cmake and doxygen github com

30 Nov 2009

motivation

i’ve just rewrote a library called libnoise to use cmake (instead of static Makefiles/libtool). i have to admit that cmake is probably the best buildsystem i’ve ever used. cmake does so many things better than others - but you probably know that already so i will focus on different things.

i had lot’s of problems using doxygen with an ‘out of source’ build. but i finally fixed that. i consider my hack an excellent example of how to use doxygen with cmake. the first thing i tried was hacking on [2], a posting from “Philippe Poilbarbe” (i don’t know this developer) which i couldn’t get running at first. exhausted i tried something else (for those who are interested, it was [3] a mail about a library called ‘libLASi’ using doxygen together with cmake (see [4] for libLASi). now happy to get doxygen working the ‘libLASi way’ at least i decided to branch back to my first attempt which was [2]. finally i got that working, too. so [2] is the basis for this posting - keep that in mind.

i don’t like the way doxygen is integrated in cmake by the ‘libLASi’ developers. why?

because they write to the source directory (called ‘in source build’) and this is not how cmake developers (that is those who wrote cmake) consider stuff to be done right.

if you ever have to use doxygen with cmake you should look at my code [2]. it will compile on linux (probably unix in general) and all you need is a g++ compiler and doxygen installed.

in general to adapt the cmake/doxygen from any other build system keep this in mind:

  • the “Doxygen” file most often static will be rewritten (then called “Doxygen.in”) and some placeholders are inserted as: ** PROJECT_NUMBER = @LIBNOISE_VERSION@**

  • in general one could say “Doxygen.in” needs some adaption to receive cmake variables contents as i already wrote in the libnoise sourcecode (see quote below)

  • the cmake script called: CMakeLists.txt dealing with the docu (doxygen) will then replace this placeholders on the fly - that is when executing ‘cmake .

  • nearly all variables (i can’t think of any which would not work but i didn’t check them either) can be modified this way

  • one variable is replaced by a REGEXP (see quote below as well)

    # you could also set the version with this, see Doxygen.in
    # there you will find a line like this:
    #      PROJECT_NUMBER         = @LIBNOISE_VERSION@
    # @LIBNOISE_VERSION@ is then replaced by our global LIBNOISE_VERSION
    #
    # for instance you could uncomment the next 3 lines and change the version for testing
    # SET(LIBNOISE_VERSION
    #     "1.2.3-foo500"
    # )
    
    # doxygen can reference external images with IMAGE_PATH, this is how we set it dynamically
    SET( CMAKE_DOXYGEN_IMAGE_PATH
    "${CMAKE_CURRENT_SOURCE_DIR}/img"
    )
    
    # doxygen searches for source code (defined in FILE_PATTERNS, for example: *.cpp *.h)
    # with DOXYGEN_SOURCE_DIR we fill a list of directories and later we write it into
    # the Doxyfile with a REGEX REPLACE (see below)
    SET( DOXYGEN_SOURCE_DIR
    ${CMAKE_SOURCE_DIR}
    )
    
    SET(DOXYGEN_OUTPUT_DIR html)
    STRING(REGEX REPLACE ";" " " CMAKE_DOXYGEN_INPUT_LIST "${DOXYGEN_SOURCE_DIR}")
    CONFIGURE_FILE(Doxyfile.in ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile)
    SET(HTML_TARGET "html" )
    ADD_CUSTOM_TARGET(${HTML_TARGET} ALL
    /usr/bin/doxygen ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile
    DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile)
    INSTALL( DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/html/" DESTINATION "/usr/share/doc/libnoise-${LIBNOISE_VERSION}" )
  • it is very important to understand what ${CMAKE_CURRENT_SOURCE_DIR} and ${CMAKE_CURRENT_BINARY_DIR} are used for

i hope you won’t loose as much time as i did figuring this out.

finally: thanks very much for help from straszheim#cmake@irc.freenode.net (general cmake questions, nothing doxygen related) and thanks to the example at [5] but it wasn’t very helpful since i didn’t understand it - nice try, maybe next time! ;-)

#links

UPDATE(30Nov09): replaced static path with ${CMAKE_SOURCE_DIR} in the quoted script above

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