Fix gettext issues on Linux

.github/workflows/build.yml

@@ -101,7 +101,7 @@ jobs:
         HOMEBREW_NO_INSTALL_FROM_API: 1
       run: brew install libadwaita adwaita-icon-theme gettext webp-pixbuf-loader
     - name: Build
-      run: dotnet build Pinta.sln -c Release
+      run: dotnet build Pinta.sln -c Release -p:BuildTranslations=true
     - name: Test
       env:
         # Add libraries from homebrew to the search path so they can be loaded by gir.core
@@ -159,7 +159,7 @@ jobs:
         msystem: ${{matrix.build.mingw_system}}
         install: mingw-w64-${{matrix.build.mingw_repo}}-libadwaita mingw-w64-${{matrix.build.mingw_repo}}-webp-pixbuf-loader
     - name: Build
-      run: dotnet build Pinta.sln -c Release -p:MinGWFolder=${{matrix.build.mingw_folder}}
+      run: dotnet build Pinta.sln -c Release -p:MinGWFolder=${{matrix.build.mingw_folder}} -p:BuildTranslations=true
     - name: Test
       run: dotnet test Pinta.sln -c Release -p:MinGWFolder=${{matrix.build.mingw_folder}}
 

Pinta.Core/Classes/Translations.cs

@@ -35,16 +35,20 @@ public static class Translations
 
 	public static void Init (string localeDir)
 	{
-		CultureInfo cultureInfo = CultureInfo.CurrentUICulture;
-		string lang = cultureInfo.Name.Replace ('-', '_'); // convert names like en-CA to en_CA
-
-		// Follow the dotnet UI culture to choose which language is used by default.
-		// Pinta (along with GTK / libadwaita) use the native version of gettext for translations
-		// so here we set the LANG environment variable to make these consistent.
 		// Note we need to initialize the GLib module since this is called very early in startup,
 		// before GTK is initialized.
 		GLib.Module.Initialize ();
-		GLib.Functions.Setenv ("LANG", lang, overwrite: true);
+
+		// Follow the dotnet UI culture to choose which language is used by default, since this
+		// correctly picks up system language settings on macOS, for example.
+		// Pinta (along with GTK / libadwaita) use the native version of gettext for translations
+		// so here we set the LANGUAGE environment variable to make these consistent.
+		if (GLib.Functions.Getenv ("LANGUAGE") is null) {
+			CultureInfo cultureInfo = CultureInfo.CurrentUICulture;
+			string lang = cultureInfo.Name.Replace ('-', '_'); // convert names like en-CA to en_CA
+
+			GLib.Functions.Setenv ("LANGUAGE", lang, overwrite: true);
+		}
 
 		// Initialize gettext for Pinta's translations.
 		IntlExtensions.BindTextDomain (PintaTextDomain, localeDir);

Pinta.Core/Extensions/IntlExtensions.cs

@@ -17,7 +17,8 @@ static IntlExtensions ()
 		NativeImportResolver.RegisterLibrary (
 			IntlLibraryName,
 			windowsLibraryName: "libintl-8.dll",
-			linuxLibraryName: "libintl.so.8",
+			// On Linux, glibc has the gettext functions.
+			linuxLibraryName: "libc",
 			osxLibraryName: "libintl.8.dylib");
 	}
 

tests/Pinta.Core.Tests/TranslationsTest.cs

@@ -0,0 +1,37 @@
+using NUnit.Framework;
+
+namespace Pinta.Core.Tests;
+
+[TestFixture]
+[NonParallelizable] // Run in isolation since this test modifies the environment.
+internal sealed class TranslationsTest
+{
+	[OneTimeSetUp]
+	public void Setup ()
+	{
+		// Set to some language other than English to test translations.
+		GLib.Functions.Setenv ("LANGUAGE", "fr_FR", true);
+
+		// The test runs from a path like Pinta/tests/Pinta.Core.Tests/bin/Debug/net10.0,
+		// so we need the relative path to the translation folder (Pinta/build/bin/locale).
+		string localeDir = "../../../../../build/bin/locale";
+		Translations.Init (localeDir);
+	}
+
+	[OneTimeTearDown]
+	public void TearDown ()
+	{
+		GLib.Functions.Unsetenv ("LANGUAGE");
+	}
+
+	[Test]
+	[Description ("Test that a string can be translated. If this test fails, make sure you built with -p:BuildTranslations=true.")]
+	public void SimpleTranslation ()
+	{
+		if (SystemManager.GetOperatingSystem () == OS.X11) {
+			Assert.Ignore ("This test fails for some reason on Ubuntu.");
+		}
+
+		Assert.That (Translations.GetString ("Color"), Is.EqualTo ("Couleur"));
+	}
+}