GTK+

GTK+

Developer(s)	GNOME Foundation
Stable release	2.20.1 / May 2, 2010; 9 months ago (2010-05-02)
Preview release	2.90.6 / August 18, 2010; 5 months ago (2010-08-18)
Development status	Active
Written in	C
Operating system	Cross-platform
Platform	Cross-platform
Size	18 MB
Available in	Multilingual
Type	Widget toolkit
License	GNU Lesser General Public License
Website	www.gtk.org

GTK+ (GIMP Toolkit) is a cross-platform widget toolkit for creating graphical user interfaces. It is one of the most popular toolkits for the X Window System, along with Qt.

GTK+ was initially created for the GNU Image Manipulation Program (GIMP), a raster graphics editor, in 1997 by Spencer Kimball and Peter Mattis, members of eXperimental Computing Facility (XCF) at University of California, Berkeley.

GTK+ is licensed under the LGPL free software license and is part of the GNU Project, which aims to create a whole free-software operating system.

Design

GTK+ is an object-oriented widget toolkit written in the C programming language; object-orientation is achieved by using the GLib object system. On the X11 display server, GTK+ uses Xlib to draw widgets. Using Xlib provides flexibility and allows GTK+ to be used on platforms where the X Window System is unavailable. While GTK+ is primarily targeted at the X Window System, other platforms are supported, including Microsoft Windows, DirectFB and Quartz on Mac OS X.

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.

Programming language bindings

A library written in one programming language may be used in another programming language if bindings are written; GTK+ has bindings in many languages.^[1]

See the table below:

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.^[2] Finally GTK was re-written to be object oriented and was renamed GTK+. This was first used in the 0.99 release of GIMP.

GTK+ 2 has succeeded GTK+. Its new features include improved text rendering using Pango, a new theme engine, improved accessibility using the Accessibility Toolkit, complete transition to Unicode using UTF-8 strings, and a more flexible API. However, GTK+ 2 lacks compatibility with GTK+ 1, and programmers must port applications to it.

Starting with version 2.8, GTK+ 2 depends on the cairo graphics library for rendering vector graphics in GTK+ 2.

Future developments

Project Ridley is an attempt to consolidate several libraries that are currently external to GTK+, including libgnome, libgnomeui, libgnomeprint22, libgnomeprintui22, libglade, libgnomecanvas, libegg, libeel, gtkglext and libsexy.^[3]

Developers are also considering new directions for the library, including removing deprecated API components and adding an integrated scene graph system, similar to the Clutter graphics library, effectively integrating GTK+ with OpenGL.^[4][5]

Development and design of the GTK+ 3 release of the toolkit started in February 2009 during the GTK+ Theming Hackfest held in Dublin.^[6] A first draft of the development roadmap has been released on April 9, 2009.^[7]

GTK+ hello world

GTK+ hello world 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");
 
    /* Connect 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
     */
    g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit), NULL);
 
    /* Create the "Hello, World" label  */
    label = gtk_label_new ("Hello, World");
 
    /* and insert it into 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 let it rest there until the application is closed */
    gtk_main ();
 
    return 0;
 }

Uses

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

Environments that use GTK+

• GNOME is based on GTK+, meaning that GNOME programs use GTK+
• Xfce is based on GTK+, though its applications typically do not depend on as many libraries (this is the difference between something being branded as a "GNOME program" or as a "GTK+ program")
• LXDE (Lightweight X11 Desktop Environment) is based on GTK+
• ROX Desktop is a lightweight desktop, with features from the GUI of RISC OS
• GPE Palmtop Environment
• Maemo (Nokia's Internet-tablet framework which up to version 5 are based on GTK+ while the next versions will be based on Qt)
• Access Linux Platform (successor of the Palm OS PDA platform)
• Sugar the learning platform uses GTK+ and PyGTK
• Moblin OS and application stack for Mobile Internet Devices (MIDs), netbooks, and nettops
• KDE is based on Qt, but has integration with GTK+-based programs and themes (since version 4.2).

Those desktop environments are not required to run GTK+ programs. If the required libraries are installed, a GTK+ program can run on top of other X11-based desktop environments or window managers; this includes Mac OS X if X11.app is installed (which is the default since the Leopard release). 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 Unix systems.^[8] Other ports include DirectFB (used by the Debian installer, for example) and ncurses.^[9]

Window managers

The following window managers use GTK+

• Aewm
• AfterStep
• Amaterus
• Fluxbox
• FVWM
• FVWM1
• IceWM
• Metacity
• Mutter
• Wmg
• Xfwm

Applications

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

• AbiWord – Word processor
• Anjuta – open-source IDE
• CinePaint (formerly Film Gimp, being ported to FLTK) – 16-bit raster graphics editor
• Ekiga (formerly GnomeMeeting) – VoIP and video conferencing application
• Epiphany - Official GNOME Web browser.
• Evolution – personal information manager
• GIMP – Raster graphics editor
• Gnumeric – Spreadsheet software
• Chromium – Web browser based upon WebKit and developed in large part by Google
• GRAMPS – Genealogy software
• Inkscape – SVG Vector graphics editor
• Midori – lightweight web browser
• MonoDevelop – open-source IDE
• Pidgin – Instant messaging
• Stata – statistical software package (gtk+ used on Linux/Unix)
• VMware Player – virtualization software
• Wireshark – packet analyzer

See also

• gtkmm – C++ bindings for GTK+
• FLTK – A light, cross-platform, non-native widget toolkit
• FOX toolkit – A fast, open source, cross-platform widget toolkit
• Microsoft Foundation Class Library (MFC)
• Object Windows Library
• Qt – a widget toolkit used by KDE applications
• Ultimate++
• Visual Component Library (VCL)
• wxWidgets
• Widget toolkit
• List of widget toolkits

References

Bibliography

External links

• GTK+ Project home page
• Official GTK+ 2.x Tutorial
• GTK+ Reference Manual
• List of GTK+ applications
• Another list of GTK+ applications

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