Introduction   GObject Introspection   GSettings   Notifications   Shell Extensions   The End




                    The GNOME3 Desktop and You

                          Guido Günther <agx@sigxcpu.org>



                                       FrOSCon 2011
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 About myself




               Freelancing Free Software Developer
               Debian Developer since 2000
               Contributions to GNOME/GTK+/GObject based apps since
               about 2008: krb5-auth-dialog, PPM, ModemManager,
               gtk-vnc, virt-manager
               I’m less an author but more a user of GNOME APIs.
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 About this talk




               Covers things I came across when working on the above
               projects in
               Tries to give an introduction so it’s simpler to dive deeper
               into it GNOME development
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       GNOME3
          GNOME is a desktop environment built on top of
          GTK+/GLib/GObject

               GNOME’s user interface is shaped by GNOME Shell
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 Overview


       1       Introduction

       2       GObject Introspection

       3       GSettings

       4       Notifications

       5       Shell Extensions

       6       The End
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 GTK+, GLib, GObject


               GLib is a cross platform C library that provides:
                    Data types: Lists, Hash Tables, Trees, Caches, Strings, ...
                    Application Support: Threads, Loadable Modules, Memory
                    Management, ...
                    Utilities: Timers, Checksums, Random Numbers, Parsers,
                    Testing framework, ...
                    gobject: The GLib Object system
                    gio: filesystem monitoring, async I/O, networking, DBus,
                    settings, ...
               GTK+3 is the widget toolkit
                    Based on GObject
                    Widgets, clipboard, key bindings, d’n’d, theming, ...
               Many other libraries are based on GObject: libsoup,
               gtk-vnc, telepathy, ...
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 GTK+, GLib, GObject


               GLib is a cross platform C library that provides:
                    Data types: Lists, Hash Tables, Trees, Caches, Strings, ...
                    Application Support: Threads, Loadable Modules, Memory
                    Management, ...
                    Utilities: Timers, Checksums, Random Numbers, Parsers,
                    Testing framework, ...
                    gobject: The GLib Object system
                    gio: filesystem monitoring, async I/O, networking, DBus,
                    settings, ...
               GTK+3 is the widget toolkit
                    Based on GObject
                    Widgets, clipboard, key bindings, d’n’d, theming, ...
               Many other libraries are based on GObject: libsoup,
               gtk-vnc, telepathy, ...
Introduction      GObject Introspection   GSettings   Notifications   Shell Extensions   The End

 GNOME Shell




               Workspace and window management
               Application life cycle
               Notification system
               Integrated IM
               Can be extended in JavaScript
               much more...
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 GNOME Shell




               Workspace and window management
               Application life cycle
               Notification system
               Integrated IM
               Can be extended in JavaScript
               much more...
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 What’s a GObject




               GLib has it’s own dynamic type system:
                    Non classed: numbers, pointers, ...
                    Instantiable classed types: objects
                    Non-instantiable classed types: interfaces
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 What’s a GObject




               GLib has it’s own dynamic type system:
                    Non classed: numbers, pointers, ...
                    Instantiable classed types: objects
                    Non-instantiable classed types: interfaces
               GObject is the base class of GLib’s type system
                    provides: signals, memory management, per-object
                    properties
               Written in C, very binding friendly
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 What is it?



                        python-gtk-vnc
         gtk-vnc                                                 Python
                           foo-gtk-vnc




                          python-notify
        libnotify                                                    Foo
                            foo-notify
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 What is it?


               Layer to use GObject based libraries written in C from
               other languages like:
                    JavaScript (gjs, seed)
                    Python (PyGObject)
                    ruby
                    scheme
                    PHP
                    and more

       GObject Introspection
               Only one dynamic binding per language needed to use all
               GObject introspection enabled libraries.
               No outdated bindings!
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 What is it?




         gtk-vnc                       PyGObject                 Python




        libnotify                      foo dynamic
                                         binding                     Foo
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 How does it work?


               When writing the C library
                    Add annotations to the libraries source code (reference
                    counting, allocation)
               C library build time
                    Scanner (g-ir-scanner) generates GIR (XML) from sources
                    and built libraries
                            Debian: *-dev packages in /usr/share/gir-1.0/*.gir
                    Compiler (g-ir-compiler) to compile GIR to typelib
                            Debian: gir1.2-* packages in /usr/lib/girepository-1.0/*.typelib
               Runtime (e.g. gjs or Python+PyGObject)
                    libgirepository to read the introspection data
                    libffi to make library callable from other language
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 What is it?




                                               PyGObject
         gtk-vnc                                                             Python
                                            libgirepository + libffi
         gtk-vnc typelib




        libnotify                             foo dynamic
                                                binding                          Foo
         libnotify typelib
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 How to use it from JavaScript?
       JavaScript VNC viewer1
       gvncviewer.js - VNC in 10 lines
       const Gtk = imports.gi.Gtk;


       Gtk.init(0, null);




       Gtk.main();

               1
                   Example taken from gtk-vnc/examples
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 How to use it from JavaScript?
       JavaScript VNC viewer1
       gvncviewer.js - VNC in 10 lines
       const Gtk = imports.gi.Gtk;


       Gtk.init(0, null);
       var win = new Gtk.Window({title: "GTK-VNC"});




       Gtk.main();

               1
                   Example taken from gtk-vnc/examples
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 How to use it from JavaScript?
       JavaScript VNC viewer1
       gvncviewer.js - VNC in 10 lines
       const Gtk = imports.gi.Gtk;
       const Vnc = imports.gi.GtkVnc;

       Gtk.init(0, null);
       var win = new Gtk.Window({title: "GTK-VNC"});




       Gtk.main();

               1
                   Example taken from gtk-vnc/examples
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 How to use it from JavaScript?
       JavaScript VNC viewer1
       gvncviewer.js - VNC in 10 lines
       const Gtk = imports.gi.Gtk;
       const Vnc = imports.gi.GtkVnc;

       Gtk.init(0, null);
       var win = new Gtk.Window({title: "GTK-VNC"});
       var disp = new Vnc.Display();

       win.add(disp);



       Gtk.main();

               1
                   Example taken from gtk-vnc/examples
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 How to use it from JavaScript?
       JavaScript VNC viewer1
       gvncviewer.js - VNC in 10 lines
       const Gtk = imports.gi.Gtk;
       const Vnc = imports.gi.GtkVnc;

       Gtk.init(0, null);
       var win = new Gtk.Window({title: "GTK-VNC"});
       var disp = new Vnc.Display();

       win.add(disp);

       disp.open_host(”localhost”, ”5901”);

       Gtk.main();

               1
                   Example taken from gtk-vnc/examples
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 How to use it from JavaScript?
       JavaScript VNC viewer1
       gvncviewer.js - VNC in 10 lines
       const Gtk = imports.gi.Gtk;
       const Vnc = imports.gi.GtkVnc;

       Gtk.init(0, null);
       var win = new Gtk.Window({title: "GTK-VNC"});
       var disp = new Vnc.Display();

       win.add(disp);

       disp.open_host(”localhost”, ”5901”);
       win.show_all();
       Gtk.main();

               1
                   Example taken from gtk-vnc/examples
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 How to use it from JavaScript?
       JavaScript VNC viewer1
       gvncviewer.js - VNC in 10 lines
       const Gtk = imports.gi.Gtk;
       const Vnc = imports.gi.GtkVnc;

       Gtk.init(0, null);
       var win = new Gtk.Window({title: "GTK-VNC"});
       var disp = new Vnc.Display();

       win.add(disp);
       win.connect(’delete-event’, Gtk.main_quit);
       disp.open_host(”localhost”, ”5901”);
       win.show_all();
       Gtk.main();

               1
                   Example taken from gtk-vnc/examples
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 How to use it from Python?


       gvncviewer.py - VNC in 9 lines
       from gi.repository import GtkVnc, Gtk

       Gtk.init(None)
       win = Gtk.Window(title="GTK-VNC with Python")
       disp = GtkVnc.Display()

       win.add(disp)
       win.connect(’delete-event’, Gtk.main_quit)
       disp.open_host("localhost", "5901")
       win.show_all()
       Gtk.main()
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 What do I need?


       Programming language, dynamic bindings, typelib files
       JavaScript example
       apt-get install gjs                   \
                          gir1.2-gtk-3.0     \
                          gir1.2-gtk-vnc-2.0

       Python example
       apt-get install python-gobject                              \
                       gir1.2-gtk-3.0                              \
                       gir1.2-gtk-vnc-2.0

       Note: no python-gtk-vnc, python-gtk2!
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 GObjects in JS, Python and C

               Constructors
               var win = new Gtk.Window({title: "foo"}));
               win = Gtk.Window(title="foo")
               win = g_object_new (GTK_TYPE_WINDOW,
                                   "title", "foo", NULL);
               Signals
               win.connect("delete-event", callable);
               win.connect("delete-event", callable);
               g_signal_connect (win, "delete-event",
                                 gcallback, NULL);
               Properties
               win["title"]; win.title
               win.props.title
               g_object_get (win, "title", &title, NULL);
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 What is it?


               API to retrieve and store configuration settings
               Easy to bind to GObject properties to settings
               Change notification via signals
               Supports different backends
                    DConf: store settings key based on disk
                    Memory
               XML schema describes location and types of keys
               Vendor overrides possible
               Delay mode
               Complex types possible using GVariant
               obsoletes gconf, gconf-bridge
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 How to use it?


       Shell example
         gsettings get \
             org.gnome.system.proxy.http enabled
         gsettings set \
             org.gnome.system.proxy.http enabled true

       Python example
         python proxysettings.py

       GUI
         dconf-editor
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 What do I need?




       Example
       apt-get install libglib2.0-bin \
                       dconf dconf-tools
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 What is it?



               GNOME Shell’s message tray displays and manages
               notifications to the user
               Notifications:
                   Provide feedback to the user
                   Displayed for a short period of time at the bottom of the
                   screen
                   By default persistent: saved until interacted with or
                   application is opened
                   Less distractive since no need to interact instantly
                   Can be globally disabled
                   Resident and transient notifications possible
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 How to use it?

       gvncviewer.notify.py
       from gi.repository import Notify
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 How to use it?

       gvncviewer.notify.py
       from gi.repository import Notify

       def notify(obj, v):
         n = Notify.Notification(
               summary="Connected to %(host)s" % v,
               body="Made VNC connection to "
                    "server %(host)s at port"
                    " %(port)s" % v)
         n.set_hint("resident",
                    GLib.Variant(’b’, True))
         n.show()
Introduction   GObject Introspection   GSettings   Notifications   Shell Extensions   The End

 How to use it?

       gvncviewer.notify.py
       from gi.repository import Notify

       def notify(obj, v):
         n = Notify.Notification(
               summary="Connected to %(host)s" % v,
               body="Made VNC connection to "
                    "server %(host)s at port"
                    " %(port)s" % v)
         n.set_hint("resident",
                    GLib.Variant(’b’, True))
         n.show()
       ...
       disp.connect("vnc-connected", notify,
                    vncserver)
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 What do I need




       Python example
       apt-get install gir1.2-notify-0.7
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 GNOME Shell




               GNOME3 desktop shell written in C and JavaScript
               Heavily uses Clutter
               Extendable via JavaScript and GObject Introspection
               Available Extensions:
               https://live.gnome.org/GnomeShell/Extensions
               The shell has a built JavaScript inspector/debugger
               (ALT-F2 → lg)
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 How to use them?




       Create new extension
       gnome-shell-extension-tool --create-extension

       Example
       Example Launch_Iceowl@sigxcpu.org/
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 What do I need?



       Example
       apt-get install -t experimental gnome-shell

       Your own extension
       git clone git://git.gnome.org/gnome-shell.git

               gjs style guide
               An idea about GObject Introspection (see above)
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 Porting to GTK+3, GDBus, GSettings, PyGObject



               GNOME3 porting guide:
               http://live.gnome.org/Gnome3PortingGuide
               GTK+2 → GTK+3:
               http://developer.gnome.org/gtk3/3.0/migrating.html
               GConf → GSettings
               http://developer.gnome.org/gio/stable/ch28.html
               dbus-glib → GDBus
               http://developer.gnome.org/gio/unstable/ch29.html
               python-gtk → PyGObject:
               http://git.gnome.org/browse/pygobject/tree/pygi-convert.sh
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 API documentation



               API Documentation for PyGObject and gjs:
                    Look at the the C API documentation, it’s well documented
                    You can infer Python or JavaScript calls form there

       Example
           gtk_widget_show_all(GtkWidget* widget);
           widget.show_all();
           widget.show_all()

               If in doubt consult the GIR file
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 API documentation


               Generating language specific docs from the introspection
               information is in the works:
                    http://www.j5live.com/2011/08/15/
                    gobjects-in-berlin-the-search-for-more-documentation/
                    https://live.gnome.org/GObjectIntrospection/Doctools

       Development with vim
       apt-get install vim-syntax-gtk \
                           devhelp libgtk-3-doc

       .vimrc
          autocmd Filetype c nmap <silent> <C-K>
               :! devhelp -s "<cword>" &<CR><CR>
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 Thank you



               Thanks!
               Questions?


               Source code and examples are at:
       git clone git://honk.sigxcpu.org/git/talks/2011-08-gnome3-froscon.git




       CC BY-SA 3.0 — Creative Commons Attribution-ShareAlike 3.0
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 Changes in GTK+, GObject, GLib


               GObject Introspection

               GSettings: Settings DB now included
               GDBus: API to access DBus now included



               GtkBuilder: UI XML now included
               GTK+3 uses Cairo
               Multiple GDK backend support (Wayland, HTML5)
               Themes use CSS
Introduction      GObject Introspection   GSettings   Notifications   Shell Extensions   The End

 Changes in GTK+, GObject, GLib


               GObject Introspection → obsoletes writing language
               bindings for each library and language
               GSettings: Settings DB now included → obsoletes GConf
               GDBus: API to access DBus now included → obsoletes
               dbus-glib


               GtkBuilder: UI XML now included → obsoletes libglade
               GTK+3 uses Cairo → obsoletes GDK drawing API
               Multiple GDK backend support (Wayland, HTML5)
               Themes use CSS
Introduction      GObject Introspection   GSettings   Notifications   Shell Extensions   The End

 Changes in GTK+, GObject, GLib


               GObject Introspection → obsoletes writing language
               bindings for each library and language
               GSettings: Settings DB now included → obsoletes GConf
               GDBus: API to access DBus now included → obsoletes
               dbus-glib


               GtkBuilder: UI XML now included → obsoletes libglade
               GTK+3 uses Cairo → obsoletes GDK drawing API
               Multiple GDK backend support (Wayland, HTML5)
               Themes use CSS
Introduction     GObject Introspection   GSettings      Notifications   Shell Extensions   The End




       Annotations example
       /**
         * soup_message_body_append_take:
         * @body: a #SoupMessageBody
         * @data: (array length=length) (transfer full): data to append
         * @length: length of @data
         *
         * Appends @length bytes from @data to @body.
         *
         * This function is exactly equivalent to soup_message_body_apppend()
         * with %SOUP_MEMORY_TAKE as second argument; it exists mainly for
         * convenience and simplifying language bindings.
         *
         * Since: 2.32
         * Rename to: soup_message_body_append
         **/
       void
       soup_message_body_append_take (SoupMessageBody *body,
                                       guchar *data, gsize length)
       {
                soup_message_body_append(body, SOUP_MEMORY_TAKE, data, length);
       }