OpenCV Sample On Android With NDK Build

 

1. unzip opencv-3.4.1-android-sdk.zip in d:/workspace/android

    directories in d:/workspace/android/OpenCV-android-sdk

    apk

    samples

    sdk

2. mkdir d:/workspace/cvtech

3. copy samples, sdk directories to d:/workspace/cvtech

4. import samples/face-detection from android studio by non-android-studio way

    and select d:/workspace/cvtech/face-detection as output directory

5. modify build.gradle of openCVSampleFaceDetectapply plugin: 'com.android.application'

android {
    compileSdkVersion 27
    buildToolsVersion "27.0.3"

    defaultConfig {
        applicationId "org.opencv.samples.facedetect"
        minSdkVersion 25
        targetSdkVersion 27

        ndk {
            abiFilters "armeabi", "armeabi-v7a"
            moduleName "detection_based_tracker"
        }
    }

    externalNativeBuild {
        ndkBuild {
            path "src/main/jni/Android.mk"
        }
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
        }
    }
}

dependencies {
    implementation project(':openCVLibrary341')
}

6. On window of Project Left Side, there will have two mk files
Android.mk
Application.mk
7. Android.mk content

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

#OPENCV_INSTALL_MODULES:=off
#OPENCV_LIB_TYPE:=SHARED
ifdef OPENCV_ANDROID_SDK
  ifneq ("","$(wildcard $(OPENCV_ANDROID_SDK)/OpenCV.mk)")
    include ${OPENCV_ANDROID_SDK}/OpenCV.mk
  else
    include ${OPENCV_ANDROID_SDK}/sdk/native/jni/OpenCV.mk
  endif
else
  include ../../sdk/native/jni/OpenCV.mk
endif

LOCAL_SRC_FILES  := DetectionBasedTracker_jni.cpp
LOCAL_C_INCLUDES += $(LOCAL_PATH)
LOCAL_LDLIBS     += -llog -ldl

LOCAL_MODULE     := detection_based_tracker

include $(BUILD_SHARED_LIBRARY)

8. copy all libraries in D:\Workspace\Android\OpenCV-android-sdk\sdk\native\libs 

to D:\Workspace\CvTech\CvTest\openCVLibrary341\src\main\jniLibs

9. add access mode for facedetec manifest.xml and  modifiy fd_activity.java

<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.READ_PHONE_STATE"/>
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE"/>
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
<uses-permission android:name="android.permission.CHANGE_CONFIGURATION"/>
<uses-permission android:name="android.permission.WAKE_LOCK"/>
<uses-permission android:name="android.permission.WRITE_SETTINGS"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.CAMERA"/>
<uses-permission android:name="android.permission.RECORD_AUDIO"/>
<uses-permission android:name="android.permission.INTERNET"/>

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    Log.i(TAG, "called onCreate");
    super.onCreate(savedInstanceState);
    getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

    setContentView(R.layout.face_detect_surface_view);

    mOpenCvCameraView = (CameraBridgeViewBase) findViewById(R.id.fd_activity_surface_view);
    mOpenCvCameraView.setVisibility(CameraBridgeViewBase.VISIBLE);
    mOpenCvCameraView.setCvCameraViewListener(this);

    if (!OpenCVLoader.initDebug()) { Log.e(this.getClass().getSimpleName(), " OpenCVLoader.initDebug(), not working."); }
    else { Log.d(this.getClass().getSimpleName(), " OpenCVLoader.initDebug(), working."); }


    System.loadLibrary("detection_based_tracker");

    try {
        // load cascade file from application resources
        InputStream is = getResources().openRawResource(R.raw.lbpcascade_frontalface);
        File cascadeDir = getDir("cascade", Context.MODE_PRIVATE);
        mCascadeFile = new File(cascadeDir, "lbpcascade_frontalface.xml");
        FileOutputStream os = new FileOutputStream(mCascadeFile);

        byte[] buffer = new byte[4096];
        int bytesRead;
        while ((bytesRead = is.read(buffer)) != -1) {
            os.write(buffer, 0, bytesRead);
        }
        is.close();
        os.close();

        mJavaDetector = new CascadeClassifier(mCascadeFile.getAbsolutePath());
        if (mJavaDetector.empty()) {
            Log.e(TAG, "Failed to load cascade classifier");
            mJavaDetector = null;
        } else
            Log.i(TAG, "Loaded cascade classifier from " + mCascadeFile.getAbsolutePath());

        mNativeDetector = new DetectionBasedTracker(mCascadeFile.getAbsolutePath(), 0);

        cascadeDir.delete();

    } catch (IOException e) {
        e.printStackTrace();
        Log.e(TAG, "Failed to load cascade. Exception thrown: " + e);
    }

    mOpenCvCameraView.setCameraIndex(1);
    mOpenCvCameraView.enableView();

}