Add support for translations

Based on earlier work by @whot:

44d8265d4a

Fixes #12.

circle.yml

@@ -14,7 +14,7 @@ jobs:
       # now install and checks the resulting file (just in case)
       - run:
           command: |
-            dnf install -y meson python3-devel pygobject3-devel
+            dnf install -y meson gettext python3-devel pygobject3-devel
       - run:
           command: |
             meson build

meson.build

@@ -18,6 +18,7 @@ pkgdatadir = join_paths(datadir, meson.project_name())
 bindir = join_paths(prefix, get_option('bindir'))
 
 subdir('data')
+subdir('po')
 
 # Find the directory to install our Python code
 python = import('python3')

po/LINGUAS

@@ -0,0 +1 @@
+# Language list must be in alphabetical order

po/POTFILES

@@ -0,0 +1,33 @@
+piper/__init__.py
+piper/application.py
+piper/buttondialog.py
+piper/buttonspage.py
+piper/devicerow.py
+piper/errorperspective.py
+piper/gi_composites.py
+piper/leddialog.py
+piper/ledspage.py
+piper/mousemap.py
+piper/mouseperspective.py
+piper/optionbutton.py
+piper/profilerow.py
+piper/ratbagd.py
+piper/resolutionrow.py
+piper/resolutionspage.py
+piper/welcomeperspective.py
+piper/window.py
+
+data/ui/AboutDialog.ui.in
+data/ui/ButtonDialog.ui
+data/ui/ButtonRow.ui
+data/ui/DeviceRow.ui
+data/ui/ErrorPerspective.ui
+data/ui/LedDialog.ui
+data/ui/Menus.ui
+data/ui/MousePerspective.ui
+data/ui/OptionButton.ui
+data/ui/ProfileRow.ui
+data/ui/ResolutionRow.ui
+data/ui/ResolutionsPage.ui
+data/ui/WelcomePerspective.ui
+data/ui/Window.ui

po/README.md

@@ -0,0 +1,36 @@
+i18n
+====
+
+This directory contains the translations of Piper.
+
+For errors in translations, please [file an
+issue](https://github.com/libratbag/piper/issues/new).
+
+New or updated translations are always welcome. To start a new translation, run:
+
+	$ meson translation-build
+	$ ninja -C translation-build piper-pot
+	# Now you can optionally remove the build directory
+	$ rm -rf translation-build
+	$ cp po/piper.pot po/$lang.po
+
+where `$lang` is the language code of your target language, e.g. `nl` for Dutch
+or `en_GB` for British English. Edit the
+[LINGUAS](https://github.com/libratbag/piper/blob/master/po/LINGUAS) file and
+add your language code, keeping the list sorted alphabetically.  Finally, open
+the `.po` file you just created and translate all the strings. Don't forget to
+fill in the information in the header!
+
+To update an existing translation, run:
+
+	$ meson translation-build
+	$ ninja -C translation-build piper-update-po
+	# Now you can optionally remove the build directory
+	$ rm -rf translation-build
+
+and update the `po/$lang.po` file of your target language.
+
+When you are done translating, file a pull request on
+[GitHub](https://github.com/libratbag/piper) or, if you don't know how to, [open
+an issue](https://github.com/libratbag/piper/issues/new) and attach the `.po`
+file there.

po/meson.build

@@ -0,0 +1,3 @@
+i18n = import('i18n')
+
+i18n.gettext('piper', preset: 'glib')