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在Android上通过JNI的形式,导入OpenCV

在Android上通过JNI的形式,导入OpenCV

作者: andforce | 来源:发表于2019-05-28 15:16 被阅读0次

下载OpnenCV For Android

OpenCV官网--Release--Android,即可下载到最新的OpenCV的Android版本

image.png

认识一下OpenCV For Android的目录结构

.
├── LICENSE
├── README.android
├── samples
│   ├── 15-puzzle
│   │   ├── AndroidManifest.xml
│   │   ├── build.gradle
│   │   ├── res
│   │   └── src
│   ├── build.gradle
│   ├── camera-calibration
│   │   ├── AndroidManifest.xml
│   │   ├── build.gradle
│   │   ├── res
│   │   └── src
│   ├── color-blob-detection
│   │   ├── AndroidManifest.xml
│   │   ├── build.gradle
│   │   ├── res
│   │   └── src
│   ├── face-detection
│   │   ├── AndroidManifest.xml
│   │   ├── build.gradle
│   │   ├── jni
│   │   ├── res
│   │   └── src
│   ├── gradle
│   │   └── wrapper
│   ├── gradle.properties
│   ├── gradlew
│   ├── gradlew.bat
│   ├── image-manipulations
│   │   ├── AndroidManifest.xml
│   │   ├── build.gradle
│   │   ├── res
│   │   └── src
│   ├── settings.gradle
│   ├── tutorial-1-camerapreview
│   │   ├── AndroidManifest.xml
│   │   ├── build.gradle
│   │   ├── res
│   │   └── src
│   ├── tutorial-2-mixedprocessing
│   │   ├── AndroidManifest.xml
│   │   ├── build.gradle
│   │   ├── jni
│   │   ├── res
│   │   └── src
│   └── tutorial-3-cameracontrol
│       ├── AndroidManifest.xml
│       ├── build.gradle
│       ├── res
│       └── src
└── sdk
    ├── build.gradle
    ├── etc
    │   ├── haarcascades
    │   ├── lbpcascades
    │   ├── licenses
    │   ├── valgrind_3rdparty.supp
    │   └── valgrind.supp
    ├── java
    │   ├── AndroidManifest.xml
    │   ├── javadoc
    │   ├── res
    │   └── src
    └── native
        ├── 3rdparty
        ├── jni
        ├── libs
        └── staticlibs

下载并配置好NDK

image.png

在SDKTools中,要下载好LLDB,CMake,NDK

image.png

用Studio创建 Native C++工程

Toolchain选C++11


image.png

拷贝OpenCV中的so库到工程中

sdk/
├── build.gradle
├── etc
│   ├── haarcascades
│   ├── lbpcascades
│   ├── licenses
│   ├── valgrind_3rdparty.supp
│   └── valgrind.supp
├── java
│   ├── AndroidManifest.xml
│   ├── javadoc
│   ├── res
│   └── src
└── native
    ├── 3rdparty
    ├── jni
    ├── libs
    └── staticlibs

把sdk/native/libs下的so拷贝到工程的app/src/main/jniLibs中

sdk/native/libs/
├── arm64-v8a
│   └── libopencv_java4.so
├── armeabi-v7a
│   └── libopencv_java4.so
├── x86
│   └── libopencv_java4.so
└── x86_64
    └── libopencv_java4.so

如下图位置:

image.png
ps:如果不打算支持x86架构,可以不需要拷贝x86开头的那几个

修改CMakeLists.txt

1.添加头文件

# OpenCV 头文件路径
include_directories(/home/andforce/Desktop/opencv-4.1.0-android-sdk/OpenCV-android-sdk/sdk/native/jni/include)

2.引入so

#引入libopencv_java4.so文件
add_library(opencv_java4 SHARED IMPORTED)

set_target_properties(opencv_java4
        PROPERTIES
        # ${PROJECT_SOURCE_DIR}
        # ${CMAKE_CURRENT_SOURCE_DIR}
        # ${CMAKE_SOURCE_DIR}
        IMPORTED_LOCATION ${CMAKE_SOURCE_DIR}/../jniLibs/${ANDROID_ABI}/libopencv_java4.so
        )

3.添加自己的so

# 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.
        flood-fill

        # Sets the library as a shared library.
        SHARED

        # Provides a relative path to your source file(s).
        cpp_java_utils.cpp
        find_objects.cpp
        mat_map_cvt.cpp
        flood_fill.cpp)

4.添加bitmap支持,一般OpenCV都需要跟Bitmap交互,如果不处理Bitmap,可以不添加

# 支持操作Bitmap的库
find_library( # Sets the name of the path variable.
        jnigraphics-lib
        # Specifies the name of the NDK library that
        # you want CMake to locate.
        jnigraphics )

5.最后把自己的库和opencv库添加上

# 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.
        flood-fill
        opencv_java4
        # Links the target library to the log library
        # included in the NDK.
        ${jnigraphics-lib}
        ${log-lib})

完整的CMakeLists.txt

# 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)

# OpenCV 头文件路径
include_directories(/home/andforce/Desktop/opencv-4.1.0-android-sdk/OpenCV-android-sdk/sdk/native/jni/include)

#引入libopencv_java4.so文件
add_library(opencv_java4 SHARED IMPORTED)

set_target_properties(opencv_java4
        PROPERTIES
        # ${PROJECT_SOURCE_DIR}
        # ${CMAKE_CURRENT_SOURCE_DIR}
        # ${CMAKE_SOURCE_DIR}
        IMPORTED_LOCATION ${CMAKE_SOURCE_DIR}/../jniLibs/${ANDROID_ABI}/libopencv_java4.so
        )

# 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.
        flood-fill

        # Sets the library as a shared library.
        SHARED

        # Provides a relative path to your source file(s).
        cpp_java_utils.cpp
        find_objects.cpp
        mat_map_cvt.cpp
        flood_fill.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)

# 支持操作Bitmap的库
find_library( # Sets the name of the path variable.
        jnigraphics-lib
        # Specifies the name of the NDK library that
        # you want CMake to locate.
        jnigraphics )

# 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.
        flood-fill
        opencv_java4
        # Links the target library to the log library
        # included in the NDK.
        ${jnigraphics-lib}
        ${log-lib})

github demo: https://github.com/andforce/OpenCV4ImportDemo

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