how to capture an image in background without using the camera application

Question

I have an android app which consists of a Button.
When you click on Button, an image should be captured from the camera without opening the camera application (the image

Answer 1

You have to create a fake Surface view that doesn't appears to the users and then you can achieve by the following code

public class MainActivity extends Activity {
    public static final int DONE = 1;
    public static final int NEXT = 2;
    public static final int PERIOD = 1;
    private Camera camera;
    private int cameraId = 0;
    private ImageView display;
    private Timer timer;
    SurfaceHolder previewHolder;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        display = (ImageView) findViewById(R.id.imageView1);
        // do we have a camera?
        if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)) 
        {
            Toast.makeText(this, "No camera on this device", Toast.LENGTH_LONG)
                    .show();
        } 
        else 
        {
            cameraId = findFrontFacingCamera();
            if (cameraId < 0)
            {
                Toast.makeText(this, "No front facing camera found.",
                        Toast.LENGTH_LONG).show();
            }
            else
            {
                safeCameraOpen(cameraId);
            }
        }
        // THIS IS JUST A FAKE SURFACE TO TRICK THE CAMERA PREVIEW
        // http://stackoverflow.com/questions/17859777/how-to-take-pictures-in-android-
        // application-without-the-user-interface


        SurfaceView dummy = new SurfaceView(this);
        previewHolder = dummy.getHolder();

        previewHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
        try {
            camera.setPreviewDisplay(previewHolder);
        } catch (IOException e1) {
            e1.printStackTrace();
        }
        /*SurfaceView view = new SurfaceView(this);
        try {
            //  camera.setPreviewDisplay(view.getHolder());
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }*/

        Camera.Parameters params = camera.getParameters();
        params.setJpegQuality(100);
        camera.setParameters(params);
        // We need something to trigger periodically the capture of a
        // picture to be processed
        timer = new Timer(getApplicationContext(), threadHandler);
        timer.execute();
    }

    // thread Handler //
    private Handler threadHandler = new Handler() {
        public void handleMessage(android.os.Message msg) {
            switch (msg.what) {
            case DONE:
                camera.startPreview();
                previewHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
                try {
                    camera.setPreviewDisplay(previewHolder);
                } catch (IOException e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                }


                camera.takePicture(null, null, mCall);
                break;
            case NEXT:
                timer = new Timer(getApplicationContext(), threadHandler);
                timer.execute();
                break;
            }
        }
    };
    Camera.PictureCallback mCall = new Camera.PictureCallback() {
        public void onPictureTaken(byte[] data, Camera camera) {
            // decode the data obtained by the camera into a Bitmap
            // display.setImageBitmap(photo);
            Bitmap bitmapPicture = BitmapFactory.decodeByteArray(data, 0,
                    data.length);
            display.setImageBitmap(bitmapPicture);
            Message.obtain(threadHandler, MainActivity.NEXT, "").sendToTarget();
            // Log.v("MyActivity","Length: "+data.length);
        }
    };

    private int findFrontFacingCamera() {
        int cameraId = -1;
        // Search for the front facing camera
        int numberOfCameras = Camera.getNumberOfCameras();
        for (int i = 0; i < numberOfCameras; i++) {
            CameraInfo info = new CameraInfo();
            Camera.getCameraInfo(i, info);
            if (info.facing == CameraInfo.CAMERA_FACING_FRONT) {
                Log.v("MyActivity", "Camera found");
                cameraId = i;
                break;
            }
        }
        return cameraId;
    }

    @Override
    protected void onPause() {
        if (timer != null) {
            timer.cancel(true);
        }
        releaseCamera();
        super.onPause();
    }

    // I think Android Documentation recommends doing this in a separate
    // task to avoid blocking main UI
    private boolean safeCameraOpen(int id) {
        boolean qOpened = false;
        try {
            releaseCamera();
            camera = Camera.open(id);
            qOpened = (camera != null);
        } catch (Exception e) {
            Log.e(getString(R.string.app_name), "failed to open Camera");
            e.printStackTrace();
        }
        return qOpened;
    }

    private void releaseCamera() {
        if (camera != null) {
            camera.stopPreview();
            camera.release();
            camera = null;
        }
    }
}