How to get single preview frame in Camera2 API Android 5.0?

Question

I'm trying to get a preview frame for QR code scanning functionality using Camera2 API . In old Camera API it's as easy as:

    android.hardware.Camera mCamera;
    ...
    mCamera.setPreviewCallback(new Camera.PreviewCallback() {
        @Override
        public void onPreviewFrame(byte[] data, Camera camera) {
            // will be invoked for every preview frame in addition to displaying them on the screen             
        }
    });

However, I can't find a way to achieve that using new Camera2 API. I'd like to receive multiple frames that I can work on - the best would be to receive byte array as in old API. Any ideas how to do that?

Answer 1

A little late but better than never:

Usually a TextureView is used to display the preview of the camera. You can use TextureView.SurfaceTextureListener to get a callback every time the surface changes. TextureView does provide a method getBitmap(Bitmap) which you can use to get the preview frame in the same size as the TextureView .

You can use this Google sample as starting point. Simply update the surfaceTextureListener like shown here:

private val surfaceTextureListener = object : TextureView.SurfaceTextureListener {

    override fun onSurfaceTextureAvailable(texture: SurfaceTexture, width: Int, height: Int) {
        openCamera(width, height)
    }

    override fun onSurfaceTextureSizeChanged(texture: SurfaceTexture, width: Int, height: Int) {
        configureTransform(width, height)
    }

    override fun onSurfaceTextureDestroyed(texture: SurfaceTexture) = true

    override fun onSurfaceTextureUpdated(texture: SurfaceTexture) {
        // Start changes
        // Get the bitmap
        val frame = Bitmap.createBitmap(textureView.width, textureView.height, Bitmap.Config.ARGB_8888)
        textureView.getBitmap(frame)

        // Do whatever you like with the frame
        frameProcessor?.processFrame(frame)
        // End changes
    }

}

Answer 2

Use Below code to do so.

 CameraManager manager = (CameraManager) context.getSystemService(Context.CAMERA_SERVICE);
        try {
            CameraCharacteristics characteristics = manager.getCameraCharacteristics(cameraDevice.getId());
            Size[] jpegSizes = null;
            if (characteristics != null) {
                jpegSizes = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP).getOutputSizes(ImageFormat.JPEG);
            }
            int width = 480;//480x320
            int height = 320;
            if (jpegSizes != null && 0 < jpegSizes.length) {
                width = jpegSizes[0].getWidth();
                height = jpegSizes[0].getHeight();
            }
            ImageReader reader = ImageReader.newInstance(width, height, ImageFormat.JPEG, 1);
            List<Surface> outputSurfaces = new ArrayList<Surface>(2);
            outputSurfaces.add(reader.getSurface());
            outputSurfaces.add(new Surface(textureView.getSurfaceTexture()));
            final CaptureRequest.Builder captureBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
            captureBuilder.addTarget(reader.getSurface());
            captureBuilder.set(CaptureRequest.CONTROL_MODE, CameraMetadata.CONTROL_MODE_AUTO);
            // Orientation
            int rotation = ((Activity) context).getWindowManager().getDefaultDisplay().getRotation();
            captureBuilder.set(CaptureRequest.JPEG_ORIENTATION, ORIENTATIONS.get(rotation));
            final File file = getFileDir();
            ImageReader.OnImageAvailableListener readerListener = new ImageReader.OnImageAvailableListener() {
                @Override
                public void onImageAvailable(ImageReader reader) {
                    Image image = null;
                    try {
                        image = reader.acquireLatestImage();
                        ByteBuffer buffer = image.getPlanes()[0].getBuffer();
                        byte[] bytes = new byte[buffer.capacity()];
                        buffer.get(bytes);
                        save(bytes);
                    } catch (FileNotFoundException e) {
                        e.printStackTrace();
                    } catch (IOException e) {
                        e.printStackTrace();
                    } finally {
                        if (image != null) {
                            image.close();
                        }
                    }
                }

                private void save(byte[] bytes) throws IOException {
                    OutputStream output = null;
                    try {
                        output = new FileOutputStream(file);
                        output.write(bytes);
                    } finally {
                        if (null != output) {
                            output.close();
                        }
                    }
                }
            };
            reader.setOnImageAvailableListener(readerListener, mBackgroundHandler);
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }