android/app/src/main/cpp/app/organicmaps/util/Language.cpp

@@ -1,4 +1,5 @@
 #include "android/app/src/main/cpp/app/organicmaps/core/jni_helper.hpp"
+#include "platform/measurement_utils.hpp"
 #include "platform/preferred_languages.hpp"
 
 extern "C"
@@ -9,4 +10,10 @@ Java_app_organicmaps_util_Language_nativeNormalize(JNIEnv *env, jclass type, jst
   std::string locale = languages::Normalize(jni::ToNativeString(env, lang));
   return jni::ToJavaString(env, locale);
 }
+
+JNIEXPORT void JNICALL
+Java_app_organicmaps_util_Language_nativeRefreshSystemLocale(JNIEnv *, jclass)
+{
+  measurement_utils::RefreshSystemLocale();
+}
 }

android/app/src/main/java/app/organicmaps/MwmApplication.java

@@ -4,7 +4,10 @@ import static app.organicmaps.location.LocationState.LOCATION_TAG;
 
 import android.app.Activity;
 import android.app.Application;
+import android.content.BroadcastReceiver;
 import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
 import android.content.SharedPreferences;
 import android.os.Bundle;
 import android.os.Handler;
@@ -41,6 +44,7 @@ import app.organicmaps.settings.StoragePathManager;
 import app.organicmaps.sound.TtsPlayer;
 import app.organicmaps.util.Config;
 import app.organicmaps.util.ConnectionState;
+import app.organicmaps.util.Language;
 import app.organicmaps.util.SharedPropertiesUtils;
 import app.organicmaps.util.StorageUtils;
 import app.organicmaps.util.ThemeSwitcher;
@@ -89,6 +93,8 @@ public class MwmApplication extends Application implements Application.ActivityL
   @Nullable
   private WeakReference<Activity> mTopActivity;
 
+  private BroadcastReceiver mLocaleChangeReceiver;
+
   @UiThread
   @Nullable
   public Activity getTopActivity()
@@ -213,6 +219,22 @@ public class MwmApplication extends Application implements Application.ActivityL
     Config.setStoragePath(writablePath);
     Config.setStatisticsEnabled(SharedPropertiesUtils.isStatisticsEnabled(this));
 
+    // Force native system locale initialization at app start-up.
+    Language.nativeRefreshSystemLocale();
+
+    // Setup BroadcastReceiver to receive changes of system locale.
+    mLocaleChangeReceiver = new BroadcastReceiver()
+    {
+      @Override
+      public void onReceive(Context context, Intent intent)
+      {
+        // Refresh the native c++ system locale.
+        Language.nativeRefreshSystemLocale();
+      }
+    };
+
+    registerReceiver(mLocaleChangeReceiver, new IntentFilter(Intent.ACTION_LOCALE_CHANGED));
+
     mPlatformInitialized = true;
     Logger.i(TAG, "Platform initialized");
   }

android/app/src/main/java/app/organicmaps/util/Language.java

@@ -58,4 +58,7 @@ public class Language
 
   @NonNull
   public static native String nativeNormalize(@NonNull String locale);
+
+  @NonNull
+  public static native void nativeRefreshSystemLocale();
 }

iphone/Maps/main.mm

@@ -1,6 +1,7 @@
 #import "MapsAppDelegate.h"
 #import "MWMSettings.h"
 
+#include "platform/measurement_utils.hpp"
 #include "platform/platform.hpp"
 
 int main(int argc, char * argv[])
@@ -9,6 +10,9 @@ int main(int argc, char * argv[])
   auto & p = GetPlatform();
   LOG(LINFO, (p.Version(), "started, detected CPU cores:", p.CpuCores()));
 
+  // Force system locale initialization at app start-up.
+  measurement_utils::RefreshSystemLocale();
+
   int retVal;
   @autoreleasepool
   {

platform/measurement_utils.cpp

@@ -18,12 +18,29 @@
 
 namespace measurement_utils
 {
+// Global Locale variable to store system locale.
+static platform::Locale g_systemLocale =
+{
+  "",  // Undefined language.
+  "",  // Undefined country.
+  "",  // Undefined currency.
+  ".", // Dot as default decimal separator.
+  ","  // Comma as default grouping (thousands) separator.
+};
+
+void SetSystemLocale(platform::Locale const & locale)
+{
+  g_systemLocale = locale;
+}
+
+void RefreshSystemLocale()
+{
+  SetSystemLocale(platform::GetCurrentLocale());
+}
+
 std::string ToStringPrecision(double d, int pr)
 {
-  // We assume that the app will be restarted if a user changes device's locale.
-  static auto const locale = platform::GetCurrentLocale();
-
-  return ToStringPrecisionLocale(locale, d, pr);
+  return ToStringPrecisionLocale(g_systemLocale, d, pr);
 }
 
 std::string ToStringPrecisionLocale(platform::Locale const & loc, double d, int pr)

platform/measurement_utils.hpp

@@ -64,5 +64,9 @@ std::string OSMDistanceToMetersString(std::string const & osmRawValue,
                                       bool supportZeroAndNegativeValues = true,
                                       int digitsAfterComma = 2);
 std::string ToStringPrecision(double d, int pr);
-std::string ToStringPrecisionLocale(platform::Locale const & locale, double d, int pr);
+std::string ToStringPrecisionLocale(platform::Locale const & loc, double d, int pr);
+
+void SetSystemLocale(platform::Locale const & locale);
+void RefreshSystemLocale();
+
 }  // namespace measurement_utils

platform/platform_tests/measurement_tests.cpp

@@ -181,5 +181,10 @@ UNIT_TEST(ToStringPrecisionLocale)
     TEST_EQUAL(measurement_utils::ToStringPrecisionLocale(loc, d1, pr1), data.d1String, ());
     TEST_EQUAL(measurement_utils::ToStringPrecisionLocale(loc, d2, pr2),
                AddGroupingSeparators(d2String, loc.m_groupingSeparator), ());
+
+    measurement_utils::SetSystemLocale(loc);
+    TEST_EQUAL(measurement_utils::ToStringPrecision(d1, pr1), data.d1String, ());
+    TEST_EQUAL(measurement_utils::ToStringPrecision(d2, pr2),
+               AddGroupingSeparators(d2String, loc.m_groupingSeparator), ());
   }
 }

qt/main.cpp

@@ -102,6 +102,9 @@ public:
 
 int main(int argc, char * argv[])
 {
+  // Refresh system locale for distance & speed formatting.
+  measurement_utils::RefreshSystemLocale();
+
   // Our double parsing code (base/string_utils.hpp) needs dots as a floating point delimiters, not commas.
   // TODO: Refactor our doubles parsing code to use locale-independent delimiters.
   // For example, https://github.com/google/double-conversion can be used.

qt/ruler.cpp

@@ -1,6 +1,7 @@
 #include "qt/ruler.hpp"
 
 #include "geometry/mercator.hpp"
+#include "platform/distance.hpp"
 
 #include <iomanip>
 #include <string>
@@ -52,13 +53,6 @@ void Ruler::SetDistance()
 
 void Ruler::SetId()
 {
-  std::ostringstream curValStream;
-  curValStream << std::fixed << std::setprecision(1);
-  if (m_sumDistanceM >= 1000.0)
-    curValStream << m_sumDistanceM / 1000.0 << " km";
-  else
-    curValStream << m_sumDistanceM << " m";
-
-  m_id = curValStream.str();
+  m_id = platform::Distance::CreateFormatted(m_sumDistanceM).ToString();
 }
 }  // namespace qt