feat: add support for standalone language packs

Load translated text and fonts from folder or ZIP language packs. Persist
custom selections and fall back to English when a pack is unavailable.

Author: zrckr

Docs/createmods.md

@@ -56,6 +56,30 @@ Code mods should use `FezGame.Tools.ModText` to read their custom keys. `GetStri
 var dialogue = ModText.GetString("MY_MOD_INTRO");
 ```
 
+### Creating a standalone language pack
+
+Language packs are independent of mods. Put a folder or ZIP archive in `FEZ/Languages`; a pack must contain `Language.xml` and an `Assets` directory. ZIP archives contain the pack root directly, rather than an additional enclosing directory.
+
+```xml
+<Language>
+  <Code>nl</Code>
+  <DisplayName>Dutch</DisplayName>
+  <Locale>LanguageDutch</Locale>
+  <SmallFont>Fonts\Latin Small</SmallFont>
+  <BigFont>Fonts\Latin Big</BigFont>
+</Language>
+```
+
+`Code` is a required lowercase two-letter code. `DisplayName` is the stable English name stored in settings. `Locale` is an optional StaticText key, such as `LanguageDutch`, used to localize the slider label; when it is absent or untranslated, `DisplayName` is used. `SmallFont` and `BigFont` are required asset paths, relative to `Assets`, without the `.xnb` extension. The declared font assets must exist in the pack.
+
+Place translated FEZ resources at these normal asset paths:
+
+- `Assets/Resources/StaticText.xnb`
+- `Assets/Resources/GameText.xnb`
+- `Assets/Resources/CreditsText.xnb`
+
+Each resource uses FEZ's existing `Dictionary<string, Dictionary<string, string>>` format. Use the pack code (`nl` in the example) as its localized dictionary key. Missing resource keys fall back to FEZ's original language text.
+
 ## Creating custom logic mod
 
 Mod loader loads library file given in metadata as an assembly, then attempts to create instances of every non-abstract public class extending the `GameComponent` class before initialization (before any services are created). After the game has been initialized (that is, as soon as all necessary services are initiated), it adds created instances into the list of game's components and initializes them, allowing their `Update` and `Draw` (use `DrawableGameComponent`) to be properly executed within the game's loop.

Plugin/Patches/MenuItemPatch.cs

@@ -0,0 +1,63 @@
+using System.Reflection;
+using System.Runtime.CompilerServices;
+using FezEngine.Tools;
+using HatModLoader.Source;
+using HatModLoader.Source.Languages;
+
+namespace FezGame.Structure
+{
+    internal class patch_MenuItem<T>
+    {
+        [MethodImpl(MethodImplOptions.ForwardRef)]
+        public extern void orig_Slide(int direction);
+
+        public void Slide(int direction)
+        {
+            if (typeof(T) != typeof(Language) || !IsLanguageSlider(this))
+            {
+                orig_Slide(direction);
+                return;
+            }
+
+            var language = (Language)GetSliderValue(this);
+            var nextLanguage = Hat.Instance.LanguagePacks.ChangeLanguage(language, direction);
+            SetLanguageToSet(this, nextLanguage);
+        }
+
+        [MethodImpl(MethodImplOptions.ForwardRef)]
+        public extern void orig_OnSelected();
+
+        public void OnSelected()
+        {
+            orig_OnSelected();
+            if (typeof(T) == typeof(Language) && IsLanguageSlider(this))
+            {
+                // FEZ serializes custom enum values as null, so correct the file after saving.
+                SettingsManager.Save();
+                LanguagePackManager.PersistSelectedLanguage();
+            }
+        }
+
+        private static bool IsLanguageSlider(object item)
+        {
+            var type = item.GetType();
+            var localized = (bool)type.GetProperty("LocalizeSliderValue")!.GetValue(item);
+            var format = (string)type.GetProperty("LocalizationTagFormat")!.GetValue(item);
+            return localized && string.Equals(format, "Language{0}", StringComparison.Ordinal);
+        }
+
+        private static object GetSliderValue(object item)
+        {
+            var getter = (Delegate)item.GetType().GetField("SliderValueGetter")!.GetValue(item);
+            return getter.DynamicInvoke();
+        }
+
+        private static void SetLanguageToSet(object item, Language language)
+        {
+            var getter = (Delegate)item.GetType().GetField("SliderValueGetter")!.GetValue(item);
+            var field = getter.Target.GetType().GetField("languageToSet",
+                BindingFlags.Instance | BindingFlags.NonPublic);
+            field!.SetValue(getter.Target, language);
+        }
+    }
+}

Plugin/Patches/Program.cs

@@ -2,6 +2,7 @@
 using HatModLoader.Source;
 using System.Globalization;
 using System.Runtime.CompilerServices;
+using HatModLoader.Source.Languages;
 
 namespace FezGame
 {
@@ -15,6 +16,9 @@ private static void Main(string[] args)
             // Ensuring that required dependencies can be resolved before anything else.
             Hat.RegisterRequiredDependencyResolvers();
 
+            // Resolve a pack display name before FEZ deserializes its settings enum.
+            LanguagePackManager.RestorePersistedLanguage();
+
             // Ensure uniform culture
             Thread.CurrentThread.CurrentCulture = CultureInfo.GetCultureInfo("en-US");
             Thread.CurrentThread.CurrentUICulture = CultureInfo.GetCultureInfo("en-US");
@@ -24,6 +28,9 @@ private static void Main(string[] args)
             // game is shutting down. We want to keep track of it.
 
             Logger.Try(orig_Main, args);
+
+            // FEZ's final save writes custom enum values as null.
+            LanguagePackManager.PersistSelectedLanguage();
         }
     }
 }

Plugin/Patches/TextPatch.cs

@@ -26,7 +26,10 @@ public static class patch_StaticText
         public static extern bool orig_TryGetString(string tag, out string text);
         public static bool TryGetString(string tag, out string text)
         {
-            return Hat.Instance.TextResources.TryGetString(tag, TextLookupScope.Localized, out text) || orig_TryGetString(tag, out text);
+            return Hat.Instance.TextResources.TryGetString(tag, TextLookupScope.Localized, out text) ||
+                   Hat.Instance.LanguagePacks.TryGetDisplayName(tag, out text) ||
+                   Hat.Instance.LanguagePacks.TryGetText("Resources\\StaticText", tag, out text) ||
+                   orig_TryGetString(tag, out text);
         }
 
         [MethodImpl(MethodImplOptions.ForwardRef)]
@@ -50,27 +53,21 @@ public static class patch_GameText
         public static extern string orig_GetString(string tag);
         public static string GetString(string tag)
         {
-            if (TextPatch.TryGetRawString(tag, out var text))
-            {
-                return text;
-            }
-
-            return ModText.TryGetString(tag, out text) 
-                ? text :
-                orig_GetString(tag);
+            return TextPatch.TryGetRawString(tag, out var text) ||
+                   ModText.TryGetString(tag, out text) ||
+                   Hat.Instance.LanguagePacks.TryGetText("Resources\\GameText", tag, out text)
+                ? text
+                : orig_GetString(tag);
         }
 
         [MethodImpl(MethodImplOptions.ForwardRef)]
         public static extern string orig_GetStringRaw(string tag);
         public static string GetStringRaw(string tag)
         {
-            if (TextPatch.TryGetRawString(tag, out var text))
-            {
-                return text;
-            }
-
-            return ModText.TryGetStringRaw(tag, out text) 
-                ? text 
+            return TextPatch.TryGetRawString(tag, out var text) ||
+                   ModText.TryGetStringRaw(tag, out text) ||
+                   Hat.Instance.LanguagePacks.TryGetText("Resources\\GameText", tag, out text)
+                ? text
                 : orig_GetStringRaw(tag);
         }
     }
@@ -81,13 +78,10 @@ public static class patch_CreditsText
         public static extern string orig_GetString(string tag);
         public static string GetString(string tag)
         {
-            if (TextPatch.TryGetRawString(tag, out var text))
-            {
-                return text;
-            }
-
-            return ModText.TryGetStringRaw(tag, out text) 
-                ? text 
+            return TextPatch.TryGetRawString(tag, out var text) ||
+                   ModText.TryGetStringRaw(tag, out text) ||
+                   Hat.Instance.LanguagePacks.TryGetText("Resources\\CreditsText", tag, out text)
+                ? text
                 : orig_GetString(tag);
         }
     }

Plugin/Source/Hat.cs

@@ -6,6 +6,7 @@
 using HatModLoader.Source.AssemblyResolving;
 using HatModLoader.Source.Assets;
 using HatModLoader.Source.FileProxies;
+using HatModLoader.Source.Languages;
 using HatModLoader.Source.ModDefinition;
 using HatModLoader.Source.Worlds;
 
@@ -25,6 +26,8 @@ public class Hat
 
         internal TextResourceManager TextResources { get; }
 
+        internal LanguagePackManager LanguagePacks { get; }
+
         public WorldsManifest Worlds { get; private set; }
 
         public int InvalidModsCount { get; private set; }
@@ -50,6 +53,7 @@ public Hat(Fez fez)
             Instance = this;
             _fezGame = fez;
             TextResources = new TextResourceManager(this);
+            LanguagePacks = new LanguagePackManager();
             AssetManager = new AssetManager(this);
             AssetManager.InitializeHooks();
         }
@@ -64,13 +68,12 @@ public void Initialize()
                 {
                     ResolveDependencies(mods);
                     LoadMods();
-                    Worlds = new WorldsManifest(Mods);
-                    InitializeAssemblies();
-                    return; // HAT initialized
                 }
             }
 
-            Logger.Log("HAT", LogSeverity.Warning, "Skip the initialization process...");
+            LanguagePacks.Load();
+            Worlds = new WorldsManifest(Mods);
+            InitializeAssemblies();
         }
 
         private static bool GetModProxies(out IEnumerable<IFileProxy> proxies)
@@ -175,6 +178,7 @@ public void InitializeComponents()
 
         public void OnGameActivated()
         {
+            LanguagePacks.ReloadActivePack();
             var changedAssets = new List<Asset>();
             foreach (var mod in Mods)
             {

Plugin/Source/Languages/LanguageMetadata.cs

@@ -0,0 +1,19 @@
+using System.Xml.Serialization;
+
+namespace HatModLoader.Source.Languages
+{
+    [Serializable]
+    [XmlRoot("Language")]
+    public class LanguageMetadata
+    {
+        public string Code { get; set; }
+
+        public string DisplayName { get; set; }
+
+        public string Locale { get; set; }
+
+        public string SmallFont { get; set; }
+
+        public string BigFont { get; set; }
+    }
+}