Sunday, November 30, 2008

FreeSpeak gains translation suggestions

Hello,
it hasn't been a long time since FreeSpeak 0.2.0 has been released. One of the TODOs for the next release was to support open-tran, and more over translation suggestions for development.
This is a screenshot of what's been included in the repository today:
From GNOME
FreeSpeak is a GNOME frontend to online translator engines.

Friday, November 28, 2008

FreeSpeak 0.2.0 has been released

Hello,
after some work in these weeks now I have released a new version of FreeSpeak.

FreeSpeak is a free (as in freedom, developed and released under the terms of GPL) frontend to online translator engines (such as Google, Yahoo, etc.). It is written in Python, it uses the GTK toolkit and some GNOME infrastructure features



.
It's been rewritten almost from scratch so I think there's no need to post release notes here. Anyway you can always read what changed from the old version released a couple of years ago here.

Notice that the project homepage has been changed. The project has now moved to BerliOS.de.

Sunday, November 23, 2008

Replace GTK+ with Clutter for fun

Hello,
lately I was having fun with Clutter and Python. I've started by creating some Gtk-like widgets (such as GtkWindow, GtkBox, and GtkButton) in Clutter.
Well, this is the result... it's a simple example of a very poor toolkit, but it works:

Try it, it's only one .py file source code

Sunday, November 16, 2008

Single app instances, Python and DBus

Hello,
I'm working on FreeSpeak lately and I needed to run the application once per session, as it's got a trayicon and a notebook (maybe windows with an applet is better?)
I decided to use DBus for making the application run only a single instance; when you try to open it again it won't start another process, instead it will use the already running one.

This is how I would create a generic single app instance with dbus-python:
import dbus
import dbus.bus
import dbus.service
import dbus.mainloop.glib
import gobject

class Application (dbus.service.Object):
def __init__ (self, bus, path, name):
dbus.service.Object.__init__ (self, bus, path, name)
self.loop = gobject.MainLoop ()

@dbus.service.method ("org.domain.YourApplication",
in_signature='a{sv}', out_signature='')
def start (self, options={}):
if self.loop.is_running ():
print 'instance already running'
else:
self.loop.run ()

dbus.mainloop.glib.DBusGMainLoop (set_as_default=True)
bus = dbus.SessionBus ()
request = bus.request_name ("org.domain.YourApplication", dbus.bus.NAME_FLAG_DO_NOT_QUEUE)
if request != dbus.bus.REQUEST_NAME_REPLY_EXISTS:
app = Application (bus, '/', "org.domain.YourApplication")
else:
object = bus.get_object ("org.domain.YourApplication", "/")
app = dbus.Interface (object, "org.domain.YourApplication")

# Get your options from the command line, e.g. with OptionParser
options = {'option1': 'value1'}
app.start (options)
How it works?
  1. Setup the mainloop for dbus
  2. Request a session bus name, so that other applications (in our case another instance of the same application) can connect to it
  3. Create a new instance at path / if the bus name doesn't exist (so we are the primary owner). If it exists, then obtain the object from dbus and call the method on the remote Application object using the known interface.
  4. The Application.start method checks if it's already running then decide what to do in both situations.
Creating a GTK+ application this way is really easy. It only needs to use the GTK+ mainloop.
Let's suppose we want to present() the GtkWindow when the user tries to open another instance of the application:
import dbus
import dbus.bus
import dbus.service
import dbus.mainloop.glib
import gobject
import gtk
import gtk.gdk
import time

class Application (dbus.service.Object):
def __init__ (self, bus, path, name):
dbus.service.Object.__init__ (self, bus, path, name)
self.running = False
self.main_window = gtk.Window ()
self.main_window.show_all ()

@dbus.service.method ("org.domain.YourApplication",
in_signature='', out_signature='b')
def is_running (self):
return self.running

@dbus.service.method ("org.domain.YourApplication",
in_signature='a{sv}i', out_signature='')
def start (self, options, timestamp):
if self.is_running ():
self.main_window.present_with_time (timestamp)
else:
self.running = True
gtk.main ()
self.running = False

dbus.mainloop.glib.DBusGMainLoop (set_as_default=True)
bus = dbus.SessionBus ()
request = bus.request_name ("org.domain.YourApplication", dbus.bus.NAME_FLAG_DO_NOT_QUEUE)
if request != dbus.bus.REQUEST_NAME_REPLY_EXISTS:
app = Application (bus, '/', "org.domain.YourApplication")
else:
object = bus.get_object ("org.domain.YourApplication", "/")
app = dbus.Interface (object, "org.domain.YourApplication")

# Get your options from the command line, e.g. with OptionParser
options = {'option1': 'value1'}
app.start (options, int (time.time ()))
if app.is_running ():
gtk.gdk.notify_startup_complete ()
How it works?

Let's say we're running the Application for the first time, the loop begins and when it ends running is set to False, so gtk.gdk.notify_startup_complete() won't be called. Instead, if the application is already running, start() will be called on the remote object running the loop. The method then returns immediately so gtk.gdk.notify_startup_complete() will be called.
If you don't notify to the launcher that the startup is complete... guess what happens to your mouse and to your taskbar panel...

If the loop is running, the window is presented to the user with a little delay. If you don't use any timestamp, the UI interaction won't let the window have the time to be presented.

Of course, you can use DBus for many more things, like both setting options from the command line, as explained in the above code, and let other applications communicate with yours and viceversa.
Nowadays almost all systems use DBus, so it won't be a pain to add such dependency. In my opinion, it would be much more painful to use lock files, FIFO, unix sockets or whatever. FreeSpeak used such old technologies and it was a very poor emulation of what DBus already offers.