# 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)# 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.    native-lib    # Sets the library as a shared library.    SHARED    # Provides a relative path to your source file(s).    src/main/cpp/native-lib.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 )# 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.      native-lib      # Links the target library to the log library      # included in the NDK.      ${log-lib} )

include_directories([AFTER|BEFORE] [SYSTEM] dir1 [dir2 ...])

#include "add.h"int add(int a,int b) { return a + b;}add.h#ifndef OPENCVTEST_ADD_H#define OPENCVTEST_ADD_Hint add(int a,int b);#endif //OPENCVTEST_ADD_H

cmake_minimum_required(VERSION 3.4.1)add_library(add SHARED   src/main/cpp/add.cpp)set(distribution_DIR ${CMAKE_CURRENT_SOURCE_DIR}/../distribution)set_target_properties(add PROPERTIES      LIBRARY_OUTPUT_DIRECTORY      ${distribution_DIR}/libs/${ANDROID_ABI})target_include_directories(add       PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/src/main/cpp)       add_custom_command(TARGET add POST_BUILD     COMMAND "${CMAKE_COMMAND}" -E     copy "${CMAKE_CURRENT_SOURCE_DIR}/src/main/cpp/add.h"     "${distribution_DIR}/include/mathlib/add.h"#     **** the following 2 lines are for potential future debug purpose ****#     COMMAND "${CMAKE_COMMAND}" -E#     remove_directory "${CMAKE_CURRENT_BINARY_DIR}"     COMMENT "Copying gmath to output directory")

externalNativeBuild {   cmake {    arguments '-DANDROID_PLATFORM=android-19',      '-DANDROID_TOOLCHAIN=clang', '-DANDROID_STL=gnustl_static'    targets 'add'   }  }

externalNativeBuild {  cmake {   path 'CMakeLists.txt'  } }

#include <jni.h>#include <string>#include "mathlib/add.h"extern "C"JNIEXPORT jstringJNICALLJava_com_example_bill_opencvtest_MainActivity_stringFromJNI(  JNIEnv *env,  jobject /* this */) { std::string hello = "Hello from C++ From Android openCVTest"; return env->NewStringUTF(hello.c_str());}extern "C"JNIEXPORT jint JNICALLJava_com_example_bill_opencvtest_MainActivity_addFromCpp(JNIEnv *env, jobject instance, jint a,               jint b) { // TODO return add(a,b);}

set(distribution_DIR ${CMAKE_SOURCE_DIR}/../distribution)include_directories(${distribution_DIR}/include)add_library(lib_add SHARED IMPORTED)set_target_properties(lib_add PROPERTIES IMPORTED_LOCATION      ${distribution_DIR}/libs/${ANDROID_ABI}/libadd.so)add_library( # Sets the name of the library.    native-math    # Sets the library as a shared library.    SHARED    # Provides a relative path to your source file(s).    src/main/cpp/native-math.cpp )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 )set_target_properties(native-math PROPERTIES      LIBRARY_OUTPUT_DIRECTORY      ${distribution_DIR}/libs/${ANDROID_ABI})target_link_libraries( # Specifies the target library.      native-math      android      log      lib_add      # Links the target library to the log library      # included in the NDK.      ${log-lib} )

externalNativeBuild {   cmake {    arguments '-DANDROID_PLATFORM=android-19',      '-DANDROID_TOOLCHAIN=clang', '-DANDROID_STL=gnustl_static'   }  }  ndk {   //abiFilters 'armeabi-v7a','x86_64'  }

static {  System.loadLibrary("native-math"); } /**  * A native method that is implemented by the 'native-lib' native library,  * which is packaged with this application.  */ public native String stringFromJNI(); public native int addFromCpp(int a, int b);

super.onCreate(savedInstanceState);  setContentView(R.layout.activity_main);  // Example of a call to a native method  TextView tv = (TextView) findViewById(R.id.sample_text);  tv.setText(stringFromJNI() + "____" + addFromCpp(2,88));

set(libs "${CMAKE_SOURCE_DIR}/src/main/jniLibs")include_directories(${distribution_DIR}/include)# set add libadd_library(libopencv_java3 SHARED IMPORTED )set_target_properties(libopencv_java3 PROPERTIES IMPORTED_LOCATION "${libs}/${ANDROID_ABI}/libopencv_java3.so")add_library( # Sets the name of the library.    native-opencv    # Sets the library as a shared library.    SHARED    # Provides a relative path to your source file(s).    src/main/cpp/native-opencv.cpp )set_target_properties(native-opencv PROPERTIES      LIBRARY_OUTPUT_DIRECTORY      ${distribution_DIR}/libs/${ANDROID_ABI})target_link_libraries( # Specifies the target library.      native-opencv      android      log      libopencv_java3      # Links the target library to the log library      # included in the NDK.      ${log-lib} )

//// Created by bill on 2018/1/13.//#include <jni.h>#include <opencv2/opencv.hpp>#include <vector>using namespace cv;using namespace std;extern "C"JNIEXPORT void JNICALLJava_com_example_bill_opencvtest_MainActivity_nativeProcessFrame(JNIEnv *env, jobject instance,  jlong addrGray, jlong addrRGBA) {// TODO Mat& gray = *(Mat *) addrGray; Mat& rgba = *(Mat *) addrRGBA; vector<KeyPoint> v; Ptr<ORB> orb = ORB::create(); orb->detect(gray, v, cv::Mat()); for (int i = 0; i < v.size(); ++i) {  const KeyPoint& kp = v[i];  circle(rgba, Point(kp.pt.x, kp.pt.y), 10, Scalar(255,0,0,255)); }}

static {  System.loadLibrary("native-opencv");  System.loadLibrary("native-math"); } /**  * A native method that is implemented by the 'native-lib' native library,  * which is packaged with this application.  */ public native String stringFromJNI(); public native int addFromCpp(int a, int b); private native void nativeProcessFrame(long addrGray, long addrRGBA);

package com.example.bill.opencvtest;import android.app.Activity;import android.os.Bundle;import android.util.Log;import android.view.WindowManager;import android.widget.TextView;import org.opencv.android.CameraBridgeViewBase;import org.opencv.android.OpenCVLoader;import org.opencv.core.CvType;import org.opencv.core.Mat;public class MainActivity extends Activity implements CameraBridgeViewBase.CvCameraViewListener2{ static {  System.loadLibrary("native-opencv");  System.loadLibrary("native-math"); } /**  * A native method that is implemented by the 'native-lib' native library,  * which is packaged with this application.  */ public native String stringFromJNI(); public native int addFromCpp(int a, int b); private native void nativeProcessFrame(long addrGray, long addrRGBA); private static final String TAG = "MainActivity"; private Mat rgba; private Mat gray; private CameraBridgeViewBase mOpenCvCameraView; @Override protected void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  setContentView(R.layout.activity_main);  // Example of a call to a native method  TextView tv = (TextView) findViewById(R.id.sample_text);  tv.setText(stringFromJNI() + "____" + addFromCpp(2,88));  getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);  mOpenCvCameraView = (CameraBridgeViewBase) findViewById(R.id.activity_camera_view);  mOpenCvCameraView.setVisibility(CameraBridgeViewBase.VISIBLE);  mOpenCvCameraView.setCvCameraViewListener(this); } @Override public void onPause() {  super.onPause();  if (mOpenCvCameraView != null){   mOpenCvCameraView.disableView();  } } @Override public void onResume() {  super.onResume();  if (!OpenCVLoader.initDebug()) {   Log.d(TAG, "Internal OpenCV library not found. Using OpenCV Manager for initialization");  } else {   Log.d(TAG, "OpenCV library found inside package. Using it!");   mOpenCvCameraView.enableView();  } } public void onDestroy() {  super.onDestroy();  if (mOpenCvCameraView != null){   mOpenCvCameraView.disableView();  } } public void onCameraViewStarted(int width, int height){  rgba = new Mat(height, width, CvType.CV_8UC4);  gray = new Mat(height, width, CvType.CV_8UC1); } public void onCameraViewStopped() {  rgba.release();  gray.release(); } public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame){  rgba = inputFrame.rgba();  gray = inputFrame.gray();  nativeProcessFrame(gray.getNativeObjAddr(), rgba.getNativeObjAddr());  return rgba; }}

<?xml version="1.0" encoding="utf-8"?><android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" xmlns:opencv="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="com.example.bill.opencvtest.MainActivity"> <TextView  android:id="@+id/sample_text"  android:layout_width="wrap_content"  android:layout_height="wrap_content"  android:text="Hello World!"  app:layout_constraintBottom_toBottomOf="parent"  app:layout_constraintLeft_toLeftOf="parent"  app:layout_constraintRight_toRightOf="parent"  app:layout_constraintTop_toTopOf="parent" /> <org.opencv.android.JavaCameraView  android:layout_width="match_parent"  android:layout_height="match_parent"  android:id="@+id/activity_camera_view"  opencv:show_fps="true"  opencv:camera_id="any"/></android.support.constraint.ConstraintLayout>

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.bill.opencvtest"> <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" /> <uses-permission android:name="android.permission.CAMERA"/> <uses-feature android:name="android.hardware.camera"/> <uses-feature android:name="android.hardware.camera.autofocus"/> <uses-feature android:name="android.hardware.camera.front"/> <uses-feature android:name="android.hardware.camera.front.autofocus"/> <application  android:allowBackup="true"  android:icon="@mipmap/ic_launcher"  android:label="@string/app_name"  android:roundIcon="@mipmap/ic_launcher_round"  android:supportsRtl="true"  android:theme="@style/AppTheme">  <activity android:name=".MainActivity"   android:screenOrientation="landscape"   android:configChanges="keyboardHidden|orientation">   <intent-filter>    <action android:name="android.intent.action.MAIN" />    <category android:name="android.intent.category.LAUNCHER" />   </intent-filter>  </activity> </application></manifest>