README.CMake.txt - 2014-09-27 - Building and using FLTK with CMake ------------------------------------------------------------------ CONTENTS ========== 1 INTRODUCTION TO CMAKE 2 USING CMAKE TO BUILD FLTK 2.1 Prerequisites 2.2 Options 2.3 Building under Linux with Unix Makefiles 2.4 Crosscompiling 3 USING CMAKE WITH FLTK 3.1 Library names 3.2 Using Fluid files 4 DOCUMENT HISTORY INTRODUCTION TO CMAKE ======================= CMake was designed to let you create build files for a project once and then compile the project on multiple platforms. Using it on any platform consists of the same steps. Create the CMakeLists.txt build file(s). Run one of the CMake executables, picking your source directory, build directory, and build target. The "cmake" executable is a one-step process with everything specified on the command line. The others let you select options interactively, then configure and generate your platform-specific target. You then run the resulting Makefile / project file / solution file as you normally would. CMake can be run in up to three ways, depending on your platform. "cmake" is the basic command line tool. "ccmake" is the curses based interactive tool. "cmake-gui" is the gui-based interactive tool. Each of these will take command line options in the form of -DOPTION=VALUE. ccmake and cmake-gui will also let you change options interactively. CMake not only supports, but works best with out-of-tree builds. This means that your build directory is not the same as your source directory or with a complex project, not the same as your source root directory. Note that the build directory is where, in this case, FLTK will be built, not its final installation point. If you want to build for multiple targets, such as VC++ and MinGW on Windows, or do some cross-compiling you must use out-of-tree builds exclusively. In-tree builds will gum up the works by putting a CMakeCache.txt file in the source root. More information on CMake can be found on its web site http://www.cmake.org. USING CMAKE TO BUILD FLTK =========================== PREREQUISITES --------------- The prerequisites for building FLTK with CMake are staightforward: CMake 2.6 or later and a recent FLTK 1.3 snapshot. Installation of CMake is covered on its web site. This howto will cover building FLTK with the default options using cmake under Linux with both the default Unix Makefiles and a MinGW cross compiling toolchain. Other platforms are just as easy to use. OPTIONS --------- Options can be specified to cmake with the -D flag: cmake -D = Example: cmake -D CMAKE_BUILD_TYPE=Debug All options have sensible defaults so you won't usually need to touch these. There are only two CMake options that you may want to specify: CMAKE_BUILD_TYPE This specifies what kind of build this is i.e. Release, Debug... Platform specific compile/link flags/options are automatically selected by CMake depending on this value. CMAKE_INSTALL_PREFIX Where everything will go on install. Defaults are /usr/local for unix and C:\Program Files\FLTK for Windows. The following are the FLTK specific options. Platform specific options are ignored on other platforms. OPTION_OPTIM Extra optimization flags. OPTION_ARCHFLAGS Extra architecture flags. OPTION_APPLE_X11 - default OFF In case you want to use X11 on OSX. Not currently supported. OPTION_USE_POLL - default OFF Don't use this one either. OPTION_BUILD_SHARED_LIBS - default OFF Normally FLTK is built as static libraries which makes more portable binaries. If you want to use shared libraries, this will build them too. OPTION_BUILD_EXAMPLES - default ON Builds the many fine example programs. OPTION_CAIRO - default OFF Enables libcairo support OPTION_CAIROEXT - default OFF Enables extended libcairo support OPTION_USE_GL - default ON Enables OpenGL support OPTION_USE_THREADS - default ON Enables multithreaded support OPTION_LARGE_FILE - default ON Enables large file (>2G) support OPTION_USE_SYSTEM_LIBJPEG - default ON OPTION_USE_SYSTEM_ZLIB - default ON OPTION_USE_SYSTEM_LIBPNG - default ON FLTK has built in jpeg zlib and png libraries. These let you use system libraries instead, unless CMake can't find them. OPTION_USE_XINERAMA - default ON OPTION_USE_XFT - default ON OPTION_USE_XDBE - default ON These are X11 extended libraries. BUILDING UNDER LINUX WITH UNIX MAKEFILES ------------------------------------------ After untaring the FLTK source, go to the root of the FLTK tree and type the following. mkdir build cd build cmake .. make sudo make install This will build and install a default configuration FLTK. Some flags can be changed during the 'make' command, such as: make VERBOSE=on ..which builds in verbose mode, so you can see all the compile/link commands. CROSSCOMPILING ---------------- Once you have a crosscompiler going, to use CMake to build FLTK you need two more things. You need a toolchain file which tells CMake where your build tools are. The CMake website is a good source of information on this file. Here's mine for MinGW under Linux. ---- # the name of the target operating system set(CMAKE_SYSTEM_NAME Windows) # which tools to use set(CMAKE_C_COMPILER /usr/bin/i486-mingw32-gcc) set(CMAKE_CXX_COMPILER /usr/bin/i486-mingw32-g++) # here is where the target environment located set(CMAKE_FIND_ROOT_PATH /usr/i486-mingw32) # adjust the default behaviour of the FIND_XXX() commands: # search programs in the host environment set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER) # search headers and libraries in the target environment, set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY) set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY) set(CMAKE_INSTALL_PREFIX ${CMAKE_FIND_ROOT_PATH}/usr CACHE FILEPATH "install path prefix") ---- Not too tough. The other thing you need is a native installation of FLTK on your build platform. This is to supply the fluid executable which will compile the *.fl into C++ source and header files. So, again from the FLTK tree root. mkdir mingw cd mingw cmake -DCMAKE_TOOLCHAIN_FILE=~/projects/toolchain/Toolchain-mingw32.cmake .. make sudo make install This will create a default configuration FLTK suitable for mingw/msys and install it in the /usr/i486-mingw32/usr tree. USING CMAKE WITH FLTK ======================= The CMake Export/Import facility can be thought of as an automated fltk-config. For example, if you link your program to the fltk library, it will automatically link in all of its dependencies. This includes any special flags. ie on Linux it includes the -lpthread flag. This howto assumes that you have FLTK libraries which were built using CMake, installed. Building them with CMake generates some CMake helper files which are installed in standard locations, making FLTK easy to find and use. Here is a basic CMakeLists.txt file using FLTK. ------ cmake_minimum_required(VERSION 2.6) project(hello) # the following line is required only if you don't install FLTK # or if find_package can't find your installation directory # it points to the build directory or the base folder, # not the library folder. set(FLTK_DIR /path/to/fltk) find_package(FLTK REQUIRED NO_MODULE) include(${FLTK_USE_FILE}) add_executable(hello WIN32 hello.cxx) target_link_libraries(hello fltk) ------ The set(FLTK_DIR ...) command is a superhint to the find_package command. This is very useful if you don't install or have a non-standard install. The find_package command tells CMake to find the package FLTK, REQUIRED means that it is an error if it's not found. NO_MODULE tells it to search only for the FLTKConfig file, not using the FindFLTK.cmake supplied with CMake, which doesn't work with this version of FLTK. Once the package is found we include the ${FLTK_USE_FILE} which adds the FLTK include directories to its knowledge base. After that your programs will be able to find FLTK headers. The WIN32 in the add_executable tells your Windows compiler that this is a gui app. It is ignored on other platforms. LIBRARY NAMES --------------- When you use the target_link_libraries command, CMake uses it's own internal names for libraries. The fltk library names are: fltk fltk_forms fltk_images fltk_gl and for the shared libraries (if built): fltk_SHARED fltk_forms_SHARED fltk_images_SHARED fltk_gl_SHARED The built-in libraries (if built): fltk_jpeg fltk_png fltk_z USING FLUID FILES ------------------- CMake has a command named fltk_wrap_ui which helps deal with fluid *.fl files. An example of its use is in test/CMakeLists.txt. Here is a short summary on its use. Set a variable to list your C++ files, say CPPFILES. Set another variable to list your *.fl files, say FLFILES. Say your executable will be called exec. Then this is what you do... fltk_wrap_ui(exec ${FLFILES}) add_executable(exec WIN32 ${CPPFILES} ${exec_FLTK_UI_SRCS}) fltk_wrap_ui calls fluid and generates the required C++ files from the *.fl files. It sets the variable, in this case exec_FLTK_UI_SRCS, to the list of generated files for inclusion in the add_executable command. The variable FLTK_FLUID_EXECUTABLE which is needed by fltk_wrap_ui is set when find_package(FLTK REQUIRED NO_MODULE) succeeds. DOCUMENT HISTORY ================== Dec 20 2010 - matt: merged and restructures May 15 2013 - erco: small formatting tweaks, added some examples Feb 23 2014 - msurette: updated to reflect changes to the CMake files