在Android中c++里调用opencv

Posted 2022-03-03 _less is more

本文接上文

函数创建方式和上文类似

但cpp调用#include <opencv2/opencv.hpp>会报错找不到

因此要在cmakelists.txt文件中引入opencv：

# For more information about using CMake with android Studio, read the
# documentation: https://d.android.com/studio/projects/add-native-code.html

# Sets the minimum version of CMake required to build the native library.

cmake_minimum_required(VERSION 3.4.1)
include_directories(C:/Users/ASUS/Desktop/OpencvProject/app/src/main/cpp/include)
# Creates and names a library, sets it as either STATIC
# or SHARED, and provides the relative paths to its source code.
# You can define multiple libraries, and CMake builds them for you.
# Gradle automatically packages shared libraries with your APK.
#add_library( # Sets the name of the library.
#        libopencv_java3
#        # Sets the library as a shared library.
#        SHARED
#
#        IMPORTED)
#set_target_properties(libopencv_java3
#        PROPERTIES IMPORTED_LOCATION
#        C:/Users/ASUS/Desktop/OpencvProject/app/libs/x86/libopencv_java3.so
##        $CMAKE_SOURCE_DIR/libs/x86/libopencv_java3.so
#        )

add_library( # Sets the name of the library.
             JniImgProc
             # Sets the library as a shared library.
             SHARED
             # Provides a relative path to your source file(s).
             JniImgProc.cpp)
add_library( # Sets the name of the library.
            matrixProc
            # Sets the library as a shared library.
            SHARED
            # Provides a relative path to your source file(s).
            matrixProc.cpp)
# Searches for a specified prebuilt library and stores the path as a
# variable. Because CMake includes system libraries in the search path by
# default, you only need to specify the name of the public NDK library
# you want to add. CMake verifies that the library exists before
# completing its build.

find_library( # Sets the name of the path variable.
              log-lib

              # Specifies the name of the NDK library that
              # you want CMake to locate.
              log )

# Specifies libraries CMake should link to your target library. You
# can link multiple libraries, such as libraries you define in this
# build script, prebuilt third-party libraries, or system libraries.

target_link_libraries( # Specifies the target library.
                       JniImgProc
                       matrixProc

                       # Links the target library to the log library
                       # included in the NDK.
                       $log-lib )

可以看到新加了很多项：
1、
这里是Android opencv的sdk里的include文件，路径在
C:\\Users\\ASUS\\Desktop\\opencv-3.4.3-android-sdk\\sdk\\native\\jni\\include，把它复制到工程里面

然后添加下一条

include_directories(C:/Users/ASUS/Desktop/OpencvProject/app/src/main/cpp/include)

2、这是引入了一个新的cpp而已

add_library( # Sets the name of the library.
            matrixProc
            # Sets the library as a shared library.
            SHARED
            # Provides a relative path to your source file(s).
            matrixProc.cpp)

3、这也是加了个matrixProc而已

target_link_libraries( # Specifies the target library.
                       JniImgProc
                       matrixProc

                       # Links the target library to the log library
                       # included in the NDK.
                       $log-lib )

所以真正能让我在cpp里使用opencv的是include里面的cpp原生代码，将其用include_directories(C:/Users/ASUS/Desktop/OpencvProject/app/src/main/cpp/include)引入即可