Android(安卓)Studio下OpenCV及JNI开发

AS下配置OpenCV环境

1.下载OpenCV4Android安装包，本实例中使用OpenCV3.1。解压后问价目录如下：

apk：OpenCV_3.1.0_Manager_3.10安装包，Android OpenCV手机端使用
samples：样例代码
sdk：Android开发程序使用SDK

2.新建project，点击file->new modular，选择OpenCV-android-sdk\sdk\java目录，确认。

3.点击file->Project Structure，选择app，添加dependencies->modular dependency，选择OpenCV3.1，确认

4.最后修改openCVLibrary310下build.gradle中配置，使其与app目录下build.gradle相同。

//openCVLibrary310下build.gradleandroid {    compileSdkVersion 23    buildToolsVersion "23.0.2"    defaultConfig {        minSdkVersion 15        targetSdkVersion 23    }

至此AS下OpenCV配置已经结束，使用样例中的代码进行测试，此不赘述。

OpenCV JNI配置

1.本示例中对图像进行轮廓提取，程序主体使用c++实现。
在MainActivity中添加如下函数public static native int[] ImgFun(int []buf,int w,int h);

2.使用javah生成其所对应的头文件：

3.在main目录下新建jni文件夹，将生成的头文件放入该文件夹下，向其中添加ImgFun.cpp Android.mk Application.mk文件。分别写入如下代码：

#Android.mk中添加代码：LOCAL_PATH := $(call my-dir)include $(CLEAR_VARS)OPENCV_LIB_TYPE:=STATICifeq ("$(wildcard $(OPENCV_MK_PATH))","")# include指向自己OpenCV-android-sdk\sdk\native\jni\OpenCV.mk对应位置include D:\download\OpenCV-3.1.0-android-sdk\OpenCV-android-sdk\sdk\native\jni\OpenCV.mkelseinclude $(OPENCV_MK_PATH)endifLOCAL_MODULE := ImgFunLOCAL_SRC_FILES := ImgFun.cppLOCAL_LDLIBS += -lm -lloginclude $(BUILD_SHARED_LIBRARY)

# Application.mk写入代码如下：APP_STL := gnustl_staticAPP_CPPFLAGS := -frtti -fexceptionsAPP_ABI := armeabi-v7a

4.向app目录下build.gradle android{}中加入如下代码：

    sourceSets.main{        jniLibs.srcDir 'src/main/libs' //set .so files directory to libs        jni.srcDirs = [] //disable automatic ndk-build call    }// call regular ndk-build(.cmd) script from app directory    task ndkBuild(type: Exec) {            commandLine 'D:\\Users\\XXX\\AppData\\Local\\Android\\sdk\\ndk-bundle\\ndk-build.cmd', '-C', file('src/main').absolutePath//windows系统下的操作；将路径替换为自己NDK所在位置；    tasks.withType(JavaCompile) {        compileTask -> compileTask.dependsOn ndkBuild    }

记得在gradle.property中加上：android.useDeprecatedNdk=true;
并且将NDK目录加入到local.properties中：

ndk.dir=D\:\\Users\\kangdekai\\AppData\\Local\\Android\\sdk\\ndk-bundlesdk.dir=D\:\\Users\\kangdekai\\AppData\\Local\\Android\\sdk

此时build project便可以看到生成的ImgFun.so文件（第一次竟然因为项目名称有特殊符号没有成功）

5.定义ImgFun.cpp如下：

#include "com_example_jniopencv_MainActivity.h"#include #include #include using namespace cv;IplImage * change4channelTo3InIplImage(IplImage * src);extern "C" {JNIEXPORT jintArray JNICALL Java_com_example_jniopencv_MainActivity_ImgFun        (JNIEnv *, jclass, jintArray, jint, jint);JNIEXPORT jintArray JNICALL Java_com_example_jniopencv_MainActivity_ImgFun        (JNIEnv *env, jclass obj, jintArray buf, jint w, jint h) {    jint *cbuf;    cbuf = env->GetIntArrayElements(buf, false);    if (cbuf == NULL) {        return 0;    }    Mat myimg(h, w, CV_8UC4, (unsigned char*) cbuf);    IplImage image=IplImage(myimg);    IplImage* image3channel = change4channelTo3InIplImage(&image);    IplImage* pCannyImage=cvCreateImage(cvGetSize(image3channel),IPL_DEPTH_8U,1);    cvCanny(image3channel,pCannyImage,50,150,3);    int* outImage=new int[w*h];    for(int i=0;iint)pCannyImage->imageData[i];    }    int size = w * h;    jintArray result = env->NewIntArray(size);    env->SetIntArrayRegion(result, 0, size, outImage);    env->ReleaseIntArrayElements(buf, cbuf, 0);    return result;}}IplImage * change4channelTo3InIplImage(IplImage * src) {    if (src->nChannels != 4) {        return NULL;    }    IplImage * destImg = cvCreateImage(cvGetSize(src), IPL_DEPTH_8U, 3);    for (int row = 0; row < src->height; row++) {        for (int col = 0; col < src->width; col++) {            CvScalar s = cvGet2D(src, row, col);            cvSet2D(destImg, row, col, s);        }    }    return destImg;}

定义MainActivity如下：

static {        System.loadLibrary("ImgFun");    }    public static native int[] ImgFun(int []buf,int w,int h);    ImageView mIv;    Button btnNdk,btnRtn;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        TextView mtv=(TextView)findViewById(R.id.tv1);//        Test mytest=new Test();//        mtv.setText(mytest.myFun());        mtv.setText("你好！");        btnNdk=(Button)findViewById(R.id.button1);        btnRtn=(Button)findViewById(R.id.button2);        btnRtn.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                mIv=(ImageView)findViewById(R.id.iV);                Bitmap img = ((BitmapDrawable) getResources().getDrawable(R.drawable.image)).getBitmap();                mIv.setImageBitmap(img);            }        });        btnNdk.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                long current = System.currentTimeMillis();                Bitmap img1 = ((BitmapDrawable) getResources().getDrawable(                        R.drawable.image)).getBitmap();                int w = img1.getWidth(), h = img1.getHeight();                int[] pix = new int[w * h];                img1.getPixels(pix, 0, w, 0, 0, w, h);                int[] resultInt = ImgFun(pix, w, h);                Bitmap resultImg = Bitmap.createBitmap(w, h, Bitmap.Config.RGB_565);                resultImg.setPixels(resultInt, 0, w, 0, 0, w, h);                long performance = System.currentTimeMillis() - current;                mIv.setImageBitmap(resultImg);            }        });    }

6.运行程序，便可看到如下效果了~

参考博文：
1.android studio 使用 jni 编译 opencv 完整实例之图像边缘检测！从此在andrid中自由使用图像匹配、识别、检测
2.Android Studio 配置OpenCV、NDK，并用Jni调用OpenCV
3.在Android中使用JNI调用Opencv本地代码配置方式边缘检测范例代码
4.OpenCV在Android环境下的使用方法
5.OpenCV4Android Samples

AS下配置OpenCV环境

OpenCV JNI配置

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