gtk: add localization support, take 3

.github/workflows/test.yml

@@ -25,6 +25,7 @@ jobs:
       - prettier
       - alejandra
       - typos
+      - translations
       - test-pkg-linux
       - test-debian-12
     steps:
@@ -593,6 +594,42 @@ jobs:
       - name: typos check
         run: nix develop -c typos
 
+  translations:
+    if: github.repository == 'ghostty-org/ghostty'
+    runs-on: namespace-profile-ghostty-sm
+    timeout-minutes: 60
+    env:
+      ZIG_LOCAL_CACHE_DIR: /zig/local-cache
+      ZIG_GLOBAL_CACHE_DIR: /zig/global-cache
+    steps:
+      - uses: actions/checkout@v4 # Check out repo so we can lint it
+      - name: Setup Cache
+        uses: namespacelabs/[email protected]
+        with:
+          path: |
+            /nix
+            /zig
+      - uses: cachix/install-nix-action@v30
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
+      - uses: cachix/cachix-action@v15
+        with:
+          name: ghostty
+          authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
+          skipPush: true
+          useDaemon: false # sometimes fails on short jobs
+      - name: check translations
+        run: |
+          old_pot=$(mktemp)
+          cp po/com.mitchellh.ghostty.pot "$old_pot"
+          nix develop -c zig build update-translations
+
+          # Compare previous POT to current POT
+          msgcmp "$old_pot" po/com.mitchellh.ghostty.pot --use-untranslated
+
+          # Compare all other POs to current POT
+          for f in po/*.po; do msgcmp "$f" po/com.mitchellh.ghostty.pot; done
+
   test-pkg-linux:
     strategy:
       fail-fast: false

CONTRIBUTING.md

@@ -21,6 +21,15 @@ All issues are actionable. Pick one and start working on it. Thank you.
 If you need help or guidance, comment on the issue. Issues that are extra
 friendly to new contributors are tagged with "contributor friendly".
 
+**I'd like to translate Ghostty to my language!**
+
+We have written a [Translator's Guide](po/README_CONTRIBUTORS.md) for
+everyone interested in contributing translations to Ghostty.
+Translations usually do not need to go through the process of issue triage
+and you can submit pull requests directly, although please make sure that
+our [Style Guide](po/README_CONTRIBUTORS.md#style-guide) is followed before
+submission.
+
 **I have a bug!**
 
 1. Search the issue tracker and discussions for similar issues.

build.zig

@@ -11,6 +11,7 @@ pub fn build(b: *std.Build) !void {
 
     // Ghostty resources like terminfo, shell integration, themes, etc.
     const resources = try buildpkg.GhosttyResources.init(b, &config);
+    const i18n = try buildpkg.GhosttyI18n.init(b, &config);
 
     // Ghostty dependencies used by many artifacts.
     const deps = try buildpkg.SharedDeps.init(b, &config);
@@ -39,6 +40,7 @@ pub fn build(b: *std.Build) !void {
     if (config.app_runtime != .none) {
         exe.install();
         resources.install();
+        i18n.install();
     }
 
     // Libghostty
@@ -103,4 +105,11 @@ pub fn build(b: *std.Build) !void {
             test_step.dependOn(&test_run.step);
         }
     }
+
+    // update-translations does what it sounds like and updates the "pot"
+    // files. These should be committed to the repo.
+    {
+        const step = b.step("update-translations", "Update translation files");
+        step.dependOn(i18n.update_step);
+    }
 }

nix/devShell.nix

@@ -34,6 +34,7 @@
   gobject-introspection,
   libadwaita,
   blueprint-compiler,
+  gettext,
   adwaita-icon-theme,
   hicolor-icon-theme,
   harfbuzz,
@@ -127,6 +128,9 @@ in
         # wasm
         wabt
         wasmtime
+
+        # Localization
+        gettext
       ]
       ++ lib.optionals stdenv.hostPlatform.isLinux [
         # My nix shell environment installs the non-interactive version

nix/package.nix

@@ -17,6 +17,7 @@
   libadwaita,
   blueprint-compiler,
   libxml2,
+  gettext,
   wrapGAppsHook4,
   gsettings-desktop-schemas,
   git,
@@ -63,6 +64,7 @@ in
           ../dist/linux
           ../images
           ../include
+          ../po
           ../pkg
           ../src
           ../vendor
@@ -86,6 +88,7 @@ in
         wrapGAppsHook4
         blueprint-compiler
         libxml2 # for xmllint
+        gettext
       ]
       ++ lib.optionals enableWayland [
         wayland-scanner

po/README_CONTRIBUTORS.md

@@ -0,0 +1,72 @@
+# Localizing Ghostty: The Contributors' Guide
+
+Ghostty uses the `gettext` library/framework for localization, which has the
+distinct benefit of being able to be consumed directly by our two main
+app runtimes: macOS and GTK (Linux). The core would ideally remain agnostic
+to localization efforts, as not all consumers of libghostty would be interested
+in localization support. Thus, implementors of app runtimes are left responsible
+for any localization that they may add.
+
+## GTK
+
+In the GTK app runtime, translable strings are mainly sourced from Blueprint
+files (located under `src/apprt/gtk/ui`). Blueprints have a native syntax for
+translatable strings, which look like this:
+
+```zig
+// Translators: This is the name of the button that opens the about dialog.
+title: _("About Ghostty");
+```
+
+The `// Translators:` comment provides additional context to the translator
+if the string itself is unclear as to what its purpose is or where it's located.
+
+By default identical strings are collapsed together into one translatable entry.
+To avoid this, assign a _context_ to the string:
+
+```zig
+label: C_("menu action", "Copy");
+```
+
+Translatable strings can also be sourced from Zig source files. This is useful
+when the string must be chosen dynamically at runtime, or when it requires
+additional formatting. The `i18n.` prefix is necessary as `_` is not allowed
+as a bare identifier in Zig.
+
+```zig
+const i18n = @import("i18n.zig");
+
+const text = if (awesome)
+    i18n._("My awesome label :D")
+else
+    i18n._("My not-so-awesome label :(");
+
+const label = gtk.Label.new(text);
+```
+
+All translatable strings are extracted into the _translation template file_,
+located under `po/com.mitchellh.ghostty.pot`. **This file must stay in sync with
+the list of translatable strings present in source code or Blueprints at all times.**
+A CI action would be run for every PR, which checks if the translation template
+requires any updates. You can update the translation template by running
+`zig build update-translations`, which would also synchronize translation files
+for other locales (`.po` files) to reflect the state of the template file.
+
+During the build process, each locale in `.po` files is compiled
+into binary `.mo` files, stored under `share/locale/<LOCALE>/LC_MESSAGES/com.mitchellh.ghostty.mo`.
+This can be directly accessed by `libintl`, which provide the various `gettext`
+C functions that can be called either by Zig code directly, or by the GTK builder
+(recommended).
+
+> [!NOTE]
+> For the vast majority of users, no additional library needs to be installed
+> in order to get localizations, since `libintl` is a part of the GNU C standard
+> library. For users using alternative C standard libraries like musl, they must
+> use a stub implementation such as [`gettext-tiny`](https://github.com/sabotage-linux/gettext-tiny)
+> that offer no-op symbols for the translation functions, or by using a build of
+> `libintl` that works for them.
+
+## macOS
+
+> [!NOTE]
+> The localization system is not yet implemented for macOS.

po/README_TRANSLATORS.md

@@ -0,0 +1,183 @@
+# Localizing Ghostty: The Translators' Guide
+
+First of all, thanks for helping us localize Ghostty!
+
+To begin contributing, please make sure that you have installed `gettext`
+on your system, which should be available under the `gettext` package
+for most Linux and macOS package managers.
+
+You can install `gettext` on Windows in a few ways:
+
+- Through [an installer](https://mlocati.github.io/articles/gettext-iconv-windows.html);
+- Through package managers like Scoop (`scoop install gettext`) and
+  WinGet (`winget install gettext`) which repackages the aforementioned installer;
+- Through Unix-like environments like [Cygwin](https://cygwin.com/cygwin/packages/summary/gettext.html)
+  and [MSYS2](https://packages.msys2.org/base/gettext).
+
+> [!WARNING]
+>
+> Unlike what some tutorials suggest, **we do not recommend installing `gettext`
+> through GnuWin32**, since it hasn't been updated since 2010 and very likely
+> does not work on modern Windows versions.
+
+You can verify that `gettext` has been successfully installed by running the
+command `gettext -V`. If everything went correctly, you should see an output like this:
+
+```console
+$ gettext -V
+gettext (GNU gettext-runtime) 0.21.1
+Copyright (C) 1995-2022 Free Software Foundation, Inc.
+License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law.
+Written by Ulrich Drepper.
+```
+
+With this, you're ready to localize!
+
+## Editing translation files
+
+All translation files lie in the `po/` directory, including the main _template_
+file called `com.mitchellh.ghostty.pot`. **Do not edit this file.** The
+template is generated automatically from Ghostty's code and resources, and are
+intended to be regenerated by code contributors. If there is a problem with
+the template file, please reach out to a code contributor.
+
+Instead, only edit the translation file corresponding to your language/locale,
+identified via the its _locale name_: for example, `de_DE.UTF-8.po` would be
+the translation file for German (language code `de`) as spoken in Germany
+(country code `DE`). The GNU `gettext` manual contains
+[further information about locale names](https://www.gnu.org/software/gettext/manual/gettext.html#Locale-Names-1),
+including a list of language and country codes.
+
+> [!NOTE]
+>
+> If the translation file for your locale does not yet exist, see the
+> ["Creating new translation files" section](#creating-new-translation-files)
+> of this document on how to create one.
+
+The `.po` file contains a list of entries that look like this:
+
+```po
+#. Translators: the category in the right-click context menu that contains split items for all directions
+#: src/apprt/gtk/ui/1.0/menu-surface-context-menu.blp:38
+#  译注：其他终端程序对 Split 皆有不同翻译，此处采取最直观的翻译方式
+msgctxt "Context menu"
+msgid "Split"
+msgstr "分屏"
+```
+
+The `msgid` line contains the original string in English, and the `msgstr` line
+should contain the translation for your language. Occasionally there will also
+be a `msgctxt` line that differentiates strings that are identical in English,
+based on its context.
+
+Lines beginning with `#` are comments, of which there are several kinds:
+
+- Pay attention to comments beginning with `#.`. They are comments left
+  by _developers_ providing more context to the string.
+
+- Comments that begin with `#:` are _source comments_: they link
+  the string to source code or resource files. You normally don't need to
+  consider these in your translations.
+
+- You may also leave comments of your own to be read by _other translators_,
+  beginning with `# `. These comments are specific to your locale and don't
+  affect translators in other locales.
+
+The first entry of the `.po` file has an empty `msgid`. This entry is special
+as it stores the metadata related to the `.po` file itself. You usually do
+not need to modify it.
+
+## Creating new translation files
+
+You can use the `msginit` tool to create new translation files.
+
+Run the command below, optionally replacing `$LANG` with the name of a locale
+that is _different_ to your system locale, or if the `LANG` environmental
+variable is not set.
+
+```console
+$ msginit -i po/com.mitchellh.ghostty.pot -l $LANG -o "po/$LANG.po"
+```
+
+> [!NOTE]
+>
+> Ghostty enforces the convention that all parts of the locale, including the
+> language code, country code, encoding, and possible regional variants
+> **must** be communicated in the file name. Files like `pt.po` are not
+> acceptable, while `pt_BR.UTF-8.po` is.
+>
+> This is to allow us to more easily accommodate regional variants of a
+> language in the future, and to reject translations that may not be applicable
+> to all speakers of a language (e.g. an unqualified `zh.po` may contain
+> terminology specific to Chinese speakers in Mainland China, which are not
+> found in Taiwan. Using `zh_CN.UTF-8.po` would allow that difference to be
+> communicated.)
+
+> [!WARNING]
+>
+> **Make sure your selected locale uses the UTF-8 encoding, as it is the sole
+> encoding supported by Ghostty and its dependencies.**
+>
+> For backwards compatibility reasons, some locales may default to a non-UTF-8
+> encoding when an encoding is not specified. For instance, `de_DE` defaults
+> to using the legacy ISO-8859-1 encoding, which is incompatible with UTF-8.
+> You need to manually instruct `msginit` to use UTF-8 in these instances,
+> by appending `.UTF-8` to the end of the locale name (e.g. `de_DE.UTF-8`).
+
+`msginit` may prompt you for other information such as your email address,
+which should be filled in accordingly. You can then add your translations
+within the newly created translation file.
+
+Afterwards, you need to update the list of known locales within Ghostty's
+build system. To do so, open `src/build/GhosttyI18n.zig` and find the list
+of locales under the `locale` variable, then append the full locale name
+into the list.
+
+```zig
+const locales = [_][]const u8{
+    "zh_CN.UTF-8",
+    // <- Add your locale here
+}
+```
+
+You should then be able to run `zig build` and see your translations in action.
+
+## Style Guide
+
+These are general style guidelines for translations. Naturally, the specific
+recommended standards will differ based on the specific language/locale,
+but these should serve as a baseline for the tone and voice of any translation.
+
+- **Prefer an instructive, yet professional tone.**
+
+  In languages that exhibit distinctions based on formality,
+  prefer the formality that is expected of instructive material on the internet.
+  The user should be considered an equal peer of the program and the translator,
+  not an esteemed customer.
+
+- **Use simple to understand language and avoid jargon.**
+
+  Explain concepts that may be familiar in an English-speaking context,
+  but are uncommon in your language.
+
+- **Do not overly literally translate foreign concepts to your language.**
+
+  Care should be taken so that your translations make sense to a reader without
+  any background knowledge of the English source text. To _localize_ is to
+  transfer a concept between languages, not to translate each word at face value.
+
+- **Be consistent with stylistic and tonal choices.**
+
+  Consult the translations made by previous translators, and try to emulate them.
+  Do not overwrite someone else's hard work without substantial justification.
+
+- **Make Ghostty fit in with surrounding applications.**
+
+  Follow existing translations for terms and concepts if possible, even when
+  they are suboptimal. Follow the writing styles prescribed by the human
+  interface guidelines of each platform Ghostty is available for, including the
+  [GNOME Human Interface Guidelines](https://developer.gnome.org/hig/guidelines/writing-style.html)
+  on Linux, and [Apple's Human Interface Guidelines](https://developer.apple.com/design/human-interface-guidelines/writing)
+  on macOS.