Add language chooser (fixes #24)

app/src/main/java/net/vonforst/evmap/MapsActivity.kt

@@ -1,5 +1,6 @@
 package net.vonforst.evmap
 
+import android.content.Context
 import android.content.Intent
 import android.net.Uri
 import android.os.Bundle
@@ -19,6 +20,7 @@ import com.google.android.material.navigation.NavigationView
 import com.google.android.material.snackbar.Snackbar
 import net.vonforst.evmap.api.goingelectric.ChargeLocation
 import net.vonforst.evmap.storage.PreferenceDataSource
+import net.vonforst.evmap.utils.LocaleContextWrapper
 
 
 const val REQUEST_LOCATION_PERMISSION = 1
@@ -34,6 +36,14 @@ class MapsActivity : AppCompatActivity() {
     var fragmentCallback: FragmentCallback? = null
     private lateinit var prefs: PreferenceDataSource
 
+    override fun attachBaseContext(newBase: Context) {
+        return super.attachBaseContext(
+            LocaleContextWrapper.wrap(
+                newBase, PreferenceDataSource(newBase).language
+            )
+        );
+    }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 

app/src/main/java/net/vonforst/evmap/fragment/SettingsFragment.kt

@@ -1,5 +1,6 @@
 package net.vonforst.evmap.fragment
 
+import android.content.SharedPreferences
 import android.os.Bundle
 import android.view.View
 import androidx.appcompat.widget.Toolbar
@@ -11,7 +12,8 @@ import net.vonforst.evmap.MapsActivity
 import net.vonforst.evmap.R
 
 
-class SettingsFragment : PreferenceFragmentCompat() {
+class SettingsFragment : PreferenceFragmentCompat(),
+    SharedPreferences.OnSharedPreferenceChangeListener {
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
         val toolbar = view.findViewById(R.id.toolbar) as Toolbar
@@ -33,4 +35,26 @@ class SettingsFragment : PreferenceFragmentCompat() {
         }
     }
 
+    override fun onSharedPreferenceChanged(sharedPreferences: SharedPreferences, key: String) {
+        when (key) {
+            "language" -> {
+                activity?.let {
+                    it.finish();
+                    it.startActivity(it.intent);
+                }
+            }
+        }
+    }
+
+    override fun onResume() {
+        super.onResume()
+        preferenceManager.sharedPreferences.registerOnSharedPreferenceChangeListener(this)
+    }
+
+    override fun onPause() {
+        preferenceManager.sharedPreferences
+            .unregisterOnSharedPreferenceChangeListener(this)
+        super.onPause()
+    }
+
 }

app/src/main/java/net/vonforst/evmap/storage/PreferenceDataSource.kt

@@ -30,4 +30,7 @@ class PreferenceDataSource(context: Context) {
         set(value) {
             sp.edit().putLong("last_chargecard_update", value.toEpochMilli()).apply()
         }
+
+    val language: String
+        get() = sp.getString("language", "default")!!
 }

app/src/main/java/net/vonforst/evmap/utils/LocaleContextWrapper.kt

@@ -0,0 +1,42 @@
+package net.vonforst.evmap.utils
+
+import android.annotation.TargetApi
+import android.content.Context
+import android.content.ContextWrapper
+import android.content.res.Configuration
+import android.os.Build
+import java.util.*
+
+
+class LocaleContextWrapper(base: Context?) : ContextWrapper(base) {
+    companion object {
+        fun wrap(context: Context, language: String): ContextWrapper {
+            val config: Configuration = context.resources.configuration
+            var sysLocale: Locale? = null
+            sysLocale = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
+                config.locales.get(0)
+            } else {
+                @Suppress("DEPRECATION")
+                config.locale
+            }
+            var ctx = context
+            if (language != "" && language != "default" && sysLocale.language != language) {
+                val locale = Locale(language)
+                Locale.setDefault(locale)
+                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
+                    config.setLocale(locale)
+                } else {
+                    @Suppress("DEPRECATION")
+                    config.locale = locale
+                }
+                ctx = context.createConfigurationContext(config)
+            }
+            return LocaleContextWrapper(ctx)
+        }
+
+        @TargetApi(Build.VERSION_CODES.N)
+        fun setSystemLocale(config: Configuration, locale: Locale?) {
+            config.setLocale(locale)
+        }
+    }
+}

app/src/main/res/values-de/arrays.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string-array name="pref_language_names">
+        <item>Gerätesprache verwenden</item>
+        <item>Englisch</item>
+        <item>Deutsch</item>
+    </string-array>
+</resources>

app/src/main/res/values-de/strings.xml

@@ -90,4 +90,6 @@
     <string name="edit">bearbeiten</string>
     <string name="cancel">Abbrechen</string>
     <string name="ok">OK</string>
+    <string name="pref_language">Sprache</string>
+    <string name="pref_language_summary">App-Sprache ändern</string>
 </resources>

app/src/main/res/values/arrays.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string-array name="pref_language_names">
+        <item>Device default</item>
+        <item>English</item>
+        <item>German</item>
+    </string-array>
+    <string-array name="pref_language_values" tranlatable="false">
+        <item>default</item>
+        <item>en</item>
+        <item>de</item>
+    </string-array>
+</resources>

app/src/main/res/values/strings.xml

@@ -89,4 +89,6 @@
     <string name="edit">edit</string>
     <string name="cancel">Cancel</string>
     <string name="ok">OK</string>
+    <string name="pref_language">Language</string>
+    <string name="pref_language_summary">Change the app language</string>
 </resources>

app/src/main/res/xml/settings.xml

@@ -10,6 +10,13 @@
             android:summaryOff="@string/pref_navigate_use_maps_off"
             android:defaultValue="true" />
 
+        <ListPreference
+            android:key="language"
+            android:title="@string/pref_language"
+            android:entries="@array/pref_language_names"
+            android:entryValues="@array/pref_language_values"
+            android:defaultValue="default"
+            android:summary="@string/pref_language_summary" />
 
     </PreferenceCategory>
 </PreferenceScreen>