通过Android Studio上的CMake将OpenCV添加到Native C代码中

Question

我试图通过Cmake将Opencv包含在我的原生C代码中.我在网上做了一些研究并从网上下载了FindOpenCV.cmake文件并将其添加到我的android项目的app目录中.这也是CMakeLists.txt所在的位置.我使用本教程将OpenCV作为模块导入到我的Android Studio项目中:https://www.learn2crack.com/2016/03/setup-opencv-sdk-android-studio.html,当我运行时:

if(!OpenCVLoader.initDebug()){
   System.out.println("Opencv not loaded");
} else {
   System.out.println("Opencv loaded");
}

我知道Opencv已经加载了.

但是,因为我正在尝试将OpenCV添加到我的本机代码而不是Java代码中,所以我认为我不能使用它.这是我现在拥有的CMakeLists:

# Sets the minimum version of CMake required to build your native library.
# This ensures that a certain set of CMake features is available to
# your build.

cmake_minimum_required(VERSION 3.4.1)

set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} FindOpenCV.cmake)

# Specifies a library name, specifies whether the library is STATIC or
# SHARED, and provides relative paths to the source code. You can
# define multiple libraries by adding multiple add.library() commands,
# and CMake builds them for you. When you build your app, Gradle
# automatically packages shared libraries with your APK.

add_library(# Specifies the name of the library.
        apriltag

        # Sets the library as a shared library.
        SHARED

        # Provides a relative path to your source file(s).
        src/main/apriltag/apriltag.c
        src/main/apriltag/apriltag_jni.c
        src/main/apriltag/apriltag_quad_thresh.c
        src/main/apriltag/common/g2d.c
        src/main/apriltag/common/getopt.c
        src/main/apriltag/common/homography.c
        src/main/apriltag/common/image_f32.c
        src/main/apriltag/common/image_u8.c
        src/main/apriltag/common/image_u8x3.c
        src/main/apriltag/common/matd.c
        src/main/apriltag/common/pnm.c
        src/main/apriltag/common/string_util.c
        src/main/apriltag/common/svd22.c
        src/main/apriltag/common/time_util.c
        src/main/apriltag/common/unionfind.c
        src/main/apriltag/common/workerpool.c
        src/main/apriltag/common/zarray.c
        src/main/apriltag/common/zhash.c
        src/main/apriltag/common/zmaxheap.c
        src/main/apriltag/tag16h5.c
        src/main/apriltag/tag25h7.c
        src/main/apriltag/tag25h9.c
        src/main/apriltag/tag36artoolkit.c
        src/main/apriltag/tag36h10.c
        src/main/apriltag/tag36h11.c
        )

STRING(REPLACE "-O0" "-O4" CMAKE_C_FLAGS_DEBUG ${CMAKE_C_FLAGS_DEBUG})
STRING(REPLACE "-O2" "-O4" CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE})

include_directories(src/main/apriltag/)
include_directories(${OpenCV_INCLUDE_DIRS})

find_package(OpenCV REQUIRED)

find_library(log-lib log)
find_library(jnigraphics-lib jnigraphics)
target_link_libraries(apriltag ${log-lib} ${jnigraphics-lib})

以下是构建gradle时遇到的错误:

By not providing "FindOpenCV.cmake" in CMAKE_MODULE_PATH this project has 
asked CMake to find a package configuration file provided by "OpenCV", but 
CMake did not find one. 
Could not find a package configuration file provided by "OpenCV" with any of 
the following names:
OpenCVConfig.cmake
opencv-config.cmake
Add the installation prefix of "OpenCV" to CMAKE_PREFIX_PATH or set 
"OpenCV_DIR" to a directory containing one of the above files. If "OpenCV" 
provides a separate development package or SDK, be sure it has been 
installed.

所以我的问题是:

1. 我可以使用导入的OpenCV,还是必须下载不同的opencv并将其存储在其他地方？
2. 我需要在CMakeLists.txt中更改哪些内容才能构建我的gradle？

理想情况下,我想建立并能够添加#include <opencv2/opencv.hpp>和using namespace cv我的C文件,并添加使用OpenCV函数功能.

谢谢你的帮助!

Answer 1

更新22日 - 5月18日:添加了缺失的第6步.

更新10月10日 - 17日:新解决方案使用CMake和Android Gradle插件2.3.1将OpenCV正确集成到应用程序中.使用Android Studio 2.3.1进行测试.

更新11月5日至17日:提供了另一种解决方案

有两种方法可以包含OpenCV.

Git/Simpler Way

访问https://github.com/ahasbini/Android-OpenCV了解更多详情.

手动/高级方式

要将OpenCV库包含到Android Studio Project中,最好在项目中创建一个新的库模块,并将OpenCV Android SDK包中的文件移植到其中:

1. 选择File> New Module创建一个新模块.
2. 选择"Android Library",然后输入详细信息:
   • 图书馆名称: OpenCV
   • 模块名称: opencv
   • 包裹名字: org.opencv
3. 创建新模块后,将path_to_opencv_sdk/sdk/java/src目录内容复制到path_to_your_project/opencv/src/main/java.
4. 在main创建直接以下路径:aidl/org/opencv/engine与移动 main/java/org/opencv/engine/OpenCVEngineInterface.aidl到它.
5. 将内容复制path_to_opencv_sdk/sdk/java/res到path_to_your_project/opencv/src/main/res.
6. sdk在里面创建文件夹path_to_your_project/opencv/src/并将path_to_opencv_sdk/sdk/native文件夹复制到其中
7. 在opencv模块中,创建CMakeLists.txt文件并按以下顺序添加以下行:

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})

8. 在opencv模块中,编辑build.gradle文件:

...
android {
    ...

    defaultConfig {
        minSdkVersion 8
        targetSdkVersion 25
        versionCode 3200
        versionName "3.2.0"

        ...

        externalNativeBuild {
            cmake {
                cppFlags "-frtti -fexceptions"
            }
        }
    }
    buildTypes {
        ...
    }
    externalNativeBuild {
        cmake {
            path "CMakeLists.txt"
        }
    }
    sourceSets {
        main {
            jni.srcDirs = [jni.srcDirs, 'src/sdk/native/jni/include']
            jniLibs.srcDirs = [jniLibs.srcDirs, 'src/sdk/native/3rdparty/libs', 'src/sdk/native/libs']
        }
    }
}
...

9. 在app(应用程序模块,可能是另一个名称)模块中,创建/编辑CMakeLists.txt文件并按以下顺序添加以下行(请注意设置的不同路径OpenCV_DIR):

set(OpenCV_DIR "../opencv/src/sdk/native/jni")
find_package(OpenCV REQUIRED)
message(STATUS "OpenCV libraries: ${OpenCV_LIBS}")
target_link_libraries(YOUR_TARGET_LIB ${OpenCV_LIBS})

10. 在app(应用程序模块,可能是另一个名称)模块中,编辑build.gradle文件:

...    
android {
    ...
    defaultConfig {
        ...
        externalNativeBuild {
            cmake {
                cppFlags "-frtti -fexceptions"
        }
    }
    buildTypes {
        ...
    }
    externalNativeBuild {
        cmake {
            path "CMakeLists.txt"
        }
    }
}

dependencies {
    ...
    compile project(':opencv')
}

11. 执行gradle同步,现在包含OpenCV本机库,头文件和Java包装器类.

当项目构建并启动apk时,您可以检查打包的apk path_to_project/path_to_app_module/build/output/(将apk拖到Android Studio的文本编辑器选项卡上)

您应该libopencv_java3.so在每个abi架构文件夹下看到一个.

在java类中初始化OpenCV SDK:

public class MyClass {

    static {
        if (BuildConfig.DEBUG) {
            OpenCVLoader.initDebug();
        }
    }

    ...
}

您应该在logcat消息中看到指定已加载OpenCV(第一个错误是正常的):

05-10 10:42:31.451 D/OpenCV/StaticHelper: Trying to get library list
05-10 10:42:31.452 E/OpenCV/StaticHelper: OpenCV error: Cannot load info library for OpenCV
05-10 10:42:31.452 D/OpenCV/StaticHelper: Library list: ""
05-10 10:42:31.452 D/OpenCV/StaticHelper: First attempt to load libs
05-10 10:42:31.452 D/OpenCV/StaticHelper: Trying to init OpenCV libs
05-10 10:42:31.452 D/OpenCV/StaticHelper: Trying to load library opencv_java3
05-10 10:42:32.031 D/OpenCV/StaticHelper: Library opencv_java3 loaded
05-10 10:42:32.031 D/OpenCV/StaticHelper: First attempt to load libs is OK
05-10 10:42:32.045 I/OpenCV/StaticHelper: General configuration for OpenCV 3.2.0 =====================================
05-10 10:42:32.045 I/OpenCV/StaticHelper:   Version control:               3.2.0
05-10 10:42:32.045 I/OpenCV/StaticHelper:   Platform:
05-10 10:42:32.045 I/OpenCV/StaticHelper:     Timestamp:                   2016-12-23T13:04:49Z
05-10 10:42:32.045 I/OpenCV/StaticHelper:     Host:                        Linux 4.8.0-25-generic x86_64
05-10 10:42:32.045 I/OpenCV/StaticHelper:     Target:                      Linux 1 x86_64
05-10 10:42:32.045 I/OpenCV/StaticHelper:     CMake:                       2.8.12.2
05-10 10:42:32.045 I/OpenCV/StaticHelper:     CMake generator:             Ninja
05-10 10:42:32.045 I/OpenCV/StaticHelper:     CMake build tool:            /usr/bin/ninja
05-10 10:42:32.045 I/OpenCV/StaticHelper:     Configuration:               Release
05-10 10:42:32.045 I/OpenCV/StaticHelper:   C/C++:
05-10 10:42:32.045 I/OpenCV/StaticHelper:     Built as dynamic libs?:      NO
05-10 10:42:32.045 I/OpenCV/StaticHelper:     C++ Compiler:                /usr/bin/ccache /opt/android/android-ndk-r10e/toolchains/x86_64-4.9/prebuilt/linux-x86_64/bin/x86_64-linux-android-g++ (ver 4.9)