Added onDetectionListener to VideoDecoder

startDetection(), stopDetection(), isRunning()

app/build.gradle

@@ -36,4 +36,13 @@ dependencies {
     testImplementation 'junit:junit:4.13.2'
     androidTestImplementation 'androidx.test.ext:junit:1.1.5'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.5.1'
+
+    // Required for CameraX
+    def camerax_version = "1.2.2"
+    implementation "androidx.camera:camera-core:${camerax_version}"
+    implementation "androidx.camera:camera-camera2:${camerax_version}"
+    implementation "androidx.camera:camera-lifecycle:${camerax_version}"
+    implementation "androidx.camera:camera-video:${camerax_version}"
+    implementation "androidx.camera:camera-view:${camerax_version}"
+    implementation "androidx.camera:camera-extensions:${camerax_version}"
 }

app/src/main/AndroidManifest.xml

@@ -2,6 +2,9 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools">
 
+    <uses-feature android:name="android.hardware.camera"/>
+    <uses-permission android:name="android.permission.CAMERA"/>
+
     <application
         android:allowBackup="true"
         android:dataExtractionRules="@xml/data_extraction_rules"

app/src/main/java/com/example/ueberwachungssystem/MainActivity.java

@@ -1,14 +1,137 @@
 package com.example.ueberwachungssystem;
 
+import androidx.annotation.NonNull;
 import androidx.appcompat.app.AppCompatActivity;
+import androidx.camera.core.Camera;
+import androidx.camera.core.CameraSelector;
+import androidx.camera.core.Preview;
+import androidx.camera.lifecycle.ProcessCameraProvider;
+import androidx.camera.view.PreviewView;
+import androidx.core.app.ActivityCompat;
+import androidx.core.content.ContextCompat;
+import androidx.camera.core.ExperimentalGetImage;
+import androidx.lifecycle.LifecycleOwner;
 
+import android.Manifest;
+import android.content.pm.PackageManager;
 import android.os.Bundle;
+import android.util.Log;
+import android.view.View;
+import android.widget.Button;
+import android.widget.TextView;
+import android.widget.Toast;
 
+import com.example.ueberwachungssystem.VideoDetection.DetectionReport;
+import com.example.ueberwachungssystem.VideoDetection.VideoDetector;
+import com.google.common.util.concurrent.ListenableFuture;
+
+import java.util.Calendar;
+import java.util.concurrent.ExecutionException;
+
+@ExperimentalGetImage
 public class MainActivity extends AppCompatActivity {
 
+    private static final int CAMERA_PERMISSION_REQUEST_CODE = 101;
+    private PreviewView previewView;
+    private TextView textView;
+    private Button previewButton;
+    private Boolean cameraPreviewIsRunning = false;
+    private Boolean isPressed = false;
+
+
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
+
+        textView = findViewById(R.id.textView);
+        previewView = findViewById(R.id.previewView);
+        previewButton = findViewById(R.id.previewButton);
+
+
+        VideoDetector vd = new VideoDetector(this);
+        vd.setPreviewView(previewView);
+        vd.setOnDetectionListener(new VideoDetector.OnDetectionListener() {
+            @Override
+            public void onDetection(DetectionReport detectionReport) {
+                Log.d("Listener", detectionReport.detectionType);
+            }
+        });
+        vd.startDetection();
+
+
+        previewButton.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                getCameraAccess();
+                if (isCameraAccessAllowed() && !isPressed)
+                {
+                    vd.stopDetection();
+                    isPressed = true;
+                }
+                else if (isCameraAccessAllowed() && isPressed) {
+                    vd.startDetection();
+                    isPressed = false;
+                }
+            }
+        });
+    }
+
+    private boolean isCameraAccessAllowed() {
+        return ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) == PackageManager.PERMISSION_GRANTED;
+    }
+
+    private void getCameraAccess() {
+        if (!isCameraAccessAllowed())
+            ActivityCompat.requestPermissions(this, new String[]{android.Manifest.permission.CAMERA}, CAMERA_PERMISSION_REQUEST_CODE);
+    }
+
+    @Override
+    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
+        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
+
+        if (requestCode == CAMERA_PERMISSION_REQUEST_CODE && grantResults.length > 0) {
+            boolean cameraRights = grantResults[0] == PackageManager.PERMISSION_GRANTED;
+            if (cameraRights) {
+                Toast.makeText(this, "camera permission granted", Toast.LENGTH_LONG).show();
+            } else {
+                Toast.makeText(this, "camera permission denied", Toast.LENGTH_LONG).show();
+            }
+        }
+    }
+
+
+    private void previewCamera() {
+        // Request Camera Access
+        getCameraAccess();
+        // Return when Camera Access not allowed or Camera Preview is running
+        if (!isCameraAccessAllowed() || cameraPreviewIsRunning)
+            return;
+        // Camera Preview is running
+        cameraPreviewIsRunning = true;
+        // Request Camera Provider
+        final ListenableFuture<ProcessCameraProvider> cameraProviderFuture = ProcessCameraProvider.getInstance(this);
+        //Check for Camera availability
+        cameraProviderFuture.addListener(new Runnable() {
+                @Override
+                public void run() {
+                    try {
+                        ProcessCameraProvider cameraProvider = cameraProviderFuture.get();
+                        bindPreview(cameraProvider);
+                    } catch (ExecutionException | InterruptedException e) {
+                        // No errors need to be handled for this Future. This should never be reached.
+                    }
+                }
+            },ContextCompat.getMainExecutor(this));
+    }
+
+    private void bindPreview(@NonNull ProcessCameraProvider cameraProvider) {
+        // Create Preview
+        Preview preview = new Preview.Builder().build();
+        // Specify which Camera to use
+        CameraSelector cameraSelector = new CameraSelector.Builder().requireLensFacing(CameraSelector.LENS_FACING_BACK).build();
+        // Connect Preview to PreviewView
+        preview.setSurfaceProvider(previewView.getSurfaceProvider());
+        Camera camera = cameraProvider.bindToLifecycle((LifecycleOwner)this, cameraSelector, preview);
     }
 }

app/src/main/java/com/example/ueberwachungssystem/VideoDetection/DetectionReport.java

@@ -0,0 +1,19 @@
+package com.example.ueberwachungssystem.VideoDetection;
+
+import java.util.Calendar;
+
+/** Detection Report Class */
+
+public class DetectionReport {
+    public String timeStamp;
+    public String detectionType;
+    public float detectedAmplitude;
+    public String detectorID;
+
+    public DetectionReport(String detectorID, String detectionType, float detectedAmplitude) {
+        this.timeStamp = String.valueOf(Calendar.getInstance().getTime());
+        this.detectionType = detectionType;
+        this.detectedAmplitude = detectedAmplitude;
+        this.detectorID = detectorID;
+    }
+}

app/src/main/java/com/example/ueberwachungssystem/VideoDetection/VideoDetector.java

@@ -0,0 +1,171 @@
+package com.example.ueberwachungssystem.VideoDetection;
+
+import android.content.Context;
+import android.graphics.ImageFormat;
+import android.media.Image;
+import android.util.Log;
+import android.util.Size;
+
+import androidx.annotation.NonNull;
+import androidx.camera.core.CameraSelector;
+import androidx.camera.core.ExperimentalGetImage;
+import androidx.camera.core.ImageAnalysis;
+import androidx.camera.core.ImageProxy;
+import androidx.camera.core.Preview;
+import androidx.camera.lifecycle.ProcessCameraProvider;
+import androidx.camera.view.PreviewView;
+import androidx.core.content.ContextCompat;
+import androidx.lifecycle.LifecycleOwner;
+
+import com.google.common.util.concurrent.ListenableFuture;
+
+import java.nio.ByteBuffer;
+import java.util.concurrent.ExecutionException;
+
+
+@ExperimentalGetImage
+public class VideoDetector {
+    // Calling Activity
+    private final Context context;
+    // Camera Provider
+    private ProcessCameraProvider cameraProvider;
+    private Boolean isDetectionRunning = false;
+    // Preview Camera Image
+    private PreviewView previewView = null;
+    // Check Violation
+    private final float DELTA_LUMINOSITY_THRESHOLD = 0.5f;
+    private float previousLuminosity = 0f;
+    // On Detection Listener
+    private OnDetectionListener listener;
+
+
+
+    /** Constructor */
+    public VideoDetector(Context context) { this.context = context; }
+
+
+    /** On Detection Listener - runs when a violation is reported */
+    public interface OnDetectionListener {
+        public void onDetection(DetectionReport detectionReport);
+    }
+    public void setOnDetectionListener(OnDetectionListener listener) {
+        this.listener = listener;
+    }
+    public void reportViolation(float amplitude) {
+        DetectionReport detectionReport = new DetectionReport("123", "Video", amplitude);
+        if (listener != null)
+            listener.onDetection(detectionReport);
+    }
+
+
+    /** Return State of Video Detector */
+    public Boolean isRunning() {
+        return isDetectionRunning;
+    }
+
+
+    /** Starts Video Detection */
+    public void startDetection() {
+        isDetectionRunning = true;
+        // Request Camera Provider
+        final ListenableFuture<ProcessCameraProvider> cameraProviderFuture = ProcessCameraProvider.getInstance(context);
+        //Check for Camera availability
+        cameraProviderFuture.addListener(new Runnable() {
+            @Override
+            public void run() {
+                try {
+                    cameraProvider = cameraProviderFuture.get();
+                    bindLuminosityAnalysis(cameraProvider);
+                } catch (ExecutionException | InterruptedException e) {
+                    // No errors need to be handled for this Future. This should never be reached.
+                }
+            }
+        },ContextCompat.getMainExecutor(context));
+    }
+
+
+    /** Stops Video Detection */
+    public void stopDetection() {
+        cameraProvider.unbindAll();
+        isDetectionRunning = false;
+    }
+
+
+    /** Set PreviewView to show Image */
+    public void setPreviewView(PreviewView previewView) {
+        this.previewView = previewView;
+    }
+
+
+    /** Binds the Luminosity Analyzer (configure and run Analysis) */
+    private void bindLuminosityAnalysis(@NonNull ProcessCameraProvider cameraProvider) {
+        // Configure and create Image Analysis
+        ImageAnalysis.Builder builder = new ImageAnalysis.Builder();
+        builder.setTargetResolution(new Size(640, 480));
+        builder.setBackpressureStrategy(ImageAnalysis.STRATEGY_KEEP_ONLY_LATEST);
+        ImageAnalysis imageAnalysis = builder.build();
+
+        // Set Analyzer
+        imageAnalysis.setAnalyzer(ContextCompat.getMainExecutor(context), new ImageAnalysis.Analyzer() {
+            @Override
+            public void analyze(@NonNull ImageProxy imageProxy) {
+                if (imageProxy.getFormat() == ImageFormat.YUV_420_888) {
+                    Image image = imageProxy.getImage();
+                    assert image != null;
+
+                    // Analyze frame
+                    float luminosity = calculateLuminosity(image);
+                    Log.d("Video Detector", String.valueOf(luminosity));
+                    checkForViolation(luminosity, previousLuminosity);
+                    previousLuminosity = luminosity;
+                }
+                imageProxy.close();
+            }
+        });
+        // Create Preview
+        Preview preview = new Preview.Builder().build();
+        // Specify which Camera to use
+        CameraSelector cameraSelector = new CameraSelector.Builder().requireLensFacing(CameraSelector.LENS_FACING_BACK).build();
+        // Update PreviewView if set
+        if (previewView != null)
+            preview.setSurfaceProvider(previewView.getSurfaceProvider());
+
+        cameraProvider.bindToLifecycle((LifecycleOwner) context, cameraSelector, imageAnalysis, preview);
+    }
+
+
+    /** Return Luminosity from Image */
+    private float calculateLuminosity (Image image) {
+        int width = image.getWidth();
+        int height = image.getHeight();
+
+        Image.Plane[] planes = image.getPlanes();
+        ByteBuffer luminosityBuffer = planes[0].getBuffer();
+
+        int yRowStride = image.getPlanes()[0].getRowStride();
+        int yPixelStride = image.getPlanes()[0].getPixelStride();
+
+        int luminosity;
+        float sum = 0;
+
+        for (int y = 0; y < height; ++y) {
+            for (int x = 0; x < width; x++) {
+                int index = (y * yRowStride) + (x * yPixelStride);
+                luminosity = (luminosityBuffer.get(index) & 0xff);
+                sum += luminosity;
+            }
+        }
+        return sum / (width * height);
+    }
+
+
+    /** Check if delta Luminosity exceeds threshold */
+    private void checkForViolation(float luminosity, float previousLuminosity) {
+        float deltaLuminosity = Math.abs(luminosity - previousLuminosity);
+        if (deltaLuminosity > DELTA_LUMINOSITY_THRESHOLD) {
+            reportViolation(deltaLuminosity);
+            Log.d("Violation", "Violation");
+        }
+        Log.d("Delta", String.valueOf(Math.abs(previousLuminosity - luminosity)));
+    }
+}

app/src/main/res/layout/activity_main.xml

@@ -1,12 +1,16 @@
 <?xml version="1.0" encoding="utf-8"?>
-<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<LinearLayout 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"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
+    android:layout_gravity="center"
+    android:gravity="center"
+    android:orientation="vertical"
     tools:context=".MainActivity">
 
     <TextView
+        android:id="@+id/textView"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:text="Hello World!"
@@ -15,4 +19,17 @@
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toTopOf="parent" />
 
-</androidx.constraintlayout.widget.ConstraintLayout>
+    <Button
+        android:id="@+id/previewButton"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Button"
+        tools:layout_editor_absoluteX="156dp"
+        tools:layout_editor_absoluteY="189dp" />
+
+    <androidx.camera.view.PreviewView
+        android:id="@+id/previewView"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent" />
+
+</LinearLayout>