无法使用 Firebase ML Kit 读取更多 30 个字符的条形码

Question

I am trying to read barcode128 and QR code using firebase ML kit standalone API. I am able to read both the barcode and QR code. But if my barcode length exceeds more than 30-35 chars then the barcode scanner not able to detect the barcode. I am able to detect QR code but not a barcode.

Here is my code :

// Use this dependency to use the dynamically downloaded model in Google Play Services
implementation 'com.google.android.gms:play-services-mlkit-barcode-scanning:16.1.2'
implementation 'com.google.mlkit:barcode-scanning:16.0.3'  

ScannerActivity :

    executor = Executors.newSingleThreadExecutor();
    PreviewView previewView = findViewById(R.id.cameraPreviewView);
    cameraProviderFuture = ProcessCameraProvider.getInstance(this);
    cameraProviderFuture.addListener(() -> {
        try {
            ProcessCameraProvider cameraProvider = cameraProviderFuture.get();
            Preview preview = new Preview.Builder().build();
            CameraSelector cameraSelector = new CameraSelector.Builder()
                    .requireLensFacing(CameraSelector.LENS_FACING_BACK)
                    .build();

            preview.setSurfaceProvider(
                    previewView.createSurfaceProvider());

            ImageCapture imageCapture = new ImageCapture.Builder()
                    .setCaptureMode(ImageCapture.CAPTURE_MODE_MINIMIZE_LATENCY)
                    .build();

            ImageAnalysis imageAnalysis =
                    new ImageAnalysis.Builder()
                            .build();

            imageAnalysis.setAnalyzer(ContextCompat.getMainExecutor(this), new ImageAnalysis.Analyzer() {

                private BarcodeScanner scanner = buildBarCodeScanner();

                @Override
                public void analyze(ImageProxy imageProxy) {
                    @SuppressLint("UnsafeExperimentalUsageError") Image mediaImage = imageProxy.getImage();
                    if (mediaImage != null) {
                        InputImage image =
                                InputImage.fromMediaImage(mediaImage, imageProxy.getImageInfo().getRotationDegrees());
                        Task<List<Barcode>> result = scanner.process(image);

                        result.addOnSuccessListener(new OnSuccessListener<List<Barcode>>() {
                            @Override
                            public void onSuccess(List<Barcode> barcodes) {
                                processBarCodes(barcodes);
                            }
                        }).addOnFailureListener(new OnFailureListener() {
                            @Override
                            public void onFailure(@NonNull Exception e) {
                                // Task failed with an exception
                                Log.i("CameraXApp3", "scanner task failed. Error:" + e);

                            }
                        }).addOnCompleteListener(new OnCompleteListener<List<Barcode>>() {
                            @Override
                            public void onComplete(@NonNull Task<List<Barcode>> task) {
                                mediaImage.close();
                                imageProxy.close();
                            }
                        });
                    }
                }

                private BarcodeScanner buildBarCodeScanner() {
                    BarcodeScannerOptions options =
                            new BarcodeScannerOptions.Builder()
                                    .setBarcodeFormats(
                                            Barcode.FORMAT_QR_CODE,
                                            Barcode.FORMAT_CODE_128)
                                    .build();
                    return BarcodeScanning.getClient(options);
                }

                private void processBarCodes(List<Barcode> barcodes) {
                    for (Barcode barcode : barcodes) {
                        confirmCounter++;
                        if (confirmCounter >= CONFIRM_VALUE) {
                            confirmCounter = 0;
                            final Rect boundingBox = barcode.getBoundingBox();
                            final Point[] cornerPoints = barcode.getCornerPoints();
                            String rawValue = barcode.getRawValue();
                            int valueType = barcode.getValueType();
                            if (valueType == Barcode.TYPE_TEXT) {
                                toast(MainActivity.this, "Received Message:" + rawValue);
                            }
                        }
                    }
                }

                public void toast(final Context context, final String text) {
                    Handler handler = new Handler(Looper.getMainLooper());
                    handler.post(() -> Toast.makeText(context, text, Toast.LENGTH_LONG).show());
                }
            });

            Camera camera = cameraProvider.bindToLifecycle(
                    ((LifecycleOwner) this),
                    cameraSelector,
                    preview,
                    imageCapture,
                    imageAnalysis);

        } catch (InterruptedException | ExecutionException e) {

        }
    }, ContextCompat.getMainExecutor(this));

I am also trying to add more focus by clicking but no luck :

 previewView.setOnTouchListener((v, event) -> {
                v.performClick();
                if (event.getAction() == MotionEvent.ACTION_UP) {
                    final MeteringPointFactory factory = previewView.getMeteringPointFactory();
                    final MeteringPoint point = factory.createPoint(event.getX(), event.getY());
                    final FocusMeteringAction action = new FocusMeteringAction.Builder(point).build();
                    camera.getCameraControl().startFocusAndMetering(action);
                    return false;
                }
                return true;
            });

Answer 1

ML Kit barcode requires thinnest bar to be minimum 3 pixels wide. Code-128 each character is 11 bar wide, so in terms of pixels it is 33 pixels wide and for 35 such character it requires 1155 pixels in terms of width. So barcode needs to be at least 1155 pixels wide in the image. This rough calculation ignores + + characters.

You may need to increase the image resolution for this format.