Android Camera Preview Fragment

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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=".MainActivity">

    <FrameLayout
        android:id="@+id/main_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

CameraPreviewFragment.java

import android.content.Context;
import android.graphics.ImageFormat;
import android.hardware.Camera;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.Display;
import android.view.LayoutInflater;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;

import java.util.List;

import static java.lang.Math.ceil;


public class CameraPreviewFragment extends Fragment implements SurfaceHolder.Callback, Camera.PreviewCallback {
    private Camera mCamera;
    private Camera.Size mPreviewSize;
    private byte[] mPreviewBuffer;

    private Context context;
    private SurfaceHolder holder;

    private boolean isPreviewRunning = false;

    public CameraPreviewFragment() {
    }

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_camera_preview, container, false);

        SurfaceView surfaceView = (SurfaceView) rootView.findViewById(R.id.preview_surface);
        holder = surfaceView.getHolder();
        holder.addCallback(this);
        holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

        return rootView;
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        this.context = context;
    }

    @Override
    public void onPreviewFrame(byte[] data, Camera camera) {
        camera.addCallbackBuffer(mPreviewBuffer);
        // TODO: Implement this: [data ==> Frame format YV12]
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        try {
            startCamera(holder);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        setupCameraParameters(context, mCamera);
        mCamera.startPreview();
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        stopCamera();
    }

    private void startCamera(SurfaceHolder surfaceHolder) throws Exception {
        if (isPreviewRunning)
            stopCamera();

        mCamera = Camera.open();

        mPreviewSize = setupCameraParameters(context, mCamera);
        mPreviewBuffer = new byte[calculateBufferSize(mPreviewSize.width, mPreviewSize.height)];

        surfaceHolder.setFixedSize(mPreviewSize.width, mPreviewSize.height);

        mCamera.setPreviewDisplay(surfaceHolder);
        mCamera.addCallbackBuffer(mPreviewBuffer);
        mCamera.setPreviewCallbackWithBuffer(this);

        mCamera.startPreview();

        isPreviewRunning = true;
    }

    private void stopCamera() {
        if (mCamera != null) {
            mCamera.setPreviewCallback(null);
            mCamera.stopPreview();
            mCamera.release();
            mCamera = null;
        }

        isPreviewRunning = false;
    }

    private static Camera.Size setupCameraParameters(Context context, Camera camera) {
        Camera.Parameters parameters = camera.getParameters();
        List<Camera.Size> previewSizes = parameters.getSupportedPreviewSizes();
        Camera.Size previewSize = previewSizes.get(0); //Max preview size

        parameters.setPreviewFormat(ImageFormat.YV12);
        parameters.setFlashMode(Camera.Parameters.FLASH_MODE_AUTO);
        parameters.setPreviewSize(previewSize.width, previewSize.height);
        parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO);

        camera.setParameters(parameters);

        Display display = ((WindowManager) context.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
        if (display.getRotation() == Surface.ROTATION_0) {
            camera.setDisplayOrientation(90);
        } else if (display.getRotation() == Surface.ROTATION_270) {
            camera.setDisplayOrientation(180);
        }

        return previewSize;
    }

    private static int calculateBufferSize(int w, int h) {
        int yStride = (int) ceil(w / 16.0) * 16;
        int uvStride = (int) ceil((yStride / 2.0) / 16.0) * 16;
        int ySize = yStride * h;
        int uvSize = uvStride * h / 2;

        return ySize + uvSize * 2;
    }
}

fragment_camera_preview.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".CameraPreviewFragment">

    <SurfaceView
        android:id="@+id/preview_surface"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_gravity="center" />

</FrameLayout>

MainActivity.java

import android.Manifest;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.content.pm.PackageManager;
import android.os.Build;
import android.support.annotation.NonNull;
import android.support.v4.app.DialogFragment;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

    public static final String[] PERMISSION_STRINGS = new String[]{Manifest.permission.CAMERA, Manifest.permission.RECORD_AUDIO};
    public static final int REQUEST_CAMERA_PERMISSION = 123;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        setContainer(new CameraPreviewFragment());
    }

    private void setContainer(Fragment fragment) {
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED ||
                ContextCompat.checkSelfPermission(this, Manifest.permission.RECORD_AUDIO) != PackageManager.PERMISSION_GRANTED) {
            requestCameraPermission();
            return;
        }

        FragmentManager fragmentManager = getSupportFragmentManager();
        fragmentManager.beginTransaction().replace(R.id.main_container, fragment).commitNow();
    }

    private void requestCameraPermission() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)
            if (shouldShowRequestPermissionRationale(Manifest.permission.CAMERA)) {
                new ConfirmationDialog().show(getSupportFragmentManager(), "Camera Permission");
            } else {
                requestPermissions(PERMISSION_STRINGS, REQUEST_CAMERA_PERMISSION);
            }
    }

    public static class ConfirmationDialog extends DialogFragment {

        @NonNull
        @Override
        public Dialog onCreateDialog(Bundle savedInstanceState) {
            final Fragment parent = getParentFragment();
            return new AlertDialog.Builder(getActivity())
                    .setMessage("Need permissions")
                    .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            parent.requestPermissions(PERMISSION_STRINGS, REQUEST_CAMERA_PERMISSION);
                        }
                    })
                    .setNegativeButton(android.R.string.cancel,
                            new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialog, int which) {
                                    Activity activity = parent.getActivity();
                                    if (activity != null) {
                                        activity.finish();
                                    }
                                }
                            })
                    .create();
        }
    }
}