FLTK#Language bindings

{{Infobox software

| name = FLTK

| logo = FLTK shadow.svg

| screenshot =

| caption =

| developer =

| released = {{Start date and age|1998}}

| latest release version = 1.4.3

| latest release date = {{Start date and age|2025|04|29}}

| programming language = C++

| operating system = Unix-like with X11 or Wayland, macOS, Microsoft Windows

| genre = User interface library

| license = GNU Lesser General Public License version 2 with an exception to allow static linking{{cite web|url=https://www.fltk.org/COPYING.php|title=FLTK License Agreement|access-date=2020-01-30|archive-date=2001-12-18|archive-url=https://web.archive.org/web/20011218154953/https://www.fltk.org/COPYING.php|url-status=live}}

| website = {{URL|https://www.fltk.org}}

}}

Fast Light Toolkit (FLTK){{Cite web|url=https://www.fltk.org/|title=Fast Light Toolkit - Fast Light Toolkit (FLTK)|website=www.fltk.org|access-date=2020-01-30|archive-date=2020-02-02|archive-url=https://web.archive.org/web/20200202212901/https://www.fltk.org/|url-status=live}} is a cross-platform widget (graphical control element) library for graphical user interfaces (GUIs), developed by Bill Spitzak and others. Made to accommodate 3D graphics programming, it has an interface to OpenGL, but it is also suitable for general GUI programming.

Using its own widget, drawing and event systems abstracted from the underlying system-dependent code, it allows for writing programs which look the same on all supported operating systems.

FLTK is free and open-source software, licensed under GNU Lesser General Public License (LGPL) with an added clause permitting static linking from applications with incompatible licenses.

In contrast to user interface libraries like GTK, Qt, and wxWidgets, FLTK uses a more lightweight design and restricts itself to GUI functionality. Because of this, the library is very small (the FLTK "Hello World" program is around 100 KiB), and is usually statically linked. It also avoids complex macros, separate code preprocessors, and use of some advanced C++ features: templates, exceptions, and run-time type information (RTTI) or, for FLTK 1.x, namespaces. Combined with the modest size of the package, this makes it relatively easy to learn for new users.{{cite web |url=http://www.cpplibs.com/libraries/fltk/ |title=Fast Light ToolKit (FLTK) » CppLibs |access-date=2015-05-13 |archive-url=https://web.archive.org/web/20150518081826/http://www.cpplibs.com/libraries/fltk/ |archive-date=2015-05-18 |url-status=usurped}}

These advantages come with corresponding disadvantages. FLTK offers fewer widgets than most GUI toolkits and, because of its use of non-native widgets, does not have native look-and-feel on any platform.

Meaning of the name

FLTK was originally designed to be compatible with the Forms Library written for Silicon Graphics (SGI) machines (a derivative of this library called XForms is still used quite often). In that library, all functions and structures start with fl_. This naming was extended to all new methods and widgets in the C++ library, and this prefix FL was taken as the name of the library. After FL was released as open source, it was discovered that searching "FL" on the Internet was a problem, because it is also the abbreviation for Florida. After much debating and searching for a new name for the toolkit, which was already in use by several people, Bill Spitzak came up with Fast Light Tool Kit (FLTK).{{Cite web|url=https://www.fltk.org/articles.php?L363+I0+TFAQ+P1+Q|title=Article #363: What does "FLTK" mean? - Fast Light Toolkit (FLTK)|website=www.fltk.org|access-date=2020-01-30|archive-date=2020-07-31|archive-url=https://web.archive.org/web/20200731224107/https://www.fltk.org/articles.php?L363+I0+TFAQ+P1+Q|url-status=live}}

Architecture

FLTK is an object-oriented widget toolkit written in the programming language C++. While GTK is mainly optimized for the X Window System, FLTK works on other platforms, including Microsoft Windows (interfaced with the Windows API), and OS X (interfaced with Quartz). A Wayland back-end has been implemented and is available since release 1.4.0.{{Cite web|title=STR #3371: Wayland Display Server Protocol support - Fast Light Toolkit (FLTK)|url=https://www.fltk.org/str.php?L3371|access-date=2020-08-06|website=www.fltk.org|archive-date=2022-11-19|archive-url=https://web.archive.org/web/20221119023708/https://www.fltk.org/str.php?L3371|url-status=live}} FLTK2 has gained experimental support for optionally using the cairo graphics library.

=Language bindings=

A library written in one programming language may be used in another language if language bindings are written. FLTK has a range of bindings for various languages.

FLTK was mainly designed for, and is written in, the programming language C++. However, bindings exist for other languages, for example Lua,{{Cite web|url=http://www.murga-projects.com/murgaLua.html|title=murgaLua homepage|access-date=2008-12-18|archive-date=2012-07-07|archive-url=https://web.archive.org/web/20120707032113/http://www.murga-projects.com/murgaLua.html|url-status=dead}} Perl,{{Cite web|url=https://www.fltk.org/links.php|title=Links: By Category - Links - Fast Light Toolkit (FLTK)|website=www.fltk.org|access-date=2023-04-07|archive-date=2023-03-15|archive-url=https://web.archive.org/web/20230315011216/https://www.fltk.org/links.php|url-status=live}} Python,{{Cite web|url=https://pyfltk.sourceforge.io/|title=pyFLTK Home Page|website=pyfltk.sourceforge.io|access-date=2023-04-07|archive-date=2023-04-07|archive-url=https://web.archive.org/web/20230407223849/https://pyfltk.sourceforge.io/|url-status=live}} Ruby,{{Cite web|url=https://ruby-fltk.sourceforge.net/|title=Ruby/FLTK|website=ruby-fltk.sourceforge.net|access-date=2023-04-07|archive-date=2023-04-13|archive-url=https://web.archive.org/web/20230413204411/https://ruby-fltk.sourceforge.net/|url-status=live}} Rust{{Cite web|url=https://docs.rs/fltk/latest/fltk/|title=fltk - Rust|website=docs.rs|access-date=2023-04-07|archive-date=2023-04-07|archive-url=https://web.archive.org/web/20230407223850/https://docs.rs/fltk/latest/fltk/|url-status=live}} and Tcl.{{Cite web|url=https://sourceforge.net/projects/fltkwish/|title=Tcl/Fltk dynamic extension for Tcl|website=SourceForge|date=3 April 2013|access-date=7 April 2023|archive-date=7 April 2023|archive-url=https://web.archive.org/web/20230407223850/https://sourceforge.net/projects/fltkwish/|url-status=live}}

For FLTK 1.x, this example creates a window with an Okay button:

include
include
include

int main(int argc, char *argv[]) {

Fl_Window* w = new Fl_Window(330, 190);

new Fl_Button(110, 130, 100, 35, "Okay");

w->end();

w->show(argc, argv);

return Fl::run();

}

=GUI designers=

FLTK includes Fast Light User Interface Designer (FLUID), a graphical GUI designer that generates C++ source and header files.

Use

Many programs and projects use FLTK, including:

Nanolinux, 14 MB Linux distribution{{Cite web|url=https://sourceforge.net/projects/nanolinux/|title=Nanolinux|website=SourceForge|date=8 October 2016|access-date=15 April 2018|archive-date=11 November 2020|archive-url=https://web.archive.org/web/20201111214058/https://sourceforge.net/projects/nanolinux/|url-status=live}}{{Cite web|url = https://eerielinux.wordpress.com/2014/11/30/tiny-to-the-extreme-nanolinux/|title = Tiny to the extreme: Nanolinux|date = 30 November 2014|access-date = 15 April 2018|archive-date = 16 April 2018|archive-url = https://web.archive.org/web/20180416134741/https://eerielinux.wordpress.com/2014/11/30/tiny-to-the-extreme-nanolinux/|url-status = live}}{{Cite web|url = https://eerielinux.wordpress.com/2014/12/30/an-interview-with-the-nanolinux-developer/|title = An interview with the Nanolinux developer|date = 30 December 2014|access-date = 15 April 2018|archive-date = 16 April 2018|archive-url = https://web.archive.org/web/20180416074135/https://eerielinux.wordpress.com/2014/12/30/an-interview-with-the-nanolinux-developer/|url-status = live}}{{cite web |url=http://tawny.cs.nott.ac.uk/~sbx/winnie/aim/overview.htm |title=Artificial Intelligence Methods |access-date=2019-08-15 |archive-url=https://web.archive.org/web/19990420083003/http://tawny.cs.nott.ac.uk/~sbx/winnie/aim/overview.htm |archive-date=1999-04-20 |url-status=live}}{{Cite web|url=http://sites.utoronto.ca/webdocs/HTMLdocs/PCTOOLS/pc_editors.html|title=PC HTML Editors|access-date=2018-04-15|archive-date=2018-04-16|archive-url=https://web.archive.org/web/20180416073704/http://sites.utoronto.ca/webdocs/HTMLdocs/PCTOOLS/pc_editors.html|url-status=live}}{{Cite web|url=http://www.georgpotthast.de/|title=Georg's Personal Homepage|website=www.georgpotthast.de|access-date=2018-04-15|archive-date=2018-08-17|archive-url=https://web.archive.org/web/20180817050742/http://www.georgpotthast.de/|url-status=live}}
XFDOS, a FreeDOS-based distribution with a GUI, porting Nano-X and FLTK{{Cite web|url=https://eerielinux.wordpress.com/2012/10/12/an-extraordinary-tk-example/|title=An extraordinary TK example!|date=12 October 2012|access-date=15 April 2018|archive-date=16 April 2018|archive-url=https://web.archive.org/web/20180416074037/https://eerielinux.wordpress.com/2012/10/12/an-extraordinary-tk-example/|url-status=live}}
Agenda VR3, a Linux-based personal digital assistant with software based on FLTK.
third-party Agenda VR3 software
Amnesia: The Dark Descent, by Frictional Games uses FLTK in its launcher application
MwendanoWD, Logic puzzle for personal computer by YPH.{{Cite web|url=http://tehelimu.ezyro.com/Subsites/enl/tls.html|title=YPH|access-date=2018-10-27|archive-date=2018-10-27|archive-url=https://web.archive.org/web/20181027101449/http://tehelimu.ezyro.com/Subsites/enl/tls.html/|url-status=live}}
Audio:
Fldigi, amateur radio software, allows data transmission and text chat via digital modes such as PSK31
Giada, looper, micro-sequencer, sample player software, open-source{{cite web |url=http://www.monocasual.com/giada |title=Giada, hardcore loopmachine |access-date=2011-09-29 |archive-url=https://web.archive.org/web/20110925183623/http://www.monocasual.com/giada/ |archive-date=2011-09-25 |url-status=dead}}
Prodatum, synthesizer preset editor, uses a lifelike interface design{{Cite web|url=https://prodatum.sourceforge.net/|title=prodatum - official homepage|website=prodatum.sourceforge.net|access-date=2023-04-07|archive-date=2023-04-07|archive-url=https://web.archive.org/web/20230407223851/https://prodatum.sourceforge.net/|url-status=live}}
ZynAddSubFX, an open-source software synthesizer
DiSTI GL Studio, human-machine interface development tool{{Cite web |url=http://www.disti.com/ |title=DiSTI GL Studio |access-date=2010-07-29 |archive-date=2012-08-15 |archive-url=https://web.archive.org/web/20120815051039/http://www.disti.com/ |url-status=dead }}
Engineering:
ForcePAD, an intuitive tool to visualise the behavior of structures subject to loading and boundary conditions{{Cite web|url=https://forcepad.sourceforge.net/|title=ForcePAD|website=forcepad.sourceforge.net|access-date=2023-04-07|archive-date=2023-04-07|archive-url=https://web.archive.org/web/20230407223849/https://forcepad.sourceforge.net/|url-status=live}}
Gmsh, an open-source finite element mesh generator
RoboCIM, software to simulate and control operation of a servo robot system and external devices{{Cite web|url=http://www.labvolt.com/products/automation-and-robotics/robotics/robocim-5250-software-5251|title=RoboCIM - Robotics software|access-date=2013-06-29|archive-date=2013-05-04|archive-url=https://web.archive.org/web/20130504071531/http://www.labvolt.com/products/automation-and-robotics/robotics/robocim-5250-software-5251|url-status=live}}
Equinox Desktop Environment (EDE)
FlBurn optical disc burning software for Linux{{Cite web|url=https://flburn.sourceforge.net/|title=Free | CD DVD burning software for Linux|website=flburn.sourceforge.net|access-date=2023-04-07|archive-date=2023-04-10|archive-url=https://web.archive.org/web/20230410111224/https://flburn.sourceforge.net/|url-status=live}}
Graphics:
CinePaint, deep-paint software, migrating from GTK to FLTK, open-source
ITK-SNAP, software application for medical image segmentation, open-source
Nuke, a digital compositing program. Until version 5, now replaced by Qt
Open Movie Editor{{Cite web|url=http://www.openmovieeditor.org/|title=Open Movie Editor - Free and Open Source Video Editor|website=www.openmovieeditor.org|access-date=2008-04-12|archive-date=2012-05-18|archive-url=https://web.archive.org/web/20120518011331/http://www.openmovieeditor.org/|url-status=live}}
OpenVSP, an open-source NASA parametric 3D CAD for aircraft design and analysing{{Cite web|url=https://openvsp.org/|title=OpenVSP|website=openvsp.org|access-date=2023-04-07|archive-date=2023-04-07|archive-url=https://web.archive.org/web/20230407223849/https://openvsp.org/|url-status=live}}
PosteRazor, open-source poster printing software for Windows, OS X, Linux{{Cite web|url=https://posterazor.sourceforge.io/|title=PosteRazor - Make your own poster!|website=posterazor.sourceforge.io|access-date=2023-04-07|archive-date=2023-04-07|archive-url=https://web.archive.org/web/20230407223850/https://posterazor.sourceforge.io/|url-status=live}}
Tilemap Studio, An open-source tilemap editor for Game Boy, Color, Advance, DS, and SNES projects{{Cite web|url = https://github.com/Rangi42/tilemap-studio|title = Tilemap Studio|website = GitHub|date = 18 October 2021|access-date = 8 September 2021|archive-date = 8 September 2021|archive-url = https://web.archive.org/web/20210908115111/https://github.com/Rangi42/tilemap-studio|url-status = live}}
SmallBASIC, Windows port
Web browsers:
Dillo, Dillo-2 was based on FLTK-2, abandoning this FLTK branch, with no official release, was a major cause of Dillo-3 being started, using FLTK1.3
Fifth, replicates functioning of early Opera{{Cite web|url=https://fifth-browser.sourceforge.net/|title=Fifth - Home|website=fifth-browser.sourceforge.net|access-date=2023-04-07|archive-date=2023-04-14|archive-url=https://web.archive.org/web/20230414051323/https://fifth-browser.sourceforge.net/|url-status=live}}
NetRider{{Cite web|url=https://sourceforge.net/projects/netrider/|title=NetRider|website=SourceForge|date=23 February 2016|access-date=7 April 2023|archive-date=7 April 2023|archive-url=https://web.archive.org/web/20230407223848/https://sourceforge.net/projects/netrider/|url-status=live}}
Brain Visualizer: An open-source interactive visualizer for large-scale 3D brain models. Part of the Brain Organization Simulation System (BOSS) developed at Stony Brook University{{Cite web|url=https://github.com/roukaour/viz-brain-visualizer|title=Viz (Brain Visualizer)|website=GitHub|date=25 August 2021|access-date=8 September 2021|archive-date=8 September 2021|archive-url=https://web.archive.org/web/20210908115107/https://github.com/roukaour/viz-brain-visualizer|url-status=live}}
X window managers:
FLWM
miwm

Versions

This version history is an example of the sometimes tumultuous nature of open-source development.{{cite web|url=https://www.fltk.org/articles.php?L825+I0+T+P1+Q|title=What are the Versions of FLTK?|access-date=2010-07-23|archive-date=2010-06-28|archive-url=https://web.archive.org/web/20100628085355/http://www.fltk.org/articles.php?L825+I0+T+P1+Q|url-status=live}}

=1.0.x=

This is a prior stable version, now unmaintained.

=1.1.x=

This is a prior stable version, now unmaintained.

=2.0 branch=

This was a development branch, long thought to be the next step in FLTK's evolution, with many new features and a cleaner programming style. It never achieved stability, and development has largely ceased. The branch is inactive now.

=1.2.x=

This was an attempt to take some of the best features of 2.0 and merge them back into the more popular 1.1 branch. It is no longer developed. All of its features have been incorporated in branch 1.3.

=1.3.x=

Previous stable release.https://www.fltk.org/articles.php?L825 {{Webarchive|url=https://web.archive.org/web/20190802225250/https://www.fltk.org/articles.php?L825 |date=2019-08-02 }} Taken 5 March 2017. Provides UTF-8 support.

=1.4.x=

Current stable branch. Adds more features to 1.3. This branch is in maintenance mode since release 1.4.2 (Feb. 23, 2025).

=1.5.x=

Current development branch. This branch is in early development stage. Since FLTK 1.5 CMake is required to build FLTK (configure/Makefile support has been dropped).

=3.0 branch=

This branch resulted from a vision to "unfork" branches 1.x and 2.0, but it was never completed. All efforts to develop this branch have been abandoned. Now inactive.