README - Fast Light Tool Kit (FLTK) Version 1.5 ------------------------------------------------ What is FLTK? The Fast Light Tool Kit (FLTK) is a cross-platform C++ GUI toolkit for UNIX®/Linux® (X11 or Wayland), Microsoft® Windows®, and macOS®. FLTK provides modern GUI functionality without bloat and supports 3D graphics via OpenGL® and its built-in GLUT emulation. It was originally developed by Mr. Bill Spitzak and is currently maintained by a small group of developers across the world with a central repository on GitHub. https://www.fltk.org/ https://github.com/fltk/fltk/ Licensing FLTK comes with complete free source code. FLTK is available under the terms of the GNU Library General Public License with exceptions (e.g. for static linking). Contrary to popular belief, it can be used in commercial software! (Even Bill Gates could use it.) Online Documentation The documentation in HTML and PDF forms can be created by Doxygen from the source files. HTML and PDF versions of this documentation are also available from the FLTK web site at: https://www.fltk.org/documentation.php Prerequisites for Building FLTK To build FLTK 1.5 and higher you need: - CMake - a C++11 capable compiler, e.g. gcc, clang, Visual Studio, Xcode - system specific build files (headers etc.) CMake is used to generate the build environment on your system. It can create build environments for a lot of different build tools, please see the CMake documentation for more info. For details and the required CMake version please see README.CMake.txt. Since FLTK 1.5 we use C++11 features and you need at least a C++11 capable compiler running in C++11 mode. The minimal C++ standard used for building FLTK and your application *may* be raised in future versions. The required header files etc. (build environment or SDK) vary across platforms and are described in platform specific README.* files, e.g. on Unix/Linux systems these are typically provided by the package manager. Building and Installing FLTK With CMake (Generic Instructions) Since FLTK 1.5 the only available build system is CMake. CMake is a "build system generator" and can be used to create Makefile's, Ninja build files, Xcode (macOS), Visual Studio (Windows) IDE files, and many more. Use `cmake --help` or the CMake GUI tools (cmake-gui or ccmake) to display the available generators on your platform. Please see also README.CMake.txt for further details. There are *many* options to configure the build as you need. CMake comes in two flavors: a commandline utility and a GUI program. On many platforms both can be used to generate the build files and even to *build* the project (i.e. the FLTK library and programs). The following paragraphs describe both tools in a nutshell. For details please see README.CMake.txt. Building and Installing FLTK With CMake (Commandline) On systems where a commandline `CMake` utility is available (this is the case even on Windows), the commands to build FLTK using CMake can be similar to: $ cd /path/to/fltk $ cmake . -B build [ options ] $ cmake --build build These commands create the build folder 'build' inside your source tree, build the library and all test programs. Note that parameters in '[ ... ]' are optional and '.' represents the current directory (the source folder). You may want to test the demo programs by running `build/bin/test/demo`. Instead of building FLTK with a CMake command you can also use the build tool you generated in the first step and/or run CMake from the build directory, for instance: $ cd /path/to/fltk $ mkdir build $ cd build $ cmake .. -G "Unix Makefiles" [ options ] $ make [ -j N ] You may want to test the demo programs by running `bin/test/demo`. After successful tests you may install the library with the following command or a similar one, but please be aware that this will install FLTK in a system directory for system-wide use if you don't change the default installation path. We don't recommend this unless you know what you're doing. $ sudo cmake --install build # from the source tree (with CMake) or $ sudo make install # from the build folder (with make) Other commands (e.g. `ninja`) may be used as well, depending on the CMake generator you used. Building and Installing FLTK With CMake (GUI) On most systems CMake comes with a GUI program called `cmake-gui`, on Unix/Linux like systems also a "TUI" called `ccmake` (a "grapical" utility for a terminal). The latter is out of scope for this README file. If you want to use CMake's GUI program, execute it by running `cmake-gui` and then follow the dialog on the screen. You need to select the source folder and the build folder at the top of the screen. After clicking on `Configure` CMake will prompt you to select the build system or compilers of your choice. In many cases you can select the default compilers, e.g Visual Studio on Windows. For more details please see the CMake documentation. Note: on Windows it may be necessary to run CMake from a "Visual Studio Command Prompt" so CMake can find the existing Visual Studio compilers and SDK's, but details are beyond the scope of this document. After running `Configure` successfully (look for error messages in the window) you need to click on `Generate` to create the actual build files, for instance Makefiles, the Visual Studio IDE project files on Windows, or the Xcode IDE project on macOS, etc.. With some CMake generators for IDE projects (VS, Xcode) you can finally click on `Open Project` to launch the IDE tool of your choice. In other cases you may execute the build system by running `make`, `ninja`, etc. after leaving the GUI to build the library and FLTK (test) programs. Building FLTK under Microsoft Windows There are two ways to build FLTK under Microsoft Windows. The first is to use CMake to create the Visual Studio IDE project or NMake files as described above, then build FLTK with Visual Studio or NMake. The second method is to use a GNU-based development tool. To build with the Cygwin, MinGW, or MSYS2 tools, use CMake to create the build files from the `cmake` commandline and build the library as described above. On some of these systems you may also install and use `cmake-gui`. See README.Windows.txt and README.CMake.txt for more info. Building HTML Documentation FLTK uses Doxygen for documentation, so you'll at least need doxygen installed for creating HTML docs, and additionally LaTeX for creating PDF documentation. If you want to build the documentation, change directory to your build folder, for instance cd /path/to/fltk/build To build the HTML or PDF documentation, use these CMake commands: cmake --build . --target html cmake --build . --target pdf Note: instead of using the generic CMake commands above you can also use equivalent commands of your build system, e.g. `make html` or `ninja pdf`, respectively. Internet Resources FLTK is available on the internet in a bunch of locations: - https://www.fltk.org/ - homepage - https://github.com/fltk/fltk - source code and discussions - https://www.fltk.org/bugs.php - info for reporting bugs - https://www.fltk.org/software.php - download source code - https://github.com/fltk/fltk/releases - source code and documentation Note that we don't provide pre-compiled (binary) distributions. Consult the package manager of your (Linux, Unix, macOS) operating system. General Questions To join the FLTK mailing list, go to the following web page: https://groups.google.com/forum/#!forum/fltkgeneral Detailed instructions on how to register for the mailing list (even without a Google account) can be found further down on this page: https://www.fltk.org/newsgroups.php Since July 2024 we offer GitHub Discussions on our GitHub project page. Use the 'Q&A' section for general questions on building and using FLTK. https://github.com/fltk/fltk/discussions/categories/q-a Reporting Bugs If you are new to FLTK, or have general questions about how to use FLTK, or aren't sure if you found a bug, please ask first on the fltk.general group forum at: https://groups.google.com/forum/#!forum/fltkgeneral or on GitHub Discussions (Q&A) as noted above: https://github.com/fltk/fltk/discussions/categories/q-a See also paragraph "General Questions" above for more info. If you are sure you found a bug, please see the following page for further information on how to report a bug: https://www.fltk.org/bugs.php Trademarks - Microsoft and Windows are registered trademarks of Microsoft Corporation. - UNIX is a registered trademark of the X/Open Group, Inc. - OpenGL is a registered trademark of Silicon Graphics, Inc. - macOS is a registered trademark of Apple Computers, Inc. Copyright FLTK is copyright 1998-2025 by Bill Spitzak and others, see the CREDITS.txt file for more info. This library is free software. Distribution and use rights are outlined in the file "COPYING" which should have been included with this file. If this file is missing or damaged, see the license at: https://www.fltk.org/COPYING.php