From fbc1a51a67fce6c6667e5cef42d2eba270816a20 Mon Sep 17 00:00:00 2001
From: Attila Szarvas <attila@juce.com>
Date: Tue, 8 Jun 2021 17:08:18 +0000
Subject: [PATCH] Windows: replace deprecated OS calls in
 SystemStats::getDisplayLanguage()

The previously used getUserDefaultUILanguage() was based on the deprecated
LCID/LANGID concept. It had an increasing number of corner cases as not
every locale had associated LCIDs. The new solution is based on locale
names (string based) and will return reasonable names in more situations.
---
 .../native/juce_win32_SystemStats.cpp         | 34 ++++++++++++++-----
 1 file changed, 25 insertions(+), 9 deletions(-)

diff --git a/modules/juce_core/native/juce_win32_SystemStats.cpp b/modules/juce_core/native/juce_win32_SystemStats.cpp
index 6ac2db7395..3a8c969928 100644
--- a/modules/juce_core/native/juce_win32_SystemStats.cpp
+++ b/modules/juce_core/native/juce_win32_SystemStats.cpp
@@ -554,20 +554,36 @@ String SystemStats::getUserRegion()       { return getLocaleValue (LOCALE_USER_D
 String SystemStats::getDisplayLanguage()
 {
     DynamicLibrary dll ("kernel32.dll");
-    JUCE_LOAD_WINAPI_FUNCTION (dll, GetUserDefaultUILanguage, getUserDefaultUILanguage, LANGID, (void))
+    JUCE_LOAD_WINAPI_FUNCTION (dll,
+                               GetUserPreferredUILanguages,
+                               getUserPreferredUILanguages,
+                               BOOL,
+                               (DWORD, PULONG, PZZWSTR, PULONG))
 
-    if (getUserDefaultUILanguage == nullptr)
-        return "en";
+    constexpr auto defaultResult = "en";
 
-    auto langID = MAKELCID (getUserDefaultUILanguage(), SORT_DEFAULT);
+    if (getUserPreferredUILanguages == nullptr)
+        return defaultResult;
 
-    auto mainLang = getLocaleValue (langID, LOCALE_SISO639LANGNAME, "en");
-    auto region   = getLocaleValue (langID, LOCALE_SISO3166CTRYNAME, nullptr);
+    ULONG numLanguages = 0;
+    ULONG numCharsInLanguagesBuffer = 0;
 
-    if (region.isNotEmpty())
-        mainLang << '-' << region;
+    // Retrieving the necessary buffer size for storing the list of languages
+    if (! getUserPreferredUILanguages (MUI_LANGUAGE_NAME, &numLanguages, nullptr, &numCharsInLanguagesBuffer))
+        return defaultResult;
 
-    return mainLang;
+    std::vector<WCHAR> languagesBuffer (numCharsInLanguagesBuffer);
+    const auto success = getUserPreferredUILanguages (MUI_LANGUAGE_NAME,
+                                                      &numLanguages,
+                                                      languagesBuffer.data(),
+                                                      &numCharsInLanguagesBuffer);
+
+    if (! success || numLanguages == 0)
+        return defaultResult;
+
+    // The buffer contains a zero delimited list of languages, the first being
+    // the currently displayed language.
+    return languagesBuffer.data();
 }
 
 } // namespace juce