如何在 CMake 中链接 SDL2？

Question

我正在尝试在 ubuntu 上使用 sdl。根据这个指令（https://gist.github.com/BoredBored/3187339a99f7786c25075d4d9c80fad5），我安装了 sdl2、sdl image 和 sdl 混合器。现在我必须在构建时链接它们。下面举例说明我应该怎么做。

g++ myProgram.cpp -o myProgram `sdl2-config --cflags --libs` -lSDL2 -lSDL2_mixer -lSDL2_image -lSDL2_ttf

我正在使用 Cmake，但我不知道如何链接它们...

下面的代码仅用于测试 sdl 是否工作。

//MAIN
#include <iostream>
#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
#include <SDL2/SDL_mixer.h>
#include <SDL2/SDL_ttf.h>

int main(int argc, char*args[])
{
 SDL_Init(SDL_INIT_EVERYTHING);
}

下面的CMakeList

# Set the minimum version of CMake that can be used
# To find the cmake version run
# $ cmake --version
cmake_minimum_required(VERSION 3.5)

# Set the project name
project (sdl)

# Create a sources variable with a link to all cpp files to compile
set(SOURCES
    src/main.cpp
)

# Add an executable with the above sources
add_executable(${PROJECT_NAME} ${SOURCES})

# Set the directories that should be included in the build command for this target
# when running g++ these will be included as -I/directory/path/
target_include_directories(sdl
    PRIVATE 
        ${PROJECT_SOURCE_DIR}/inc
)

如何在 Cmake 中链接它们？感谢您的宝贵时间。

Answer 1

要在 cmake 中链接库（共享/静态），您可以使用 target_link_libraries 命令：

target_link_libraries(<target> ... <item>... ...)

根据文档：

<target> 必须是由add_executable() 或add_library() 等命令创建的

所以首先我们需要找到 SDL 库，为此我们将使用以下命令：

find_package(SDL2 REQUIRED)

要使其包含目录可供您使用，请使用以下命令：

include_directories(${SDL2_INCLUDE_DIRS})

最后要链接 SDL2，你需要这样做：

target_link_libraries(${PROJECT_NAME} ${SDL2_LIBRARIES})

或可选地：

target_link_libraries(${PROJECT_NAME} PRIVATE SDL2::SDL2)

PRIVATE，表示${PROJECT_NAME} 在其实现中使用SDL2，但SDL2 未在${PROJECT_NAME} 的公共API 的任何部分中使用。 More here

这里的${PROJECT_NAME} 是<target>，后面的都是库的名称。

最终结果

    # Set the minimum version of CMake that can be used
    # To find the cmake version run
    # $ cmake --version
    cmake_minimum_required(VERSION 3.5)

    # Set the project name
    project (sdl)

    find_package(SDL2 REQUIRED)

    # Create a sources variable with a link to all cpp files to compile
    set(SOURCES
        src/main.cpp
    )

    # Add an executable with the above sources
    add_executable(${PROJECT_NAME} ${SOURCES})

    target_link_libraries(sdl ${SDL2_LIBRARIES})

    # Set the directories that should be included in the build command for this target
    include_directories(SDL2Test ${SDL2_INCLUDE_DIRS})

参考：

1. https://cmake.org/cmake/help/latest/command
   
2. https://cmake.org/pipermail/cmake/2016-May/063400.html

Answer 2

编辑添加了完整的 CMAKE

# Set the minimum version of CMake that can be used
# To find the cmake version run
# $ cmake --version
cmake_minimum_required(VERSION 3.5)

# Set the project name
project (sdl)

# Create a sources variable with a link to all cpp files to compile
set(SOURCES
    src/main.cpp
)

 target_include_directories(sdl
        PRIVATE 
            ${PROJECT_SOURCE_DIR}/inc
    )

# Add an executable with the above sources

link_directories(path_to_lib)
    add_executable(${PROJECT_NAME} ${SOURCES})


# Set the directories that should be included in the build command for this target
# when running g++ these will be included as -I/directory/path/


 target_link_libraries((${PROJECT_NAME} SDL2 SDL2_mixer SDL2_image SDL2_ttf)