Feature: translations, configurable casing, and search box alignment

Makefile

@@ -1,16 +1,45 @@
 MAIN := ./cmd/nirilayout
 SRCS := $(wildcard *.go cmd/nirilayout/*.go) go.mod go.sum style.css
 
-nirilayout: $(SRCS)
+# Localization (gettext). Source files to scan for translatable T("...") calls.
+I18N_SRCS := $(wildcard *.go cmd/nirilayout/*.go)
+POT := locales/nirilayout.pot
+POFILES := $(wildcard locales/*/LC_MESSAGES/*.po)
+MOFILES := $(POFILES:.po=.mo)
+
+nirilayout: $(SRCS) $(MOFILES)
 	go build -o $@ $(MAIN)
 
-nirilayout-profile: $(SRCS)
+nirilayout-profile: $(SRCS) $(MOFILES)
 	go build -o $@ -tags profile $(MAIN)
 
-install: $(SRCS)
+install: $(SRCS) $(MOFILES)
 	go install $(MAIN)
 
+# Regenerate the .pot template from the Go sources.
+pot: $(POT)
+$(POT): $(I18N_SRCS)
+	xgettext --language=C --from-code=UTF-8 --keyword=T:1 --keyword=Tf:1 --keyword=N:1 \
+		--package-name=nirilayout \
+		--msgid-bugs-address="https://github.com/calico32/nirilayout/issues" \
+		--copyright-holder="nirilayout contributors" \
+		-o $@ $(I18N_SRCS)
+
+# Merge the latest .pot into every existing .po, preserving translations.
+update-po: $(POT)
+	@for po in $(POFILES); do \
+		echo "msgmerge $$po"; \
+		msgmerge --update --backup=none $$po $(POT); \
+	done
+
+# Compile .po files to .mo. Build targets depend on these.
+%.mo: %.po
+	msgfmt --check -o $@ $<
+
+# Regenerate translations: refresh .po files from sources, then recompile .mo.
+i18n: update-po $(MOFILES)
+
 clean:
 	rm -f nirilayout nirilayout-profile
 
-.PHONY: clean
+.PHONY: clean pot update-po i18n

README.md

@@ -188,10 +188,99 @@ prefixes of each other.
 Layouts are presented in lexicographical order by name. If you want to change
 the order, you can rename the files in the config directory.
 
+## Command-line options
+
+| Option        | Description                                                                                  |
+| ------------- | -------------------------------------------------------------------------------------------- |
+| `-c <dir>`    | niri config directory (default `~/.config/niri`).                                            |
+| `-lang <code>`| Interface language code, e.g. `it`. Overrides the system locale. See [Localization](#localization). |
+| `-lowercase`  | Render all of nirilayout's own interface text in lowercase. See [Casing](#casing).           |
+| `-leftalign`  | Left-align the text in the search box. See [Search box alignment](#search-box-alignment).    |
+
+Run `nirilayout -h` for the full list.
+
+## Appearance
+
+### Casing
+
+By default nirilayout uses standard sentence casing for its own interface text
+(for example `Esc to quit`). If you prefer everything in lowercase, pass the
+`-lowercase` flag:
+
+```sh
+nirilayout -lowercase
+```
+
+This only affects nirilayout's own interface strings — the names of your layouts
+and outputs are always shown exactly as you wrote them.
+
+### Search box alignment
+
+The text you type into the search box is centered by default. Pass the
+`-leftalign` flag to left-align it instead:
+
+```sh
+nirilayout -leftalign
+```
+
+## Localization
+
+nirilayout's interface can be translated. The language is chosen automatically,
+with the following precedence:
+
+1. The `-lang` flag, when set, wins over everything (e.g. `nirilayout -lang it`).
+2. Otherwise the operating system locale is used, read from the `LC_ALL`,
+   `LC_MESSAGES`, and `LANG` environment variables (in that order). A locale
+   like `it_IT.UTF-8` is matched to its base language `it`.
+3. Otherwise English is used.
+
+If the selected language has no translation, nirilayout falls back to English.
+
+Currently available languages:
+
+- English (`en`, source language)
+- Italian (`it`)
+
+### Adding a translation
+
+Translations use [gettext](https://www.gnu.org/software/gettext/). The compiled
+`.mo` catalogs are committed to the repository and embedded into the binary, so
+**building or running nirilayout never requires any gettext tooling**. You only
+need the gettext tools (`xgettext`, `msgmerge`, `msgfmt`) to *edit* translations.
+
+To add a new language (using French, `fr`, as an example):
+
+1. Refresh the message template and existing translations from the source:
+
+   ```sh
+   make update-po
+   ```
+
+2. Create the catalog directory and initialize the `.po` file from the template:
+
+   ```sh
+   mkdir -p locales/fr/LC_MESSAGES
+   msginit -i locales/nirilayout.pot -o locales/fr/LC_MESSAGES/nirilayout.po -l fr
+   ```
+
+3. Translate the `msgstr` entries in `locales/fr/LC_MESSAGES/nirilayout.po`.
+
+4. Compile the catalogs (this produces the committed `.mo` files):
+
+   ```sh
+   make i18n
+   ```
+
+5. Add the new language to the list above and open a pull request.
+
+To update an existing translation, edit its `.po` file, run `make i18n`, and
+commit both the `.po` and the regenerated `.mo`.
+
 # Contributing
 
 Contributions are welcome! If you find a bug or have a feature request, please
-open an issue or a pull request.
+open an issue or a pull request. Translations are especially welcome — see
+[Adding a translation](#adding-a-translation).
 
 # License
 

cmd/nirilayout/main.go

@@ -15,15 +15,28 @@ import (
 )
 
 func main() {
+	// Initialize i18n from the system locale first so that flag.Usage (which
+	// flag.Parse may invoke on -h or a parse error) is already localized. It
+	// is re-initialized after flag.Parse to honor -lang and -lowercase.
+	nirilayout.InitI18n()
+
 	flag.Usage = func() {
-		fmt.Printf("nirilayout is a layout switcher for niri.\n\nCommand-line options:\n")
+		fmt.Print(nirilayout.T("nirilayout is a layout switcher for niri.\n\nCommand-line options:\n"))
+		// Translate each flag's usage string in place, then let the flag
+		// package handle the formatting (types, defaults, alignment).
+		flag.VisitAll(func(f *flag.Flag) {
+			f.Usage = nirilayout.T(f.Usage)
+		})
 		flag.PrintDefaults()
-		fmt.Printf("\nTo use nirilayout, create layouts in files called ~/.config/niri/layout_<name>.kdl and run nirilayout.\nSee the README for more details:\n")
-		fmt.Printf("  https://github.com/calico32/nirilayout/blob/main/README.md\n")
+		fmt.Print(nirilayout.T("\nTo use nirilayout, create layouts in files called ~/.config/niri/layout_<name>.kdl and run nirilayout.\nSee the README for more details:\n"))
+		fmt.Print("  https://github.com/calico32/nirilayout/blob/main/README.md\n")
 	}
 
 	flag.Parse()
 
+	// Apply -lang and -lowercase now that flags are parsed.
+	nirilayout.InitI18n()
+
 	var layouts []nirilayout.Layout
 	var current string
 

config.go

@@ -26,7 +26,13 @@ const (
 	defaultLineSpacing = 4
 )
 
-var niriConfigDir = flag.String("c", "~/.config/niri", "niri config directory")
+var niriConfigDir = flag.String("c", "~/.config/niri", N("niri config directory"))
+
+var (
+	langFlag      = flag.String("lang", "", N("interface language code (e.g. \"it\"); overrides the system locale"))
+	lowercaseFlag = flag.Bool("lowercase", false, N("render all interface text in lowercase"))
+	leftAlignFlag = flag.Bool("leftalign", false, N("left-align the text in the search box (default is centered)"))
+)
 
 func GetNiriConfigDir() (configDir string, err error) {
 	if strings.HasPrefix(*niriConfigDir, "~") {

draw.go

@@ -123,10 +123,11 @@ func drawLayout(layout Layout) *gtk.DrawingArea {
 		cr.MoveTo(0, 0)
 
 		if len(outputs) == 0 {
-			extents := cr.TextExtents("no preview available")
+			msg := T("No preview available")
+			extents := cr.TextExtents(msg)
 			cr.MoveTo(float64(width)/2-extents.Width/2-extents.XBearing, float64(height)/2-extents.Height/2-extents.YBearing)
 			cr.SetSourceRGBA(rgba(gray400))
-			cr.ShowText("no preview available")
+			cr.ShowText(msg)
 			return
 		}
 

go.mod

@@ -17,4 +17,5 @@ require (
 	github.com/diamondburned/gotk4-layer-shell/pkg v0.0.0-20240109211357-6efa9f6dc438
 	github.com/diamondburned/gotk4/pkg v0.3.1
 	github.com/google/go-cmp v0.7.0
+	github.com/leonelquinteros/gotext v1.7.2
 )

go.sum

@@ -10,6 +10,8 @@ github.com/diamondburned/gotk4/pkg v0.3.1 h1:uhkXSUPUsCyz3yujdvl7DSN8jiLS2BgNTQE
 github.com/diamondburned/gotk4/pkg v0.3.1/go.mod h1:DqeOW+MxSZFg9OO+esk4JgQk0TiUJJUBfMltKhG+ub4=
 github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
 github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
+github.com/leonelquinteros/gotext v1.7.2 h1:bDPndU8nt+/kRo1m4l/1OXiiy2v7Z7dfPQ9+YP7G1Mc=
+github.com/leonelquinteros/gotext v1.7.2/go.mod h1:9/haCkm5P7Jay1sxKDGJ5WIg4zkz8oZKw4ekNpALob8=
 go4.org/unsafe/assume-no-moving-gc v0.0.0-20231121144256-b99613f794b6 h1:lGdhQUN/cnWdSH3291CUuxSEqc+AsGTiDxPP3r2J0l4=
 go4.org/unsafe/assume-no-moving-gc v0.0.0-20231121144256-b99613f794b6/go.mod h1:FftLjUGFEDu5k8lt0ddY+HcrH/qU/0qk+H8j9/nTl3E=
 golang.org/x/sync v0.21.0 h1:HLII4xRRTtCRkxYp4HNFF0Js/Og6q2i++KXbg0gHCwM=