GTK+

GTK+

gtk3-widget-factory, is a collection of examples demonstrating many of the GUI widgets in GTK+ version 3
Original author(s)	Spencer Kimball, Peter Mattis, eXperimental Computing Facility (XCF)
Developer(s)	The GNOME Project
Initial release	April 14, 1998 (1998-04-14)
Stable release	3.18.7 (January 28, 2016 (2016-01-28)) [±]
Preview release	3.20 (Not Released Yet[1]) [±]
Development status	Active
Written in	C[2]
Operating system	Linux, Unix-like, OS X, Windows
Available in	Multilingual
Type	Widget toolkit
License	LGPL version 2.1
Website	www.gtk.org

GTK+ (formerly GIMP Toolkit, sometimes incorrectly termed the GNOME Toolkit) is a cross-platform^[3] widget toolkit for creating graphical user interfaces. It is licensed under the terms of the LGPL, allowing both free and proprietary software to use it. It is one of the most popular toolkits for the Wayland and X11 windowing systems, along with Qt.^[4]

Software architecture

Simplified software architecture of GTK+. Pango, GDK, ATK, GIO, Cairo and GLib

GDK contains back-ends to X11, Wayland, Broadway (HTTP), Quartz and GDI and relies on Cairo for the rendering. Its new SceneGraph is work-in-progress.

The GTK+ library contains a set of graphical control elements (widgets), version 3.13.3 contains 203 active and 37 deprecated widgets. GTK+ is an object-oriented widget toolkit written in the C programming language; it uses GObject, that is the GLib object system, for the object orientation. While GTK+ is primarily targeted at windowing systems based upon X11 and Wayland, it works on other platforms, including Microsoft Windows (interfaced with the Windows API), and Mac OS X (interfaced with Quartz). There is also an HTML5 back-end called Broadway.

GTK+ can be configured to change the look of the widgets drawn; this is done using different display engines. Several display engines exist which try to emulate the look of the native widgets on the platform in use.

Starting with version 2.8, released in 2005, GTK+ began the transition to using Cairo to render the majority of its graphical control elements.^[5] Since GTK+ version 3.0, all the rendering is done using Cairo.

GTK+ Scene Graph Kit (GSK)

• GTK+ Scene Graph Kit (GSK) is the forthcoming scene graph (canvas) for GTK+ in the process of being written by Emanuele Bassi.^[6]

GSK is planned to be ready and fully integrated into GTK+ version 3.20, to be released in March 2016.^[7]

• Graphene is a collection of geometry types — points, sizes, rectangles, vectors, quads, quaternions, matrices. It tries to optimize them so that the naive, four floats for vertex/four vertices for matrix implementation is not the only one available. Graphene's API makes it possible to avoid exposing C arrays of floating point values, or opaque memory regions, enabling the manipulation of vectors and matrices in other languages as well.

Having OpenGL (or OpenGL ES) support in GDK facilitates a slightly better control of the graphics pipeline; OpenGL is well suited for compositing textured data but totally unsuited for drawing.^[8]

Before the adoption of GSK, application developers could optionally use Clutter. The way widgets were drawn in GTK+, was, that a draw function drew everything. There was no way to know, what has just been drawn. To know where the mouse pointer was currently hovering over, the current position had to be computed.

With GSK, it should be fairly easy to write complex graphical control elements (widgets) and still track easily the whereabout of the mouse pointer. Getting more conformation with CSS should also arrive.

GTK+ input system

The GTK+ input system is basically the X input system. To handle anything more complicated than a simple mouse button press, e.g. a double click or a long button press, the developer is required to track time and add a time out somewhere.

GtkInspector

GtkInspector has been introduced with version 3.14.^[9][10] GtkInspector can only be invoked after installing the development package libgtk-3-dev/gtk+-devel.

GUI designers

There are several GUI designers for GTK+. The following projects are active as of July 2011:

• Glade, supports GtkBuilder, which is a GTK+ built-in GUI description format.
• Gazpacho, GUI builder for the GTK+ toolkit written in Python^[11]
• Crow Designer, relies on its own GuiXml format and GuiLoader library.^[12]
• Stetic, part of MonoDevelop, oriented towards Gtk#.

GtkBuilder

GtkBuilder offers you the opportunity to design user interfaces without writing a single line of code. This is possible through describing the interface by a XML file and then loading the XML description at runtime and create the objects automatically, which the Builder class does for you. For the purpose of not needing to write the XML manually the Glade Interface Designer lets you create the user interface in a WYSIWYG manner.

This method has several advantages:

• Less code needs to be written.
• UI changes can be seen more quickly, so UIs are able to improve.
• Designers without programming skills can create and edit UIs.
• The description of the user interface is independent from the programming language being used.

There is still code required for handling interface changes triggered by the user, but Gtk.Builder allows you to focus on implementing that functionality.^[13]

Language bindings

A library written in one programming language may be used in another language if bindings are written; GTK+ has a range of bindings for various languages.^[14]

Gtk#

Gtk#

Developer(s)	Xamarin
Stable release	2.12.22 / April 5, 2012 (2012-04-05)
Written in	C#, XML, Perl, C
Operating system	Windows, OS X, Linux
Type	Widget toolkit
License	GNU Lesser General Public License
Website	mono-project.com/GtkSharp

Gtk# is a set of .NET bindings for the GTK+ GUI toolkit and assorted GNOME libraries. The library facilitates building graphical GNOME applications using Mono or any other compliant CLR. Gtk# is an event-driven system like any other modern windowing library where every widget allows you to associate handler methods, which get called when particular events happen.

Applications built using Gtk# will run on many platforms including Linux, Windows and OS X. The Mono packages for Windows include GTK+, Gtk# and a native theme to make applications look like native Windows applications. Starting with Mono 1.9, running Gtk# applications on Mac OS X no longer requires the user to run the X11 server.^[15]

Glade can be used with the Glade# bindings to easily design GUI applications. A GUI designer called Stetic is integrated with the MonoDevelop IDE.

In addition to support the standard GTK/GNOME stack of development tools, the gtk-dotnet.dll assembly provides a bridge to consume functionality available on the .NET stack. At this point this includes the functionality to use System.Drawing to draw on a widget.

Uses

The GTK+ support for Wayland, co-requisites applications to be adapted to Wayland as well

Screenshot of GIMP 2.4. GTK+ is responsible for managing the interface components of the program, including the menus, buttons, and input fields.

Applications

• GNOME Core Applications – employs the newest GUI widgets from the cutting-edge version of GTK+ and demonstrates its capabilities.

Desktop environments

Several desktop environments utilize GTK+ as the widget toolkit.

• Unity, the default desktop environment of Ubuntu
• GNOME, based on GTK+, meaning that programs native to GNOME use GTK+
• Consort, the GNOME 3.4 Fallback Mode – fork from SolusOS
• Cinnamon, a fork of GNOME 3 and uses GTK+ version 3
• MATE, a fork of GNOME 2 made after the release of GNOME 3 and thus uses GTK+ version 2 (support for GTK+ version 3 is in development.)
• Xfce, currently based on GTK+ 2 with support for and eventual plans for a migration to GTK+ 3
• LXDE (Lightweight X11 Desktop Environment) is based on GTK+ 2
• Pantheon uses GTK+ 3 exclusively, being developed by elementary OS
• Sugar is a desktop environment oriented towards children's education, which uses GTK+, especially PyGTK
• ROX Desktop, a lightweight desktop, with features from the GUI of RISC OS
• GPE, the GPE Palmtop Environment
• Access Linux Platform (successor of the Palm OS PDA platform)
• KDE, though based on Qt, has integration with GTK+-based programs and themes since version 4.2

GTK+ programs can run on top of X11-based desktop environments or window managers even those not made with GTK+, provided the required libraries are installed; this includes Mac OS X if X11.app is installed. GTK+ can also run under Microsoft Windows, where it is used by some popular cross-platform applications like Pidgin and GIMP. wxWidgets, a cross-platform GUI toolkit, uses GTK+ for GNU/Linux operating systems.^[16] Other ports include DirectFB (used by the Debian installer, for example) and ncurses.^[17]

Window managers

The following window managers use GTK+:

Applications

Some notable applications that use GTK+ as a widget toolkit include:

Example

The following code presents a graphical GTK+ hello-world program in the C programming language. This program has a window with the title "Hello, world!" and a label with similar text.

#include <gtk/gtk.h>

int main (int argc, char *argv[])
{
    GtkWidget *window;
    GtkWidget *label;

    gtk_init(&argc, &argv);

    /* Create the main, top level window */
    window = gtk_window_new(GTK_WINDOW_TOPLEVEL);

    /* Give it the title */
    gtk_window_set_title(GTK_WINDOW(window), "Hello, world!");

    /* Center the window */
    gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);

    /* Set the window's default size */
    gtk_window_set_default_size(GTK_WINDOW(window), 200, 100);

    /*
    ** Map the destroy signal of the window to gtk_main_quit;
    ** When the window is about to be destroyed, we get a notification and
    ** stop the main GTK+ loop by returning 0
    */
    g_signal_connect(window, "destroy", G_CALLBACK(gtk_main_quit), NULL);

    /*
    ** Assign the variable "label" to a new GTK label,
    ** with the text "Hello, world!"
    */
    label = gtk_label_new("Hello, world!");

    /* Plot the label onto the main window */
    gtk_container_add(GTK_CONTAINER(window), label);

    /* Make sure that everything, window and label, are visible */
    gtk_widget_show_all(window);

    /*
    ** Start the main loop, and do nothing (block) until
    ** the application is closed
    */
    gtk_main();

    return 0;
}

Needs installing the libraries first in debian or derivatives:

$ sudo apt-get install libgtk-3-dev

Using pkg-config in a Unix shell, this code can be compiled with the following command (assume above source has file name "helloworld.c"):

$ cc -Wall helloworld.c -o helloworld $(pkg-config --cflags --libs gtk+-3.0)

Invoke the program

$ ./helloworld

History

GTK+ was originally designed and used in the GNU Image Manipulation Program (GIMP) as a replacement of the Motif toolkit; at some point Peter Mattis became disenchanted with Motif and began to write his own GUI toolkit called the GIMP toolkit and had successfully replaced Motif by the 0.60 release of GIMP.^[18] Finally GTK was re-written to be object-oriented and was renamed GTK+.^[19] This was first used in the 0.99 release of GIMP. GTK+ was subsequently adopted for maintenance by the GNOME Foundation, which uses it in the GNOME desktop environment.

The GTK+ 2.0.0 release series introduced new features which include improved text rendering using Pango, a new theme engine, improved accessibility using the Accessibility Toolkit, transition to Unicode using UTF-8 strings, and a more flexible API. Starting with version 2.8, GTK+ 2 depends on the Cairo graphics library for rendering vector graphics.

GTK+ version 3.0.0 included revised input device handling, support for themes written with CSS-like syntax, and the ability to receive information about other opened GTK+ applications.

Releases

The GNOME team releases new versions on a regular basis.

Future developments

As of version 3.14.1 the development of GTK+ is still ongoing at a fast pace. Components are being worked on and with the arrival of the new scene graph system (canvas) may be finally released with version 4.0.

Criticisms

The most common criticism towards GTK+ is a lack of backwards-compatibility in major updates, most notably in the API:^[34]

• Dirk Hohndel, co-developer of Subsurface and member of Intel's Open-Source Technology Center, criticized the GTK+ developers for being abrasive and ignoring most community requests.^[35]
• Hong Jen Yee, developer of LXDE, expressed disdain for version 3 of the GTK+ toolkit's radical API changes and increased memory usage, and ported PCManFM to Qt as a result.^[36]
• The Audacious music player plans to move back to GTK+ version 2 starting with version 3.6, with the long-term goal of migrating to Qt.^[37] The reasons stated by the developers for this include a transition to client-side window decorations, which they claim cause the application to look "GNOME-y and out of place."^[38]
• Wireshark also is transitioning to use Qt for poor GTK+'s cross-platform support.^[39]

See also

• GDK – the GIMP Drawing Kit lies between the xlib and the GTK+ library, handling basic rendering such as drawing primitives, raster graphics (bitmaps), cursors, fonts, as well as window events and drag-and-drop functionality
• gtkmm – C++ bindings for GTK+
• Qt - cross platform framework and toolkit
• Enlightenment Foundation Libraries (EFL) – widget toolkit written for the Enlightenment window manager
• FLTK – A light, cross-platform, non-native widget toolkit
• FOX toolkit – A fast, open source, cross-platform widget toolkit
• IUP – a multi-platform toolkit for building native graphical user interfaces
• Object Windows Library (OWL)
• Ultimate++
• Visual Component Library (VCL)
• Windows Forms – the system for creating graphical user interfaces and elements in the Microsoft family of products
• Windows Presentation Foundation – the system created by Microsoft to replace Windows Forms in GUI development
• List of widget toolkits

References

Bibliography

External links

The Wikibook X Window Programming has a page on the topic of: GTK+

• Official website
• GTK+ 3 Reference Manual
• List of GTK+ applications
• GTK+ for Windows (MinGW) on SourceForge.net

GTK+ applications Platform GTK+ GTK+ GDK ATK ClutterActor GTK+ Scene Graph Kit Pango Pigment Language bindings PyGTK PyGObject GLib GObject GIO IBus Orca dconf Genie Vala Keyring GNOME-DB GVfs Hildon Librsvg MetaTracker libxslt libxml2 freedesktop.org (shared) AppStream D-Bus GStreamer NetworkManager Poppler libcanberra Wayland X.Org Server PulseAudio PackageKit HarfBuzz Cairo Development GUI designer, RAD Glade Interface Designer GNOME Builder IDEs Anjuta Builder Bluefish Meld Devhelp Nemiver Poedit Geany Gtranslator gPHPedit PyRoom SciTE UberWriter PIDA GNOME GNOME Shell GNOME Games Core Applications Boxes Calculator Character Map Dictionary Disks Files Software Terminal Videos Web Other dconf editor Cinnamon Nemo Xfce Thunar LXDE PCMan File Manager LXMusic Graphical shells GNOME Panel Docky GNOME Do Avant Window Navigator GLX-Dock 3rd-party applications Office AbiWord Dia Gnumeric Evince Evolution Dictionary Ease OCRFeeder Education Gramps GCompris DrGeo GeoGebra Ghemical Celestia Chemtool Wine-Doors Graphics GIMP GNU Paint Inkscape gThumb gPhoto Eye of GNOME Sushi Shotwell F-Spot Viewnior Internet Balsa Sylpheed Claws Mail Empathy Ekiga Gobby gtk-gnutella GpsDrive SFLphone Vino (VNC server) Vinagre Midori Uzbl transmission-gtk Audio Audacious Banshee Buzztrax Exaile Rhythmbox Sound Juicer Quod Libet Ex Falso EasyTag Asunder Cheese Snappy Video gtkam Avidemux Cinelerra Kino LiVES OpenShot Video Editor Pitivi Gnome MPlayer Utilities Archive Manager Brasero dconf-editor Diodon gedit gnote Screenshot GParted Guake Leafpad Tilda Tomboy Workrave Category:GTK+ Category:Software that uses GTK+ Commons

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