[Android Studio] Using Java to call OpenCV

Environment: Android studio 2.2.3, OpenCV 2.4.9 For Android, Android 6 with api 23 for X86

---

一、File: build.gradle (app)

apply plugin: 'com.android.application'

android {
    compileSdkVersion
    buildToolsVersion "23.0.2"
    defaultConfig {
        applicationId "com.example.unsw.jeff"
        minSdkVersion
        targetSdkVersion
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:23.1.1'
    testCompile 'junit:junit:4.12'
    compile project(':openCVLibrary249')
}

二、File: build.gradle (openCVLibrary249)

apply plugin: 'com.android.library'

android {
    compileSdkVersion
    buildToolsVersion "23.0.2"

    defaultConfig {
        minSdkVersion
        targetSdkVersion
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
        }
    }
}

三、模拟器（支持本地摄像头）：

模拟器中app摄像头权限打开：

Set --> app --> 摄像头权限Open

显示效果：

开发代码

---

一、布局

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id ="@+id/activity_main"
    android:layout_width ="match_parent"
    android:layout_height="match_parent"

    tools:context="com.example.unsw.jeff.MainActivity">

    <org.opencv.android.JavaCameraView
        android:layout_width ="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/java_camera_view"
        />

</RelativeLayout>

二、功能实现核心：JavaCameraView

@Override
protected void onCreate(Bundle savedInstanceState) {
　　super.onCreate(savedInstanceState);
　　setContentView(R.layout.activity_main);

　　javaCameraView = (JavaCameraView)findViewById(R.id.java_camera_view);
　　javaCameraView.setVisibility(SurfaceView.VISIBLE);
　　javaCameraView.setCvCameraViewListener(this);     // 因为MainActivity实现了接口：CameraBridgeViewBase.CvCameraViewListener2

}

    @Override
    protected void onPause() {
        super.onPause();
        if (javaCameraView != null) {
            javaCameraView.disableView();
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (javaCameraView != null) {
            javaCameraView.disableView();
        }
    }

    @Override
    protected void onResume() {
        super.onResume();
        if (OpenCVLoader.initDebug()) {
            Log.i(TAG, "OpenCV loaded successfully.");
            mLoaderCallBack.onManagerConnected(LoaderCallbackInterface.SUCCESS);
        }
        else {
            Log.i(TAG, "OpenCV not loaded.");
            OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_9, this, mLoaderCallBack);
        }
    }

其他Activity生命周期

    @Override
    public void onCameraViewStarted(int width, int height) {
        mRgba = new Mat(height, width, CvType.CV_8UC4);
    }

    @Override
    public void onCameraViewStopped() {
        mRgba.release();
    }

    @Override
    public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame) {
        mRgba = inputFrame.rgba();

　　　　 // By opencv api in java here, do what you want to do.
          return mRgba;
    }

补充：

OpenCV4Android开发实录(1)：移植OpenCV3.3.0库到Android Studio