android ndk opencv jni 编译集成

OpenCV (Open Source Computer Vision Library)

https://docs.opencv.org/2.4/doc/tutorials/introduction/android_binary_package/dev_with_OCV_on_Android.html#native-c

1，下载opencv for android 的sdk

https://opencv.org/releases.html

打开 sdk/native/jni，如无意外，里面肯定有个 文件叫做 OpenCV.mk，它就是我们在 android.mk 脚本文件中要引入 opencv C++库所要参照的文件。

2，写mk

Android.mk

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

OPENCV_INSTALL_MODULES := on #Copies necessary OpenCV dynamic libs to the project libs folder

OPENCV_CAMERA_MODULES := off #Skip native OpenCV camera related libs copying to the project libs folder.

OPENCV_LIB_TYPE:=STATIC

include E:\work\starRTC\opencv\jni\OpenCV-android-sdk\sdk\native\jni\OpenCV.mk

LOCAL_MODULE := starRTC

LOCAL_SRC_FILES := main.cpp

LOCAL_LDLIBS += -llog -lz -lm

include $(BUILD_SHARED_LIBRARY)

Application.mk

APP_OPTIM:=debug

APP_ABI := armeabi-v7a

APP_PLATFORM=android-18

APP_STL := gnustl_static

#APP_CPPFLAGS := -std=c++11

APP_CPPFLAGS := -frtti -fexceptions

3，写jni代码

main.h

#ifndef _android_starLiveVideo_

#define _android_starLiveVideo_

#include <jni.h>

#include <opencv2/opencv.hpp>

#define NELEM(x) ((int) (sizeof(x) / sizeof((x)[0])))

IplImage * change4channelTo3InIplImage(IplImage * src);

#endif

main.cpp

#include <main.h>

#include <stdio.h>

#include <stdlib.h>

using namespace cv;

JNIEXPORT jintArray JNICALL interface_test(JNIEnv* env, jobject obj,

jintArray buf, int w, int 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;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;

}

static JNINativeMethod gMethodsSrc[] = {

{"interface_test", "([III)[I", (void*)interface_test}

};

int register_native_mothods(JNIEnv *env, const char *class_name, JNINativeMethod *gMethods, int numMethods){

jclass clazz;

clazz = env->FindClass(class_name);

if(clazz == NULL){

//loge("err:FindClass failed,className=%s\n",class_name);

return 0;

}

if(env->RegisterNatives(clazz, gMethods, numMethods) < 0){

//loge("err:RegisterNatives failed, numMethods=%d\n", numMethods);

return 0;

}

return 1;

}

JNIEXPORT

jint JNI_OnLoad(JavaVM *jvm, void *reserved){

JNIEnv *env = NULL;

jint result = JNI_ERR;

int i;

if(jvm->GetEnv((void**)&env, JNI_VERSION_1_4) != JNI_OK){

//loge("err:GetEnv failed");

return result;

}

register_native_mothods(env, "com/starrtc/starrtcsdk/socket/StarSocket", gMethodsSrc, NELEM(gMethodsSrc));

return JNI_VERSION_1_4;

}

4,ndk-build