CMakeLists.txt

# ==== Define cmake build policies that affect compilation and linkage default behaviors
#
# Set the ITK_NEWEST_VALIDATED_POLICIES_VERSION string to the newest cmake version
# policies that provide successful builds. By setting ITK_NEWEST_VALIDATED_POLICIES_VERSION
# to a value greater than the oldest policies, all policies between
# ITK_OLDEST_VALIDATED_POLICIES_VERSION and CMAKE_VERSION (used for this build)
# are set to their NEW behaivor, thereby suppressing policy warnings related to policies
# between the ITK_OLDEST_VALIDATED_POLICIES_VERSION and CMAKE_VERSION.
#
# CMake versions greater than the ITK_NEWEST_VALIDATED_POLICIES_VERSION policies will
# continue to generate policy warnings "CMake Warning (dev)...Policy CMP0XXX is not set:"
#
set(ITK_OLDEST_VALIDATED_POLICIES_VERSION "3.10.2")
set(ITK_NEWEST_VALIDATED_POLICIES_VERSION "3.19.7")
cmake_minimum_required(VERSION ${ITK_OLDEST_VALIDATED_POLICIES_VERSION} FATAL_ERROR)
if("${CMAKE_VERSION}" VERSION_LESS_EQUAL "${ITK_NEWEST_VALIDATED_POLICIES_VERSION}")
  #Set and use the newest available cmake policies that are validated to work
  set(ITK_CMAKE_POLICY_VERSION "${CMAKE_VERSION}")
else()
  set(ITK_CMAKE_POLICY_VERSION "${ITK_NEWEST_VALIDATED_POLICIES_VERSION}")
endif()
cmake_policy(VERSION ${ITK_CMAKE_POLICY_VERSION})
#
# Now enumerate specific policies newer than ITK_NEWEST_VALIDATED_POLICIES_VERSION
# that may need to be individually set to NEW/OLD
#
foreach(pnew "") # Currently Empty
  if(POLICY ${pnew})
    cmake_policy(SET ${pnew} NEW)
  endif()
endforeach()
foreach(pold "CMP0120" "CMP0091") # CMP0120 will require non-trivial effort to address
  if(POLICY ${pold})
    cmake_policy(SET ${pold} OLD)
  endif()
endforeach()

# ==== Define language standard configurations requiring at least c++11 standard
if(CMAKE_CXX_STANDARD EQUAL "98" )
   message(FATAL_ERROR "CMAKE_CXX_STANDARD:STRING=98 is not supported in ITK version 5 and greater.")
endif()

#####
##  Set the default target properties for ITK
if(NOT CMAKE_CXX_STANDARD)
  set(CMAKE_CXX_STANDARD 11) # Supported values are ``11``, ``14``, and ``17``.
endif()
if(NOT CMAKE_CXX_STANDARD_REQUIRED)
  set(CMAKE_CXX_STANDARD_REQUIRED ON)
endif()
if(NOT CMAKE_CXX_EXTENSIONS)
  set(CMAKE_CXX_EXTENSIONS OFF)
endif()

# ====
include(${CMAKE_CURRENT_SOURCE_DIR}/CMake/ITKInitializeBuildType.cmake)

set(CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/CMake ${CMAKE_MODULE_PATH})

include(itkVersion)
set(ITK_VERSION
    "${ITK_VERSION_MAJOR}.${ITK_VERSION_MINOR}.${ITK_VERSION_PATCH}")
project(ITK
  VERSION ${ITK_VERSION}
  LANGUAGES CXX C)

set(ITK_CMAKE_DIR "${ITK_SOURCE_DIR}/CMake")

if (APPLE)
  include(itkApple)
endif ()

include(itkCompilerChecks)
include(itkSupportMacros)

# Configure CMake variables that will be used in the module macros
# ITK_USE_FILE is used when a remote module includes an example directory
# that can be configured as an independent project.
set(ITK_CONFIG_CMAKE_DIR "${ITK_SOURCE_DIR}/CMake")
set(ITK_USE_FILE "${ITK_CONFIG_CMAKE_DIR}/UseITK.cmake")
# ITKInternalConfig.cmake is used to handle find_package(ITK) calls. This is useful
# to remote module examples which are set up as independent projects that can be copied
# outside of their original project and used without any modification.
configure_file(CMake/ITKInternalConfig.cmake ${ITK_BINARY_DIR}/CMakeTmp/ITKConfig.cmake COPYONLY)


include(CMakeDependentOption)
#
# use ExternalProject
include(ExternalProject)

if( CMAKE_HOST_WIN32 )
  if(NOT DEFINED ITK_SKIP_PATH_LENGTH_CHECKS)
    if(${CMAKE_SYSTEM_VERSION} VERSION_GREATER "10.0.14392") # Win10 version 1607
      set(_LongPathKey LongPathsEnabled)
      execute_process(COMMAND reg query HKLM\\SYSTEM\\CurrentControlSet\\Control\\FileSystem /v ${_LongPathKey} OUTPUT_VARIABLE _output)
      string(REGEX MATCH "${_LongPathKey}.*REG_DWORD.*[0-9]x([0-9])" _regex ${_output})
      if (${CMAKE_MATCH_1})
        set(ITK_SKIP_PATH_LENGTH_CHECKS 0 CACHE BOOL "Skips max path length checks. These checks can be disabled for Windows version 10.0.14393 and later if registry key HKLM\\SYSTEM\\CurrentControlSet\\Control\\FileSystem\\LongPathsEnabled is set to 1 and all tools support long paths. As of January 2018, MSBuild and Visual Studio do not support it yet.")
      endif()
    endif()
  endif()
endif()

if( CMAKE_HOST_WIN32 AND NOT ITK_SKIP_PATH_LENGTH_CHECKS )

  string( LENGTH "${CMAKE_CURRENT_SOURCE_DIR}" n )
  if( n GREATER 50 )
    message(
      FATAL_ERROR
      "ITK source code directory path length is too long (${n} > 50)."
      "Please move the ITK source code directory to a directory with a shorter path."
      )
  endif()

  string( LENGTH "${CMAKE_CURRENT_BINARY_DIR}" n )
  if( n GREATER 50 )
    message(
      FATAL_ERROR
      "ITK build directory path length is too long (${n} > 50)."
      "Please set the ITK build directory to a directory with a shorter path."
      )
  endif()

endif()

#-----------------------------------------------------------------------------
if(NOT EXISTS "${ITK_SOURCE_DIR}/.ExternalData/README.rst")
  # This file is always present in version-controlled source trees
  # so we must have been extracted from a source tarball with no
  # data objects needed for testing.  Turn off tests by default
  # since enabling them requires network access or manual data
  # store configuration.
  option(BUILD_TESTING "Build the testing tree." OFF)
endif()
include(CTest)
mark_as_advanced(CLEAR BUILD_TESTING)

include(ITKDownloadSetup)
include(PreventInSourceBuilds)
include(PreventInBuildInstalls)
include(ITKModuleMacros)
include(ITKExternalData)
include(ITKModuleTest)
include(itkCheckSourceTree)


set(main_project_name ${_ITKModuleMacros_DEFAULT_LABEL})

#-----------------------------------------------------------------------------
configure_file(CMake/ITKConfigVersion.cmake.in ITKConfigVersion.cmake @ONLY)

if(NOT ITK_INSTALL_RUNTIME_DIR)
  set(ITK_INSTALL_RUNTIME_DIR bin)
endif()
if(NOT ITK_INSTALL_LIBRARY_DIR)
  set(ITK_INSTALL_LIBRARY_DIR lib)
endif()
if(NOT ITK_INSTALL_ARCHIVE_DIR)
  set(ITK_INSTALL_ARCHIVE_DIR lib)
endif()
if(NOT ITK_INSTALL_INCLUDE_DIR)
  set(ITK_INSTALL_INCLUDE_DIR include/ITK-${ITK_VERSION_MAJOR}.${ITK_VERSION_MINOR})
endif()
if(NOT ITK_INSTALL_DATA_DIR)
  set(ITK_INSTALL_DATA_DIR share/ITK-${ITK_VERSION_MAJOR}.${ITK_VERSION_MINOR})
endif()
if(NOT ITK_INSTALL_DOC_DIR)
  set(ITK_INSTALL_DOC_DIR share/doc/ITK-${ITK_VERSION_MAJOR}.${ITK_VERSION_MINOR})
endif()
if(NOT ITK_INSTALL_PACKAGE_DIR)
  set(ITK_INSTALL_PACKAGE_DIR "lib/cmake/ITK-${ITK_VERSION_MAJOR}.${ITK_VERSION_MINOR}")
endif()

# Override CMake's built-in add_* commands: assign LABELS to tests and targets
# automatically. Depends on the CMake variable itk-module being set to the
# "current" module when add_* is called.
macro(verify_itk_module_is_set)
  if("" STREQUAL "${itk-module}")
    message(FATAL_ERROR "CMake variable itk-module is not set")
  endif()
endmacro()

#-----------------------------------------------------------------------------
# Do we try to use system libraries by default?
option(ITK_USE_SYSTEM_LIBRARIES "Use the system's libraries by default.
If this is not set during the initial configuration, it will have no effect." OFF)
mark_as_advanced(ITK_USE_SYSTEM_LIBRARIES)

#-----------------------------------------------------------------------------
# Enable the download and use of BrainWeb datasets.
# When this data is available, additional 3D tests are enabled.
option(ITK_USE_BRAINWEB_DATA "Download and use BrainWeb data for advanced testing" OFF)
mark_as_advanced(ITK_USE_BRAINWEB_DATA)
if(ITK_BRAINWEB_DATA_ROOT)
  message(WARNING
    "ITK_BRAINWEB_DATA_ROOT is not longer supported!"
    "Please update to ITK_USE_BRAINWEB_DATA."
    )
endif()

#-----------------------------------------------------------------------------
# CMAKE_C_COMPILER_ARG1 is a CMake internal variable. It should not be used
# in ITK's configuration. If it is set, it most likely means that
# a developer is configuring ITK to be built with a launcher such as ccache
# or distcc. This should be done with the CMake variable
# CMAKE_C_COMPILER_LAUNCHER_FLAG.
if(CMAKE_C_COMPILER_ARG1)
  message(WARNING "The CMake variable CMAKE_C_COMPILER_ARG1 is set. This most\
  likely mean that the developer is trying to use ccache or distcc. The CMake\
  variable CMAKE_C_COMPILER_LAUNCHER_FLAG should be used instead.")
endif()

#-----------------------------------------------------------------------------
# ITK build configuration options.
option(BUILD_SHARED_LIBS "Build ITK with shared libraries." OFF)
set(ITK_BUILD_SHARED_LIBS ${BUILD_SHARED_LIBS})

option(ITK_DYNAMIC_LOADING "Support run-time loading of shared libraries" ON)
mark_as_advanced(ITK_DYNAMIC_LOADING)

#-----------------------------------------------------------------------------
# Wrapping options
include(Wrapping/CMakeUtilityFunctions.cmake)
include(Wrapping/WrappingOptions.cmake)
include(ITKSetStandardCompilerFlags)
#---------------------------------------------------------------


set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${ITK_REQUIRED_C_FLAGS}")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${ITK_REQUIRED_CXX_FLAGS}")
set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${ITK_REQUIRED_LINK_FLAGS}")
set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} ${ITK_REQUIRED_LINK_FLAGS}")
set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} ${ITK_REQUIRED_LINK_FLAGS}")
if(NOT CMAKE_POSITION_INDEPENDENT_CODE)
  set(CMAKE_POSITION_INDEPENDENT_CODE ON)
endif()
# Because GoogleTest sets CMAKE_DEBUG_POSTFIX CMake CACHE variable to "d" when it is
# built in debug, we preemptively set it to an empty string to avoid having a postfix
# added to the ITK library names.
set(CMAKE_DEBUG_POSTFIX "" CACHE STRING "Generate debug library name with a postfix.")
mark_as_advanced(CMAKE_DEBUG_POSTFIX)

# Configure find_package behavior
if("${CMAKE_VERSION}" VERSION_GREATER_EQUAL "3.16")
  if(NOT DEFINED CMAKE_FIND_USE_PACKAGE_REGISTRY)
    set(CMAKE_FIND_USE_PACKAGE_REGISTRY 0)
  endif()
else()
  if(NOT DEFINED CMAKE_FIND_PACKAGE_NO_PACKAGE_REGISTRY)
    set(CMAKE_FIND_PACKAGE_NO_PACKAGE_REGISTRY 1)
  endif()
endif()

# Setup build locations for shared libraries ----START
#     ITK/CMakeLists.txt -- use ITK_BINARY_DIR as root
#     ITK/CMake/ITKModuleExternal.cmake -- use ITK_DIR as root
#
# The default path when not wrapping.  Restore standard build location
# if python wrapping is turned on, and then turned off.
if(NOT CMAKE_LIBRARY_OUTPUT_DIRECTORY)
  set(NO_WRAP_CMAKE_LIBRARY_OUTPUT_DIRECTORY ${ITK_BINARY_DIR}/lib CACHE PATH "Shared library directory")
else()
  set(NO_WRAP_CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_LIBRARY_OUTPUT_DIRECTORY} CACHE PATH "Shared library directory")
endif()
if(NOT CMAKE_RUNTIME_OUTPUT_DIRECTORY)
  set(NO_WRAP_CMAKE_RUNTIME_OUTPUT_DIRECTORY ${ITK_BINARY_DIR}/bin CACHE PATH "Shared library directory")
else()
  set(NO_WRAP_CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_RUNTIME_OUTPUT_DIRECTORY} CACHE PATH "Shared library directory")
endif()

if(ITK_WRAPPING)
  # WRAPPER_LIBRARY_OUTPUT_DIR. Directory in which generated cxx, xml, and idx files will be placed.
  set(WRAPPER_LIBRARY_OUTPUT_DIR "${ITK_BINARY_DIR}/Wrapping" CACHE INTERNAL "Need to specify the output library directory globally")
  if(ITK_WRAP_PYTHON)
    set(ITK_WRAP_PYTHON_ROOT_BINARY_DIR "${WRAPPER_LIBRARY_OUTPUT_DIR}/Generators/Python" CACHE INTERNAL "python binary dir")
    # create the directory to avoid loosing case on windows
    file(MAKE_DIRECTORY ${ITK_WRAP_PYTHON_ROOT_BINARY_DIR})

    set(ITK_PYTHON_PACKAGE_DIR "${ITK_WRAP_PYTHON_ROOT_BINARY_DIR}/itk")
    # create the directory to avoid loosing case on windows
    file(MAKE_DIRECTORY ${ITK_PYTHON_PACKAGE_DIR})

    set(ITK_WRAP_PYTHON_SWIG_CONFIGURATION_DIR "${ITK_PYTHON_PACKAGE_DIR}/Configuration" CACHE INTERNAL "python binary dir")
    # create the directory to avoid loosing case on windows
    file(MAKE_DIRECTORY ${ITK_WRAP_PYTHON_SWIG_CONFIGURATION_DIR})

    # IF WRAP_PYTHON then we must unconditionally set the CMAKE_LIBRARY_OUTPUT_DIRECTORY
    # If wrapping for python, then put all the shared libraries (both core shared libs,
    # and python shared libs) in the itk python package directory.
    #
    # https://cmake.org/cmake/help/v3.10/prop_tgt/LIBRARY_OUTPUT_DIRECTORY.html#prop_tgt:LIBRARY_OUTPUT_DIRECTORY
    # Multi-configuration generators (VS, Xcode) append a per-configuration subdirectory
    # to the specified directory unless a generator expression is used.
    # Using an always true generator expression to disable multi-config standard behavior
    #
    # When wrapping, the multi-config generators can only be used in degraded state
    # of allowing only a single element int the CMAKE_CONFIGURATION_TYPES and enforcing
    # that CMAKE_BUILD_TYPE match that type (see Wrapping/CMakeLists.txt enforcement)
    set(CMAKE_LIBRARY_OUTPUT_DIRECTORY "$<1:${ITK_PYTHON_PACKAGE_DIR}>" CACHE PATH "Shared library directory with generator override" FORCE)
    set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "$<1:${ITK_PYTHON_PACKAGE_DIR}>" CACHE PATH "Shared library directory with generator override" FORCE)
  endif()
else()
  set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${NO_WRAP_CMAKE_LIBRARY_OUTPUT_DIRECTORY}   CACHE PATH "Shared library directory")
  set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${NO_WRAP_CMAKE_RUNTIME_OUTPUT_DIRECTORY}   CACHE PATH "Runtime library directory")
endif()
mark_as_advanced(FORCE
  CMAKE_RUNTIME_OUTPUT_DIRECTORY
  CMAKE_LIBRARY_OUTPUT_DIRECTORY
  NO_WRAP_CMAKE_LIBRARY_OUTPUT_DIRECTORY
  NO_WRAP_CMAKE_RUNTIME_OUTPUT_DIRECTORY
  Python3_ROOT_DIR)
# Setup build locations for shared libraries ----STOP

if(CMAKE_CONFIGURATION_TYPES AND ITK_WRAPPING)
  add_custom_target(remove_all_wrapped_libs
    COMMAND ${CMAKE_COMMAND} -E rm -rf
             ${ITK_PYTHON_PACKAGE_DIR}/*.so
             ${ITK_PYTHON_PACKAGE_DIR}/*.dylib
             ${ITK_PYTHON_PACKAGE_DIR}/*.dll
    WORKING_DIRECTORY ${ITK_BINARY_DIR}
    COMMENT "A convenience target to cleanup library directories when
    switching between ITK_WRAP/nowrap, or between configs
    in a multi-config build."
  )
endif()

if(NOT CMAKE_ARCHIVE_OUTPUT_DIRECTORY)
  set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${ITK_BINARY_DIR}/lib)
endif()
set(ITK_MODULES_DIR "${ITK_BINARY_DIR}/${ITK_INSTALL_PACKAGE_DIR}/Modules")


#-----------------------------------------------------------------------------
# Provide compatibility options.
# During major release updates deprecated interface may be needed for backwards compatibility
cmake_dependent_option(ITK_LEGACY_REMOVE
  "Remove current legacy code completely." OFF
  "NOT ITK_WRAPPING" ON)

# During minor releases bugs may be identified that identify broken interface, or
# useless interfaces that need to be retained to not break backwards compatibilty.
# These ITK_FUTURE_LEGACY_REMOVE are another level of granularity for
# which backwards compatible features we want to maintain.
cmake_dependent_option(ITK_FUTURE_LEGACY_REMOVE
      "Completely remove compilation of code which will become deprecated by default in ITKv5." OFF
      "ITK_LEGACY_REMOVE" OFF)
cmake_dependent_option(ITK_LEGACY_SILENT
      "Silence all legacy code messages when ITK_LEGACY_REMOVE:BOOL=OFF." OFF
      "NOT ITK_LEGACY_REMOVE" OFF)
# The disabling of legacy code, and the ITKv4 compatibility option can not both be
# requested. If removal of legacy code is requested, then ITKV4_COMPATIBILITY must
# be off.
cmake_dependent_option(ITKV4_COMPATIBILITY
      "Enable LEGACY compatibility with ITK4.x when possible." OFF
      "NOT ITK_LEGACY_REMOVE" OFF)
mark_as_advanced(ITK_LEGACY_SILENT ITK_LEGACY_REMOVE ITK_FUTURE_LEGACY_REMOVE ITKV4_COMPATIBILITY)

if (ITKV3_COMPATIBILITY)
  message(FATAL_ERROR "ITKV3_COMPATIBILITY is removed starting in ITK version 5.0, this option is no longer valid.")
endif()

# Chose flavour of Analyze reader
set(ITK_NIFTI_IO_ANALYZE_FLAVOR_DOC_STRING "Which flavour of Analyze reader to use by default")

set(ITK_NIFTI_IO_ANALYZE_FLAVOR "ITK4Warning" CACHE STRING ${ITK_NIFTI_IO_ANALYZE_FLAVOR_DOC_STRING})

set_property(CACHE ITK_NIFTI_IO_ANALYZE_FLAVOR PROPERTY STRINGS ITK4Warning ITK4 SPM FSL Reject)

if( NOT ("${ITK_NIFTI_IO_ANALYZE_FLAVOR}" STREQUAL "ITK4Warning" OR
         "${ITK_NIFTI_IO_ANALYZE_FLAVOR}" STREQUAL "ITK4" OR
         "${ITK_NIFTI_IO_ANALYZE_FLAVOR}" STREQUAL "SPM" OR
         "${ITK_NIFTI_IO_ANALYZE_FLAVOR}" STREQUAL "FSL" OR
         "${ITK_NIFTI_IO_ANALYZE_FLAVOR}" STREQUAL "Reject"
         ) )
  set(ITK_NIFTI_IO_ANALYZE_FLAVOR "ITK4Warning" CACHE STRING ${ITK_NIFTI_IO_ANALYZE_FLAVOR_DOC_STRING} FORCE)
endif()
mark_as_advanced(ITK_NIFTI_IO_ANALYZE_FLAVOR)


#-----------------------------------------------------------------------------
# ITK build classes that are in the review process
# ITK_USE_REVIEW is deprecated, only kept for backward compatibility
if (ITK_USE_REVIEW AND NOT Module_ITKReview)
  message(WARNING "ITK_USE_REVIEW is deprecated, please use Module_ITKReview to turn Review module ON/OFF")
  set(Module_ITKReview ON CACHE BOOL "Module containing code from the Review directory of ITKv4." FORCE)
endif()

#-----------------------------------------------------------------------------
# ITK uses KWStyle for checking the coding style
include(${ITK_SOURCE_DIR}/Utilities/KWStyle/KWStyle.cmake)

#-----------------------------------------------------------------------------
# Build the Examples that are illustrated in the Software Guide.
option(BUILD_EXAMPLES "Build the examples from the ITK Software Guide." OFF)

#-----------------------------------------------------------------------------
# Enable GPU support. Requires OpenCL to be installed
option(ITK_USE_GPU "GPU acceleration via OpenCL" OFF)
mark_as_advanced(ITK_USE_GPU)

if(ITK_USE_GPU)
  include(itkOpenCL)
endif()

#-----------------------------------------------------------------------------
# Manage FFT v3 Options
#
option(ITK_USE_MKL "Use system Intel Math Kernel Library (MKL) for FFT computation." OFF)
mark_as_advanced(ITK_USE_MKL)
if(ITK_USE_MKL)
  # The following lines are only useful if one sets `ITK_USE_MKL` to ON in
  # the command line. Otherwise, the first CMake run will always initialize
  # these variables to false. The error message will help the user to set
  # the appropriate values.
  set(ITK_USE_FFTWD ON CACHE BOOL "Use double precision fftw if found")
  set(ITK_USE_FFTWF ON CACHE BOOL "Use single precision fftw if found")
  set(ITK_USE_SYSTEM_FFTW ON CACHE BOOL "Use an installed version of fftw")
  if(NOT ITK_USE_FFTWD OR NOT ITK_USE_FFTWF OR NOT ITK_USE_SYSTEM_FFTW)
    message(FATAL_ERROR "ITK_USE_MKL is set to ON. ITK_USE_FFTWD, ITK_USE_FFTWF\
 and ITK_USE_SYSTEM_FFTW must be set to ON, too.")
  endif()
endif()
option(ITK_USE_CUFFTW "Use NVidia CUDA cuFFT with its FFTW interface for FFT computation." OFF)
mark_as_advanced(ITK_USE_CUFFTW)
if(ITK_USE_CUFFTW)
  # The following lines are only useful if one sets `ITK_USE_CUFFTW` to ON in
  # the command line. Otherwise, the first CMake run will always initialize
  # these variables to false. The error message will help the user to set
  # the appropriate values.
  set(ITK_USE_FFTWD ON CACHE BOOL "Use double precision fftw if found")
  set(ITK_USE_FFTWF ON CACHE BOOL "Use single precision fftw if found")
  set(ITK_USE_SYSTEM_FFTW ON CACHE BOOL "Use an installed version of fftw")
  if(NOT ITK_USE_FFTWD OR NOT ITK_USE_FFTWF OR NOT ITK_USE_SYSTEM_FFTW)
    message(FATAL_ERROR "ITK_USE_CUFFTW is set to ON. ITK_USE_FFTWD, ITK_USE_FFTWF\
 and ITK_USE_SYSTEM_FFTW must be set to ON, too.")
  endif()
endif()
# ITK_USE_FFTWD -- use double precision fftw
if(DEFINED USE_FFTWD)
  set(ITK_USE_FFTWD_DEFAULT ${USE_FFTWD})
else()
  set(ITK_USE_FFTWD_DEFAULT OFF)
endif()
option(ITK_USE_FFTWD "Use double precision fftw if found" ${ITK_USE_FFTWD_DEFAULT})
mark_as_advanced(ITK_USE_FFTWD)
#
# ITK_USE_FFTWF -- use single precision fftw
if(DEFINED USE_FFTWF)
  set(ITK_USE_FFTWF_DEFAULT ${USE_FFTWF})
else()
  set(ITK_USE_FFTWF_DEFAULT OFF)
endif()
option(ITK_USE_FFTWF "Use single precision fftw if found" ${ITK_USE_FFTWF_DEFAULT})
mark_as_advanced(ITK_USE_FFTWF)

# ITK_USE_SYSTEM_FFTW -- locate a readybuilt fftw installation
if(DEFINED USE_SYSTEM_FFTW)
  set(ITK_USE_SYSTEM_FFTW_DEFAULT ${USE_SYSTEM_FFTW})
else()
  set(ITK_USE_SYSTEM_FFTW_DEFAULT ${ITK_USE_SYSTEM_LIBRARIES})
endif()
option(ITK_USE_SYSTEM_FFTW "Use an installed version of fftw" ${ITK_USE_SYSTEM_FFTW_DEFAULT})
mark_as_advanced(ITK_USE_SYSTEM_FFTW)


if( ITK_USE_FFTWD OR ITK_USE_FFTWF )
  include(itkExternal_FFTW)
  # This pollutes the global namespace, but is needed for backward compatibility
  include_directories(${FFTW_INCLUDE})
  link_directories(${FFTW_LIBDIR})
endif()

set(ITK_USE_64BITS_IDS_DEFAULT "OFF")
# Note WIN32 is true when targeting any windows system
if(CMAKE_SIZEOF_VOID_P EQUAL "8" AND WIN32)
  set(ITK_USE_64BITS_IDS_DEFAULT "ON")
endif()
option(ITK_USE_64BITS_IDS "When ON, ITK will use 64-bit integer types instead of long types for sizes and indexes. This is needed for managing images larger than 4Gb in some platforms." "${ITK_USE_64BITS_IDS_DEFAULT}")
mark_as_advanced(ITK_USE_64BITS_IDS)

# ITK turn on concept checking
option(ITK_USE_CONCEPT_CHECKING "Turn on concept checking to give helpful errors at compile time if a type cannot be used as a template parameter." ON)
mark_as_advanced(ITK_USE_CONCEPT_CHECKING)
if(ITK_USE_STRICT_CONCEPT_CHECKING)
  message(WARNING "Compilers requiring ITK_USE_STRICT_CONCEPT_CHECKING are no longer suppported.  This variable is no longer used.")
endif()

#-----------------------------------------------------------------------------
# Mandatory wrapping options.
# These are not correctly set when using cmake without the -DITK_WRAP_PYTHON:BOOL=ON flag.
# In this case we need to tell the user that he has to change the flags manually to the right values.
if(ITK_WRAPPING)
  set(CMAKE_POSITION_INDEPENDENT_CODE 1)
endif()

#----------------------------------------------------------------------------
set(ITK_TEST_OUTPUT_DIR "${ITK_BINARY_DIR}/Testing/Temporary")

# Configure the default ITK_DATA_ROOT for the location of ITK Data.
set(ITK_DATA_ROOT ${ITK_SOURCE_DIR}/Testing/Data)

# Location of ITK Example Data.
set(ITK_EXAMPLE_DATA_ROOT "${ITK_SOURCE_DIR}/Examples/Data")

# This flag is used in particular, to enable some tests that require large memory to run.
# Test that have significant memory requirements should use
# "set_tests_properties( testname PROPERTIES RESOURCE_LOCK MEMORY_SIZE )",
# so that only 1 of the memory constrained tests is run at a time.  (NOTE: Other low
# memory tests that do not have the RESOURCE_LOCK requirement can be run at the same time.)
# Allow for tests that may use upto 80% of the computer memory to be used for testing.
cmake_host_system_information(RESULT ITK_COMPUTER_MEMORY_AVAILABLE_MB QUERY TOTAL_PHYSICAL_MEMORY)
math(EXPR EIGHTY_PERCENT_AVAILABLE_MEMORY_IN_GB "(${ITK_COMPUTER_MEMORY_AVAILABLE_MB} * 80) / ( 1024 * 100)" )
set(ITK_COMPUTER_MEMORY_SIZE ${EIGHTY_PERCENT_AVAILABLE_MEMORY_IN_GB} CACHE STRING "Provide here the size of your RAM in gibibytes")
unset(EIGHTY_PERCENT_AVAILABLE_MEMORY_IN_GB)
unset(ITK_COMPUTER_MEMORY_AVAILABLE_MB)
mark_as_advanced(ITK_COMPUTER_MEMORY_SIZE)

#This flag sets the floating point type used in itk::ImageBase for
# spacing/direction/origin to single precision
option(ITK_USE_FLOAT_SPACE_PRECISION "Use single precision for origin/spacing/directions in itk::Image" OFF)
mark_as_advanced(ITK_USE_FLOAT_SPACE_PRECISION)

# This flag allows to not build itkTestDrivers while still configuring all the tests and disable all
# tests that are implemented in the `test` folder in each ITK module. It does not disable tests
# that are implemented in the wrapping folder.
# This is used by dashboards to speed up compilation and testing on certain platforms.
option(DISABLE_MODULE_TESTS "Disable all ITK module tests in `test` folder" OFF)
mark_as_advanced(DISABLE_MODULE_TESTS)

#-----------------------------------------------------------------------------
# Configure Eigen3 before ITKModuleEnablement
# No download or build is performed. Generates Targets and Config.cmake files for Eigen
include(itkExternal_Eigen3)

#----------------------------------------------------------------------
# Make sure remote modules are downloaded before sorting out the module
# dependencies.
add_subdirectory(Modules/Remote)

# Enable modules according to user inputs and the module dependency DAG.
include(ITKModuleEnablement)

# Setup clang-format for code style enforcement
include(ITKClangFormatSetup)
#----------------------------------------------------------------------
# Generate ITKConfig.cmake for the build tree.
set(ITK_CONFIG_CODE "
set(ITK_MODULES_DIR \"${ITK_MODULES_DIR}\")")

set(ITK_CONFIG_TARGETS_CONDITION " AND NOT ITK_BINARY_DIR")
set(ITK_CONFIG_TARGETS_FILE "${ITK_BINARY_DIR}/ITKTargets.cmake")
set(ITK_CONFIG_MODULE_API_FILE "${ITK_SOURCE_DIR}/CMake/ITKModuleAPI.cmake")
configure_file(CMake/ITKConfig.cmake.in ITKConfig.cmake @ONLY)

# Generate ITKConfig.cmake for the install tree.
set(ITK_CONFIG_CODE "
# Compute the installation prefix from this ITKConfig.cmake file location.
get_filename_component(ITK_INSTALL_PREFIX \"\${CMAKE_CURRENT_LIST_FILE}\" PATH)")
# Construct the proper number of get_filename_component(... PATH)
# calls to compute the installation prefix.
string(REGEX REPLACE "/" ";" _count "${ITK_INSTALL_PACKAGE_DIR}")
foreach(p ${_count})
  set(ITK_CONFIG_CODE "${ITK_CONFIG_CODE}
get_filename_component(ITK_INSTALL_PREFIX \"\${ITK_INSTALL_PREFIX}\" PATH)")
endforeach()
set(ITK_CONFIG_CODE "${ITK_CONFIG_CODE}
set(ITK_MODULES_DIR \"\${ITK_INSTALL_PREFIX}/${ITK_INSTALL_PACKAGE_DIR}/Modules\")")
set(ITK_USE_FILE "\${ITK_INSTALL_PREFIX}/${ITK_INSTALL_PACKAGE_DIR}/UseITK.cmake")
set(ITK_CONFIG_CMAKE_DIR "\${ITK_INSTALL_PREFIX}/${ITK_INSTALL_PACKAGE_DIR}")
set(ITK_CONFIG_TARGETS_CONDITION "")
set(ITK_CONFIG_TARGETS_FILE "\${ITK_INSTALL_PREFIX}/${ITK_INSTALL_PACKAGE_DIR}/ITKTargets.cmake")
set(ITK_CONFIG_MODULE_API_FILE "\${ITK_INSTALL_PREFIX}/${ITK_INSTALL_PACKAGE_DIR}/ITKModuleAPI.cmake")
if(NOT ITK_USE_SYSTEM_FFTW)
  # Location installed with the FFTW ExternalProject.
  set(FFTW_LIBDIR "\${ITK_INSTALL_PREFIX}/lib/ITK-${ITK_VERSION_MAJOR}.${ITK_VERSION_MINOR}")
  set(FFTW_INCLUDE_PATH "\${ITK_INSTALL_PREFIX}/include/ITK-${ITK_VERSION_MAJOR}.${ITK_VERSION_MINOR}/Algorithms")
endif()
configure_file(CMake/ITKConfig.cmake.in CMakeFiles/ITKConfig.cmake @ONLY)

#-----------------------------------------------------------------------------
install(FILES ${ITK_BINARY_DIR}/CMakeFiles/ITKConfig.cmake
              ${ITK_BINARY_DIR}/ITKConfigVersion.cmake
              CMake/ITKModuleAPI.cmake
              CMake/UseITK.cmake
              CMake/itkImageIOFactoryRegisterManager.h.in
              CMake/itkTransformIOFactoryRegisterManager.h.in
              CMake/itkMeshIOFactoryRegisterManager.h.in
  DESTINATION ${ITK_INSTALL_PACKAGE_DIR}
  COMPONENT Development)
get_property(ITKTargets_MODULES GLOBAL PROPERTY ITKTargets_MODULES)
if(ITKTargets_MODULES)
  install(EXPORT ITKTargets DESTINATION ${ITK_INSTALL_PACKAGE_DIR}
          COMPONENT Development)
else()
  set(CMAKE_CONFIGURABLE_FILE_CONTENT "# No targets!")
  configure_file(${CMAKE_ROOT}/Modules/CMakeConfigurableFile.in
                 ${ITK_BINARY_DIR}/CMakeFiles/ITKTargets.cmake @ONLY)
  install(FILES ${ITK_BINARY_DIR}/CMakeFiles/ITKTargets.cmake
          DESTINATION ${ITK_INSTALL_PACKAGE_DIR} COMPONENT Development)
endif()

install(FILES "LICENSE" "NOTICE" "README.md" DESTINATION ${ITK_INSTALL_DOC_DIR} COMPONENT Runtime)

if(BUILD_TESTING OR ITK_BUILD_DOCUMENTATION OR ITK_WRAP_PYTHON)
  set(PYTHON_DEVELOPMENT_REQUIRED ${ITK_WRAP_PYTHON})
  include(${CMAKE_CURRENT_SOURCE_DIR}/CMake/ITKSetPython3Vars.cmake)

  if(ITK_WRAP_PYTHON AND NOT Python3_INCLUDE_DIRS)
    message(FATAL_ERROR "Python version ${Python3_VERSION} development environment not found for wrapping.")
  endif()
  if(NOT Python3_ROOT_DIR)
    get_filename_component(Python3_ROOT_DIR ${Python3_EXECUTABLE} DIRECTORY)
  endif()
endif()

# Add user-visible cache entry
set(Python3_ROOT_DIR ${Python3_ROOT_DIR} CACHE PATH
  "Which installation or virtual environment of Python to use" FORCE)

if(BUILD_TESTING)
  # If building the testing, write the test costs (i.e. time to run)
  # analysis to disk to more easily review long-running test times
  set(CTEST_COST_DATA_FILE "${CMAKE_BINARY_DIR}/test_cost.list" CACHE FILEPATH "Configurable path to CTest cost data file.")
  mark_as_advanced(CTEST_COST_DATA_FILE)
  add_subdirectory(Utilities/InstallTest)
endif()



#-----------------------------------------------------------------------------
# The subdirectories added below this line should use only the public
# interface with find_package(ITK). Set ITK_DIR to use this ITK build.
set(ITK_DIR "${ITK_BINARY_DIR}")

if(ITK_WRAPPING)
  add_subdirectory(Wrapping)
endif()

if(BUILD_EXAMPLES)
  add_subdirectory(Examples)
endif()

#----------------------------------------------------------------------
# Provide an option for generating documentation.
add_subdirectory(Utilities/Doxygen)

# Create target to download data from the ITKData group. This must come after
# all tests have been added that reference the group, so we put it last.
include(ExternalData)
ExternalData_Add_Target(ITKData)

mark_as_advanced(FORCE
  Module_AdaptiveDenoising
  Module_AnalyzeObjectLabelMap
  Module_AnisotropicDiffusionLBR
  Module_BioCell
  Module_BoneEnhancement
  Module_BoneMorphometry
  Module_BSplineGradient
  Module_Cuberille
  Module_FixedPointInverseDisplacementField
  Module_GenericLabelInterpolator
  Module_HigherOrderAccurateGradient
  Module_IOFDF
  Module_IOMeshSTL
  Module_IOOpenSlide
  Module_IOScanco
  Module_IOTransformDCMTK
  Module_IsotropicWavelets
  Module_LabelErodeDilate
  Module_LesionSizingToolkit
  Module_MeshNoise
  Module_MGHIO
  Module_MinimalPathExtraction
  Module_Montage
  Module_MorphologicalContourInterpolation
  Module_MultipleImageIterator
  Module_ParabolicMorphology
  Module_PerformanceBenchmarking
  Module_PhaseSymmetry
  Module_PolarTransform
  Module_PrincipalComponentsAnalysis
  Module_RLEImage
  Module_RTK
  Module_SCIFIO
  Module_SimpleITKFilters
  Module_SkullStrip
  Module_SmoothingRecursiveYvvGaussianFilter
  Module_SphinxExamples
  Module_SplitComponents
  Module_Strain
  Module_SubdivisionQuadEdgeMeshFilter
  Module_TextureFeatures
  Module_Thickness3D
  Module_TotalVariation
  Module_TubeTK
  Module_TwoProjectionRegistration
  Module_Ultrasound
  Module_VariationalRegistration)