locale: Implemented SDL_GetPreferredLocales().

This was something I proposed a long time ago, Sylvain Becker did
additional work on it, then back to me.

Fixes Bugzilla #2131.

src/core/android/SDL_android.c

@@ -44,6 +44,8 @@
 #include "../../haptic/android/SDL_syshaptic_c.h"
 
 #include <android/log.h>
+#include <android/configuration.h>
+#include <android/asset_manager_jni.h>
 #include <sys/system_properties.h>
 #include <pthread.h>
 #include <sys/types.h>
@@ -2796,6 +2798,82 @@ SDL_bool Android_JNI_RequestPermission(const char *permission)
 	return bPermissionRequestResult;
 }
 
+int Android_JNI_GetLocale(char *buf, size_t buflen)
+{
+    struct LocalReferenceHolder refs = LocalReferenceHolder_Setup(__FUNCTION__);
+    JNIEnv* env = Android_JNI_GetEnv();
+    int retval = -1;
+
+    JNIEnv *mEnv = Android_JNI_GetEnv();
+    if (!LocalReferenceHolder_Init(&refs, env)) {
+        LocalReferenceHolder_Cleanup(&refs);
+        return -1;
+    }
+
+    SDL_assert(buflen > 6);
+
+    jmethodID mid;
+    jobject context;
+    jobject assetManager;
+
+    /* context = SDLActivity.getContext(); */
+    mid = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
+            "getContext","()Landroid/content/Context;");
+    context = (*mEnv)->CallStaticObjectMethod(mEnv, mActivityClass, mid);
+
+    /* assetManager = context.getAssets(); */
+    mid = (*mEnv)->GetMethodID(mEnv, (*mEnv)->GetObjectClass(mEnv, context),
+            "getAssets", "()Landroid/content/res/AssetManager;");
+    assetManager = (*mEnv)->CallObjectMethod(mEnv, context, mid);
+
+
+    /* API from NDK: android/configuration.h */
+    /* API from NDK: android/asset_manager_jni.h */
+    AAssetManager* asset_mgr = AAssetManager_fromJava(env, assetManager);
+    AConfiguration *cfg = AConfiguration_new();
+
+    if (asset_mgr && cfg)
+    {
+        char language[2] = {};
+        char country[2] = {};
+        size_t id = 0;
+
+        AConfiguration_fromAssetManager(cfg, asset_mgr);
+        AConfiguration_getLanguage(cfg, language);
+        AConfiguration_getCountry(cfg, country);
+
+        retval = 0;
+
+        /* copy language (not null terminated) */
+        if (language[0]) {
+            buf[id++] = language[0];
+            if (language[1]) {
+                buf[id++] = language[1];
+            }
+        }
+
+        buf[id++] = '_';
+
+        /* copy country (not null terminated) */
+        if (country[0]) {
+            buf[id++] = country[0];
+            if (country[1]) {
+                buf[id++] = country[1];
+            }
+        }
+        
+        buf[id++] = '\0';
+        SDL_assert(id <= buflen);
+    }
+
+    if (cfg) {
+        AConfiguration_delete(cfg);
+    }
+
+    LocalReferenceHolder_Cleanup(&refs);
+    return retval;
+}
+
 #endif /* __ANDROID__ */
 
 /* vi: set ts=4 sw=4 expandtab: */

src/core/android/SDL_android.h

@@ -104,6 +104,9 @@ void Android_JNI_InitTouch(void);
 JNIEnv *Android_JNI_GetEnv(void);
 int Android_JNI_SetupThread(void);
 
+/* Locale */
+int Android_JNI_GetLocale(char *buf, size_t buflen);
+
 /* Generic messages */
 int Android_JNI_SendMessage(int command, int param);
 

src/dynapi/SDL_dynapi_overrides.h

@@ -763,3 +763,4 @@
 #define SDL_Metal_GetDrawableSize SDL_Metal_GetDrawableSize_REAL
 #define SDL_trunc SDL_trunc_REAL
 #define SDL_truncf SDL_truncf_REAL
+#define SDL_GetPreferredLocales SDL_GetPreferredLocales_REAL

src/dynapi/SDL_dynapi_procs.h

@@ -822,3 +822,4 @@ SDL_DYNAPI_PROC(void*,SDL_Metal_GetLayer,(SDL_MetalView a),(a),return)
 SDL_DYNAPI_PROC(void,SDL_Metal_GetDrawableSize,(SDL_Window *a, int *b, int *c),(a,b,c),)
 SDL_DYNAPI_PROC(double,SDL_trunc,(double a),(a),return)
 SDL_DYNAPI_PROC(float,SDL_truncf,(float a),(a),return)
+SDL_DYNAPI_PROC(SDL_Locale *,SDL_GetPreferredLocales,(void),(),return)

src/events/SDL_events.c

@@ -1009,6 +1009,12 @@ SDL_SendKeymapChangedEvent(void)
     return SDL_SendAppEvent(SDL_KEYMAPCHANGED);
 }
 
+int
+SDL_SendLocaleChangedEvent(void)
+{
+    return SDL_SendAppEvent(SDL_LOCALECHANGED);
+}
+
 int
 SDL_EventsInit(void)
 {

src/events/SDL_events_c.h

@@ -46,6 +46,7 @@ extern void SDL_QuitInterrupt(void);
 extern int SDL_SendAppEvent(SDL_EventType eventType);
 extern int SDL_SendSysWMEvent(SDL_SysWMmsg * message);
 extern int SDL_SendKeymapChangedEvent(void);
+extern int SDL_SendLocaleChangedEvent(void);
 
 extern int SDL_SendQuit(void);
 

src/locale/SDL_locale.c

@@ -0,0 +1,103 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2020 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+#include "../SDL_internal.h"
+#include "SDL_syslocale.h"
+#include "SDL_hints.h"
+
+static SDL_Locale *
+build_locales_from_csv_string(char *csv)
+{
+    size_t num_locales = 1;  /* at least one */
+    size_t slen;
+    size_t alloclen;
+    char *ptr;
+    SDL_Locale *loc;
+    SDL_Locale *retval;
+
+    if (!csv || !csv[0]) {
+        return NULL;  /* nothing to report */
+    }
+
+    for (ptr = csv; *ptr; ptr++) {
+        if (*ptr == ',') {
+            num_locales++;
+        }
+    }
+
+    num_locales++;  /* one more for terminator */
+
+    slen = ((size_t) (ptr - csv)) + 1;  /* strlen(csv) + 1 */
+    alloclen = slen + (num_locales * sizeof (SDL_Locale));
+
+    loc = retval = (SDL_Locale *) SDL_calloc(1, alloclen);
+    if (!retval) {
+        SDL_OutOfMemory();
+        return NULL;  /* oh well */
+    }
+    ptr = (char *) (retval + num_locales);
+    SDL_strlcpy(ptr, csv, slen);
+
+    while (SDL_TRUE) {  /* parse out the string */
+        while (*ptr == ' ') ptr++;  /* skip whitespace. */
+        if (*ptr == '\0') {
+            break;
+        }
+        loc->language = ptr++;
+        while (SDL_TRUE) {
+            const char ch = *ptr;
+            if (ch == '_') {
+                *(ptr++) = '\0';
+                loc->country = ptr;
+            } else if (ch == ' ') {
+                *(ptr++) = '\0';  /* trim ending whitespace and keep going. */
+            } else if (ch == ',') {
+                *(ptr++) = '\0';
+                loc++;
+                break;
+            } else if (ch == '\0') {
+                loc++;
+                break;
+            } else {
+                ptr++;  /* just keep going, still a valid string */
+            }
+        }
+    }
+
+    return retval;
+}
+
+SDL_Locale *
+SDL_GetPreferredLocales(void)
+{
+    char locbuf[128];  /* enough for 21 "xx_YY," language strings. */
+    const char *hint = SDL_GetHint(SDL_HINT_PREFERRED_LOCALES);
+    if (hint) {
+        SDL_strlcpy(locbuf, hint, sizeof (locbuf));
+    } else {
+        SDL_zeroa(locbuf);
+        SDL_SYS_GetPreferredLocales(locbuf, sizeof (locbuf));
+    }
+    return build_locales_from_csv_string(locbuf);
+}
+
+/* vi: set ts=4 sw=4 expandtab: */
+

src/locale/SDL_syslocale.h

@@ -0,0 +1,29 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2020 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+#include "SDL_config.h"
+
+/* This is the system specific header for the SDL locale API */
+
+#include "SDL_locale.h"
+
+extern void SDL_SYS_GetPreferredLocales(char *buf, size_t buflen);
+
+/* vi: set ts=4 sw=4 expandtab: */

src/locale/android/SDL_syslocale.c

@@ -0,0 +1,32 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2020 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+#include "../../SDL_internal.h"
+#include "../SDL_syslocale.h"
+
+void
+SDL_SYS_GetPreferredLocales(char *buf, size_t buflen)
+{
+    Android_JNI_GetLocale(buf, buflen);
+}
+
+/* vi: set ts=4 sw=4 expandtab: */
+

src/locale/dummy/SDL_syslocale.c

@@ -0,0 +1,33 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2020 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+#include "../../SDL_internal.h"
+#include "../SDL_syslocale.h"
+
+void
+SDL_SYS_GetPreferredLocales(char *buf, size_t buflen)
+{
+    /* dummy implementation. Caller already zero'd out buffer. */
+    SDL_Unsupported();
+}
+
+/* vi: set ts=4 sw=4 expandtab: */
+

src/locale/emscripten/SDL_syslocale.c

@@ -0,0 +1,72 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2020 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+#include <emscripten.h>
+
+#include "../../SDL_internal.h"
+#include "../SDL_syslocale.h"
+
+void
+SDL_SYS_GetPreferredLocales(char *buf, size_t buflen)
+{
+    EM_ASM({
+        var buf = $0;
+        var buflen = $1;
+        var list = undefined;
+
+        if (navigator.languages && navigator.languages.length) {
+            list = navigator.languages;
+        } else {
+            var oneOfThese = navigator.userLanguage || navigator.language || navigator.browserLanguage || navigator.systemLanguage;
+            if (oneOfThese !== undefined) {
+                list = [ oneOfThese ];
+            }
+        }
+
+        if (list === undefined) {
+            return;  /* we've got nothing. */
+        }
+
+        var str = "";  /* Can't do list.join() because we need to fit in buflen. */
+        for (var i = 0; i < list.length; i++) {
+            var item = list[i];
+            if ((str.length + item.length + 1) > buflen) {
+                break;   /* don't add, we're out of space. */
+            }
+            if (str.length > 0) {
+                str += ",";
+            }
+            str += item;
+        }
+
+        str = str.replace(/-/g, "_");
+        if (buflen > str.length) {
+            buflen = str.length;  /* clamp to size of string. */
+        }
+
+        for (var i = 0; i < buflen; i++) {
+            setValue(buf + i, str.charCodeAt(i), "i8");  /* fill in C array. */
+        }
+    }, buf, buflen);
+}
+
+/* vi: set ts=4 sw=4 expandtab: */
+

src/locale/haiku/SDL_syslocale.cc

@@ -0,0 +1,75 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2020 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+#include <LocaleRoster.h>
+
+#include "../../SDL_internal.h"
+#include "../SDL_syslocale.h"
+
+void
+SDL_SYS_GetPreferredLocales(char *buf, size_t buflen)
+{
+    BLocaleRoster *roster = BLocaleRoster::Default();
+    roster->Refresh();
+
+    BMessage msg;
+    if (roster->GetPreferredLanguages(&msg) != B_OK) {
+        SDL_SetError("BLocaleRoster couldn't get preferred languages");
+        return;
+    }
+
+    const char *key = "language";
+    type_code typ = B_ANY_TYPE;
+    int32 numlangs = 0;
+    if ((msg.GetInfo(key, &typ, &numlangs) != B_OK) || (typ != B_STRING_TYPE)) {
+        SDL_SetError("BLocaleRoster message was wrong");
+        return;
+    }
+
+    for (int32 i = 0; i < numlangs; i++) {
+        const char *str = NULL;
+        if (msg.FindString(key, i, &str) != B_OK) {
+            continue;
+        }
+
+        const size_t len = SDL_strlen(str);
+        if (buflen <= len) {
+            break;  // can't fit it, we're done.
+        }
+
+        SDL_strlcpy(buf, str, buflen);
+        buf += len;
+        buflen -= len;
+
+        if (i < (numlangs - 1)) {
+            if (buflen <= 1) {
+                break;  // out of room, stop looking.
+            }
+            buf[0] = ',';  // add a comma between entries.
+            buf[1] = '\0';
+            buf++;
+            buflen--;
+        }
+    }
+}
+
+/* vi: set ts=4 sw=4 expandtab: */
+

src/locale/macosx/SDL_syslocale.m

@@ -0,0 +1,76 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2020 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+#include "../../SDL_internal.h"
+#include "../SDL_syslocale.h"
+
+#import <Foundation/Foundation.h>
+
+void
+SDL_SYS_GetPreferredLocales(char *buf, size_t buflen)
+{ @autoreleasepool {
+    NSArray *languages = NSLocale.preferredLanguages;
+    size_t numlangs = 0;
+    size_t i;
+
+    numlangs = (size_t) [languages count];
+
+    for (i = 0; i < numlangs; i++) {
+        NSString *nsstr = [languages objectAtIndex:i];
+        size_t len;
+        char *ptr;
+
+        if (nsstr == nil) {
+            break;
+        }
+
+        [nsstr getCString:buf maxLength:buflen encoding:NSASCIIStringEncoding];
+        len = SDL_strlen(buf);
+
+        // convert '-' to '_'...
+        //  These are always full lang-COUNTRY, so we search from the back,
+        //  so things like zh-Hant-CN find the right '-' to convert.
+        if ((ptr = SDL_strrchr(buf, '-')) != NULL) {
+            *ptr = '_';
+        }
+
+        if (buflen <= len) {
+            *buf = '\0';  // drop this one and stop, we can't fit anymore.
+            break;
+        }
+
+        buf += len;
+        buflen -= len;
+
+        if (i < (numlangs - 1)) {
+            if (buflen <= 1) {
+                break;  // out of room, stop looking.
+            }
+            buf[0] = ',';  // add a comma between entries.
+            buf[1] = '\0';
+            buf++;
+            buflen--;
+        }
+    }
+}}
+
+/* vi: set ts=4 sw=4 expandtab: */
+

src/locale/unix/SDL_syslocale.c

@@ -0,0 +1,110 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2020 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+#include "../../SDL_internal.h"
+#include "../SDL_syslocale.h"
+#include "SDL_assert.h"
+
+static void
+normalize_locale_str(char *dst, char *str, size_t buflen)
+{
+    char *ptr;
+
+    ptr = SDL_strchr(str, '.');  /* chop off encoding if specified. */
+    if (ptr != NULL) {
+        *ptr = '\0';
+    }
+
+    ptr = SDL_strchr(str, '@');  /* chop off extra bits if specified. */
+    if (ptr != NULL) {
+        *ptr = '\0';
+    }
+
+    /* The "C" locale isn't useful for our needs, ignore it if you see it. */
+    if ((str[0] == 'C') && (str[1] == '\0')) {
+        return;
+    }
+
+    if (*str) {
+        if (*dst) {
+            SDL_strlcat(dst, ",", buflen);  /* SDL has these split by commas */
+        }
+        SDL_strlcat(dst, str, buflen);
+    }
+}
+
+static void
+normalize_locales(char *dst, char *src, size_t buflen)
+{
+    char *ptr;
+
+    /* entries are separated by colons */
+    while ((ptr = SDL_strchr(src, ':')) != NULL) {
+        *ptr = '\0';
+        normalize_locale_str(dst, src, buflen);
+        src = ptr + 1;
+    }
+    normalize_locale_str(dst, src, buflen);
+}
+
+void
+SDL_SYS_GetPreferredLocales(char *buf, size_t buflen)
+{
+    /* !!! FIXME: should we be using setlocale()? Or some D-Bus thing? */
+    SDL_bool isstack;
+    const char *envr;
+    char *tmp;
+
+    SDL_assert(buflen > 0);
+    tmp = SDL_small_alloc(char, buflen, &isstack);
+    if (!tmp) {
+        SDL_OutOfMemory();
+        return;
+    }
+
+    *tmp = '\0';
+
+    /* LANG is the primary locale (maybe) */
+    envr = SDL_getenv("LANG");
+    if (envr) {
+        SDL_strlcpy(tmp, envr, buflen);
+    }
+
+    /* fallback languages */
+    envr = SDL_getenv("LANGUAGE");
+    if (envr) {
+        if (*tmp) {
+            SDL_strlcat(tmp, ":", buflen);
+        }
+        SDL_strlcat(tmp, envr, buflen);
+    }
+
+    if (*tmp == '\0') {
+        SDL_SetError("LANG environment variable isn't set");
+    } else {
+        normalize_locales(buf, tmp, buflen);
+    }
+
+    SDL_small_free(tmp, isstack);
+}
+
+/* vi: set ts=4 sw=4 expandtab: */
+

src/locale/windows/SDL_syslocale.c

@@ -0,0 +1,119 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2020 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+#include "../../SDL_internal.h"
+#include "../../core/windows/SDL_windows.h"
+#include "../SDL_syslocale.h"
+#include "SDL_assert.h"
+
+typedef BOOL (WINAPI *pfnGetUserPreferredUILanguages)(DWORD,PULONG,PZZWSTR,PULONG);
+#ifndef MUI_LANGUAGE_NAME
+#define MUI_LANGUAGE_NAME 0x8 
+#endif
+
+static pfnGetUserPreferredUILanguages pGetUserPreferredUILanguages = NULL;
+static HMODULE kernel32 = 0;
+
+
+/* this is the fallback for WinXP...one language, not a list. */
+static void
+SDL_SYS_GetPreferredLocales_winxp(char *buf, size_t buflen)
+{
+    const char **retval = NULL;
+    char lang[16];
+    char country[16];
+
+	const int langrc = GetLocaleInfoA(LOCALE_USER_DEFAULT,
+                                      LOCALE_SISO639LANGNAME,
+                                      lang, sizeof (lang));
+
+	const int ctryrc =  GetLocaleInfoA(LOCALE_USER_DEFAULT,
+                                       LOCALE_SISO3166CTRYNAME,
+                                       country, sizeof (country));
+
+    /* Win95 systems will fail, because they don't have LOCALE_SISO*NAME ... */
+    if (langrc == 0) {
+        SDL_SetError("Couldn't obtain language info");
+    } else {
+        SDL_snprintf(buf, buflen, "%s%s%s", lang, ctryrc ? "_" : "", ctryrc ? country : "");
+    }
+}
+
+/* this works on Windows Vista and later. */
+static void
+SDL_SYS_GetPreferredLocales_vista(char *buf, size_t buflen)
+{
+    ULONG numlangs = 0;
+    WCHAR *wbuf = NULL;
+    ULONG wbuflen = 0;
+    SDL_bool isstack;
+
+    SDL_assert(pGetUserPreferredUILanguages != NULL);
+    pGetUserPreferredUILanguages(MUI_LANGUAGE_NAME, &numlangs, NULL, &wbuflen);
+
+    wbuf = SDL_small_alloc(WCHAR, wbuflen, &isstack);
+    if (!wbuf) {
+        SDL_OutOfMemory();
+        return;
+    }
+
+    if (!pGetUserPreferredUILanguages(MUI_LANGUAGE_NAME, &numlangs, wbuf, &wbuflen)) {
+        SDL_SYS_GetPreferredLocales_winxp(buf, buflen);  /* oh well, try the fallback. */
+    } else {
+        const ULONG endidx = SDL_min(buflen, wbuflen - 1);
+        ULONG str_start = 0;
+        ULONG i;
+        for (i = 0; i < endidx; i++) {
+            const char ch = (char) wbuf[i];  /* these should all be low-ASCII, safe to cast */
+            if (ch == '\0') {
+                buf[i] = ',';  /* change null separators to commas */
+                str_start = i;
+            } else if (ch == '-') {
+                buf[i] = '_';  /* change '-' to '_' */
+            } else {
+                buf[i] = ch;   /* copy through as-is. */
+            }
+        }
+        buf[str_start] = '\0';  /* terminate string, chop off final ',' */
+    }
+
+    SDL_small_free(wbuf, isstack);
+}
+
+void
+SDL_SYS_GetPreferredLocales(char *buf, size_t buflen)
+{
+    if (!kernel32) {
+        kernel32 = LoadLibraryW(L"kernel32.dll");
+        if (kernel32) {
+            pGetUserPreferredUILanguages = (pfnGetUserPreferredUILanguages) GetProcAddress(kernel32, "GetUserPreferredUILanguages");
+        }
+    }
+
+    if (pGetUserPreferredUILanguages == NULL) {
+        SDL_SYS_GetPreferredLocales_winxp(buf, buflen);  /* this is always available */
+    } else {
+        SDL_SYS_GetPreferredLocales_vista(buf, buflen);  /* available on Vista and later. */
+    }
+}
+
+/* vi: set ts=4 sw=4 expandtab: */
+

src/locale/winrt/SDL_syslocale.c

@@ -0,0 +1,58 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2020 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+#include <Windows.h>
+
+#include "../../SDL_internal.h"
+#include "../SDL_syslocale.h"
+
+/*using namespace Windows::Graphics::Display;*/
+#include <wchar.h>
+
+void
+SDL_SYS_GetPreferredLocales(char *buf, size_t buflen)
+{
+    WCHAR wbuffer[128] = L"";
+    int ret = 0;
+
+    /* !!! FIXME: do we not have GetUserPreferredUILanguages on WinPhone or UWP? */
+# if WINAPI_FAMILY == WINAPI_FAMILY_PHONE_APP
+    ret = GetLocaleInfoEx(LOCALE_NAME_SYSTEM_DEFAULT, LOCALE_SNAME, wbuffer, SDL_arraylen(wbuffer));
+# else
+    ret = GetSystemDefaultLocaleName(wbuffer, SDL_arraysize(wbuffer));
+# endif
+
+    if (ret > 0)
+    {
+        /* Need to convert LPWSTR to LPSTR, that is wide char to char. */
+        int i;
+
+        if (ret >= (buflen - 1) ) {
+            ret = (int) (buflen - 1);
+        }
+        for (i = 0; i < ret; i++) {
+            buf[i] = (char) wbuffer[i];  /* assume this was ASCII anyhow. */
+        }
+    }
+}
+
+/* vi: set ts=4 sw=4 expandtab: */
+

src/main/haiku/SDL_BApp.h

@@ -22,6 +22,7 @@
 #define SDL_BAPP_H
 
 #include <InterfaceKit.h>
+#include <LocaleRoster.h>
 #if SDL_VIDEO_OPENGL
 #include <OpenGLKit.h>
 #endif
@@ -153,6 +154,10 @@ public:
             _HandleWindowResized(message);
             break;
 
+        case B_LOCALE_CHANGED:
+            SDL_SendLocaleChangedEvent();
+            break;
+
         case BAPP_SCREEN_CHANGED:
             /* TODO: Handle screen resize or workspace change */
             break;

src/video/cocoa/SDL_cocoaevents.m

@@ -117,6 +117,7 @@ static void Cocoa_DispatchEvent(NSEvent *theEvent)
 }
 
 - (id)init;
+- (void)localeDidChange:(NSNotification *)notification;
 @end
 
 @implementation SDLAppDelegate : NSObject
@@ -137,6 +138,11 @@ static void Cocoa_DispatchEvent(NSEvent *theEvent)
                    selector:@selector(focusSomeWindow:)
                        name:NSApplicationDidBecomeActiveNotification
                      object:nil];
+
+        [center addObserver:self
+                   selector:@selector(localeDidChange:)
+                       name:NSCurrentLocaleDidChangeNotification
+                     object:nil];
     }
 
     return self;
@@ -148,6 +154,7 @@ static void Cocoa_DispatchEvent(NSEvent *theEvent)
 
     [center removeObserver:self name:NSWindowWillCloseNotification object:nil];
     [center removeObserver:self name:NSApplicationDidBecomeActiveNotification object:nil];
+    [center removeObserver:self name:NSCurrentLocaleDidChangeNotification object:nil];
 
     [super dealloc];
 }
@@ -226,6 +233,11 @@ static void Cocoa_DispatchEvent(NSEvent *theEvent)
     }
 }
 
+- (void)localeDidChange:(NSNotification *)notification;
+{
+    SDL_SendLocaleChangedEvent();
+}
+
 - (BOOL)application:(NSApplication *)theApplication openFile:(NSString *)filename
 {
     return (BOOL)SDL_SendDropFile(NULL, [filename UTF8String]) && SDL_SendDropComplete(NULL);