How to bind a text domain to a local folder for gettext under GTK3

Question

With gettext you can either use the default system-wide locale directory, or specify one yourself using bindtextdomain. This is useful when running a program directly from source when the compiled .mo translation files are not available in the system's default location.

In Python you would do this:

import gettext
from gettext import gettext as _
gettext.bindtextdomain('nautilus-image-manipulator', '/path/to/mo/folder')
gettext.textdomain('nautilus-image-manipulator')

where /path/to/mo/folder contains the familiar fr/LC_MESSAGES/nautilus-image-manipulator.mo structure. Calls like this:

print _("Delete this profile")

return the properly translated string from the local .mo files, thank you very much.

In GTK+2/pygtk, there existed gtk.glade.bindtextdomain, but I'm wondering if there is any equivalent in GTK+3/PyGObject.

To give you a specific example, this is how Nautilus Image Manipulator;s UI is created from its Glade file:

from gi.repository import Gtk
builder = Gtk.Builder()
builder.set_translation_domain('nautilus-image-manipulator')
builder.add_from_file(ui_filename)
return builder

Parts of the UI that are not built from the Glade file (i.e. set from code) show up properly translated, but the strings from the Glade file still show up in English.

It seems to me that I'm missing a call to some kind of builder.bind_text_domain('nautilus-image-manipulator', '/path/to/mo/folder') before the call to builder.set_translation_domain... Any idea how to perform this?

Owing

Have you tried just the usual gettext.bindtextdomain()? – Gilboa

Answer 1

In PyGtk you can use Gtk.Builder too. Accordingly to the PyGtk Gtk.Builder documentation:

http://developer.gnome.org/pygtk/stable/class-gtkbuilder.html#properties-gtkbuilder

The translation domain used when translating property values that have been marked as translatable in interface descriptions. If the translation domain is None, GtkBuilder uses gettext(), otherwise dgettext(). Default value: None

That is, Gtk.Builder uses dgettext() from "C library". The problem is that Python's gettext module, function bindtextdomain(), for some reason unknown to me, don't set the "C library". The option is to use the locale module that also exposes that interface. From the Python locale module documentation:

http://docs.python.org/library/locale#access-to-message-catalogs

The locale module exposes the C library’s gettext interface on systems that provide this interface. It consists of the functions gettext(), dgettext(), dcgettext(), textdomain(), bindtextdomain(), and bind_textdomain_codeset(). These are similar to the same functions in the gettext module, but use the C library’s binary format for message catalogs, and the C library’s search algorithms for locating message catalogs.

Python applications should normally find no need to invoke these functions, and should use gettext instead. A known exception to this rule are applications that link with additional C libraries which internally invoke gettext() or dcgettext(). For these applications, it may be necessary to bind the text domain, so that the libraries can properly locate their message catalogs.

Which, is the current case. What a hack :S

This will do it, file test.py:

from gi.repository import Gtk
from os.path import abspath, dirname, join, realpath
import gettext
import locale

APP = 'myapp'
WHERE_AM_I = abspath(dirname(realpath(__file__)))
LOCALE_DIR = join(WHERE_AM_I, 'mo')

locale.setlocale(locale.LC_ALL, '')
locale.bindtextdomain(APP, LOCALE_DIR)
gettext.bindtextdomain(APP, LOCALE_DIR)
gettext.textdomain(APP)
_ = gettext.gettext

print('Using locale directory: {}'.format(LOCALE_DIR))

class MyApp(object):

    def __init__(self):
        # Build GUI
        self.builder = Gtk.Builder()
        self.glade_file = join(WHERE_AM_I, 'test.glade')
        self.builder.set_translation_domain(APP)
        self.builder.add_from_file(self.glade_file)

        print(_('File'))
        print(_('Edit'))
        print(_('Find'))
        print(_('View'))
        print(_('Document'))

        # Get objects
        go = self.builder.get_object
        self.window = go('window')

        # Connect signals
        self.builder.connect_signals(self)

        # Everything is ready
        self.window.show()

    def main_quit(self, widget):
        Gtk.main_quit()

if __name__ == '__main__':
    gui = MyApp()
    Gtk.main()

My Glade file test.glade:

<?xml version="1.0" encoding="UTF-8"?>
<interface>
  <!-- interface-requires gtk+ 3.0 -->
  <object class="GtkWindow" id="window">
    <property name="can_focus">False</property>
    <property name="window_position">center-always</property>
    <property name="default_width">400</property>
    <signal name="destroy" handler="main_quit" swapped="no"/>
    <child>
      <object class="GtkBox" id="box1">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <property name="orientation">vertical</property>
        <child>
          <object class="GtkLabel" id="label1">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="label" translatable="yes">File</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">0</property>
          </packing>
        </child>
        <child>
          <object class="GtkLabel" id="label2">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="label" translatable="yes">Edit</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">1</property>
          </packing>
        </child>
        <child>
          <object class="GtkLabel" id="label3">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="label" translatable="yes">Find</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">2</property>
          </packing>
        </child>
        <child>
          <object class="GtkLabel" id="label4">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="label" translatable="yes">View</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">3</property>
          </packing>
        </child>
        <child>
          <object class="GtkLabel" id="label5">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="label" translatable="yes">Document</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">4</property>
          </packing>
        </child>
      </object>
    </child>
  </object>
</interface>

Remember to create the mo in mo/LANG/LC_MESSAGES/myapp.mo based on .po extracted with:

xgettext --keyword=translatable --sort-output -o en.po test.glade

What it looks like:

Kind regards

Uranometry

Thanks, this works fine. But I'm wondering what the line "locale.setlocale(locale.LC_ALL, '')" actually does - my application is translated even when I remove it... Is that call actually necessary? – Dunson

I added it as suggested here: docs.python.org/2/library/locale.html#locale.setlocale "This sets the locale for all categories to the user’s default setting (typically specified in the LANG environment variable)." This might be in cases where you night have for some reason LC_* variables different from LC_ALL I suppose, or in the case there is no locale variables, but I'm not really sure. – Uranometry

I know it's old, but I'm facing it now... This method seems to work on Linux only, since Windows doesn't have C library with gettext – Moskowitz

@Moskowitz If I remember you have to this something like this in Windows: github.com/carlos-jenkins/nested/blob/1.x/nested/… ... and maybe this to set the enviroment variable to gettext to work: github.com/carlos-jenkins/nested/blob/1.x/nested/… – Uranometry

Does it work with OS X? Last time I checked, locale.bindtextdomain didn't exist on this platform... (see github.com/multani/sonata/issues/67 ) – Lace

Answer 2

Well after the bounty failing so miserably to attract a mac os x answer, I had to do my own research. Here's the snippet I use:

import locale, ctypes, sys, os
import gettext

# setup textdomain and install _() for strings from python
gettext.install('domain', '/path/to/locale/dir')

try:
    if hasattr(locale, 'bindtextdomain'):
        libintl = locale
    elif os.name == 'nt':
        libintl = ctypes.cdll.LoadLibrary('libintl-8.dll')
    elif sys.platform == 'darwin':
        libintl = ctypes.cdll.LoadLibrary('libintl.dylib')

    # setup the textdomain in gettext so Gtk3 can find it
    libintl.bindtextdomain('domain', '/path/to/locale/dir')

except (OSError, AttributeError):
    # disable translations altogether for consistency
    gettext.install('')

Later, when you have the Gtk.Builder, set the domain:

builder.set_translation_domain('domain')

This will only work if gettext's library libintl is in the library path, otherwise fail gracefully. For transaltions to work, you will need to install gettext as a dependency.

Compton

Answer 3

The solution to activate gettext translations in Gtk / python under Windows is elib_intl.py It is easy to find the file with Google. This allows translation of text in the code and text in a glade UI.

Here is the code used for the following environment :

Windows 7 Python 2.7 Gtk 3+ loaded by : pygi-aio-3.10.2-win32_rev18-setup.exe

It should work in any windows and also for Python 3. elib_intl.py can be used with pyGtk (Gtk 2).

from gi.repository import Gtk, Gdk
import cairo

import locale       #for multilanguage support
import gettext
import elib_intl
elib_intl.install("pdfbooklet", "share/locale")

If you are using Gtk 3, you will probably receive an error : for line 447 :

libintl = cdll.intl

This error indicates : module not found. The reason is that in Gtk3, the name of the dll has been changed. It is no longer intl.dll. In the described Pygi installation the name is : libintl-8. You must replace the line which provoques the error by :

libintl = cdll.LoadLibrary("libintl-8.dll")

You can find a full working example here : pdfBooklet 2.4.0 (Warning : not yet in line when I write)

thanks to dieter Verfaillie who has written elib_intl

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