxString = gpxString + addTrack(track);
-
-        // add closing tag
-        gpxString = gpxString + "</gpx>\n";
-
-        return gpxString;
-    }
-
-
-    /* Creates Track */
-    private static String addTrack(Track track) {
-        StringBuilder gpxTrack = new StringBuilder("");
-        DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'", Locale.US);
-        dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
-
-        // add opening track tag
-        gpxTrack.append("\t<trk>\n");
-
-        // add name to track
-        gpxTrack.append("\t\t<name>");
-        gpxTrack.append("Trackbook Recording");
-        gpxTrack.append("</name>\n");
-
-        // add opening track segment tag
-        gpxTrack.append("\t\t<trkseg>\n");
-
-        // add route point
-        for (WayPoint wayPoint:track.getWayPoints()) {
-            // get location from waypoint
-            Location location = wayPoint.getLocation();
-
-            // add longitude and latitude
-            gpxTrack.append("\t\t\t<trkpt lat=\"");
-            gpxTrack.append(location.getLatitude());
-            gpxTrack.append("\" lon=\"");
-            gpxTrack.append(location.getLongitude());
-            gpxTrack.append("\">\n");
-
-            // add time
-            gpxTrack.append("\t\t\t\t<time>");
-            gpxTrack.append(dateFormat.format(new Date(location.getTime())));
-            gpxTrack.append("</time>\n");
-
-            // add altitude
-            gpxTrack.append("\t\t\t\t<ele>");
-            gpxTrack.append(location.getAltitude());
-            gpxTrack.append("</ele>\n");
-
-            // add closing tag
-            gpxTrack.append("\t\t\t</trkpt>\n");
-        }
-
-        // add closing track segment tag
-        gpxTrack.append("\t\t</trkseg>\n");
-
-        // add closing track tag
-        gpxTrack.append("\t</trk>\n");
-
-        return gpxTrack.toString();
-    }
-
-}

app/src/main/java/org/y20k/trackbook/helpers/FileHelper.kt

@@ -0,0 +1,431 @@
+/*
+ * FileHelper.kt
+ * Implements the FileHelper object
+ * A FileHelper provides helper methods for reading and writing files from and to device storage
+ *
+ * This file is part of
+ * TRACKBOOK - Movement Recorder for Android
+ *
+ * Copyright (c) 2016-20 - Y20K.org
+ * Licensed under the MIT-License
+ * http://opensource.org/licenses/MIT
+ *
+ * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
+ * https://github.com/osmdroid/osmdroid
+ */
+
+
+package org.y20k.trackbook.helpers
+
+import android.content.Context
+import android.database.Cursor
+import android.graphics.Bitmap
+import android.net.Uri
+import android.provider.OpenableColumns
+import androidx.core.net.toFile
+import androidx.core.net.toUri
+import com.google.gson.Gson
+import com.google.gson.GsonBuilder
+import org.y20k.trackbook.Keys
+import org.y20k.trackbook.core.Track
+import org.y20k.trackbook.core.Tracklist
+import org.y20k.trackbook.core.TracklistElement
+import java.io.*
+import java.text.NumberFormat
+import java.util.*
+import kotlin.coroutines.resume
+import kotlin.coroutines.suspendCoroutine
+
+
+/*
+ * FileHelper object
+ */
+object FileHelper {
+
+    /* Define log tag */
+    private val TAG: String = LogHelper.makeLogTag(FileHelper::class.java)
+
+
+    /* Return an InputStream for given Uri */
+    fun getTextFileStream(context: Context, uri: Uri): InputStream? {
+        var stream : InputStream? = null
+        try {
+            stream = context.contentResolver.openInputStream(uri)
+        } catch (e : Exception) {
+            e.printStackTrace()
+        }
+        return stream
+    }
+
+
+    /* Get file size for given Uri */
+    fun getFileSize(context: Context, uri: Uri): Long {
+        val cursor: Cursor? = context.contentResolver.query(uri, null, null, null, null)
+        if (cursor != null) {
+            val sizeIndex: Int = cursor.getColumnIndex(OpenableColumns.SIZE)
+            cursor.moveToFirst()
+            val size: Long = cursor.getLong(sizeIndex)
+            cursor.close()
+            return size
+        } else {
+            return 0L
+        }
+    }
+
+
+    /* Get file name for given Uri */
+    fun getFileName(context: Context, uri: Uri): String {
+        val cursor: Cursor? = context.contentResolver.query(uri, null, null, null, null)
+        if (cursor != null) {
+            val nameIndex: Int = cursor.getColumnIndex(OpenableColumns.DISPLAY_NAME)
+            cursor.moveToFirst()
+            val name: String = cursor.getString(nameIndex)
+            cursor.close()
+            return name
+        } else {
+            return String()
+        }
+    }
+
+
+    /* Clears given folder - keeps given number of files */
+    fun clearFolder(folder: File?, keep: Int, deleteFolder: Boolean = false) {
+        if (folder != null && folder.exists()) {
+            val files = folder.listFiles()
+            val fileCount: Int = files.size
+            files.sortBy { it.lastModified() }
+            for (fileNumber in files.indices) {
+                if (fileNumber < fileCount - keep) {
+                    files[fileNumber].delete()
+                }
+            }
+            if (deleteFolder && keep == 0) {
+                folder.delete()
+            }
+        }
+    }
+
+
+    /* Reads tracklist from storage using GSON */
+    fun readTracklist(context: Context): Tracklist {
+        LogHelper.v(TAG, "Reading Tracklist - Thread: ${Thread.currentThread().name}")
+        // get JSON from text file
+        val json: String = readTextFile(context, getTracklistFileUri(context))
+        var tracklist: Tracklist = Tracklist()
+        when (json.isNotBlank()) {
+            // convert JSON and return as tracklist
+            true -> try {
+                tracklist = getCustomGson().fromJson(json, Tracklist::class.java)
+            } catch (e: Exception) {
+                e.printStackTrace()
+            }
+        }
+        return tracklist
+    }
+
+
+    /* Reads track from storage using GSON */
+    fun readTrack(context: Context, fileUri: Uri): Track {
+        // get JSON from text file
+        val json: String = readTextFile(context, fileUri)
+        var track: Track = Track()
+        when (json.isNotEmpty()) {
+            // convert JSON and return as track
+            true -> try {
+                track = getCustomGson().fromJson(json, Track::class.java)
+            } catch (e: Exception) {
+                e.printStackTrace()
+            }
+        }
+        return track
+    }
+
+
+    /* Deletes temp track file */
+    fun deleteTempFile(context: Context) {
+        getTempFileUri(context).toFile().delete()
+    }
+
+
+    /* Checks if temp track file exists */
+    fun tempFileExists(context: Context): Boolean {
+        return getTempFileUri(context).toFile().exists()
+    }
+
+
+    /* Creates Uri for Gpx file of a track */
+    fun getGpxFileUri(context: Context, track: Track): Uri {
+        val fileName: String = DateTimeHelper.convertToSortableDateString(track.recordingStart) + Keys.GPX_FILE_EXTENSION
+        return File(context.getExternalFilesDir(Keys.FOLDER_GPX), fileName).toUri()
+    }
+
+
+    /* Creates Uri for json track file */
+    fun getTrackFileUri(context: Context, track: Track): Uri {
+        val fileName: String = DateTimeHelper.convertToSortableDateString(track.recordingStart) + Keys.TRACKBOOK_FILE_EXTENSION
+        return File(context.getExternalFilesDir(Keys.FOLDER_TRACKS), fileName).toUri()
+    }
+
+
+    /* Creates Uri for json temp track file */
+    fun getTempFileUri(context: Context): Uri {
+        return File(context.getExternalFilesDir(Keys.FOLDER_TEMP), Keys.TEMP_FILE).toUri()
+    }
+
+
+    /* Suspend function: Wrapper for saveTracklist */
+    suspend fun addTrackAndSaveTracklistSuspended(context: Context, track: Track, modificationDate: Date = track.recordingStop) {
+        return suspendCoroutine { cont ->
+            val tracklist: Tracklist = readTracklist(context)
+            tracklist.tracklistElements.add(track.toTracklistElement(context))
+            cont.resume(saveTracklist(context, tracklist, modificationDate))
+        }
+    }
+
+
+    /* Suspend function: Wrapper for renameTrack */
+    suspend fun renameTrackSuspended(context: Context, track: Track, newName: String) {
+        return suspendCoroutine { cont ->
+            cont.resume(renameTrack(context, track, newName))
+        }
+    }
+
+
+    /* Suspend function: Wrapper for saveTracklist */
+    suspend fun saveTracklistSuspended(context: Context, tracklist: Tracklist, modificationDate: Date) {
+        return suspendCoroutine { cont ->
+            cont.resume(saveTracklist(context, tracklist, modificationDate))
+        }
+    }
+
+
+    /* Suspend function: Wrapper for saveTrack */
+    suspend fun saveTrackSuspended(track: Track, saveGpxToo: Boolean) {
+        return suspendCoroutine { cont ->
+            cont.resume(saveTrack(track, saveGpxToo))
+        }
+    }
+
+
+    /* Suspend function: Wrapper for saveTempTrack */
+    suspend fun saveTempTrackSuspended(context: Context, track: Track) {
+        return suspendCoroutine { cont ->
+            cont.resume(saveTempTrack(context, track))
+        }
+    }
+
+
+    /* Suspend function: Wrapper for deleteTrack */
+    suspend fun deleteTrackSuspended(context: Context, position: Int, tracklist: Tracklist): Tracklist {
+        return suspendCoroutine { cont ->
+            cont.resume(deleteTrack(context, position, tracklist))
+        }
+    }
+
+
+    /* Suspend function: Wrapper for readTracklist */
+    suspend fun readTracklistSuspended(context: Context): Tracklist {
+        return suspendCoroutine {cont ->
+            cont.resume(readTracklist(context))
+        }
+    }
+
+
+    /* Suspend function: Wrapper for copyFile */
+    suspend fun saveCopyOfFileSuspended(context: Context, originalFileUri: Uri, targetFileUri: Uri) {
+        return suspendCoroutine { cont ->
+            cont.resume(copyFile(context, originalFileUri, targetFileUri, deleteOriginal = true))
+        }
+    }
+
+
+    /* Save Track as JSON to storage */
+    private fun saveTrack(track: Track, saveGpxToo: Boolean) {
+        val jsonString: String = getTrackJsonString(track)
+        if (jsonString.isNotBlank()) {
+            // write track file
+            writeTextFile(jsonString, Uri.parse(track.trackUriString))
+        }
+        if (saveGpxToo) {
+            val gpxString: String = TrackHelper.createGpxString(track)
+            if (gpxString.isNotBlank()) {
+                // write GPX file
+                writeTextFile(gpxString, Uri.parse(track.gpxUriString))
+            }
+        }
+    }
+
+
+    /* Save Temp Track as JSON to storage */
+    private fun saveTempTrack(context: Context, track: Track) {
+        val json: String = getTrackJsonString(track)
+        if (json.isNotBlank()) {
+            writeTextFile(json, getTempFileUri(context))
+        }
+    }
+
+
+    /* Saves track tracklist as JSON text file */
+    private fun saveTracklist(context: Context, tracklist: Tracklist, modificationDate: Date) {
+        tracklist.modificationDate = modificationDate
+        // convert to JSON
+        val gson: Gson = getCustomGson()
+        var json: String = String()
+        try {
+            json = gson.toJson(tracklist)
+        } catch (e: Exception) {
+            e.printStackTrace()
+        }
+        if (json.isNotBlank()) {
+            // write text file
+            writeTextFile(json, getTracklistFileUri(context))
+        }
+    }
+
+
+    /* Creates Uri for tracklist file */
+    private fun getTracklistFileUri(context: Context): Uri {
+        return File(context.getExternalFilesDir(""), Keys.TRACKLIST_FILE).toUri()
+    }
+
+
+
+    /* Renames track */
+    private fun renameTrack(context: Context, track: Track, newName: String) {
+        // search track in tracklist
+        val tracklist: Tracklist = readTracklist(context)
+        var trackUriString: String = String()
+        tracklist.tracklistElements.forEach { tracklistElement ->
+            if (tracklistElement.getTrackId() == track.getTrackId()) {
+                // rename tracklist element
+                tracklistElement.name = newName
+                trackUriString = tracklistElement.trackUriString
+            }
+        }
+        if (trackUriString.isNotEmpty()) {
+            // save tracklist
+            saveTracklist(context, tracklist, GregorianCalendar.getInstance().time)
+            // rename track
+            track.name = newName
+            // save track
+            saveTrack(track, saveGpxToo = true)
+        }
+    }
+
+
+    /* Deletes track */
+    private fun deleteTrack(context: Context, position: Int, tracklist: Tracklist): Tracklist {
+        val tracklistElement: TracklistElement = tracklist.tracklistElements[position]
+        // delete track files
+        tracklistElement.trackUriString.toUri().toFile().delete()
+        tracklistElement.gpxUriString.toUri().toFile().delete()
+        // remove track element from list
+        tracklist.tracklistElements.removeIf { TrackHelper.getTrackId(it) == TrackHelper.getTrackId(tracklistElement) }
+        saveTracklist(context, tracklist, GregorianCalendar.getInstance().time)
+        return tracklist
+    }
+
+
+    /* Copies file to specified target */
+    private fun copyFile(context: Context, originalFileUri: Uri, targetFileUri: Uri, deleteOriginal: Boolean = false) {
+        val inputStream = context.contentResolver.openInputStream(originalFileUri)
+        val outputStream = context.contentResolver.openOutputStream(targetFileUri)
+        if (outputStream != null) {
+            inputStream?.copyTo(outputStream)
+        }
+        if (deleteOriginal) {
+            context.contentResolver.delete(originalFileUri, null, null)
+        }
+    }
+
+
+    /* Converts track to JSON */
+    private fun getTrackJsonString(track: Track): String {
+        val gson: Gson = getCustomGson()
+        var json: String = String()
+        try {
+            json = gson.toJson(track)
+        } catch (e: Exception) {
+            e.printStackTrace()
+        }
+        return json
+    }
+
+
+    /* Creates a Gson object */
+    private fun getCustomGson(): Gson {
+        val gsonBuilder = GsonBuilder()
+        gsonBuilder.setDateFormat("M/d/yy hh:mm a")
+        gsonBuilder.excludeFieldsWithoutExposeAnnotation()
+        return gsonBuilder.create()
+    }
+
+
+
+    /* Converts byte value into a human readable format */
+    // Source: https://programming.guide/java/formatting-byte-size-to-human-readable-format.html
+    fun getReadableByteCount(bytes: Long, si: Boolean = true): String {
+
+        // check if Decimal prefix symbol (SI) or Binary prefix symbol (IEC) requested
+        val unit: Long = if (si) 1000L else 1024L
+
+        // just return bytes if file size is smaller than requested unit
+        if (bytes < unit) return "$bytes B"
+
+        // calculate exp
+        val exp: Int = (Math.log(bytes.toDouble()) / Math.log(unit.toDouble())).toInt()
+
+        // determine prefix symbol
+        val prefix: String = ((if (si) "kMGTPE" else "KMGTPE")[exp - 1] + if (si) "" else "i")
+
+        // calculate result and set number format
+        val result: Double = bytes / Math.pow(unit.toDouble(), exp.toDouble())
+        val numberFormat = NumberFormat.getNumberInstance()
+        numberFormat.maximumFractionDigits = 1
+
+        return numberFormat.format(result) + " " + prefix + "B"
+    }
+
+
+    /* Reads InputStream from file uri and returns it as String */
+    private fun readTextFile(context: Context, fileUri: Uri): String {
+        // todo read https://commonsware.com/blog/2016/03/15/how-consume-content-uri.html
+        // https://developer.android.com/training/secure-file-sharing/retrieve-info
+        val file: File = fileUri.toFile()
+        // check if file exists
+        if (!file.exists()) {
+            return String()
+        }
+        // read until last line reached
+        val stream: InputStream = file.inputStream()
+        val reader: BufferedReader = BufferedReader(InputStreamReader(stream))
+        val builder: StringBuilder = StringBuilder()
+        reader.forEachLine {
+            builder.append(it)
+            builder.append("\n") }
+        stream.close()
+        return builder.toString()
+    }
+
+
+    /* Writes given text to file on storage */
+    private fun writeTextFile(text: String, fileUri: Uri) {
+        val file: File = fileUri.toFile()
+        file.writeText(text)
+    }
+
+
+    /* Writes given bitmap as image file to storage */
+    private fun writeImageFile(context: Context, bitmap: Bitmap, file: File, format: Bitmap.CompressFormat = Bitmap.CompressFormat.JPEG, quality: Int = 75) {
+        if (file.exists()) file.delete ()
+        try {
+            val out = FileOutputStream(file)
+            bitmap.compress(format, quality, out)
+            out.flush()
+            out.close()
+        } catch (e: Exception) {
+            e.printStackTrace()
+        }
+    }
+
+}

app/src/main/java/org/y20k/trackbook/helpers/ImportHelper.kt

@@ -0,0 +1,165 @@
+/*
+ * ImportHelper.kt
+ * Implements the ImportHelper object
+ * A ImportHelper manages the one-time import of old .trackbook files
+ *
+ * This file is part of
+ * TRACKBOOK - Movement Recorder for Android
+ *
+ * Copyright (c) 2016-20 - Y20K.org
+ * Licensed under the MIT-License
+ * http://opensource.org/licenses/MIT
+ *
+ * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
+ * https://github.com/osmdroid/osmdroid
+ */
+
+
+package org.y20k.trackbook.helpers
+
+import android.content.Context
+import android.location.Location
+import com.google.gson.GsonBuilder
+import com.google.gson.annotations.SerializedName
+import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.launch
+import org.y20k.trackbook.Keys
+import org.y20k.trackbook.core.Track
+import org.y20k.trackbook.core.WayPoint
+import java.io.BufferedReader
+import java.io.File
+import java.io.InputStream
+import java.io.InputStreamReader
+import java.util.*
+
+
+/*
+ * ImportHelper data class
+ */
+object ImportHelper {
+
+
+    /* Define log tag */
+    private val TAG: String = LogHelper.makeLogTag(ImportHelper::class.java)
+
+
+
+    /* Converts older tracks of type .trackbook into the new format  */
+    fun convertOldTracks(context: Context) {
+        val oldTracks: ArrayList<Track> = arrayListOf()
+        val trackFolder: File? = context.getExternalFilesDir(Keys.FOLDER_TRACKS)
+
+        if (trackFolder != null && trackFolder.exists() && trackFolder.isDirectory) {
+            trackFolder.listFiles()?.forEach { file ->
+                if (file.name.endsWith(".trackbook")) {
+                    // read until last line reached
+                    val stream: InputStream = file.inputStream()
+                    val reader: BufferedReader = BufferedReader(InputStreamReader(stream))
+                    val builder: StringBuilder = StringBuilder()
+                    reader.forEachLine {
+                        builder.append(it)
+                        builder.append("\n") }
+                    stream.close()
+                    // get content of file
+                    val fileContent: String = builder.toString()
+                    // get LegacyTrack from JSON
+                    val gsonBuilder = GsonBuilder()
+                    gsonBuilder.setDateFormat("M/d/yy hh:mm a")
+                    val oldTrack: LegacyTrack = gsonBuilder.create().fromJson(fileContent, LegacyTrack::class.java)
+                    oldTracks.add(oldTrack.toTrack())
+                }
+            }
+        }
+
+        // save track using "deferred await"
+        if (oldTracks.isNotEmpty()) {
+            GlobalScope.launch {
+                oldTracks.forEach { oldTrack ->
+                    // step 1: create and store filenames for json and gpx files
+                    oldTrack.trackUriString = FileHelper.getTrackFileUri(context, oldTrack).toString()
+                    oldTrack.gpxUriString = FileHelper.getGpxFileUri(context, oldTrack).toString()
+                    // step 2: save track
+                    FileHelper.saveTrackSuspended(oldTrack, saveGpxToo = true)
+                    // step 3: save tracklist
+                    FileHelper.addTrackAndSaveTracklistSuspended(context, oldTrack)
+                }
+            }
+        }
+
+    }
+
+
+    /*
+     * Inner class: Legacy version of Track - used for one-time import only
+     * Warning: Works only as long as targetSdkVersion < 28
+     */
+    private data class LegacyTrack (
+        @SerializedName("b") var mTrackFormatVersion: Int = 0,
+        @SerializedName("c") var mWayPoints: List<LegacyWayPoint>,
+        @SerializedName("d") var mTrackLength: Float = 0f,
+        @SerializedName("e") var mDuration: Long = 0,
+        @SerializedName("f") var mStepCount: Float = 0f,
+        @SerializedName("g") var mRecordingStart: Date = GregorianCalendar.getInstance().time,
+        @SerializedName("h") var mRecordingStop: Date = mRecordingStart,
+        @SerializedName("i") var mMaxAltitude: Double = 0.0,
+        @SerializedName("j") var mMinAltitude: Double = 0.0,
+        @SerializedName("k") var mPositiveElevation: Double = 0.0,
+        @SerializedName("l") var mNegativeElevation: Double = 0.0) {
+
+
+        /* Converts */
+        fun toTrack():Track {
+            val track: Track = Track()
+            track.trackFormatVersion = mTrackFormatVersion
+            mWayPoints.forEach { legacyWayPoint ->
+                val wayPoint: WayPoint= WayPoint(
+                    provider = legacyWayPoint.mLocation.provider,
+                    latitude = legacyWayPoint.mLocation.latitude,
+                    longitude = legacyWayPoint.mLocation.longitude,
+                    altitude = legacyWayPoint.mLocation.altitude,
+                    accuracy = legacyWayPoint.mLocation.accuracy,
+                    time = legacyWayPoint.mLocation.time,
+                    distanceToStartingPoint = legacyWayPoint.mDistanceToStartingPoint,
+                    numberSatellites = legacyWayPoint.mNumberSatellites,
+                    isStopOver = legacyWayPoint.mIsStopOver
+                )
+                track.wayPoints.add(wayPoint)
+            }
+            track.length = mTrackLength
+            track.duration = mDuration
+            track.stepCount = mStepCount
+            track.recordingStart = mRecordingStart
+            track.recordingStop = mRecordingStop
+            track.maxAltitude = mMaxAltitude
+            track.minAltitude = mMinAltitude
+            track.positiveElevation = mPositiveElevation
+            track.negativeElevation = mNegativeElevation
+            track.latitude = track.wayPoints[0].latitude
+            track.longitude = track.wayPoints[0].longitude
+            track.name = DateTimeHelper.convertToReadableDate(mRecordingStart)
+            return track
+        }
+
+    }
+    /*
+     * End of inner class
+     */
+
+
+    /*
+     * Inner class: Legacy version of WayPoint - used for one-time import only
+     * Warning: Works only as long as targetSdkVersion < 28
+     */
+    private data class LegacyWayPoint (
+        var mLocation: Location,
+        var mIsStopOver: Boolean = false,
+        var mDistanceToStartingPoint: Float = 0f,
+        var mNumberSatellites: Int = 0) {
+    }
+    /*
+     * End of inner class
+     */
+
+
+
+}

app/src/main/java/org/y20k/trackbook/helpers/LengthUnitHelper.java

@@ -1,96 +0,0 @@
-/**
- * LengthUnitHelper.java
- * Implements the LengthUnitHelper class
- * A LengthUnitHelper offers helper methods for dealing with unit systems and locales
- *
- * This file is part of
- * TRACKBOOK - Movement Recorder for Android
- *
- * Copyright (c) 2016-19 - Y20K.org
- * Licensed under the MIT-License
- * http://opensource.org/licenses/MIT
- *
- * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
- * https://github.com/osmdroid/osmdroid
- */
-
-package org.y20k.trackbook.helpers;
-
-import java.text.NumberFormat;
-import java.util.Arrays;
-import java.util.List;
-import java.util.Locale;
-
-
-/**
- * LengthUnitHelper class
- */
-public final class LengthUnitHelper implements TrackbookKeys {
-
-
-    /* Converts for the default locale a distance value to a readable string */
-    public static String convertDistanceToString(double distance) {
-        return convertDistanceToString(distance, getUnitSystem());
-    }
-
-
-    /* Converts for the given uni System a distance value to a readable string */
-    public static String convertDistanceToString(double distance, int unitSystem) {
-        String unit;
-        NumberFormat numberFormat =  NumberFormat.getNumberInstance();
-
-        // check for locale and set unit system accordingly
-        if (unitSystem == IMPERIAL) {
-            // miles and feet
-            if (distance > 1610) {
-                // convert distance to miles
-                distance = distance * 0.000621371192;
-                // set measurement unit
-                unit = "mi";
-                // set number precision
-                numberFormat.setMaximumFractionDigits(2);
-            } else {
-                // convert distance to feet
-                distance = distance * 3.28084f;
-                // set measurement unit
-                unit = "ft";
-                // set number precision
-                numberFormat.setMaximumFractionDigits(0);
-            }
-
-
-        } else {
-            // kilometer and meter
-            if (distance >= 1000) {
-                // convert distance to kilometer
-                distance = distance * 0.001f;
-                // set measurement unit
-                unit = "km";
-                // set number precision
-                numberFormat.setMaximumFractionDigits(2);
-            } else {
-                // set measurement unit
-                unit = "m";
-                // set number precision
-                numberFormat.setMaximumFractionDigits(0);
-            }
-
-        }
-        // format distance according to current locale
-        return numberFormat.format(distance) + " " + unit;
-    }
-
-
-    /* Determines which unit system the device is using (metric or imperial) */
-    public static int getUnitSystem() {
-        // America (US), Liberia (LR), Myanmar(MM) use the imperial system
-        List<String> imperialSystemCountries = Arrays.asList("US", "LR", "MM");
-        String countryCode = Locale.getDefault().getCountry();
-        if (imperialSystemCountries.contains(countryCode)){
-            return IMPERIAL;
-        } else {
-            return METRIC;
-        }
-    }
-
-}

app/src/main/java/org/y20k/trackbook/helpers/LengthUnitHelper.kt

@@ -0,0 +1,95 @@
+/*
+ * LengthUnitHelper.kt
+ * Implements the LengthUnitHelper object
+ * A LengthUnitHelper offers helper methods for dealing with unit systems and locales
+ *
+ * This file is part of
+ * TRACKBOOK - Movement Recorder for Android
+ *
+ * Copyright (c) 2016-20 - Y20K.org
+ * Licensed under the MIT-License
+ * http://opensource.org/licenses/MIT
+ *
+ * Trackbook uses osmdroid - OpenStreetMap-Tools for Android
+ * https://github.com/osmdroid/osmdroid
+ */
+
+
+package org.y20k.trackbook.helpers
+
+import java.text.NumberFormat
+import java.util.*
+
+
+/*
+ * LengthUnitHelper object
+ */
+object LengthUnitHelper {
+
+
+    /* Converts for the given uni System a distance value to a readable string */
+    fun convertDistanceToString(distance: Float, useImperial: Boolean = false): String {
+        return convertDistanceToString(distance.toDouble(), useImperial)
+    }
+
+
+    /* Converts for the given uni System a distance value to a readable string */
+    fun convertDistanceToString(distance: Double, useImperial: Boolean = false): String {
+        val readableDistance: Double
+        val unit: String
+        val numberFormat = NumberFormat.getNumberInstance()