IF(DOXYGEN_FOUND AND Python_Interpreter_FOUND)
    execute_process(COMMAND ${DOXYGEN_EXECUTABLE} --version
                  OUTPUT_VARIABLE DOXYGEN_VERSION OUTPUT_STRIP_TRAILING_WHITESPACE)

    if(DOXYGEN_VERSION VERSION_LESS 1.8)
        set(DOXYGEN_BEFORE_1_8 "")
        set(DOXYGEN_FROM_1_8_2 "#")
    elseif(DOXYGEN_VERSION VERSION_LESS 1.8.2)
        set(DOXYGEN_BEFORE_1_8 "#")
        set(DOXYGEN_FROM_1_8_2 "#")
    else()
        set(DOXYGEN_BEFORE_1_8 "#")
        set(DOXYGEN_FROM_1_8_2 "")
    endif()

    CONFIGURE_FILE(
        ${CMAKE_CURRENT_SOURCE_DIR}/Doxyfile.in
        ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile
        @ONLY)

    ADD_CUSTOM_TARGET (doc_cpp
        COMMAND ${CMAKE_COMMAND} -E make_directory ${DOCDIR}
        COMMAND ${CMAKE_COMMAND} -E make_directory ${DOCDIR}/vigra
        COMMAND ${DOXYGEN_EXECUTABLE}
        COMMENT "Generating documentation with doxygen ${DOXYGEN_VERSION}")

    ADD_CUSTOM_COMMAND(
        TARGET doc_cpp
        POST_BUILD
        COMMAND ${Python_EXECUTABLE}
            ${CMAKE_CURRENT_SOURCE_DIR}/makeFunctionIndex.py
            ${DOCDIR}/vigra
        COMMAND ${Python_EXECUTABLE}
            ${CMAKE_CURRENT_SOURCE_DIR}/post.py
            ${DOCDIR}/vigra
            ${vigra_version}
        COMMAND ${CMAKE_COMMAND} -E copy_directory
            ${CMAKE_CURRENT_SOURCE_DIR}/documents
            ${DOCDIR}/vigra/documents
        COMMAND ${CMAKE_COMMAND} -E copy_if_different
            ${CMAKE_CURRENT_SOURCE_DIR}/../LICENSE.txt
            ${DOCDIR}/vigra/LICENSE.txt
        COMMAND ${CMAKE_COMMAND} -E copy_if_different
            ${CMAKE_CURRENT_SOURCE_DIR}/../src/matlab/doc/tutorial_reference.pdf
            ${DOCDIR}/vigra/documents/tutorial_reference.pdf
        COMMENT "Postprocessing html files")

ELSE()
    ADD_CUSTOM_TARGET (doc_cpp
        COMMAND ${CMAKE_COMMAND} -E echo
            \"Cannot generate C++ documentation -- doxygen or Python not found.\")

ENDIF()

# create fallback index.html that simply refers to the online documentation
file(MAKE_DIRECTORY ${DOCDIR}/vigra)
file(GLOB INDEX_HTML_EXISTS ${DOCDIR}/vigra/index.html)
configure_file(vigra-icon.ico ${DOCDIR}/vigra/vigra-icon.ico COPYONLY)
if(NOT INDEX_HTML_EXISTS)
    configure_file(index_fallback.html ${DOCDIR}/vigra/index.html COPYONLY)
    configure_file(vigra.css ${DOCDIR}/vigra/vigra.css COPYONLY)
endif()

INSTALL(DIRECTORY ${DOCDIR}/
         DESTINATION ${DOCINSTALL}/)

ADD_DEPENDENCIES(doc doc_cpp)