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

@@ -1,5 +1,6 @@
 package com.example.ueberwachungssystem;
 
+import android.content.Context;
 import androidx.annotation.NonNull;
 
 
@@ -7,7 +8,7 @@ abstract public class Detector {
     private OnDetectionListener listener;
 
     /** Constructor - takes context of current activity */
-    public Detector() {}
+    public Detector(Context context) {};
 
 
     /** On Detection Listener - runs when violation is reported */

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

@@ -21,6 +21,11 @@ import com.example.ueberwachungssystem.VideoDetection.VideoDetector;
 public class MainActivity extends AppCompatActivity {
 
     private static final int CAMERA_PERMISSION_REQUEST_CODE = 101;
+    private PreviewView previewView;
+    private TextView textView;
+    private ToggleButton toggleButton;
+    private Boolean cameraPreviewIsRunning = false;
+    private Boolean isPressed = false;
 
 
     @Override
@@ -28,15 +33,16 @@ public class MainActivity extends AppCompatActivity {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
 
-        TextView textView = findViewById(R.id.textView);
+        textView = findViewById(R.id.textView);
-        PreviewView previewView = findViewById(R.id.previewView);
+        previewView = findViewById(R.id.previewView);
+        toggleButton = findViewById(R.id.previewButton);
 
 
         VideoDetector vd = new VideoDetector(this);
         vd.setPreviewView(previewView);
         vd.setOnDetectionListener(new VideoDetector.OnDetectionListener() {
             @Override
-            public void onDetection(@NonNull DetectionReport detectionReport) {
+            public void onDetection(DetectionReport detectionReport) {
                 detectionReport.log("OnDetection");
                 textView.setText(detectionReport.toString());
             }
@@ -44,7 +50,6 @@ public class MainActivity extends AppCompatActivity {
         //vd.startDetection();
 
 
-        ToggleButton toggleButton = findViewById(R.id.previewButton);
         toggleButton.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {

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

@@ -3,26 +3,28 @@ 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.example.ueberwachungssystem.Detector;
+import com.example.ueberwachungssystem.DetectionReport;
 import com.google.common.util.concurrent.ListenableFuture;
 
 import java.nio.ByteBuffer;
 import java.util.concurrent.ExecutionException;
 
 @ExperimentalGetImage
-public class VideoDetector extends Detector {
+public class VideoDetector {
 
     // Calling Activity
     private final Context context;
@@ -31,43 +33,64 @@ public class VideoDetector extends Detector {
     private Boolean isDetectionRunning = false;
     // Preview Camera Image
     private PreviewView previewView = null;
-    // Detect Violation
+    // Check Violation
-    private static final int PIXEL_THRESHOLD = 60;  // Luminosity (brightness channel of YUV_420_888)
+    private final float DELTA_LUMINOSITY_THRESHOLD = 1.5f;
-    private static final float ALARM_THRESHOLD = 0.5f;   // Percent of pixels changed
+    private Float previousLuminosity = null;
-    private ByteBuffer previousBuffer = null;
+    // On Detection Listener
+    private OnDetectionListener listener;
 
 
 
     /** Constructor */
     public VideoDetector(Context context) {
-
-        super();
         this.context = context;
     }
 
 
+    /** On Detection Listener - runs when a violation is reported */
+    public interface OnDetectionListener {
+        void onDetection(DetectionReport detectionReport);
+    }
+    public void setOnDetectionListener(OnDetectionListener listener) {
+        this.listener = listener;
+    }
+    private void reportViolation(float amplitude) {
+        if (listener != null) {
+            DetectionReport detectionReport = new DetectionReport("123", "Video", amplitude);
+            listener.onDetection(detectionReport);
+        }
+    }
+
+
+    /** Return State of Video Detector */
+    public Boolean isRunning() {
+        return isDetectionRunning;
+    }
+
+
     /** Starts Video Detection */
-    @Override
     public void startDetection() {
         if (isDetectionRunning)
             return;
         // Request Camera Provider
         final ListenableFuture<ProcessCameraProvider> cameraProviderFuture = ProcessCameraProvider.getInstance(context);
         //Check for Camera availability
-        cameraProviderFuture.addListener(() -> {
+        cameraProviderFuture.addListener(new Runnable() {
-            try {
+            @Override
-                cameraProvider = cameraProviderFuture.get();
+            public void run() {
-                bindLuminosityAnalysis(cameraProvider);
+                try {
-                isDetectionRunning = true;
+                    cameraProvider = cameraProviderFuture.get();
-            } catch (ExecutionException | InterruptedException e) {
+                    bindLuminosityAnalysis(cameraProvider);
-                // No errors need to be handled for this Future. This should never be reached.
+                    isDetectionRunning = true;
+                } catch (ExecutionException | InterruptedException e) {
+                    // No errors need to be handled for this Future. This should never be reached.
+                }
             }
         },ContextCompat.getMainExecutor(context));
     }
 
 
     /** Stops Video Detection */
-    @Override
     public void stopDetection() {
         if (!isDetectionRunning)
             return;
@@ -88,26 +111,25 @@ public class VideoDetector extends Detector {
         ImageAnalysis.Builder builder = new ImageAnalysis.Builder();
         builder.setTargetResolution(new Size(640, 480));
         builder.setBackpressureStrategy(ImageAnalysis.STRATEGY_KEEP_ONLY_LATEST);
-        builder.setOutputImageFormat(ImageAnalysis.OUTPUT_IMAGE_FORMAT_YUV_420_888);
         ImageAnalysis imageAnalysis = builder.build();
 
         // Set Analyzer
-        imageAnalysis.setAnalyzer(ContextCompat.getMainExecutor(context), imageProxy -> {
+        imageAnalysis.setAnalyzer(ContextCompat.getMainExecutor(context), new ImageAnalysis.Analyzer() {
-            if (imageProxy.getFormat() == ImageFormat.YUV_420_888) {
+            @Override
-                Image image = imageProxy.getImage();
+            public void analyze(@NonNull ImageProxy imageProxy) {
-                assert image != null;
+                if (imageProxy.getFormat() == ImageFormat.YUV_420_888) {
+                    Image image = imageProxy.getImage();
+                    assert image != null;
 
-                // Changed Pixel Detection
+                    // Analyze frame
-                int pixelChanged = getChangedPixelCount(image);
+                    float luminosity = calculateLuminosity(image);
-                int width = image.getWidth();
+                    Log.d("Video Detector", String.valueOf(luminosity));
-                int height = image.getHeight();
+                    if (previousLuminosity != null)
-
+                        checkForViolation(luminosity, previousLuminosity);
-                float percentPixelChanged = (float) 100f * pixelChanged / (width * height);
+                    previousLuminosity = luminosity;
-
+                }
-                if (percentPixelChanged > ALARM_THRESHOLD)
+                imageProxy.close();
-                    reportViolation("0", "Video", percentPixelChanged);
             }
-            imageProxy.close();
         });
         // Create Preview
         Preview preview = new Preview.Builder().build();
@@ -122,42 +144,38 @@ public class VideoDetector extends Detector {
     }
 
 
-    /** Calculate Amount of Pixels changed */
+    /** Return Luminosity from Image */
-    private int getChangedPixelCount(Image image) {
+    private float calculateLuminosity (Image image) {
         int width = image.getWidth();
         int height = image.getHeight();
 
         Image.Plane[] planes = image.getPlanes();
-        ByteBuffer buffer = planes[0].getBuffer();
+        ByteBuffer luminosityBuffer = planes[0].getBuffer();
 
         int yRowStride = image.getPlanes()[0].getRowStride();
         int yPixelStride = image.getPlanes()[0].getPixelStride();
 
-        int changedPixelCount = 0;
+        int luminosity;
-
+        float sum = 0;
-        if (previousBuffer == null) {
-            previousBuffer = ByteBuffer.allocate(buffer.capacity());
-            buffer.rewind();
-            previousBuffer.put(buffer);
-            previousBuffer.rewind();
-            return 0;
-        }
 
         for (int y = 0; y < height; ++y) {
             for (int x = 0; x < width; x++) {
                 int index = (y * yRowStride) + (x * yPixelStride);
-                int luminosity = (buffer.get(index) & 0xff);
+                luminosity = (luminosityBuffer.get(index) & 0xff);
-                int previousLuminosity = (previousBuffer.get(index) & 0xff);
+                sum += luminosity;
-                int diff = Math.abs(luminosity - previousLuminosity);
-                if (diff > PIXEL_THRESHOLD)
-                    changedPixelCount++;
             }
         }
-        // Reset and copy Byte Buffer
+        return sum / (width * height);
-        buffer.rewind();
+    }
-        previousBuffer.rewind();
-        previousBuffer.put(buffer);
 
-        return changedPixelCount;
+
+    /** 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(luminosity);
+            Log.d("Violation", "Violation");
+        }
+        Log.d("Delta", String.valueOf(Math.abs(previousLuminosity - luminosity)));
     }
 }