Android Studio中使用JNI调用OpenCV本地代码Canny 边缘检测

Android Studio中使用JNI调用OpenCV本地代码Canny 边缘检测

1.add activity_canny.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical">    <Button        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:id="@+id/btn_ndk"        android:text="use C++ OpenCV process img"/>    <Button        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:id="@+id/btn_restore"        android:text="restore"/>    <ImageView        android:layout_width="match_parent"        android:layout_height="match_parent"        android:id="@+id/img"/></LinearLayout>

2.CannyActivity

public class CannyActivity extends Activity {    static {        System.loadLibrary("canny");    }    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);    }    public static native int[] cannyImg(int[] buf,int w, int h);}

3.add img process

public class CannyActivity extends Activity {    private ImageView img;    private Button btnNdk,btnRestore;    static {        System.loadLibrary("canny");    }    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_canny);        init();    }    private void init() {//        this.setTitle("use ndk to change img to grayscale");        btnNdk = (Button) findViewById(R.id.btn_ndk);        btnNdk.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                processImg();            }        });        btnRestore = (Button) findViewById(R.id.btn_restore);        btnRestore.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                setOriImg();            }        });        img = (ImageView) findViewById(R.id.img);        setOriImg();    }    private void processImg() {        long current = System.currentTimeMillis();        Bitmap imgBitmapProc = ((BitmapDrawable) getResources().getDrawable(                R.drawable.starry_night)).getBitmap();        int w = imgBitmapProc.getWidth();        int h = imgBitmapProc.getHeight();        int [] pix = new int[w*h];        imgBitmapProc.getPixels(pix,0,w,0,0,w,h);        int[] resInt = cannyImg(pix,w,h);        Bitmap resImg = Bitmap.createBitmap(w,h, Bitmap.Config.RGB_565);        resImg.setPixels(resInt,0,w,0,0,w,h);        long performance = System.currentTimeMillis() - current;        img.setImageBitmap(resImg);        btnNdk.setText("w:" + String.valueOf(imgBitmapProc.getWidth()        +",h:"+String.valueOf(imgBitmapProc.getHeight())        +",ndk perform time:"+String.valueOf(performance)+" millsecond"));    }    private void setOriImg() {        Bitmap imgBit = ((BitmapDrawable) getResources().getDrawable(                R.drawable.starry_night)).getBitmap();        img.setImageBitmap(imgBit);    }    /**     *     * @param buf     * @param w width the current view width     * @param h height the current view height     */    public static native int[] cannyImg(int[] buf,int w, int h);}

4.build project

5.generate .h

6.
javah -classpath app/build/intermediates/classes/debug:
/home/gjc/Android/Sdk/platforms/android-23/android.jar:
openCVLibrary300/build/intermediates/classes/debug
-d app/src/main/jni com.gjc.androidopencv.canny.CannyActivity

7.   .h file

/* * Class:     com_gjc_androidopencv_canny_CannyActivity * Method:    cannyImg * Signature: ([III)[I */JNIEXPORT jintArray JNICALL Java_com_gjc_androidopencv_canny_CannyActivity_cannyImg  (JNIEnv *, jclass, jintArray, jint, jint);

8.cannyImg.cpp

#include <jni.h>#include <stdio.h>#include <stdlib.h>#include <opencv2/opencv.hpp>using namespace cv;IplImage * change4channelTo3InIplImage(IplImage * src);extern "C" {JNIEXPORT jintArray JNICALL Java_com_gjc_androidopencv_canny_CannyActivity_cannyImg        (JNIEnv *env, jclass clazz, jintArray buf, jint w, jint h){    jint *cbuf;    cbuf = env->GetIntArrayElements(buf,JNI_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;i<w*h;i++) {        outImage[i] = (int)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;}

9.Android.mk

LOCAL_PATH :=$(call my-dir)include $(CLEAR_VARS)OPENCV_LIB_TYPE:=STATICinclude /home/gjc/Downloads/OpenCV-android-sdk/sdk/native/jni/OpenCV.mkLOCAL_MODULE:=cannyLOCAL_SRC_FILES:=cannyImg.cppinclude $(BUILD_SHARED_LIBRARY)

10.Application.mk

APP_STL:=gnustl_static    APP_CPPFLAGS:=-frtti -fexceptions    APP_ABI:=armeabi armeabi-v7a   

11.compile .so use ndk-build