mirror of https://github.com/fltk/fltk
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<H1 ALIGN=RIGHT><A NAME=intro>1 - Introduction to FLTK</A></H1>
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The Fast Light Tool Kit ("FLTK", pronounced "fulltick") is a LGPL'd
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C++ graphical user interface toolkit for X (UNIX®), OpenGL®, and
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Microsoft® Windows® NT 4.0, 95, or 98. It was originally developed by
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Mr. Bill Spitzak and is currently maintained by a small group of
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developers across the world with a central repository in the US.
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<H2>History of FLTK</H2>
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It has always been Bill's belief that the GUI API of all modern
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systems is much too high level. Toolkits (even FL) are <I>not</I> what
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should be provided and documented as part of an operating system. The
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system only has to provide arbitrary shaped but featureless windows, a
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powerful set of graphics drawing calls, and a simple <I>unalterable</I>
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method of delivering events to the owners of the windows. NeXT (if
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you ignored NextStep) provided this, but they chose to hide it and
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tried to push their own baroque toolkit instead...
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<P>Many of the ideas in FLTK were developed on a NeXT (but <I>not</I>
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using NextStep) in 1987 in a C toolkit Bill called "views". Here he
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came up with passing events downward in the tree and having the handle
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routine return a value indicating the used the event, and the
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table-driven menus. In general he was trying to prove that complex UI
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ideas could be entirely implemented in a user space toolkit, with no
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knowledge or support by the system. </P>
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<P>After going to film school for a few years, Bill worked at Sun
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Microsystems on the (doomed) NeWS project. Here he found an even
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better and cleaner windowing system, and he reimplemented "views" atop
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that. NeWS did have an unnecessarily complex method of delivering
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events which hurt it. But the designers did admit that perhaps the
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user could write just as good of a button as they could, and officially
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exposed the lower level interface. </P>
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<P>With the death of NeWS Bill realized that he would have to live with
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X. The biggest problem with X is the "window manager", which means
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that the toolkit can no longer control the window borders or drag the
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window around. </P>
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<P>At Digital Domain Bill discovered another toolkit, "Forms". Forms
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was similar to his work, but provided many more widgets, since it was
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used in many real applications, rather then as theoretical work. He
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decided to use Forms, except he integrated his table-driven menus into
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it. Several very large programs were created using this version of
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Forms. </P>
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<P>The need to switch to OpenGL and GLX, portability, and a desire to
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use C++ subclassing required a rewrite of Forms. This produced the
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first version of FLTK. The conversion to C++ required so many changes
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it made it impossible to recompile any Forms objects. Since it was
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incompatible anyway, Bill decided to incorporate his older ideas as
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much as possible by simplifying the lower level interface and the event
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passing mechanisim. </P>
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<P>Bill received permission to release it for free on the Internet,
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with the GNU general public license. Response from Internet users
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indicated that the Linux market dwarfed the SGI and high-speed GL
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market, so he rewrote it to use X for all drawing, greatly speeding it
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up on these machines. That is the version you have now. </P>
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<P>Digital Domain has since withdrawn support for FLTK. While Bill is
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no longer able to actively develop it, he still contributes to FLTK in
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his free time and is a part of the FLTK development team. </P>
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<H2>Features</H2>
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FLTK was designed to be statically linked. This was done by splitting
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it into many small objects and desigining it so that functions that are
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not used do not have pointers to them in the parts that are used, and
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thus do not get linked in. This allows you to make an easy-to-install
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program, or to modify FLTK to the exact requirements of your
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application, without worrying about bloat. FLTK works fine as a shared
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library, though, and has started being included on Linux distributions.
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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) == 40 to 48.</LI>
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<LI>The "core" (the "hello" program compiled & linked with a static
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FLTK library using gcc on a 486 and then stripped) is 110K.</LI>
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<LI>The FLUID program (which includes every widget) is 372k.
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<LI>Written directly atop Xlib (or WIN32) for maximum speed, and
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carefully optimized for code size and performance.</LI>
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<LI>Precise low-level compatability between the X11 and WIN32 version
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(only about 10% of the code is 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 X11 overlay hardware (emulation if none and under
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WIN32.)</LI>
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<LI>Very small & fast portable 2-D drawing library to hide Xlib and
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WIN32.</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 WIN32.
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Emulation if none.</LI>
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<LI>Text input fields with Emacs key bindings, X cut & paste, and
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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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<LI>Much too much to list here...</LI>
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</UL>
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<H2>Licensing</H2>
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FLTK comes with complete free source code. FLTK is available under the
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terms of the <A href=#licensing>GNU Library General Public License</A>.
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Contrary to popular belief, it can be used in commercial software!
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(Even Bill Gates could use it.)
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<H2>What Does "FLTK" Mean?</H2>
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FLTK was originally designed to be compatible with the Forms Library
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written for SGI machines. In that library all the functions and
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structures started with "fl_". This naming was extended to all new
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methods and widgets in the C++ library, and this prefix was taken as
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the name of the library. It is almost impossible to search for "FL" on
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the 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 the
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toolkit, which was already in use by several people, Bill came up with
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"FLTK", and even a bogus excuse that it stands for "The Fast Light Tool
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Kit".
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<H2>Building and Installing FLTK Under UNIX</H2>
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In most cases you can just type "make". This will run configure with
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the default of no options and then compile everything.
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<P>FLTK uses GNU autoconf to configure itself for your UNIX platform.
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The main things that the configure script will look for are the X11 and
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OpenGL (or Mesa) header and library files. If these cannot be
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found in the standard include/library locations you'll need to define the
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<tt>CFLAGS</tt>, <tt>CXXFLAGS</tt>, and <tt>LDFLAGS</tt> environment
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variables. 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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For C shell and tcsh, use:
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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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By default configure will look for a C++ compiler named <tt>CC</tt>, <tt>c++</tt>,
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<tt>g++</tt>, or <tt>gcc</tt> in that order. To use another compiler you need
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to set the <tt>CXX</tt> environment variable:
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<UL><PRE>
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CXX=xlC; export xlC
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setenv CXX "xlC"
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</PRE></UL>
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The <tt>CC</tt> environment variable can also be used to override the
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default C compiler (<tt>cc</tt> or <tt>gcc</tt>), which is used for a
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few FLTK source files.
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<P>You can run configure yourself to get the exact setup you need. Type
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"./configure <options>", where options are: </P>
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<DL>
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<DT>--enable-debug</DT>
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<DD>Enable debugging code & symbols</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>--bindir=/path</DT>
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<DD>Set the location for executables [default = /usr/local/bin]</DD>
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<DT>--libdir=/path</DT>
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<DD>Set the location for libraries [default = /usr/local/lib]</DD>
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<DT>--includedir=/path</DT>
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<DD>Set the location for include files. [default = /usr/local/include]</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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When the configure script is done you can just run the "make" command.
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This will build the library, FLUID tool, and all of the test programs.
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<P>To install the library, become root and type "make install". This
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will copy the "fluid" executable to "bindir", the header files to
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"includedir", and the library files to "libdir". </P>
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<H2>Building FLTK Under Microsoft Windows</H2>
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There are two ways to build FLTK under Microsoft Windows. The first
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is to use the Visual C++ 5.0 project files under the "visualc"
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directory. Just open (or double-click on) the "fltk.dsw" file to get
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the whole shebang.
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<P>The second method is to use a GNU-based development tool with the
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files in the "makefiles" directory. To build using one of these tools
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simply copy the appropriate makeinclude and config files to the main
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directory and do a make: </P>
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<UL>
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<PRE>
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copy makefiles\Makefile.<env> Makefile
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make
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</PRE>
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</UL>
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<H3>Using the Visual C++ DLL Library</H3>
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The "fltkdll.dsp" project file builds a DLL-version of the FLTK
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library. Because of name mangling differences between PC compilers (even
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between different versions of Visual C++!) you can only use the DLL that
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is generated with the same version compiler that you built it with.
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<P>When compiling an application or DLL that uses the FLTK DLL, you will need
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to define the <tt>FL_DLL</tt> preprocessor symbol to get the correct linkage
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commands embedded within the FLTK header files.
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<H2>Building FLTK Under OS/2</H2>
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The current OS/2 build requires XFree86 for OS/2 to work. A native
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Presentation Manager version has not been implemented yet (volunteers
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are welcome!).
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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>
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<PRE>
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copy makefiles\Makefile.os2x Makefile
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make
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</PRE>
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</UL>
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<H2>Internet Resources</H2>
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FLTK is available on the 'net in a bunch of locations:
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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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</DL>
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To send a message to the FLTK mailing list ("fltk@fltk.org") you
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must first join the list. Non-member submissions are blocked to avoid
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problems with unsolicited email.
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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" in the message body. A
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digest of this list is available by subscribing to the "fltk-digest"
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mailing list. </P>
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<H2>Reporting Bugs</H2>
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To report a bug in FLTK, send an email to "fltk-bugs@fltk.org".
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Please include the FLTK version, operating system & version, and
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compiler that you are using when describing the bug or problem.
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<P>For general support and questions, please use the FLTK mailing list
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at "fltk@fltk.org". </P>
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