GTK+

GTK+

Developer(s)	GNOME Foundation
Stable release	2.16.4 / 2009-07-02; 2 days ago
Written in	C
Operating system	Cross-platform
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.

Licensed under the LGPL, GTK+ is free software and is part of the GNU Project.

Design

GTK+ is an object oriented widget toolkit written in the c programming language; object orientation is achieved by using the Glib object system (GObject). On the X11 display server GTK+ uses xlib to draw widgets, an alternative choice that could have been made is to use Xt; 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 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][2][3] 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.^[4] 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+ 1. 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 library for rendering with 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 and gtkglext.^[5]

Developers are also considering new directions for the library, including breaking ABI, removing deprecated API components, and adding an integrated scene graph system, similar to the Clutter graphics library, effectively integrating GTK+ with OpenGL.^[6][7]

Development and design of the next GTK+ 3 release of the toolkit started in February 2009 during the GTK+ Theming Hackfest held in Dublin ^[8]. A first draft of the development roadmap has been released on April 9th, 2009 ^[9].

GTK+ hello world

GTK+ hello world in C, 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 is based on GTK+, stands for "Lightweight X11 Desktop Environment"
• ROX Desktop a lightweight desktop, with features from the GUI of RISC OS
• GPE Palmtop Environment
• Maemo (Nokia's Internet-tablet framework)
• Access Linux Platform (successor of the Palm OS PDA platform)
• One Laptop Per Child project uses GTK+ and PyGTK
• Broncho project (A mobile linux project)

Those desktop environments are not required to run GTK+ programs. If the libraries the program requires are installed, a GTK+ program can run on top of other X11-based environments such as KDE or an X11-plus-window manager environment; this includes Mac OS X if X11.app is installed. (default since Leopard) GTK+ can also run under Microsoft Windows, used by some popular cross-platform applications like Pidgin and GIMP. wxWidgets, a cross-platform GUI toolkit, uses GTK+ for Unix systems.^[10] Other ports include DirectFB (used by the Debian installer, for example) and ncurses^[11].

Window managers

• Metacity and Xfwm4 use GTK+ 2.

Applications

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

• AbiWord - Word processor
• CinePaint (ex FilmGimp, being ported to FLTK) - Raster HDR animated graphics editor
• Eclipse - IDE and rich-client platform (on Linux and Solaris only)
• Ekiga (ex GnomeMeeting) - H.323/SIP VoIP softphone
• Evolution - Mailer
• Firefox - Web browser (on Unix/Linux platforms)
• 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
• K-3D - free 3d modeling and animation program
• Marionnet - An interactive network simulator
• Midori - A portable web browser
• Nero Linux - An optical disc media authoring program
• Pidgin - Instant messaging
• VMware Player - Virtual Machine
• Wireshark - Packet capture, decode and analyzer

See also

Free software portal

• List of widget toolkits

References

External links

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

• GTK+ homepage
• GTK+ Planet
• List of GTK+ applications
• Another list of GTK+ applications

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