gluon/docs/dev/i18n.rst

Internationalization support
============================

General guidelines
------------------

* All config mode packages must be fully translatable, with complete English and German texts.
* All new expert mode packages must be fully translatable. English texts are required.
* German translations are recommended. Other supported languages, especially French, are
  nice-to-have, but not required. If you don't know a language well, rather leave the translation
  blank, so it is obvious that there is no proper translation yet.
* Existing expert mode packages should be made translatable as soon as possible.
* The "message IDs" (which are the arguments to the ``translate`` function) should be the
  English texts.

i18n support in LuCI
--------------------

Internationalization support can be found in the ``luci.i18n`` package.
Strings are translated using the ``i18n.translate`` and ``i18n.translatef`` functions
(``translate`` for static strings, ``translatef`` for printf-like formatted string).

Example from the ``gluon-config-mode-geo-location`` package::

  local i18n = require "luci.i18n"
  o = s:option(cbi.Flag, "_location", i18n.translate("Show node on the map"))

Adding translation templates to Gluon packages
----------------------------------------------

The i18n support is based on the standard gettext system. For each translatable package,
a translation template with extension ``.pot`` can be created using the ``i18n-scan.pl``
script from the LuCI repository::

  cd package/gluon-config-mode-geo-location
  mkdir i18n
  cd i18n
  ../../../packages/luci/build/i18n-scan.pl ../files > gluon-config-mode-geo-location.pot

The entries in the template can be reordered after the generation if desirable. Lots of standard
translations like "Cancel" are already available in the LuCI base translation file (see
``packages/luci/po/templates/base.pot``) and can be removed from the template.

In addition, some additions to the Makefile must be made. Instead of OpenWrt's default ``package.mk``,
the Gluon version ``$(GLUONDIR)/include/package.mk`` must be used. The i18n files must be installed
and PKG_CONFIG_DEPENDS must be added::

  ...
  include $(GLUONDIR)/include/package.mk

  PKG_CONFIG_DEPENDS += $(GLUON_I18N_CONFIG)
  ...
  define Build/Compile
    $(call GluonBuildI18N,gluon-config-mode-geo-location,i18n)
  endef

  define Package/gluon-config-mode-geo-location/install
    ...
    $(call GluonInstallI18N,gluon-config-mode-geo-location,$(1))
  endef
  ...


Adding translations
-------------------

A new translation file for a template can be added using the ``msginit`` command::

  cd package/gluon-config-mode-geo-location/i18n
  msginit -l de

This will create the file ``de.po`` in which the translations can be added.

The translation file can be updated to a new template version using the ``msgmerge`` command::

  msgmerge -U de.po gluon-config-mode-geo-location.pot

After the merge, the translation file should be checked for "fuzzy matched" entries where
the original English texts have changed. All entries from the translation file should be
translated in the ``.po`` file (or removed from it, so the original English texts are displayed
instead).

Adding support for new languages
--------------------------------

A list of all languages supported by LuCI can be found in the ``packages/luci/luci.mk`` file after
Gluon's dependencies have been downloaded using ``make update``. Adding translations for these
languages is straightforward using the ``msginit`` command.

For other languages, support must be added to LuCI first, which constitutes completely translating
the ``base.pot``. Please contact the upstream LuCI maintainers at https://github.com/openwrt/luci/
if you'd like to do this.