cmake:用于查找libjpeg-turbo的module FindTurboJPEG.cmake

矫情吗；* 2022-05-26 05:25 299阅读 0赞

libjpeg-turbo的安装包没有提供用于CONFIG模式查找包(find\_package)的cmake脚本,如果cmake脚本中要查找libjpeg-turbo库，就得自己写脚本。  
于是我参照cmake 查找标准libjpeg库 的Module [FindJPEG][]源码的写法实现了libjpeg-turbo的Module FindTurboJPEG.cmake。  
为了更方便引用libjpeg-turbo，module中不仅提供了传统的变量方式`TURBOJPEG_INCLUDE_DIR`，`TURBOJPEG_LIBRARY`提供libjpeg-turbo的信息，还提供import target:`turbojpep`,`turbojpeg-static`

# 通过查找turbojpeg.h定位libjpeg-turbo的include文件夹位置
    find_path(TURBOJPEG_INCLUDE_DIR turbojpeg.h)
    
    set(TURBOJPEG_NAMES ${TURBOJPEG_NAMES} turbojpeg libturbojpeg)
    find_library(TURBOJPEG_LIBRARY NAMES ${TURBOJPEG_NAMES} )
    
    # handle the QUIETLY and REQUIRED arguments and set TURBOJPEG_FOUND to TRUE if
    # all listed variables are TRUE
    include(FindPackageHandleStandardArgs)
    FIND_PACKAGE_HANDLE_STANDARD_ARGS(TURBOJPEG DEFAULT_MSG TURBOJPEG_LIBRARY TURBOJPEG_INCLUDE_DIR)
    
    if(TURBOJPEG_FOUND)
        # for compatility of find_dependency
        set (TurboJPEG_FOUND TRUE)
        # Create imported target turbojpeg
        add_library(turbojpep SHARED IMPORTED)
        # import target中指定include文件夹
        set_target_properties(turbojpep PROPERTIES
          IMPORTED_LINK_INTERFACE_LANGUAGES "C"
          INTERFACE_INCLUDE_DIRECTORIES "${TURBOJPEG_INCLUDE_DIR}"
          IMPORTED_LOCATION "${TURBOJPEG_LIBRARY}"
          )
        if(MSVC)
            set(_stati_library_name ${CMAKE_STATIC_LIBRARY_PREFIX}turbojpeg-static${CMAKE_STATIC_LIBRARY_SUFFIX})
        else()
            set(_stati_library_name ${CMAKE_STATIC_LIBRARY_PREFIX}turbojpeg${CMAKE_STATIC_LIBRARY_SUFFIX})
        endif()
        # 查找libjpeg-turbo静态库
        find_library(TURBOJPEG_LIBRARY_STATIC ${_stati_library_name})
        # 如果找到静态库，则创建turbojpeg-static target
        if(TURBOJPEG_LIBRARY_STATIC)
            # Create imported target turbojpeg-static
            add_library(turbojpeg-static STATIC IMPORTED)
            # import target中指定include文件夹
            set_target_properties(turbojpeg-static PROPERTIES
              IMPORTED_LINK_INTERFACE_LANGUAGES "C"
              INTERFACE_INCLUDE_DIRECTORIES "${TURBOJPEG_INCLUDE_DIR}"
              IMPORTED_LOCATION "${TURBOJPEG_LIBRARY_STATIC}"
              )
            message(STATUS "TURBOJPEG_LIBRARY_STATIC=${TURBOJPEG_LIBRARY_STATIC}")
        else()
            message(STATUS "NOT FOUND jpeg-turbo static library")
        endif()
    
        unset(_stati_library_name)
    endif()
    
    mark_as_advanced(TURBOJPEG_LIBRARY TURBOJPEG_INCLUDE_DIR )

import target引用示例：

# 需要将FindTurboJPEG.cmake的位置加入CMAKE_PREFIX_PATH,cmake才能找到
    find_package(TurboJPEG REQUIRED)
    ## 优先使用静态库
    if(TARGET turbojpeg-static)
        set (_turbojpeg_target "turbojpeg-static")
    else()
        set (_turbojpeg_target "turbojpeg")
    endif()
    # 因为import target已经包含了libjpeg-turbo的include信息，
    # 所以会自动传递被引入的项目mytarget，所以mytarget 不必再单独添加include_directories
    target_link_libraries(mytarget ${_turbojpeg_target})

`FindTurboJPEG.cmake`应用的完整示例参见：  
[https://gitee.com/l0km/jpegwrapper/blob/master/jpegwrapper/CMakeLists.txt][https_gitee.com_l0km_jpegwrapper_blob_master_jpegwrapper_CMakeLists.txt]

`FindTurboJPEG.cmake`源码的gitee仓库存储位置：  
[https://gitee.com/l0km/jpegwrapper/blob/master/cmake/Modules/FindTurboJPEG.cmake][https_gitee.com_l0km_jpegwrapper_blob_master_cmake_Modules_FindTurboJPEG.cmake]

[FindJPEG]: https://cmake.org/cmake/help/v3.1/module/FindJPEG.html
[https_gitee.com_l0km_jpegwrapper_blob_master_jpegwrapper_CMakeLists.txt]: https://gitee.com/l0km/jpegwrapper/blob/master/jpegwrapper/CMakeLists.txt
[https_gitee.com_l0km_jpegwrapper_blob_master_cmake_Modules_FindTurboJPEG.cmake]: https://gitee.com/l0km/jpegwrapper/blob/master/cmake/Modules/FindTurboJPEG.cmake