From 8c0a045c0d514ddc1696c7751c6665e81da4aa4b Mon Sep 17 00:00:00 2001
From: Mengjue Wang <mengjuew@fb.com>
Date: Tue, 26 Jul 2016 14:40:15 -0700
Subject: [PATCH] Connect the OS setting with isRTL

Summary: Provide two function in I18nUtil to get the device and app current using language. And Set isRTL with both allowRTL and current app using language.

Reviewed By: fkgozali

Differential Revision: D3603412

fbshipit-source-id: 6bb280d56af9a12901148df9fab368366073680f
---
 .../com/facebook/react/modules/i18nmanager/BUCK  |  1 +
 .../react/modules/i18nmanager/I18nUtil.java      | 16 ++++++++++++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/ReactAndroid/src/main/java/com/facebook/react/modules/i18nmanager/BUCK b/ReactAndroid/src/main/java/com/facebook/react/modules/i18nmanager/BUCK
index ea33bd1ee..deece94dc 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/modules/i18nmanager/BUCK
+++ b/ReactAndroid/src/main/java/com/facebook/react/modules/i18nmanager/BUCK
@@ -4,6 +4,7 @@ android_library(
   name = 'i18nmanager',
   srcs = glob(['*.java']),
   deps = [
+    react_native_dep('third-party/android/support/v4:lib-support-v4'),
     react_native_dep('third-party/java/infer-annotations:infer-annotations'),
     react_native_dep('third-party/java/jsr-305:jsr-305'),
     react_native_target('java/com/facebook/react/bridge:bridge'),
diff --git a/ReactAndroid/src/main/java/com/facebook/react/modules/i18nmanager/I18nUtil.java b/ReactAndroid/src/main/java/com/facebook/react/modules/i18nmanager/I18nUtil.java
index e0199b265..dd42db2fb 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/modules/i18nmanager/I18nUtil.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/modules/i18nmanager/I18nUtil.java
@@ -12,6 +12,10 @@ package com.facebook.react.modules.i18nmanager;
 import android.content.Context;
 import android.content.SharedPreferences;
 import android.content.SharedPreferences.Editor;
+import android.support.v4.text.TextUtilsCompat;
+import android.support.v4.view.ViewCompat;
+
+import java.util.Locale;
 
 public class I18nUtil {
   private static I18nUtil sharedI18nUtilInstance = null;
@@ -32,10 +36,11 @@ public class I18nUtil {
     return sharedI18nUtilInstance;
   }
 
-  // If set allowRTL on the JS side,
+  // If the current device language is RTL and RTL is allowed for the app,
   // the RN app will automatically have a RTL layout.
   public boolean isRTL(Context context) {
-    return allowRTL(context);
+    return allowRTL(context) &&
+      isDevicePreferredLanguageRTL();
   }
 
   private boolean allowRTL(Context context) {
@@ -50,4 +55,11 @@ public class I18nUtil {
     editor.putBoolean(KEY_FOR_PREFS, allowRTL);
     editor.apply();
   }
+
+  // Check if the current device language is RTL
+  private boolean isDevicePreferredLanguageRTL() {
+    final int directionality =
+      TextUtilsCompat.getLayoutDirectionFromLocale(Locale.getDefault());
+    return directionality == ViewCompat.LAYOUT_DIRECTION_RTL;
+   }
 }