将自由字体与cmake链接 [英] Linking freetype with cmake

问题描述

在构建C ++ 11项目时，我在使用 cmake 在Linux下使用 cmake 链接 freetype 2 时遇到麻烦使用 extern C 库。

I'm having troubles with linking freetype 2 under linux using cmake when building a C++11 project with an extern C library.

使用cmake和freetype 2，我基本上有2个选择：

With cmake and freetype 2 I basically have 2 options :

• 使用实用程序 freetype-config 像 freetype-config --libs


• 使用 FindFreetype cmake模块

• use the utility freetype-config like freetype-config --libs
• use the FindFreetype cmake module

现在我正在尝试实现第二个选项而且我对 cmake 不太熟练，也不了解它的逻辑。

Now I'm trying to implement the second option and I'm not very skilled with cmake nor I understand the logic of it.

我的问题是链接阶段，我不知道如何正确执行此操作，而且此模块不如 freetype-config --libs 的结果那样完整，该模块实际上包括所有库和标志，我需要的，不仅仅是文件的路径；因此我假设我必须对 zlib 和 libpng 做同样的事情。

My problem is the linking phase, I have no idea how to do that properly plus this module is not as complete as the result of freetype-config --libs which really includes all the libraries and flags that I need, and not just the path of a file; so I'm assuming that I have to do the same for zlib and libpng.

CMakeLists.txt

cmake_minimum_required (VERSION 2.6)
project (FreetypeTutorials1)

include(FindFreetype)
include_directories(${FREETYPE_INCLUDE_DIRS})

SET(CMAKE_CXX_FLAGS "-O2 -std=c++11")

SET(CMAKE_EXE_LINKER_FLAGS "-v -lfreetype")

add_executable( demo "${CMAKE_CURRENT_SOURCE_DIR}/src/main.cpp")

./ src / main.cpp （只是

extern "C" {
#include <ft2build.h>
#include FT_FREETYPE_H
}
#include <iostream>
int main()
{
  FT_Library library;
  auto error = FT_Init_FreeType(&library);
  if (error)
  {
    std::cout << "An error !\n";
  }
}

推荐答案

到加载 FindFreetype.cmake 这样的模块，您需要使用 find_package -命令在cmake中使用它。第一个参数是程序包名称。 cmake会自动添加其对应文件名的查找。

To load a module like FindFreetype.cmake you need to use it in cmake with the find_package-command. The first argument is the package name. The "Find" of its corresponding filename is added automatically by cmake.

include 可能与<$ c一起使用$ c> find_package ，您可以添加一些标志。例如，如下所示，必需，当找不到自由类型时，使cmake失败。

While include might work with find_package you can add some flags. For example, as shown below, REQUIRED, to make cmake fail when freetype wasn't found.

附加链接使用cmake应该通过命令 target_link_libraries 完成。

Additionally linking with cmake should be done with the command target_link_libraries.

这就是我写给CMakeLists.txt的方式：

This is how I would write you CMakeLists.txt:

cmake_minimum_required (VERSION 2.6)
project (FreetypeTutorials1)

find_package(Freetype REQUIRED)

SET(CMAKE_CXX_FLAGS "-O2 -std=c++11")

SET(CMAKE_EXE_LINKER_FLAGS "-v")

add_executable( demo src/main.cpp) # CMAKE_CURRENT_SOURCE_DIR is implicit here
target_link_libraries(demo ${FREETYPE_LIBRARIES})
target_include_directories(demo PRIVATE ${FREETYPE_INCLUDE_DIRS})

target_link_libraries 与平台无关，而'-lfreetype 在 CMAKE_EXE_LINKER_FLAGS 不是。

target_link_libraries is platform independent whereas '-lfreetype in CMAKE_EXE_LINKER_FLAGS is not.

CMakeLists.txt将在具有freetype的其他平台上运行。

The CMakeLists.txt will work on other platforms where freetype is available.

（编辑2019：使用 target_include_directories（）代替 include_directories（）

(Edit 2019: use target_include_directories() instead of include_directories()

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