How to update a Deluge 1.3 plugin for 2.0

With the new code in Deluge 2.0 there are changes that require authors of existing plugins to update their plugins to work on Deluge 2.0.

The main changes are with Python 3 support and the new GTK3 user interface with the dropping of GTK2. However it is still possible for a 1.3 plugin to be made compatible with 2.0 and this guide aims to helps with that process.

Note that the Deluge 2.0 plugins now use namespace packaging which is not compatible with Deluge 1.3.

Python

Python version matching

Ensure your code is both Python 2.7 and Python >=3.5 compatible.

In 1.3-stable the plugins that were built with a specfific version of Python could on be loaded if the system Python also matched.

This has change in Deluge 2.0 and it will load any Python version of plugin eggs so compatibility is essential for end-users not to encounter issues.

Six

Use six to assist with compatibility.

Unicode literals

Add this to files to ensure strings and bytes separatation so there are no surprises when running on Python 3.

GTK 3 addition

In order to support both Deluge 1.3 and 2.0 all existing plugin GTK UI files must be copied and then converted to contain only GTK3 code with the old files still using PyGTK e.g.:

cp gtkui.py gtk3ui.py

Convert from libglade to GtkBuilder

With PyGTK there were two library options for creating the user interface from XML files by default Deluge plugins used libglade but that has been deprecated and removed in GTK3. So the libglade .glade files will need converted to GtkBuilder .ui files and the Python code updated.

https://developer.gnome.org/gtk2/stable/gtk-migrating-GtkBuilder.html

gtk-builder-convert

Install the gtk-builder-convert converter on Ubuntu with:

sudo apt install libgtk2.0-dev

To convert your GTK run it like so:

gtk-builder-convert data/config.glade data/config.ui

Glade UI designer for GTK2

The above conversion can be done in Glade UI designer (version <=3.8), ensuring that the minimum Gtk version is set to 2.24 and any deprecated widgets are fixed. The updated file should be saved with file extension .ui.

Python code changes

The code needs to replace gtk.glade references with gtk.Builder and the first step is updating how the files are loaded:

- self.glade = gtk.glade.XML(get_resource("config.glade"))
+ self.builder = gtk.Builder()
+ self.builder.add_from_file(get_resource("config.ui"))

The next stage is to replace every occurange of these glade methods with the builder equivalents:

glade.signal_autoconnect -> builder.connect_signals
glade.get_widget -> builder.get_object

Migrate XML files to GTK3

If you open and save the file it will update with the new requirement header:

<!-- Generated with glade 3.18.3 -->
<interface>
  <requires lib="gtk+" version="3.0"/>

You can fix deprecated widgets but keep the minimum GTK version to <= 3.10 for desktop compatiblity.

An example of migrating a Deluge plugin to GtkBuilder: AutoAdd GtkBuilder

Gtk import rename

Move from PyGTK to GTK3 using Python bindings.

https://pygobject.readthedocs.io/en/latest/guide/porting.html

wget https://gitlab.gnome.org/GNOME/pygobject/raw/master/tools/pygi-convert.sh
cp gtkui.py gtk3ui.py
sh pygi-convert.sh gtk3ui.py

-import gtk
+from gi.repository import Gtk

- self.builder = gtk.Builder()
+ self.builder = Gtk.Builder()

Deluge GTK3

Imports will need updated from deluge.ui.gtkui to deluge.ui.gtk3.

PluginBase

-from deluge.plugins.pluginbase import GtkPluginBase
+from deluge.plugins.pluginbase import Gtk3PluginBase
-class GtkUI(GtkPluginBase):
+class Gtk3UI(Gtk3PluginBase):