Add LanguageHelper & language picker

app/README.md

@@ -4,6 +4,7 @@
 2. [DownloadManager](https://github.com/AsemLab/Samples/blob/main/app/src/main/java/com/asemlab/samples/download/FileDownloaderImp.kt): is a system service that handles long-running HTTP downloads. Clients may request that a URI be downloaded to a particular destination file. [Official](https://developer.android.com/reference/android/app/DownloadManager)
 3. [Epoxy](https://github.com/AsemLab/Samples/blob/main/app/src/main/java/com/asemlab/samples/epoxy/EpoxyActivity.kt): is an Android library for building complex screens in a RecyclerView. [Official](https://github.com/airbnb/epoxy)
 4. [Pass data between components](https://github.com/AsemLab/Samples/tree/main/app/src/main/java/com/asemlab/samples/passdata): demonstrate how to pass data from Activity to Activity/Fragment and from Fragment to Activity/Fragment.
-5. [Photo Picker](https://github.com/AsemLab/Samples/blob/main/app/src/main/java/com/asemlab/samples/ui/RegisterForResultActivity.kt): provides a browsable interface that presents the user with their media library, sorted by date from newest to oldest. [Official](https://developer.android.com/training/data-storage/shared/photopicker)
-6. [Progress in Notifications](https://github.com/AsemLab/Samples/blob/main/app/src/main/java/com/asemlab/samples/ui/NotificationProgressActivity.kt): display and update progressBar in notification.
-7. [RegisterForActivityResult](https://github.com/AsemLab/Samples/blob/main/app/src/main/java/com/asemlab/samples/ui/RegisterForResultActivity.kt): call an activity and retrieve the result from it. [Official](https://developer.android.com/training/basics/intents/result)
+5. [Per-app language preferences](https://github.com/AsemLab/Samples/blob/main/app/src/main/java/com/asemlab/samples/utils/LanguageHelper.kt):  allow users to set their preferred language for each app. The app specific preferred language will override the system language for that particular application. [Official](https://developer.android.com/guide/topics/resources/app-languages)
+6. [Photo Picker](https://github.com/AsemLab/Samples/blob/main/app/src/main/java/com/asemlab/samples/ui/RegisterForResultActivity.kt): provides a browsable interface that presents the user with their media library, sorted by date from newest to oldest. [Official](https://developer.android.com/training/data-storage/shared/photopicker)
+7. [Progress in Notifications](https://github.com/AsemLab/Samples/blob/main/app/src/main/java/com/asemlab/samples/ui/NotificationProgressActivity.kt): display and update progressBar in notification.
+8. [RegisterForActivityResult](https://github.com/AsemLab/Samples/blob/main/app/src/main/java/com/asemlab/samples/ui/RegisterForResultActivity.kt): call an activity and retrieve the result from it. [Official](https://developer.android.com/training/basics/intents/result)

app/src/main/java/com/asemlab/samples/ui/MainActivity.kt

@@ -1,12 +1,9 @@
 package com.asemlab.samples.ui
 
 import android.Manifest
-import android.app.LocaleConfig
-import android.app.LocaleManager
 import android.content.pm.PackageManager
 import android.os.Build
 import android.os.Bundle
-import android.os.LocaleList
 import android.view.View
 import androidx.annotation.RequiresApi
 import androidx.appcompat.app.AppCompatActivity
@@ -39,11 +36,6 @@ class MainActivity : AppCompatActivity() {
             true
         )
 
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.UPSIDE_DOWN_CAKE) {
-            // TODO Set per-app supported languages dynamically
-            updateSupportedLocales()
-        }
-
     }
 
     fun selectFragment(view: View) {
@@ -61,20 +53,4 @@ class MainActivity : AppCompatActivity() {
         fragmentTransaction.commit()
     }
 
-    @RequiresApi(Build.VERSION_CODES.UPSIDE_DOWN_CAKE)
-    fun updateSupportedLocales() {
-        val localeManager = applicationContext
-            .getSystemService(LocaleManager::class.java)
-
-        // For getOverrideLocaleConfig
-        val overrideLocaleConfig = localeManager.overrideLocaleConfig
-        val supportedLocales = overrideLocaleConfig?.supportedLocales
-
-        // For setOverrideLocaleConfig, update supported and remove old ones
-        localeManager.overrideLocaleConfig = LocaleConfig(
-            LocaleList.forLanguageTags("en-US,ja-JP,ar")
-        )
-
-    }
-
 }

app/src/main/java/com/asemlab/samples/utils/LanguageHelper.kt

@@ -0,0 +1,62 @@
+package com.asemlab.samples.utils
+
+import android.app.LocaleConfig
+import android.app.LocaleManager
+import android.content.Context
+import android.os.Build
+import android.os.LocaleList
+import androidx.annotation.RequiresApi
+import androidx.appcompat.app.AlertDialog
+import androidx.appcompat.app.AppCompatDelegate
+import androidx.core.os.LocaleListCompat
+import com.asemlab.samples.R
+
+object LanguageHelper {
+
+    // TODO Set per-app supported languages dynamically
+    @RequiresApi(Build.VERSION_CODES.UPSIDE_DOWN_CAKE)
+    fun updateSupportedLocales(context: Context) {
+        val localeManager = context
+            .getSystemService(LocaleManager::class.java)
+
+        // For getOverrideLocaleConfig
+        val overrideLocaleConfig = localeManager.overrideLocaleConfig
+        val supportedLocales = overrideLocaleConfig?.supportedLocales
+
+        // For setOverrideLocaleConfig, update supported and remove old ones
+        localeManager.overrideLocaleConfig = LocaleConfig(
+            LocaleList.forLanguageTags("en-US,ar")
+        )
+
+    }
+
+
+    // TODO Use AndroidX to change locale
+    fun showPickerDialog(context: Context) {
+        var selectedLocale = AppCompatDelegate.getApplicationLocales()[0]?.language ?: "en"
+        val selectedItem =
+            context.resources.getStringArray(R.array.language_codes).indexOf(selectedLocale)
+
+        AlertDialog.Builder(context)
+            .setTitle("Choose your language")
+            .setSingleChoiceItems(R.array.languages, selectedItem) { _, which ->
+                when (which) {
+                    0 -> selectedLocale = "en"
+                    1 -> selectedLocale = "ar"
+                    2 -> selectedLocale = "de"
+                }
+            }
+            .setNegativeButton("Close") { d, _ ->
+                d.dismiss()
+            }
+            .setPositiveButton("Apply") { d, _ ->
+
+                val appLocale: LocaleListCompat = LocaleListCompat.forLanguageTags(selectedLocale)
+                // Call this on the main thread as it may require Activity.restart()
+                AppCompatDelegate.setApplicationLocales(appLocale)
+
+                d.dismiss()
+            }
+            .show()
+    }
+}

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

@@ -1,4 +1,15 @@
 <resources>
     <string name="app_name" translatable="false">ContactsContent</string>
     <string name="language_title">English</string>
+    <string-array name="languages" translatable="false">
+        <item>English</item>
+        <item>العربية</item>
+        <item>Deutsch</item>
+    </string-array>
+
+    <string-array name="language_codes" translatable="false">
+        <item>en</item>
+        <item>ar</item>
+        <item>de</item>
+    </string-array>
 </resources>