【快速查询】https://cmake.org/cmake/help/v2.8.8/cmake.html#section_Commands
1、CMake简介
CMake是跨平台编译工具,比make更高级一些。其编译的主要工作是生成CMakeLists.txt文件,然后根据该文件生成Makefile,最后调用make来生成可执行程序或者动态库。所以基本步骤就只有两步:(1)cmake生成CMakeLists.txt文件;(2)make执行编译工作。
下面一张图对比一下AutoTools与CMake的工作流程(可见CMake比较清晰简洁):
2、CMakeLists.txt文件
详情参考:http://wiki.ros.org/catkin/CMakeLists.txt
1、Required CMake Version (cmake_minimum_required) 2、Package Name (project()) 3、Find other CMake/Catkin packages needed for build (find_package()) 4、Message/Service/Action Generators (add_message_files(), add_service_files(), add_action_files()) 5、Invoke message/service/action generation (generate_messages()) 6、Specify package build info export (catkin_package()) 7、Libraries/Executables to build (add_library()/add_executable()/target_link_libraries()) 8、Tests to build (catkin_add_gtest()) 9、Install rules (install())
(1)CMake Version:
每一个 catkin CMakeLists.txt 必须以 CMake 需要的版本开始,Catkin 需要版本 2.8.3 或者更高
cmake_minimum_required(VERSION 2.8.3)
(2)Package name:
CMake project function 指定的文件名。
project(robot_brain)
在 CMake script 文件中,引用 CMake package 可以使用变量 ${PROJECT_NAME}
(3)依赖功能包:
寻找需要用到的其他 CMake packages,用函数 find_package。
至少依赖一个关于 catkin 的功能包
find_package(catkin REQUIRED)
如果要使用 C++ 和 Boost,则需要引用 find_package 包含 Boost,并且指明 Boost 的类型,如使用 Boost threads,则:
find_package(Boost REQUIRED COMPONENTS thread)
(4)catkin_package()
catkin_package() 是 catkin 支持的 CMake 宏指令。用来向编译系统指明 catkin-specific 的信息,而编译系统来生成 pkg-config and CMake files。
该函数必须用在用 add_library() or add_executable() 声明之前。
有5个可选参数:
INCLUDE_DIRS - The exported include paths (i.e. cflags) for the package LIBRARIES - The exported libraries from the project CATKIN_DEPENDS - Other catkin projects that this project depends on DEPENDS - Non-catkin CMake projects that this project depends on CFG_EXTRAS - Additional configuration options
例如:
catkin_package(
INCLUDE_DIRS include
LIBRARIES ${PROJECT_NAME}
CATKIN_DEPENDS roscpp nodelet
DEPENDS eigen opencv)
(5)Specifying Build Targets
3、一个简单的CMakeLists.txt入门示例
外部编译:单独建立一个空目录专门用于cmake编译,便于管理编译中间文件。在空目录中用 cmake ../(CMakeLists.txt所在目录)就行了,中间文件生成在当前目录。
工程结构:
. ├── build ├── CMakeLists.txt ├── include │ └── math_lib.h └── src ├── main.cpp └── math_lib.cpp 3 directories, 4 files
CMakeLists.txt示例(借鉴网友配置):
# 1.cmake verson,指定cmake版本 cmake_minimum_required(VERSION 3.4.1) # 2.project name,指定项目的名称,一般和项目的文件夹名称对应 PROJECT(test_math_lib) # 3.head file path,头文件目录 INCLUDE_DIRECTORIES(include) # 4.source directory,源文件目录 AUX_SOURCE_DIRECTORY(src DIR_SRCS) # 5.set environment variable,设置环境变量,编译用到的源文件全部都要放到这里,否则编译能够通过,但是执行的时候会出现各种问题,比如"symbol lookup error xxxxx , undefined symbol" SET(TEST_MATH ${DIR_SRCS}) # 6.add executable file,添加要编译的可执行文件 ADD_EXECUTABLE(${PROJECT_NAME} ${TEST_MATH}) # 7.add link library,添加可执行文件所需要的库,比如我们用到了libm.so(命名规则:lib+name+.so),就添加该库的名称 TARGET_LINK_LIBRARIES(${PROJECT_NAME} m)
编译方法(直接生成目标程序):
kuliuheng@ubuntu:~/_8GB_EXT/workspace/cpp/testCmake$ cd build/ kuliuheng@ubuntu:~/_8GB_EXT/workspace/cpp/testCmake/build$ cmake ../ -- The C compiler identification is GNU 7.4.0 -- The CXX compiler identification is GNU 7.4.0 -- Check for working C compiler: /usr/bin/cc -- Check for working C compiler: /usr/bin/cc -- works -- Detecting C compiler ABI info -- Detecting C compiler ABI info - done -- Detecting C compile features -- Detecting C compile features - done -- Check for working CXX compiler: /usr/bin/c++ -- Check for working CXX compiler: /usr/bin/c++ -- works -- Detecting CXX compiler ABI info -- Detecting CXX compiler ABI info - done -- Detecting CXX compile features -- Detecting CXX compile features - done -- Configuring done -- Generating done -- Build files have been written to: /home/kuliuheng/_8GB_EXT/workspace/cpp/testCmake/build
4、示例:如何给动态库添加三方库依赖
方法一:用LINK_DIRECTORIES 来指定三方库路径,然后通过库名称去链接。需要注意一个坑就是LINK_DIRECTORIES 要放到 ADD_LIBRARY 前面才行。
file(GLOB_RECURSE header1_files "src/main/cpp/3rd/*.h") file(GLOB_RECURSE source1_files "src/main/cpp/3rd/*.cpp") LINK_DIRECTORIES("libs/${ANDROID_ABI}") # 添加三方库的绝对/相对路径,用于搜索三方库。但是千万要注意一点:要放到ADD_LIBRARY之前,否则不生效! ADD_LIBRARY ( my_lib # 设置生成动态库的名称 SHARED # 设置库类型,STATIC 或 SHARED # 需要编译的c/c++ 文件 ${source1_files} src/main/cpp/jni_main.cpp ) target_link_libraries( my_lib # 链接目标 # Links the target library to the log library included in the NDK ${log-lib} plug_ins_project # 这个就是对应libplug_ins_project.so库文件 )
方法二:通过ADD_LIBRARY 结合 SET_TARGET_PROPERTIER 来指定第三方库绝对路径信息,然后连接库名即可。
TIPS:可以用MESSAGE打印调试日志—— MESSAGE(WARNING "${PROJECT_SOURCE_DIR}/libs/${ANDROID_ABI}")
# 通过add_library 可以引入三方库,通过set_target_properties 指定具体三方库的属性 add_library(plug_ins SHARED IMPORTED) set_target_properties( plug_ins PROPERTIES IMPORTED_LOCATION ${PROJECT_SOURCE_DIR}/libs/${ANDROID_ABI}/libplug_ins_project.so) target_link_libraries( # Specifies the target library. # 指定链接的目标库 my_lib # Links the target library to the log library # included in the NDK. ${log-lib} plug_ins )