CMakeLists.txt is what describes cmake file
cmake build . : execute CMakeLists.txt from current (.) directory
cmake -G "generator" . : generates files for a different build system. Default generator is make. Possible generators: Unix Makefiles , Ninja , XCode ,
cmake --trace . : run trace, which shows all variables set (for debugging)
# this is how to de-obfuscate build commands i.e. see what commands are being executed
#
When working on CMakeLists.txt you often need to clean cmake cache. I add this alias to my .bash_profile : alias cmake_clean="rm -f CMakeCache.txt; rm -rf CMakeFiles/; rm -f cmake_install.cmake" (or just the commends)
cmake_minimum_required (VERSION 3.8)
project (djvu)
set(CMAKE_BUILD_TYPE Release)
include_directories("libdjvu")
add_executable(djvudump tools/djvudump.cpp)
Cmake defines lots of internal variables that affect what happens. You can define your own variables (e.g. to define a list of files to compile).
set(CMAKE_BUILD_TYPE Release) : set internal variable CMAKE_BUILD_TYPE to Release.
file(GLOB LIB_SOURCES "libdjvu/*.cpp") : set LIB_SOURCES variable to list of files in directory libdjvu that match glob patter *.cpp
${LIB_SOURCES} refers to a variable.
Wehn debugging you can print the value of a variable with MESSAGE(STATUS "CMAKE_CURRENT_BINARY_DIR:" ${CMAKE_CURRENT_BINARY_DIR})
include_directories("libdjvu") : adds libdjvu/ directory to list of directories compiler will search for include files (.h etc.).
add_library(libdjvu SHARED ${LIBDJVU_SOURCES}) : builds a shared (dll) library from source files defined by LIBDJVU_SOURCES variable. STATIC will build a static library.
add_executable(djvudump tools/djvudump.cpp) : this defines djvudump binary built from tools/djvudump.cpp . Cmake figures out from .cpp extension that this is C++ binary and will use C++ rules to compile and link the executable.
target_link_libraries(djvudump libdjvu) : tells to link executable djvudump with libdjuv library (defined with add_library() command)
add_definitions(-DWITH_OPENCV2)
add_definitions(-DOPENCV_VERSION=${OpenCV_VERSION})
target_compile_definitions(my_target PRIVATE FOO=1 BAR=1) : only for a specific target (e.g. a specific library of executable)
set_source_files_properties(foo.cpp PROPERTIES COMPILE_DEFINITIONS -DFOO=1) : only for a specific file
https://stackoverflow.com/questions/6594796/how-do-i-make-cmake-output-into-a-bin-dir
By default cmake creates libraries/executables in top-level directory. You can change it by setting those variables:
set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib) set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib) set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
https://cmake.org/Wiki/CMake_Useful_Variables#Compilers_and_Tools
https://cmake.org/cmake/help/latest/manual/cmake-variables.7.html
Only applies to single-configuration generators (e.g. make, ninja as opposed to e.g. msvc).
Effect: e.g. if is Debug, CMAKE_C_FLAGS_DEBUG gets added to CMAKE_C_FLAGS
- https://cliutils.gitlab.io/modern-cmake/
- https://codingnest.com/basic-cmake/#fnref6
- https://pabloariasal.github.io/2018/02/19/its-time-to-do-cmake-right/
- https://www.youtube.com/watch?v=rLopVhns4Zs&feature=youtu.be : effective CMake
- https://github.com/crezefire/cxp : modern CMake template for C++ cross-platform apps
- http://thetoeb.de/2016/08/30/modern-cmake-presentation/
- http://derekmolloy.ie/hello-world-introductions-to-cmake/
- https://www.slideshare.net/DanielPfeifer1/cmake-48475415
- https://rix0r.nl/blog/2015/08/13/cmake-guide/
- http://preshing.com/20170511/how-to-build-a-cmake-based-project/
- http://preshing.com/20170522/learn-cmakes-scripting-language-in-15-minutes/
- https://asmbits.blogspot.com/2017/06/idiomatic-cmake.html
- http://www.goodbits.ca/index.php/2017/09/25/building-an-apple-osx-kernel-module-with-cmake-cc/
- https://github.com/buggins/coolreader/blob/master/CMakeLists.txt
- https://github.com/koreader/koreader-base/blob/e1974cbc8841dbdff2f837da1d2cde6ec6b107e3/thirdparty/djvulibre/CMakeLists.txt
- https://stackoverflow.com/questions/46553436/building-with-cmake-ninja-and-clang-on-windows
- https://www.reddit.com/r/cpp/comments/67av0m/is_there_a_better_way_to_marry_cmake_clang_and_vs/
- https://stackoverflow.com/questions/38171878/how-do-i-tell-cmake-to-use-clang-on-windows
- https://www.reddit.com/r/cpp/comments/67av0m/is_there_a_better_way_to_marry_cmake_clang_and_vs/
- https://github.com/webmproject/libwebm/blob/master/CMakeLists.txt
- http://bastian.rieck.me/blog/posts/2018/cmake_tips/
Links:
- http://stackoverflow.com/questions/2368811/how-to-set-warning-level-in-cmake
- https://github.com/libgit2/libgit2/blob/development/CMakeLists.txt : useful stuff for windows
- https://rix0r.nl/blog/2015/08/13/cmake-guide/
- http://www.slideshare.net/DanielPfeifer1/cmake-48475415
# comment
cmake_minimum_required(VERSION 2.8)
message(STATUS "this is a message, for debugging")
# in Visual Studio this is .sln solution. In Xcode, this is .xcodeproj
# in make and ninja, this is a target
project(all)
## building a static library
# set LIB_SRC variable to list of files matching a list of file patterns
file (GLOB LIB_SRC
“lib/*.c”
“lib/*.h”
“lib/readme.txt”
)
# “mystaticlib” is the name of the library, STATIC it’s static and ${LIB_SRC}
# is a list of source files to compile to build this library
add_library(mystaticlib STATIC ${LIB_SRC})
## build an executable that links with static library
file (GLOB EXE_SRC
“src/*.cpp”
“src/*.h”
)
# so that #include can find mystaticlib header files
include_directories(“lib”)
add_executable(my exe ${EXE_SRC})
# the executable links my staticlib
targer_link_libraries(my_exe mystaticlib)
# adds -DFOO -DBAR=3 only to target my_exe
set_property(
TARGET my_exe
PROPERTY COMPILE_DEFINITIONS
FOO
BAR=3
)
IF(WIN32)
target_link_libraries(my_exe "gdiplus" "comctl32" "shlwapi" "Version")
ENDIF()Cmake build types:
CMAKE_BUILD_TYPE: DEBUG RELEASE RELWITHDEBINFO MINSIZEREL Some variables are per-build type, e.g.: CMAKE_C_FLAGS_[DEBUG | RELEASE …] CMAKE_C_FLAGS_DEBUG gets added to CMAKE_C_FLAGS when generating DEBUG build
Cmake variables
Check if variable is true:
IF(WIN32)
….
ENDIF()
IF((MSVC_VERSION GREATER 1700) OR (MSVC_VERSION EQUAL 1700))
…
ENDIF()
Using variable: “${MSVC_VERSION}
Important variables:
WIN32 - true for Windows (both 32 and 64 bit) UNIX - true for unix including mac and cygwin MSVC - true if using Visual Studio MSVC_VERSION : 1400 - VS 8 i.e. Visual Studio 2005 1500 - VS 9 i.e. Visual Studio 2008 1600 - VS 10 i.e. Visual Studio 2010 1700 - VS 11 i.e. Visual Studio 2012 1800 - VS 12 i.e. Visual Studio 2013 CMAKE_CL_64 - 64bit of Visual Studio CMAKE_C_FLAGS CMAKE_CXX_FLAGS