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<TITLE>1 - Introduction to FLTK</TITLE>
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<H1 ALIGN="RIGHT"><A NAME="intro">1 - Introduction to FLTK</A></H1>
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<P>The Fast Light Tool Kit ("FLTK", pronounced
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"fulltick") is a cross-platform C++ GUI toolkit for
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UNIX®/Linux® (X11), Microsoft® Windows®, and
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MacOS® X. FLTK provides modern GUI functionality without the
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bloat and supports 3D graphics via OpenGL® and its built-in
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GLUT emulation. It was originally developed by Mr. Bill Spitzak
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and is currently maintained by a small group of developers
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across the world with a central repository in the US.</P>
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<H2>History of FLTK</H2>
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<P>It has always been Bill's belief that the GUI API of all
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modern systems is much too high level. Toolkits (even FLTK) are
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<I>not</I> what should be provided and documented as part of an
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operating system. The system only has to provide arbitrary
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shaped but featureless windows, a powerful set of graphics
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drawing calls, and a simple <I>unalterable</I> method of
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delivering events to the owners of the windows. NeXT (if you
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ignored NextStep) provided this, but they chose to hide it and
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tried to push their own baroque toolkit instead.</P>
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<P>Many of the ideas in FLTK were developed on a NeXT (but
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<I>not</I> using NextStep) in 1987 in a C toolkit Bill called
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"views". Here he came up with passing events downward
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in the tree and having the handle routine return a value
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indicating whether it used the event, and the table-driven menus. In
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general he was trying to prove that complex UI ideas could be
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entirely implemented in a user space toolkit, with no knowledge
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or support by the system.</P>
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<P>After going to film school for a few years, Bill worked at
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Sun Microsystems on the (doomed) NeWS project. Here he found an
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even better and cleaner windowing system, and he reimplemented
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"views" atop that. NeWS did have an unnecessarily
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complex method of delivering events which hurt it. But the
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designers did admit that perhaps the user could write just as
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good of a button as they could, and officially exposed the lower
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level interface.</P>
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<P>With the death of NeWS Bill realized that he would have to
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live with X. The biggest problem with X is the "window
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manager", which means that the toolkit can no longer
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control the window borders or drag the window around.</P>
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<P>At Digital Domain Bill discovered another toolkit,
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"Forms". Forms was similar to his work, but provided
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many more widgets, since it was used in many real applications,
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rather then as theoretical work. He decided to use Forms, except
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he integrated his table-driven menus into it. Several very large
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programs were created using this version of Forms.</P>
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<P>The need to switch to OpenGL and GLX, portability, and a
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desire to use C++ subclassing required a rewrite of Forms.
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This produced the first version of FLTK. The conversion to C++
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required so many changes it made it impossible to recompile any
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Forms objects. Since it was incompatible anyway, Bill decided
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to incorporate his older ideas as much as possible by
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simplifying the lower level interface and the event passing
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mechanisim.</P>
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<P>Bill received permission to release it for free on the
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Internet, with the GNU general public license. Response from
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Internet users indicated that the Linux market dwarfed the SGI
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and high-speed GL market, so he rewrote it to use X for all
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drawing, greatly speeding it up on these machines. That is the
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version you have now.</P>
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<P>Digital Domain has since withdrawn support for FLTK. While
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Bill is no longer able to actively develop it, he still
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contributes to FLTK in his free time and is a part of the FLTK
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development team.</P>
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<H2>Features</H2>
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<P>FLTK was designed to be statically linked. This was done by
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splitting it into many small objects and designing it so that
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functions that are not used do not have pointers to them in the
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parts that are used, and thus do not get linked in. This allows
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you to make an easy-to-install program or to modify FLTK to
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the exact requirements of your application without worrying
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about bloat. FLTK works fine as a shared library, though, and
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is now included with several Linux distributions.</P>
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<P>Here are some of the core features unique to FLTK:</P>
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<UL>
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<LI>sizeof(Fl_Widget) == 64 to 92.</LI>
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<LI>The "core" (the "hello" program
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compiled & linked with a static FLTK library using
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gcc on a 486 and then stripped) is 114K.</LI>
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<LI>The FLUID program (which includes every widget) is
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538k.</LI>
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<LI>Written directly atop core libraries (Xlib, WIN32 or
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Carbon) for maximum speed, and carefully optimized for
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code size and performance.</LI>
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<LI>Precise low-level compatability between the X11,
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WIN32 and MacOS versions - only about 10% of the code is
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different.</LI>
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<LI>Interactive user interface builder program. Output is
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human-readable and editable C++ source code.</LI>
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<LI>Support for overlay hardware, with emulation if none
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is available.</LI>
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<LI>Very small & fast portable 2-D drawing library
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to hide Xlib, WIN32, or QuickDraw.</LI>
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<LI>OpenGL/Mesa drawing area widget.</LI>
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<LI>Support for OpenGL overlay hardware on both X11 and
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WIN32, with emulation if none is available.</LI>
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<LI>Text widgets with Emacs key bindings, X cut &
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paste, and foreign letter compose!</LI>
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<LI>Compatibility header file for the GLUT library.</LI>
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<LI>Compatibility header file for the XForms library.</LI>
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</UL>
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<H2>Licensing</H2>
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<P>FLTK comes with complete free source code. FLTK is available
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under the terms of the <A href="license.html">GNU Library
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General Public License</A> with exceptions that allow for static
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linking. Contrary to popular belief, it can be used in
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commercial software - even Bill Gates could use it!</P>
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<H2>What Does "FLTK" Mean?</H2>
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<P>FLTK was originally designed to be compatible with the Forms
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Library written for SGI machines. In that library all the
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functions and structures started with "fl_". This
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naming was extended to all new methods and widgets in the C++
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library, and this prefix was taken as the name of the library.
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It is almost impossible to search for "FL" on the
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Internet, due to the fact that it is also the abbreviation for
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Florida. After much debating and searching for a new name for
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the toolkit, which was already in use by several people, Bill
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came up with "FLTK", including a bogus excuse that it
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stands for "The Fast Light Toolkit".</P>
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<H2>Building and Installing FLTK Under UNIX and MacOS X</H2>
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<P>In most cases you can just type "make". This will
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run configure with the default of no options and then compile
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everything.</P>
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<P>FLTK uses GNU autoconf to configure itself for your UNIX
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platform. The main things that the configure script will look
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for are the X11 and OpenGL (or Mesa) header and library files.
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If these cannot be found in the standard include/library
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locations you'll need to define the <tt>CFLAGS</tt>,
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<tt>CXXFLAGS</tt>, and <tt>LDFLAGS</tt> environment variables.
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For the Bourne and Korn shells you'd use:</P>
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<UL><PRE>
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CFLAGS=-I<I>includedir</I>; export CFLAGS
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CXXFLAGS=-I<I>includedir</I>; export CXXFLAGS
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LDFLAGS=-L<I>libdir</I>; export LDFLAGS
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</PRE></UL>
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<P>For C shell and tcsh, use:</P>
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<UL><PRE>
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setenv CFLAGS "-I<I>includedir</I>"
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setenv CXXFLAGS "-I<I>includedir</I>"
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setenv LDFLAGS "-L<I>libdir</I>"
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</PRE></UL>
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<P>By default configure will look for a C++ compiler named
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<tt>CC</tt>, <tt>c++</tt>, <tt>g++</tt>, or <tt>gcc</tt> in that
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order. To use another compiler you need to set the <tt>CXX</tt>
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environment variable:</P>
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<UL><PRE>
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CXX=xlC; export CXX
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setenv CXX "xlC"
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</PRE></UL>
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<P>The <tt>CC</tt> environment variable can also be used to
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override the default C compiler (<tt>cc</tt> or <tt>gcc</tt>),
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which is used for a few FLTK source files.</P>
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<P>You can run configure yourself to get the exact setup you
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need. Type "./configure <options>", where
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options are:</P>
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<DL>
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<DT>--enable-cygwin</DT>
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<DD>Enable the Cygwin libraries under WIN32</DD>
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<DT>--enable-debug</DT>
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<DD>Enable debugging code & symbols</DD>
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<DT>--disable-gl</DT>
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<DD>Disable OpenGL support</DD>
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<DT>--enable-shared</DT>
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<DD>Enable generation of shared libraries</DD>
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<DT>--enable-threads</DT>
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<DD>Enable multithreading support</DD>
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<DT>--enable-xdbe</DT>
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<DD>Enable the X double-buffer extension</DD>
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<DT>--enable-xft</DT>
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<DD>Enable the Xft library for anti-aliased fonts under X11</DD>
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<DT>--bindir=/path</DT>
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<DD>Set the location for executables [default = $prefix/bin]</DD>
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<DT>--datadir=/path</DT>
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<DD>Set the location for data files. [default = $prefix/share]</DD>
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<DT>--libdir=/path</DT>
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<DD>Set the location for libraries [default = $prefix/lib]</DD>
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<DT>--includedir=/path</DT>
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<DD>Set the location for include files. [default = $prefix/include]</DD>
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<DT>--mandir=/path</DT>
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<DD>Set the location for man pages. [default = $prefix/man]</DD>
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<DT>--prefix=/dir</DT>
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<DD>Set the directory prefix for files [default = /usr/local]</DD>
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</DL>
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<P>When the configure script is done you can just run the
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"make" command. This will build the library, FLUID
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tool, and all of the test programs.</P>
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<P>To install the library, become root and type "make
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install". This will copy the "fluid" executable
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to "bindir", the header files to
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"includedir", and the library files to
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"libdir".</P>
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<H2>Building FLTK Under Microsoft Windows</H2>
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<P>There are three ways to build FLTK under Microsoft Windows.
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The first is to use the Visual C++ 5.0 project files under the
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"visualc" directory. Just open (or double-click on)
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the "fltk.dsw" file to get the whole shebang.</P>
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<P>The second method is to use the <TT>configure</TT> script
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included with the FLTK software; this has only been tested with
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the CygWin tools:</P>
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<UL><PRE>
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sh configure --prefix=C:/FLTK
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make
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</PRE></UL>
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<P>The final method is to use a GNU-based development tool with
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the files in the "makefiles" directory. To build
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using one of these tools simply copy the appropriate
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makeinclude and config files to the main directory and do a
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make:</P>
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<UL><PRE>
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copy makefiles\Makefile.<env> Makefile
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make
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</PRE></UL>
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<H3>Using the Visual C++ DLL Library</H3>
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<P>The "fltkdll.dsp" project file builds a DLL-version
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of the FLTK library. Because of name mangling differences
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between PC compilers (even between different versions of Visual
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C++!) you can only use the DLL that is generated with the same
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version compiler that you built it with.</P>
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<P>When compiling an application or DLL that uses the FLTK DLL,
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you will need to define the <tt>FL_DLL</tt> preprocessor symbol
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to get the correct linkage commands embedded within the FLTK
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header files.</P>
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<H2>Building FLTK Under OS/2</H2>
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<P>The current OS/2 build requires XFree86 for OS/2 to work. A
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native Presentation Manager version has not been implemented
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yet (volunteers are welcome!).</P>
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<p>The current set of Makefiles/configuration failes assumes that
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EMX 0.9d and libExt
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(from <A HREF="http://posix2.sourceforge.net">posix2.sourceforge.net</A>)
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is installed.
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<P>To build the XFree86 version of FLTK for OS/2, copy the appropriate
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makeinclude and config files to the main directory and do a make: </P>
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<UL><PRE>
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copy makefiles\Makefile.os2x Makefile
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make
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</PRE></UL>
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<H2>Internet Resources</H2>
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<P>FLTK is available on the 'net in a bunch of locations:</P>
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<DL>
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<DT>WWW
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<DD><A href="http://www.fltk.org/">http://www.fltk.org/</A>
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<DT>FTP
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<DD><A HREF="ftp://ftp.fltk.org/pub/fltk">California, USA (ftp.fltk.org)</A>
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<DD><A HREF="ftp://ftp2.fltk.org/pub/fltk">Maryland, USA (ftp2.fltk.org)</A>
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<DD><A HREF="ftp://ftp.funet.fi/pub/mirrors/ftp.fltk.org/pub/fltk">Espoo, Finland (ftp.funet.fi)</A>
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<DD><A HREF="ftp://linux.mathematik.tu-darmstadt.de/pub/linux/mirrors/misc/fltk">Germany (linux.mathematik.tu-darmstadt.de)</A>
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<DD><A HREF="ftp://gd.tuwien.ac.at/hci/fltk">Austria (gd.tuwien.ac.at)</A>
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<DT>EMail</DT>
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<DD><A href="mailto:fltk@fltk.org">fltk@fltk.org</A> [see
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instructions below]
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<DD><A href="mailto:fltk-bugs@fltk.org">fltk-bugs@fltk.org</A> [for
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reporting bugs]
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<DT>NNTP Newsgroups</DT>
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<DD>news.easysw.com</DD>
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</DL>
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<P>To send a message to the FLTK mailing list
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("fltk@fltk.org") you must first join the list.
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Non-member submissions are blocked to avoid problems with
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unsolicited email.</P>
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<P>To join the FLTK mailing list, send a message to
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"majordomo@fltk.org" with "subscribe fltk"
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in the message body. A digest of this list is available by
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subscribing to the "fltk-digest" mailing list.</P>
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<H2>Reporting Bugs</H2>
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<P>To report a bug in FLTK, send an email to
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"fltk-bugs@fltk.org". Please include the FLTK version,
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operating system & version, and compiler that you are using
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when describing the bug or problem. We will be unable to provide
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any kind of help without that basic information.</P>
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<P>Bugs can also be reported to the "fltk.bugs" newsgroup or on the
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SourceForge bug tracker pages.</P>
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<P>For general support and questions, please use the FLTK mailing list
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at "fltk@fltk.org" or one of the newsgroups.</P>
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