Kamera Preview ergänzt

app/src/main/AndroidManifest.xml

         <activity
             android:name=".AccelerometerActivity"
             android:exported="false" />
+        <activity
+            android:name=".VideoPreviewActivity"
+            android:exported="false" />
         <activity
             android:name=".MainActivity"
             android:exported="true">

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

     private Button audiodetectionAndAccelerometerButton;
     private Button videodetectionAndAccelerometerButton;
     private Button connectionButton;
+    private Button prewview_kamera;
     private MainActivityViewModel mMainActivityViewModel;
 
     @Override
         audiodetectionAndAccelerometerButton = (Button) findViewById(R.id.audiodetectionAndAccelerometerButton);
         videodetectionAndAccelerometerButton = (Button) findViewById(R.id.videodetectionAndAccelerometerButton);
         connectionButton = (Button) findViewById(R.id.connectionButton);
+        prewview_kamera = (Button) findViewById(R.id.preview_kamera);
 
         RecyclerView deviceListRecyclerView = findViewById(R.id.deviceListRecyclerView);
         deviceListRecyclerView.setLayoutManager(new LinearLayoutManager(this));
             }
         });
 
+        prewview_kamera.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                if (mMainActivityViewModel.isCameraAccessAllowed(MainActivity.this)) {
+                    openVideoPrewvoewActivity();
+                }
+                else {
+                    mMainActivityViewModel.accessRequestCamera(MainActivity.this);
+                }
+            }
+        });
         audiodetectionButton.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {
             }
         });
     }
+    public void openVideoPrewvoewActivity() {
+        Intent intent = new Intent(this, VideoPreviewActivity.class);
+        startActivity(intent);
+    }
     public void openAudiodetectionActivity(){
         Intent intent = new Intent(this, AudiodetectionActivity.class);
         startActivity(intent);

app/src/main/java/com/example/greenwatch/VideoPreviewActivity.java

+package com.example.greenwatch;
+
+import android.os.Bundle;
+import android.util.Size;
+import android.widget.Button;
+
+import androidx.appcompat.app.AppCompatActivity;
+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.content.ContextCompat;
+import androidx.lifecycle.LifecycleOwner;
+
+import com.google.common.util.concurrent.ListenableFuture;
+
+import java.util.concurrent.ExecutionException;
+
+public class VideoPreviewActivity extends AppCompatActivity {
+
+    private Button backToMainActivity;
+    private PreviewView previewView;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_preview_kamera);
+
+        backToMainActivity = (Button) findViewById(R.id.videodetectorBackToMainActivity);
+        previewView = findViewById(R.id.previewView);
+
+        backToMainActivity.setOnClickListener(v -> finish());
+
+
+        final ListenableFuture<ProcessCameraProvider> cameraProviderFuture = ProcessCameraProvider.getInstance(this);
+        cameraProviderFuture.addListener(() -> {
+            try {
+                bindImageAnalysis(cameraProviderFuture.get());
+            } catch (ExecutionException | InterruptedException e) {
+                e.printStackTrace();
+            }
+        }, ContextCompat.getMainExecutor(this));
+    }
+
+    private void bindImageAnalysis(ProcessCameraProvider cameraProvider) {
+        ImageAnalysis.Builder builder = new ImageAnalysis.Builder();
+        builder.setTargetResolution(new Size(640, 480));
+        builder.setBackpressureStrategy(ImageAnalysis.STRATEGY_KEEP_ONLY_LATEST);
+        ImageAnalysis imageAnalysis = builder.build();
+        imageAnalysis.setAnalyzer(
+                ContextCompat.getMainExecutor(this),
+                ImageProxy::close);
+
+        Preview preview = new Preview.Builder().build();
+        CameraSelector cameraSelector = new CameraSelector.Builder().requireLensFacing(CameraSelector.LENS_FACING_BACK).build();
+        preview.setSurfaceProvider(previewView.getSurfaceProvider());
+        cameraProvider.bindToLifecycle((LifecycleOwner) this, cameraSelector, imageAnalysis, preview);
+    }
+}

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

     android:padding="10dp"
     tools:context=".MainActivity">
 
+    <Button
+        android:id="@+id/preview_kamera"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="PrewView Kamera" />
+
     <androidx.recyclerview.widget.RecyclerView
         android:id="@+id/alarmHistoryListRecyclerView"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:layout_weight="3"
         tools:listitem="@layout/device_item">
+
     </androidx.recyclerview.widget.RecyclerView>
     
     <LinearLayout

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

+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout 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"
+    tools:context="">
+
+    <Button
+        android:id="@+id/videodetectorBackToMainActivity"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:text="Back to MainActivity">
+    </Button>
+
+    <FrameLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:id="@+id/erklaerung">
+
+        <androidx.camera.view.PreviewView
+            android:id="@+id/previewView"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"/>
+    </FrameLayout>
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:orientation="vertical"/>
+
+</androidx.constraintlayout.widget.ConstraintLayout>