如何在安卓系统中使用CMake编译和共享两个c++库？

Question

我有自定义的C++类，我想在我的android应用上运行。我已经成功地使用 CMakeLists. 但由于我的类使用opencv，我得到了一个很明显的问题

fatal error: 'opencv2/core.hpp' file not found

然后我试着在我的android应用上添加opencv库，下载了open cv android sdk并累加到我的项目上。以下是文件夹结构

android 
   -> app
       -> opencv2
          All the opencv2 c++ files and folders
       ->folder1
          My custom c++ classes which will import opencv2.

以下是我的CMakeLists.txt文件。

cmake_minimum_required(VERSION 3.4.1)  # for example

set(CMAKE_TRY_COMPILE_TARGET_TYPE "STATIC_LIBRARY")

PROJECT(tag)


set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")

 add_library( tag_native
              # Sets the library as a shared library.
              SHARED
              # Provides a relative path to your source file(s).
              "./folder1/tag_native.cpp" )


add_library( opencv2
             # Sets the library as a shared library.
             SHARED
             # Provides a relative path to your source file(s).
             "./opencv2/" )

set_target_properties(opencv2 PROPERTIES LINKER_LANGUAGE CXX)

这是我的cpp文件的例子

#include <stdint.h>
#include <string.h>
#include <stdio.h>
#include <vector>
#include <iostream>
#include <opencv2/core.hpp>

从c++编译的所有东西都很好，但我还是得到同样的问题。

* What went wrong:
Execution failed for task ':app:externalNativeBuildDebug'.
> Build command failed.
  Error while executing process C:\Users\Brainants with arguments {Technology\AppData\Local\Android\Sdk\cmake\3.10.2.4988404\bin\ninja.exe -C E:\Squtag\Squtag Mobile\android\app\.cxx\cmake\debug\armeabi-v7a opencv2 squtag_native}
  ninja: Entering directory `E:\Squtag\Squtag Mobile\android\app\.cxx\cmake\debug\armeabi-v7a'
  [1/2] Building CXX object CMakeFiles/squtag_native.dir/E_/Squtag/Squtag_Mobile/ios/Runner/Squtag_Native/squtag_native.cpp.o
  FAILED: CMakeFiles/squtag_native.dir/E_/Squtag/Squtag_Mobile/ios/Runner/Squtag_Native/squtag_native.cpp.o 
  C:\Users\BRAINA~1\AppData\Local\Android\Sdk\ndk\210~1.611\TOOLCH~1\llvm\prebuilt\WINDOW~1\bin\CLANG_~1.EXE --target=armv7-none-linux-androideabi24 --gcc-toolchain="C:/Users/Brainants Technology/AppData/Local/Android/Sdk/ndk/21.0.6113669/toolchains/llvm/prebuilt/windows-x86_64" --sysroot="C:/Users/Brainants Technology/AppData/Local/Android/Sdk/ndk/21.0.6113669/toolchains/llvm/prebuilt/windows-x86_64/sysroot"  -Dsqutag_native_EXPORTS  -g -DANDROID -fdata-sections -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -D_FORTIFY_SOURCE=2 -march=armv7-a -Wformat -Werror=format-security  -fsanitize=address -fno-omit-frame-pointer -std=c++11 -O0 -fno-limit-debug-info  -fPIC -MD -MT CMakeFiles/squtag_native.dir/E_/Squtag/Squtag_Mobile/ios/Runner/Squtag_Native/squtag_native.cpp.o -MF CMakeFiles\squtag_native.dir\E_\Squtag\Squtag_Mobile\ios\Runner\Squtag_Native\squtag_native.cpp.o.d -o CMakeFiles/squtag_native.dir/E_/Squtag/Squtag_Mobile/ios/Runner/Squtag_Native/squtag_native.cpp.o -c "E:/Squtag/Squtag Mobile/ios/Runner/Squtag Native/squtag_native.cpp"
  E:/Squtag/Squtag Mobile/ios/Runner/Squtag Native/squtag_native.cpp:6:10: fatal error: 'opencv2/core.hpp' file not found
  #include <opencv2/core.hpp>
           ^~~~~~~~~~~~~~~~~~
  1 error generated.
  ninja: build stopped: subcommand failed.

Answer 1

你得到的错误是告诉你它找不到opencv的包含文件。

#include <opencv2/core.hpp>

你需要找到opencv2文件夹，并把它作为一个额外的include目录传递给cmake。

https:/cmake.orgcmakehelpv3.0commandinclude_directories.html。

例子: 在Android Studio上通过CMake将OpenCV添加到Native C代码中。

cmake_minimum_required(VERSION 3.4.1)
set(OpenCV_DIR "src/sdk/native/jni")
find_package(OpenCV REQUIRED)
message(STATUS "OpenCV libraries: ${OpenCV_LIBS}")
include_directories(${OpenCV_INCLUDE_DIRS})

或者你可以使用这种方法。https:/github.comahasbiniAndroid-OpenCVblobmasterappCMakeLists.txt。

Answer 2

看起来你的 cmake 项目找不到安装的 opencv，所以要么你把路径设置成了 ${complete_path_to_opencv_installation}/apt 或者你把opencv安装在 通用安装文件夹

无论哪种方式，你都需要将其传播到你的项目中。如果你把它安装在典型的地方（例如 /usr/local/ 在linux中，你需要设置 export PATH=$PATH:${opencv_installation_path} 或 c:\Path 然后在Windows中设置 路径 在 环境变量.

这样做，就能使 find_package(OpenCV) 应该可以找到opencv库和 OpenCV_INCLUDE_DIRS 设置.这 CMakeLists.txt 应该可以。

cmake_minimum_required(VERSION 3)
project( DisplayImage )
find_package( OpenCV REQUIRED )
include_directories( ${OpenCV_INCLUDE_DIRS} )
add_executable( DisplayImage DisplayImage.cpp )
target_link_libraries( DisplayImage ${OpenCV_LIBS} )

或者你也可以 set OpenCV_INCLUDE_DIRS "./app/opencv2" 之前 include_directories传播 opencv2/core.hpp.

你也可以对这个感兴趣 旧职 关于在Android中使用opencv。