added Video Decoder Class

app/build.gradle

@@ -38,6 +38,11 @@ dependencies {
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.5.1'
 
     // Required for CameraX
-    implementation 'androidx.camera:camera-core:1.2.2'
+    def camerax_version = "1.2.2"
-    implementation 'androidx.camera:camera-camera2:1.2.2'
+    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/java/com/example/ueberwachungssystem/MainActivity.java

@@ -2,38 +2,69 @@ 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.ImageAnalysis;
+import androidx.camera.core.ImageProxy;
+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.app.AlertDialog;
-import android.content.DialogInterface;
 import android.content.pm.PackageManager;
+import android.graphics.ImageFormat;
+import android.media.Image;
 import android.os.Bundle;
+import android.util.Log;
+import android.util.Size;
 import android.view.View;
 import android.widget.Button;
+import android.widget.TextView;
 import android.widget.Toast;
 
+import com.google.common.util.concurrent.ListenableFuture;
+
+import java.nio.ByteBuffer;
+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;
+
 
     @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);
 
-        Button B1 = findViewById(R.id.B1);
+
-        B1.setOnClickListener(new View.OnClickListener() {
+        VideoDetector vd = new VideoDetector(this);
+
+        previewButton.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {
-                    getCameraAccess();
+                getCameraAccess();
+                if (isCameraAccessAllowed())
+                    vd.runImageAnalysis();
             }
         });
     }
 
 
+
     private boolean isCameraAccessAllowed() {
         return ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) == PackageManager.PERMISSION_GRANTED;
     }
@@ -57,17 +88,38 @@ public class MainActivity extends AppCompatActivity {
         }
     }
 
-    private void showDialogue(String message) {
+
-        new AlertDialog.Builder(this)
+    private void previewCamera() {
-                .setMessage(message)
+        // Request Camera Access
-                .setPositiveButton("OK", new DialogInterface.OnClickListener() {
+        getCameraAccess();
-                    @Override
+        // Return when Camera Access not allowed or Camera Preview is running
-                    public void onClick(DialogInterface dialog, int which) {
+        if (!isCameraAccessAllowed() || cameraPreviewIsRunning)
-                        requestPermissions(new String[] {Manifest.permission.CAMERA}, CAMERA_PERMISSION_REQUEST_CODE);
+            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.
                     }
-                })
+                }
-                .setNegativeButton("Cancel", null)
+            },ContextCompat.getMainExecutor(this));
-                .create()
+    }
-                .show();
+
+    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/VideoDetector.java

@@ -0,0 +1,106 @@
+package com.example.ueberwachungssystem;
+
+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.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 {
+
+    private final Context context;
+    private float currentLuminosity;
+
+
+    public VideoDetector(Context context) {
+        this.context = context;
+    }
+
+    public void runImageAnalysis() {
+        // Request Camera Provider
+        final ListenableFuture<ProcessCameraProvider> cameraProviderFuture = ProcessCameraProvider.getInstance(context);
+        //Check for Camera availability
+        cameraProviderFuture.addListener(new Runnable() {
+            @Override
+            public void run() {
+                try {
+                    ProcessCameraProvider cameraProvider = cameraProviderFuture.get();
+                    bindImageAnalysis(cameraProvider);
+                } catch (ExecutionException | InterruptedException e) {
+                    // No errors need to be handled for this Future. This should never be reached.
+                }
+            }
+        },ContextCompat.getMainExecutor(context));
+    }
+
+    private void bindImageAnalysis(@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;
+
+                    float luminosity = calculateLuminosity(image);
+                    currentLuminosity = luminosity;
+                    Log.d("Video Detector", String.valueOf(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();
+        // Connect Preview to PreviewView
+        cameraProvider.bindToLifecycle((LifecycleOwner) context, cameraSelector, imageAnalysis, preview);
+    }
+
+
+    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);
+    }
+}

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

@@ -10,6 +10,7 @@
     tools:context=".MainActivity">
 
     <TextView
+        android:id="@+id/textView"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:text="Hello World!"
@@ -19,11 +20,16 @@
         app:layout_constraintTop_toTopOf="parent" />
 
     <Button
-        android:id="@+id/B1"
+        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>