CMake/Examples

Welcome to the CMake Wiki Examples! These short snippets which show you how to perform many common CMake procedures. Please see [1] for the verbose documentation.

Please add examples as you find common procedures which are not explained here!

Basics

Set a CMake variable

<source lang="cmake"> SET(VARIABLE VALUE) </source>

View a CMake variable

<source lang="cmake"> MESSAGE("CMAKE_BINARY_DIR: ${CMAKE_BINARY_DIR}") </source>

Output (print) statement

<source lang="cmake"> MESSAGE("Hello world") </source>

View a system variable

<source lang="cmake"> \verb|MESSAGE("$ENV{PATH}") </source>

Check operating system

<source lang="cmake">

IF(WIN32)
  ...do something...
ELSE(WIN32)
  ...do something else...
ENDIF(WIN32)

</source>

Logical Operators

These operators work exactly as you would expect.

AND

if(A AND B)

OR

if(A OR B)

NOT

if(NOT A)

Compound

if(NOT(A AND B))

Fix Mininum Version Error/Warning

<source lang="cmake"> cmake_minimum_required(VERSION 2.6.0 FATAL_ERROR) </source>

Look in the directory that the CMakeLists.txt file is for header and implementation files

<source lang="cmake"> INCLUDE_DIRECTORIES(${CMAKE_SOURCE_DIR}) </source>

Set Link Directories

<source lang="cmake"> LINK_DIRECTORIES(${LINK_DIRECTORIES} /usr/local/lib) </source>

Set Include Directories

This command adds a path to the include directories, you do NOT have to do the 'export' style ``keep everything that is here and add this one syntax. <source lang="cmake"> INCLUDE_DIRECTORIES(/some/directory) </source>

View the directories that are set

<source lang="cmake"> get_property(inc_dirs DIRECTORY PROPERTY INCLUDE_DIRECTORIES) message("inc_dirs = ${inc_dirs}") </source>

Automate configure and generate

Note 'cmake' instead of 'ccmake' (ccmake is curses cmake (curses is the terminal gui)) <source lang="cmake"> cmake -DCMAKE_BUILD_TYPE=Debug -DCMAKE_INSTALL_PREFIX=/usr/mylocation ../ </source>

Compiler options

Set a cmake flag

<source lang="cmake"> ccmake ../../src/boost -DCMAKE_IS_EXPERIMENTAL=YES_I_KNOW </source>

Set a cpp flag

<source lang="cmake"> SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -D__WXGTK__") </source>

Force g++

Ocassionally you will come across files with the extension .c that actually contain c++ code. CMake treats the file based on its extension. If you want to override this behavior (in this case, compile .c files with your c++ compiler), do the following:

<source lang="cmake"> set(MySources main.c anotherFile.c) add_executable(SpinRecognize ${MySource}) set_source_files_properties(${MySources} PROPERTIES LANGUAGE CXX) </source>

Per-target

<source lang="cmake"> set_target_properties(myexe_target

                               PROPERTIES COMPILE_FLAGS "-Wall") 

</source>

Set the default build type

<source lang="cmake"> SET(CMAKE_BUILD_TYPE Debug CACHE STRING "default to debug" FORCE) </source>

Custom variable

Here is a list of supported variable types: http://www.cmake.org/cmake/help/cmake2.6docs.html#command:set

String

<source lang="cmake"> SET(BUILD_PARAVIEW_PLUGIN ON CACHE STRING "Build Paraview plugin?" FORCE) </source>

Bool

<source lang="cmake"> SET(DAI_WITH_BP ON CACHE BOOL "Belief Propagation" FORCE) </source>

Comparison

if(DAI_WITH_BP EQUALS ON)

1. do something

endif(DAI_WITH_BP EQUALS ON)

Linking to specific libraries

ITK

Add the path to your environment: <source lang="text"> export ITK_DIR=/home/doriad/bin/ITK </source>

Then in the CMakeLists.txt use: <source lang="cmake"> FIND_PACKAGE(ITK REQUIRED) INCLUDE(${ITK_USE_FILE})

ADD_EXECUTABLE(CastImageFilter CastImageFilter.cxx) TARGET_LINK_LIBRARIES(CastImageFilter vtkHybrid ITKIO ITKBasicFilters ITKCommon ) </source>

VXL

Add the path to your environment: <source lang="text"> export VXLBIN="/home/doriad/bin/vxl" </source>

Then in the CMakeLists.txt use: <source lang="cmake"> FIND_PACKAGE(VXL REQUIRED) INCLUDE(${VXL_CMAKE_DIR}/UseVXL.cmake) </source>

VTK

Add the path to your environment: <source lang="text"> export VTK_DIR="/home/doriad/bin/VTK" </source>

Then in the CMakeLists.txt use: <source lang="cmake"> FIND_PACKAGE(VTK REQUIRED) INCLUDE(${VTK_USE_FILE}) </source>

Boost

Add to the environment: <source lang="text"> export BOOST_ROOT="/home/doriad/src/boost" export BOOST_LIBRARYDIR="/home/doriad/bin/boost/lib" </source>

Then in the CMakeLists.txt use: <source lang="cmake"> SET(Boost_USE_MULTITHREAD ON) #set a flag FIND_PACKAGE(Boost 1.34.1 COMPONENTS date_time filesystem) INCLUDE_DIRECTORIES(${INCLUDE_DIRECTORIES} ${Boost_INCLUDE_DIRS}) LINK_DIRECTORIES(${LINK_DIRECTORIES} ${Boost_LIBRARY_DIRS}) </source>

OpenCV

Add to the environment: <source lang="text"> export OpenCV_DIR=/home/doriad/bin/OpenCV </source>

Then in the CMakeLists.txt use: <source lang="cmake"> FIND_PACKAGE(OpenCV REQUIRED ) INCLUDE_DIRECTORIES( ${OPENCV_INCLUDE_DIR} )

ADD_EXECUTABLE(Scalar Scalar.cxx) TARGET_LINK_LIBRARIES(Scalar ${OpenCV_LIBS}) </source>

Get Help Using a Library

<source lang="cmake"> cmake --help-module FindBoost </source>

Add new libraries to CMake

<source lang="cmake"> /usr/share/cmake/Modules/FindOpenGL.cmake| </source>

Dependency Graph

<source lang="cmake"> ccmake ../src/Program/ --graphviz=test.graph dotty test.graph </source>

CTest

Run a specific test by number

e.g. Test 622 <source lang="cmake"> ctest -I 622,622 </source>

Run a range of tests

e.g. Test 622 to 625 <source lang="cmake"> ctest -I 622,625 </source>

Run a test by name

<source lang="cmake"> ctest -R "itkTransformPoint*"| </source>

Link to a library

<source lang="cmake"> ADD_EXECUTABLE(ColoredLines ColoredLines.cpp) TARGET_LINK_LIBRARIES(ColoredLines vtkHybrid) </source>

Create a library

<source lang="cmake"> add_library(MatlabLibrary ./MatlabDll/LidarK.cpp) </source>