GTK (formerly GIMP ToolKit[2] and GTK+[3]) is a free software cross-platform widget toolkit for creating graphical user interfaces (GUIs).[4] It is licensed under the terms of the GNU Lesser General Public License, allowing both free and proprietary software to use it. It is one of the most popular toolkits for the Wayland and X11 windowing systems.[5]
Original author(s) | Spencer Kimball, Peter Mattis |
---|---|
Developer(s) | The GNOME Project, eXperimental Computing Facility (XCF) |
Initial release | April 14, 1998 |
Stable release | 4.14.4
/ April 2, 2024 |
Preview release | 4.15.1
/ May 21, 2024 |
Repository | |
Written in | C, CSS[1] |
Operating system | Linux, Unix-like, macOS, Windows |
Type | Widget toolkit |
License | LGPLv2.1+ |
Website | gtk |
The GTK team releases new versions on a regular basis.[6] GTK 4 and GTK 3 are maintained, while GTK 2 is end-of-life.[7] GTK1 is independently maintained by the CinePaint project.[8]
Software architecture
This section needs to be updated. (May 2024) |
The GTK library contains a set of graphical control elements (widgets); version 3.22.16 contains 186 active and 36 deprecated widgets.[9] GTK is an object-oriented widget toolkit written in the programming language C; it uses GObject, that is the GLib object system, for the object orientation. While GTK is mainly for windowing systems based on X11 and Wayland, it works on other platforms, including Microsoft Windows (interfaced with the Windows API), and macOS (interfaced with Quartz). There is also an HTML5 back-end named Broadway.[10][11]
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 most of its graphical control elements widgets.[12] Since GTK version 3.0, all rendering is done using Cairo.[13]
On January 26, 2018 at DevConf.cz, Matthias Clasen gave an overview of the current state of GTK 4 development, including a high-level explanation of how rendering and input worked in GTK 3, what changes are being made in GTK 4 (>3.90), and why.[14] On February 6, 2019 it was announced that GTK 4 will drop the “+” from the project's name.[3]
GTK Drawing Kit (GDK)
GDK acts as a wrapper around the low-level functions provided by the underlying windowing and graphics systems.
GTK Scene Graph Kit (GSK)
GSK is the rendering and scene graph API for GTK. GSK lies between the graphical control elements (widgets) and the rendering. GSK was finally merged into GTK version 3.90 released March 2017.
GtkBuilder
GtkBuilder allows user interfaces to be designed without writing code. The interface is described in an Extensible Markup Language (XML) file which is written by hand or generated by a GUI designer, which is then loaded at runtime and the objects created automatically. The description of the user interface is independent from the programming language being used.
Language bindings
Language bindings are available for using GTK from languages other than C, including C++, Genie, JavaScript, Perl, Python, Vala, and others.[15]
Backends
GTK supports various backends, which provides different ways to display GTK applications depending on the system and environment. Examples of GTK backends are:
- Wayland – Used with the Wayland display server on Linux systems, it is a modern replacement for X11.
- X11 – The default on Linux systems using the X.Org display server.
- Win32 – For running GTK applications on Windows.
- Quartz – For macOS support.
- Broadway – Allows GTK applications to run in web browsers using HTML5 and WebSockets.[10][11]
Development tools
GUI designers
There are several GUI designers for GTK. Here is a selection of GTK GUI designers:
- Cambalache - a successor to Glade, supports GTK 4.[16][17]
- Glade - supports GtkBuilder, which is a GTK built-in GUI description format. (not actively maintained)
- Gazpacho - GUI builder for the GTK toolkit written in Python[18]
- Crow Designer - relies on its own GuiXml format and GuiLoader library.[19]
- Stetic - part of MonoDevelop, oriented toward Gtk#.
- Gambas (since version 2.0 atop BASIC)
- Xojo
- Lazarus (on Linux defaults to interfacing with GTK 2)
GTK Inspector
The GTK Inspector is a built-in interactive debugging tool in GTK, allowing developers to inspect and modify UI elements, test CSS changes, and analyze widget structure in real time. It can be enabled using the Control + Shift + I
or Control + Shift + D
shortcuts, or by setting the GTK_DEBUG=interactive
environment variable.[20] It was introduced with GTK version 3.14.[21][22]
Features
- Interactive debugging
- Real-time CSS testing and modifications
- Widget magnification for detailed inspection
- UI structure analysis and object property examination
- Customizable display settings via environment variables
- Detailed object inspection (type, state, properties, CSS, actions, etc.)
- Global application information display
- CSS rule debugging
- Rendering pipeline recording and inspection
Development
GTK is mainly developed by The GNOME Project, which also develops the GNOME Development Platform and the GNOME Desktop Environment.[23] GTK is mainly written in C.[24] Many language bindings are available. GTK development is loosely managed.
GNOME developers and users gather at an annual GNOME Users And Developers European Conference GUADEC meeting to discuss GNOME's current state and future direction.[25] GNOME incorporates standards and programs from freedesktop.org to better interoperate with other desktops.[citation needed]
On September 1, 2016, a post on the GTK development blog denoted, among other things, the future numbering scheme of GTK.[26] GTK version 3.22, released in Autumn 2016, was planned to be the last 3.x release, although version 3.24 followed in Fall 2018 with the delay of GTK 4.[27] The development of GTK 4 used version names 3.90, 3.92, etc. until the first GTK 4.0 stable release was launched in December 2020.[28] Despite the first stable GTK 4 release, some applications using GTK still rely on GTK 2. For example, as of January 2022, GIMP is still being ported to GTK 3.[29]
Build automation
The master branch of GTK utilizes Meson for its build automation. GTK (and GNOME, GLib, etc.) formerly utilized the GNU Build System (named Autotools) as the build automation system of choice. Since August 14, 2017, the Autotools build system files have been dropped.[30]
Criticism
The most common criticism of GTK is the lack of backward-compatibility in major updates, most notably in the application programming interface (API)[31] and theming.[32] The result is that application developers or theme developers have to rewrite parts of their code to make it work with a newer version of GTK.
The compatibility breaks between minor releases during the GTK 3.x development cycle was explained by Benjamin Otte as due to strong pressures to innovate, such as providing the features modern users expect and supporting the increasingly influential Wayland display server protocol. With the release of GTK 4, the pressure from the need to innovate will have been released and the balance between stability and innovation will tip toward stability.[33] Similarly, recent changes to theming are specifically intended to improve and stabilise that part of the API, meaning some investment now should be rewarded later.
- Dirk Hohndel, codeveloper of Subsurface and member of Intel's Open-Source Technology Center, criticized the GTK developers for being abrasive and ignoring most community requests.[34]
- Hong Jen Yee, developer of LXDE (the GTK version of which was dropped and all efforts focused on the Qt port), expressed disdain for version 3 of the GTK toolkit's radical API changes and increased memory usage, and ported PCMan File Manager (PCManFM) to Qt. PCManFM is being developed with a GTK and with a Qt backend at the same time.[35]
- The Audacious music player moved to Qt in version 3.6.[36] 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."[37]
- Wireshark has switched to Qt due to not having a good experience with GTK's cross-platform support.[38]
Use
Applications
Some notable applications that use GTK as a widget toolkit include:
- Ardour, a digital audio workstation (DAW)
- Deluge, a BitTorrent client
- Foliate, an ebook reader
- GIMP, a raster graphics editor
- GNOME Core Applications, a collection of applications as a standard bundle of the GNOME desktop environment
- GNOME Circle, a collection of applications created to work within the GNOME ecosystem
- GNOME Evolution, a personal information manager
- HandBrake, digital video transcoder
- Inkscape, a vector graphics editor
- LibreOffice, an office suite
- Lutris, a game manager
- Mozilla Firefox, a web browser
- Mozilla Thunderbird, a personal information manager
- Pitivi, a video editor
- PCSX-Reloaded, a video game console emulator
- REAPER, a digital audio workstation (DAW)
- Remmina, a remote desktop client
- Transmission, a Bit Torrent client
GTK programs can be run on desktop environments based on X11 and Wayland, or others including ones not made with GTK, provided the needed libraries are installed; this includes macOS if X11.app is installed. GTK can be also run on Microsoft Windows. It is used by some popular cross-platform applications like Pidgin and GIMP. wxWidgets, a cross-platform GUI tool-kit, uses GTK on Linux by default.[39] Other ports include DirectFB (for example used by the Debian installer).
Desktop environments
Several desktop environments utilize GTK as the widget toolkit.
Current
- GNOME, based on GTK, meaning that programs native to GNOME use GTK
- Budgie, built from scratch for the SolusOS successor, Solus Operating System
- Cinnamon, a fork of GNOME 3 which uses GTK version 3
- MATE, a fork of GNOME 2 which uses GTK 3 since version 1.18
- Xfce, based on GTK 3 since version 4.14
- Pantheon uses GTK 3 exclusively, being developed by elementary OS
- Sugar, a desktop environment for youth primary education, which uses GTK, especially PyGTK
- Phosh, a mobile UI designed for PureOS
- LXDE (Lightweight X11 Desktop Environment) is based on GTK 2
- Unity, the former default desktop environment of Ubuntu
Inactive
- Access Linux Platform (successor of the Palm OS PDA platform)
- Consort, the GNOME 3.4 Fallback Mode – fork from Solus
- GPE, the GPE Palmtop Environment
- ROX Desktop, a lightweight desktop, with features from the GUI of RISC OS
Window managers
The following window managers use GTK:
GtkSourceView
For syntax highlighting there is GtkSourceView, "source code editing widget". GtkSourceView is maintained by GNOME separately from GTK as a library: gtksourceview. There are plans to rename to gsv.[citation needed]
GtkSpell
GtkSpell is a library separate from GTK. GtkSpell depends on GTK and Enchant. Enchant is a wrapper for ispell, hunspell, etc., the actual spell checker engine/software. GtkSpell uses GTK's GtkTextView widget, to highlight misspelled words and offer replacement.
History
GNU/Linux
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 named the GIMP toolkit and had successfully replaced Motif by the 0.60 release of GIMP.[40] Finally GTK was re-written to be object-oriented and was renamed GTK+.[41] 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.
The '+' was dropped returning to simply 'GTK' in February 2019 during a Hackathon.[42]
macOS
Windows
- After GTK 2.24.10 and 3.6.4 Development of Windows with Installer was closed by Gnome. Installation of MSYS2 on Windows is a good way to use actual GTK.[45]
- GTK 2.24.10 and 3.6.4 is available in Internet, but very buggy and limited against actual versions.[46][47]
- A version for Windows 64-bit is prepared by Tom Schoonjans with 2.24.33 (actual like Linux) and 3.24.24 (actual like Linux) from January 2021 available.[48]
- Windows 10's Fall Creators Update includes Windows Subsystem for Linux (WSL). With Linux distributions like Ubuntu or Debian available from the Microsoft Store and an X server like Xming or VcXsvr, thousands of programs like GTK 2 or 3 can run with X or terminal support.
OpenVMS
HP stated that their goal was to merge the needed OpenVMS changes into the GTK Version 1.3 development stream, however this never materialised.[49] The latest version of GTK for OpenVMS is version 1.2.10.[50]
GTK 4
One of the cardinal novelties implemented during the GTK 4 development cycle (i.e. GTK 3.92, etc.) has been the removal of customization options for the user side (like individual keyboard shortcuts that could be set in GTK+ 2), and the delegation of functionality to ancillary objects instead of encoding it into the base classes provided by GTK.
- the event handling from signal handlers described by GtkWidget is delegated to event controllers
- the rendering is delegated to GtkSnapshot objects
- the layout mechanism from GtkWidget is delegated to GtkLayoutManager
In January 2018 at DevConf.cz Matthias Clasen gave an overview of the then current state of GTK 4 development, including a high-level explanation of how rendering and input worked in GTK 3, what changes were being made to GTK 4, and the reasons for those changes. Examples of things that have become possible with GTK 4 were given as well.[51]
Releases
Legend: Old version, not maintained Old version, still maintained Latest version Latest preview version Future release | |||
Release series | Initial release | Major enhancements | Latest minor version |
---|---|---|---|
1.0 | 1998-04-13[52] | First stable version | 1.0. |
1.2 | 1999-02-25[53] | New widgets:
|
1.2.10 |
2.0 | 2002-03-11[54] | GObject
Overall support for UTF-8 |
2.0.9 |
2.2 | 2002-12-22[55] | Multihead support | 2.2.4 |
2.4 | 2004-03-16[56] | New widgets:
|
2.4.14 |
2.6 | 2004-12-16[57] | New widgets:
The last to support Windows 98/Me |
2.6.10 |
2.8 | 2005-08-13[58] | Most widgets are rendered by Cairo | 2.8.20 |
2.10 | 2006-07-03[59] | New widgets:
Print support: GtkPrintOperation |
2.10.14 |
2.12 | 2007-09-14[60] | GtkBuilder | 2.12.12 |
2.14 | 2008-09-04[61] | JPEG 2000 load support | 2.14.7 |
2.16 | 2009-03-13[62] | New widget: GtkOrientable
Caps Lock warning in password entry Improvements on GtkScale, GtkStatusIcon, GtkFileChooser |
2.16.6 |
2.18 | 2009-09-23[63] | New widget: GtkInfoBar
Improvement on file chooser, printing To remove much of the necessary IPC between the X11 application and the X11 server, GDK is rewritten (mainly by Alexander Larsson) to use "client-side windows", i.e., the GdkWindow, which every widget must have, belongs now to the client |
2.18.9 |
2.20 | 2010-03-23[64] | New widgets:
Improvement on file chooser, keyboard handling, GDK Introspection data is now included in GTK |
2.20.1 |
2.22 | 2010-09-23[65] | GdkPixbuf moved to separate module
Most GDK drawing are based on Cairo Many internal data are now private and can be sealed in preparation to GTK 3 |
2.22.1 |
2.24 | 2011-01-30[66] | New widget: GtkComboBoxText which had previously been a custom widget shipped with Gtkmm
The CUPS print backend can send print jobs as PDF GtkBuilder has gained support for text tags and menu toolbuttons and many introspection annotation fixes were added Migrating from GTK+ 2.x to GTK+ 3 |
2.24.33 (2020-12-21)[67] |
3.0 | 2011-02-10[68] | Development and design of the GTK 3 release of the toolkit started in February 2009 during the GTK Theming Hackfest held in Dublin[69]
Completed mostly Project Ridley
All the rendering is done using Cairo GDK became more X11 agnostic XInput2, theme API is based on Cascading Style Sheets (CSS), worsening the achievable performance for 60 Hz frame rates |
3.0.12 |
3.2 | 2011-09-25[72] | New widgets:
New Font Chooser dialog New experimental backends: |
3.2.4 |
3.4 | 2012-03-26[73] | Menu support in GtkApplication
A new color chooser Added support for touch devices Added support for smooth scrolling GtkScrolledWindow will do kinetic scrolling with touch devices macOS support is improved This is the first version of GTK 3 that works well on Windows The Wayland backend is updated to the current Wayland version Spin buttons have received a new look Accessibility: the treeview accessible support is rewritten More complete CSS theming support |
3.4.4 |
3.6 | 2012-09-24[74] | New widgets:
Vertical spin buttons CSS animations, blur shadows Support for cross-fading and transitions in themes |
3.6.5 |
3.8 | 2013-03-25[75] | Wayland 1.0 stable support
Support for the broadwayd server Improved theming Better geometry management Touch improvements Support with the window manager for the frame synchronization protocol GdkFrameClock added[76] |
3.8.9 |
3.10 | 2013-09-23[77] | New widgets:
Support for Wayland 1.2
Added:
Removed:
Tear-off menu-items, plus many GTK settings The modern GTK drawing model |
3.10.9 |
3.12 | 2014-03-25[78] | Client-side decorations[79]
Support for Wayland 1.5 New widget: GtkPopover (an alternative to menus and dialogs) |
3.12.2 |
3.14 | 2014-09-22[80] | GtkInspector (a copy of gtkparasite) introduced[81][82]
Improved support for gestures/multi-touch merged[83][84] Deprecated:[85]
Most widgets converted to use gestures internally Wayland supports GNOME Shell classic mode[86] |
3.14.15 |
3.16 | 2015-03-22[87] | GDK supports rendering windows using OpenGL for X11 and Wayland using libepoxy
New widgets:
|
3.16.7 |
3.18 | 2015-09-23[90] | Add CSS node infrastructure
More filechooser design refresh and better filechooser search Dropped Windows XP support Model support for list and flow box Kinetic touchpad scrolling Touchpad gestures (Wayland) gtk-builder-tool utility Output-only windows |
3.18.9 |
3.20 | 2016-03-21[91] | Further Integration of CSS nodes[92]
Move drag and drop down to GDK New widget: GtkShortcutsWindow (shows keyboard shortcuts and gestures of an application) |
3.20.10 |
3.22 | 2016-09-21[93] | Last 3.x release[26]
Wayland tablet support is merged,[94] support for graphics tablets is considered feature complete[95] GTK 3.22 shall be as rock-stable (and hence "boring") as GTK 2[33][96][97] |
for 3+ years 3.22.29 |
3.24 | 2018-09-03[98] | 3.22 was supposed to be the last version of GTK 3 series
Dependency bumps – require:
New font chooser features:
New Emoji features:
Other new APIs: gdk_window_move_to_rect Wayland: use anonymous shared memory on FreeBSD Backported event controllers from GTK 4:
Deprecate a few APIs that are gone in GTK 4:
|
3.23.0 3.23.1 3.23.2 3.23.3 3.24.0 ...3.24.5 3.24.14 ... 3.24.29 |
3.90 | 2017-03-31[99] | GTK Scene Graph Kit (GSK) merged[6]
Remove any API marked as deprecated Heavy development |
3.89.1 3.89.2 |
3.92 | 2017-10-18[101][102] | As GNOME 3.26 was released already on September 13, 2017,[103] it was not based on GTK 3.92.
GNU autotools was replaced with Meson. |
3.91.0 3.91.1 |
3.94 | 2018-06-26[104] | 3.93
GdkWindow renamed to GdkSurface New abstraction for drawable content: GdkPaintable There is support for displaying media with:
|
3.93 3.94.0 |
3.96 | 2019-05-07[105] | The gtk4-builder-tool simplify command has gained a --3to4 option to convert GTK3 ui files to GTK4; though with AMTK menus, toolbars or other objects like GtkShortcutsWindow are created programmatically (not with a *.ui file), but with convenient APIs.[106]
GtkWidget can now use a GtkLayoutManager for size allocation
Focus handling has been rewritten, and focus-change event generation has been unified with crossing events Events have been simplified and are just used for input:
|
3.96.0 |
3.98 | 2020-02-10[105] |
|
3.98.5 |
3.99.0 | 2020-07-31[108] |
|
3.99.4 |
4.0 | 2020-12-16[110] | 4.0.2 | |
4.2 | 2021-03-30[111] | ||
4.4 | 2021-08-23[112] | ||
4.6 | 2021-12-30[113] | ||
4.8 | 2022-09-06[114] | ||
4.10 | 2023-03-04[115] | GtkFileChooser deprecated (use GtkFileDialog)[116] |
See also
- Client-Side Decoration
- List of widget toolkits
- gtkmm – C++ bindings for GTK
- 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
- Ultimate++
- Visual Component Library (VCL)
References
Bibliography
External links
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