Over on launchpad, I’ve released version 1.4 of the lab-session-manager, included in this release is:
You can get your hands on the PPA and give it try here: DoctorMo’s Greeter PPA, Let me know what you think below in the comments.
I’ve been really wanting to show all you lovely internet based friends the exciting and totally awesome Ubuntu based community center I’m setting up. So I created a video where I show off the login/registration greeter and the rest of the physical space.
Check out the video, it’s only about 4 minutes long: To play this video see the source mpeg or go here for flash player.
Post your comments below.
One of the requirements for this community greeter (login screen for community center machines) is the ability to switch languages. Normally to switch a language you would unload the greeter and relaunch it with a LANG environment variable and your new language would fall into place from gettext.
But I wanted more. First, what languages are installed on the computer? For this I used python-pybabel and gettext, these two tools working together allow me to both get all the installed languages, limit them to just those I have translations for and show the translated name for the language (see screenshot below).
I decided that what I wanted to do was to hot-swap the text in the widgets. Since I’m using gtkme extensions, I could achieve this by creating a TranslatableWindow class. It’s job is simply to go through the window container at load time and note down all the translatable strings from labels and tooltips:
class TranslatableWindow(gtkme.Window):
“””Provides functions for translating the window on the fly”””
def __init__(self, *args, **kwargs):
Window.__init__(self, *args, **kwargs)
self.labels = []
self.tips = []
self.store_translations(self.window)def store_translations(self, widget):
“””Go through all widgets and store the translatable elements”””
for child in widget.get_children():
if isinstance(child, Gtk.Container):
self.store_translations(child)
if isinstance(child, Gtk.Label):
self.labels.append( (child, child.get_label()) )
if child.get_has_tooltip():
self.tips.append( (child, child.get_tooltip_text()) )def translate_to(self, lang):
“””Loop through everything and translate on the fly”””
lang = TEXTS[lang]
for (child, text) in self.labels:
child.set_label(lang.gettext(text))
for (child, text) in self.tips:
child.set_tooltip_markup(lang.gettext(text))
logging.debug(“Performed translation to %s” % lang)
Once I had translatable windows, I could tell my application class to go through each window and translate it if it was translatable:
def translate_to(self, lang):
“””Translate all windows to target language”””
for window in self._loaded.values():
if isinstance(window, TranslatableWindow):
logging.debug(“I18n window %s to %s” % (window.name, lang))
window.translate_to(lang)
Obviously because I’m not modifying the environment, when I log you on I need to update your language settings. I actually only show major language varieties and only ask about minor languages at registration time or when you change your setting:
If you’re even more curious, you can check out the code here: Launchpad Code or look at the translations here.
Update from my previous post: Here we have a branch containing a working gdm greeter user interface with a nice python module set for interacting with the gdm greeter service.
What’s nice about this code is how little of it you need to hack on the gdm. Binding up the username and password box to the events pretty much does everything. Most of the original functionality is simple to do.
The design isn’t final, there are gtk limitations and since gdm doesn’t really do clutter or opengl, it’d be impossible to do anything more interesting unfortunately.
The difference in functionality here is that you enter your full name (not your username) and it suggests people to you. The idea with this is that if you type in your name and you’re not a user, the next screen you see will be a register screen.
I selected my name from the list and then entered my passphrase:
Then it will log you in exactly as it should. Have a look at the code and see if you can hack on the gdm, it’s really very easy if you know a bit of python and gtk.
Comment if you do anything interesting.
In Ubuntu we use Gnome and the GDM (Gnome Display Manager) login screen called gdm-simple-greeter. This program is fairly fully featured for a normal Ubuntu install and even has a configuration in /etc/gdm/custom.conf which you can play around with.
But, I want to do something special, I’m making a computer lab with a registration screen and other fun stuff. I’ll blog about the designs and code for that in a future blog post. Today I’m going to talk about how I made a gdm greeter in python despite the lack of documentation and the round-about API challenges.
First thing to realise is that GDM 2.30 which shipped with Ubuntu 10.10 has a rich and full service/client API via DBus. This allows me to do what I’m going to do because it allows my program to act just like the shipped simple greeter. Only a single greeter can talk over the DBus API and it’s worth noting that the API isn’t over the normal System or Session Dbus, it’s over a private dbus unix socket to prevent all sorts of security issues with passing passwords around.
I first deactivated the GDM greeter: `mv /usr/share/gdm/autostart/LoginWindow/gdm-simple-greeter.desktop ~/Desktop/` this will now not allow you to log into Ubuntu!
Next I developed a script which uses python’s DBus lower layers to connect over the private dbus address. The address is given to us via an environment variable ‘GDM_GREETER_DBUS_ADDRESS’ and we just feed that in as it’s randomly generated. Fill in the PASSWORD and USERNAME variables to have GDM handle the communication and log in, this is certainly not a script you should leave installed and I have written a better one with a gui now, just use it as an example.
Finally I developed a .desktop file which will autoload the example script when the login is ready. Copying that into the directory `/usr/share/gdm/autostart/LoginWindow/`.
To restart GDM I used this command as root: `service gdm stop && sleep 1 && service gdm start`
I used a VirtualBox machine which I communicated over via SSH in order to test this out, over and over, hacking away at how this could be done. You can try the same. The log files you should be watching are in `/var/log/gdm/:0-greeter.log` you’ll get all the stderr messages from your login screen in there as well as all the errors.
You can use DBus System connections on org.gnome.DisplayManager.Display to control the display and org.gnome.DisplayManager.UserManager to get lists of users, user information and events for when users are added and removed from the system, same goes for network manager and a bunch of other services running during the login session.
I’ll blog more, and perhaps video when I’m finished. For now, if you’re interested in login screen development for Gnome2 (I don’t know what they’re doing for Gnome3) then this will interest you.