Merge pull request #919 from 4ian/refactor/cra2-and-jslingui

Add support for translations in GDevelop 5 🌎

For contributors, please merge master in your branches for your Pull Requests. 
See this comment: #919 (comment)
Don't forget to remove `node_modules` folder in `newIDE/app`, and relaunch `npm install` or `yarn`, then `npm start` or `yarn start`.

.gitignore

@@ -9,6 +9,7 @@
 /ExtLibs/*.7z
 /scripts/Repository keys
 /scripts/logs/*.txt
+/scripts/gdcore-gdcpp-gdjs-extensions-messages.pot
 /Binaries/.build*
 /Binaries/.embuild*
 /Binaries/build*

Core/GDCore/Extensions/Builtin/TimeExtension.cpp

@@ -61,14 +61,15 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsTimeExtension(
       .MarkAsAdvanced();
 
   extension
-      .AddAction("ResetTimer",
-                 _("Start (or reset) a scene timer"),
-                 _("Reset the specified scene timer, if the timer doesn't exist "
-                   "it's created and started."),
-                 _("Reset the timer _PARAM1_"),
-                 _("Timers and time"),
-                 "res/actions/timer24.png",
-                 "res/actions/timer.png")
+      .AddAction(
+          "ResetTimer",
+          _("Start (or reset) a scene timer"),
+          _("Reset the specified scene timer, if the timer doesn't exist "
+            "it's created and started."),
+          _("Reset the timer _PARAM1_"),
+          _("Timers and time"),
+          "res/actions/timer24.png",
+          "res/actions/timer.png")
       .AddCodeOnlyParameter("currentScene", "")
       .AddParameter("string", _("Timer's name"));
 
@@ -200,7 +201,10 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsTimeExtension(
           "stringWithSelector",
           _("Hour: hour - Minutes: min - Seconds: sec - Day of month: "
             "mday - Months since January: mon - Year since 1900: year - Days "
-            "since Sunday: wday - Days since Jan 1st: yday - Timestamp (ms): timestamp\"), "[\"hour\", \"min\", \"sec\", \"mon\", \"year\", \"wday\", \"mday\", \"yday\", \"timestamp\"]");
+            "since Sunday: wday - Days since Jan 1st: yday - Timestamp (ms): "
+            "timestamp\""),
+          "[\"hour\", \"min\", \"sec\", \"mon\", \"year\", \"wday\", \"mday\", "
+          "\"yday\", \"timestamp\"]");
 
 #endif
 }

Core/GDCore/Extensions/Metadata/InstructionMetadata.cpp

@@ -15,7 +15,11 @@
 
 namespace gd {
 InstructionMetadata::InstructionMetadata()
-    : sentence(_("Unknown or unsupported instruction")),
+    : sentence(
+          "Unknown or unsupported instruction"),  // Avoid translating this
+                                                  // string, so that it's safe
+                                                  // and *fast* to use a
+                                                  // InstructionMetadata.
       canHaveSubInstructions(false),
       hidden(true) {}
 

Core/GDCore/Tools/Localization.cpp

@@ -0,0 +1,35 @@
+/*
+ * GDevelop Core
+ * Copyright 2008-present Florian Rival (Florian.Rival@gmail.com). All rights
+ * reserved. This project is released under the MIT License.
+ */
+
+#if defined(EMSCRIPTEN)
+#include <emscripten.h>
+#include "GDCore/String.h"
+
+namespace gd {
+gd::String GetTranslation(const char* str) {  // TODO: Inline?
+  const char* translatedStr = (const char*)EM_ASM_INT(
+      {
+        var getTranslation = Module['getTranslation'];
+        if (!getTranslation) {
+          return $0;
+        }
+
+        // Uncomment lines to display a warning if the cache
+        // for strings is not ready.
+        // if (!ensureCache) {
+        //   console.warn('No ensureCache initialized');
+        //   return $0;
+        // }
+        ensureCache.prepare();
+
+        var translatedStr = getTranslation(Pointer_stringify($0));
+        return ensureString(translatedStr);
+      },
+      str);
+  return gd::String(translatedStr);  // TODO: Is copying necessary?
+}
+}  // namespace gd
+#endif

Core/GDCore/Tools/Localization.h

@@ -6,20 +6,55 @@
 #ifndef GDCORE_LOCALIZATION_H
 #define GDCORE_LOCALIZATION_H
 
+/** @file
+ * Provide a way to mark strings to be translated.
+ * 
+ * Strings to be translated in GDevelop Core codebase (and GDCpp),
+ * are marked with the underscore macro, for example: _("Hello World").
+ * 
+ * The macro is then defined to be using the translation function
+ * of the underlying platform (Emscripten for GD5, wxWidgets for GD4,
+ * no translation for GDCpp Runtime).
+ */
+
 #if defined(GD_IDE_ONLY) && !defined(GD_NO_WX_GUI)
+// When compiling with wxWidgets, use the translation method
+// provided by wxWidgets, but return a gd::String.
+
 #include <wx/intl.h>
 #include "GDCore/String.h"
+
 // Create a new macro to return UTF8 gd::String from a translation
 #if defined(_)
 #undef _
 #endif
 #define _(s) gd::String(wxGetTranslation(wxString::FromUTF8(u8##s)))
+
+#elif defined(EMSCRIPTEN)
+// When compiling with Emscripten, use a translation function that is calling a
+// JS method on the module, so that an external translation library can be used.
+
+#include "GDCore/String.h"
+#if defined(_)
+#undef _
+#endif
+
+namespace gd {
+gd::String GetTranslation(const char* str);
+}
+
+#define _(s) gd::GetTranslation(u8##s)
+
 #else
+// When compiling without Emscripten or wxWidgets (typically for GDC++ Runtime),
+// just return an untranslated gd::String.
+
 // Create a new macro to return UTF8 gd::String from a translation
 #if defined(_)
 #undef _
 #endif
 #define _(s) gd::String(u8##s)
+
 #endif
 
 #endif  // GDCORE_LOCALIZATION_H