Unable to read FNC1 character at the first positio

2019-06-10 10:19发布

站内文章 / Android
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问题:

I have developed an application for barcode decoding in android using Google vision Library for GS1 data matrix and Zbar Library for GS1 128 barcode Unable to read FNC1 character at the first position of a GS1 128 Barcode using Zbar library.

The Zbar library is unable to display any sign of FNC1 character at the start of the Barcode!

Any Solutions. . . .

Instant Help is appreciable . . .

Below is my ZBar Scanner Activity

 @SuppressWarnings("deprecation")
 public class ZBarFirstScannerActivity extends AppCompatActivity{

//TextView tv;
ImageView iv;
LinearLayout ll;
private Camera mCamera;
private CameraPreview mPreview;
private Handler autoFocusHandler;
private ImageScanner scanner;
private boolean barcodeScanned = false;
private boolean previewing = true;
TextView tv;

static {
    System.loadLibrary("iconv");
}
static {
    System.loadLibrary("zbarjni");
}



public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);



    setContentView(R.layout.barcode_capture1d);


    tv = (TextView) findViewById(R.id.textVertical);
    tv.setRotation(90);

    initToolbar();


    autoFocusHandler = new Handler();
    mCamera = getCameraInstance();
    // Instance barcode scanner

    scanner = new ImageScanner();
    scanner.setConfig(0, Config.X_DENSITY, 1);
    scanner.setConfig(0, Config.Y_DENSITY, 1);
    scanner.setConfig(Symbol.CODE128, Config.ENABLE,1);
    scanner.setConfig(Symbol.EAN13, Config.ENABLE,1);

    mPreview = new CameraPreview(this, mCamera, previewCb, autoFocusCB);
    FrameLayout preview = (FrameLayout)findViewById(R.id.cameraPreview);
    preview.addView(mPreview);


}

private void initToolbar() {

    final Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    final ActionBar actionBar = getSupportActionBar();

    if (actionBar != null) {


        actionBar.setHomeButtonEnabled(true);
        actionBar.setHomeAsUpIndicator(ContextCompat.getDrawable(this, R.drawable.abc_ic_ab_back_mtrl_am_alpha));

        actionBar.setDisplayHomeAsUpEnabled(true);
    }
}
/** A safe way to get an instance of the Camera object. */
public static Camera getCameraInstance()
{
    Camera c = null;
    try
    {
        c = Camera.open();
    } catch (Exception e)
    {
        //nada
    }
    return c;
}

private void releaseCamera()
{
    if (mCamera != null)
    {
        previewing = false;
        mCamera.setPreviewCallback(null);
        mCamera.release();
        mCamera = null;
    }
}

PreviewCallback previewCb = new PreviewCallback()
{
    public void onPreviewFrame(byte[] data, Camera camera)
    {
        Camera.Parameters parameters = camera.getParameters();
        Size size = parameters.getPreviewSize();

        Image barcode = new Image(size.width, size.height, "Y800");
        barcode.setData(data);

        int result = scanner.scanImage(barcode);
        if (result != 0)
        {
            previewing = false;
            mCamera.setPreviewCallback(null);
            mCamera.stopPreview();
            SymbolSet syms = scanner.getResults();
            for (Symbol sym : syms)
            {
                barcodeScanned = true;

                Intent returnIntent = new Intent();
                returnIntent.putExtra("BARCODE", sym.getData());
                setResult(MainActivity.BAR_CODE_TYPE_128,returnIntent);
                releaseCamera();
                finish();
                break;
            }
        }
    }
};

// Mimic continuous auto-focusing
AutoFocusCallback autoFocusCB = new AutoFocusCallback()
{
    public void onAutoFocus(boolean success, Camera camera)
    {
        autoFocusHandler.postDelayed(doAutoFocus, 3000);
    }
};

private Runnable doAutoFocus = new Runnable()
{
    public void run()
    {
        if (previewing)
            mCamera.autoFocus(autoFocusCB);
    }
};

public void onPause() {
    super.onPause();
    releaseCamera();
}

public void onResume(){
    super.onResume();
    new ZBarFirstScannerActivity();

}

@Override
public void onBackPressed() {

    releaseCamera();

    finish();
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    int id = item.getItemId();

    if (id == android.R.id.home) {
        onBackPressed();
        return true;
    }
    return super.onOptionsItemSelected(item);
}
}

Below is my Google Scanner Activity

public final class GoogleScannerActivity extends AppCompatActivity {
private static final String TAG = "Barcode-reader";

// intent request code to handle updating play services if needed.
private static final int RC_HANDLE_GMS = 9001;

// permission request codes need to be < 256
private static final int RC_HANDLE_CAMERA_PERM = 2;

// constants used to pass extra data in the intent
public static final String AutoFocus = "AutoFocus";
public static final String UseFlash = "UseFlash";
public static final String BarcodeObject = "Barcode";
Bitmap bmp;
FileOutputStream fos = null;
private Camera c;

Switch aSwitch;
private CameraSource mCameraSource;
private CameraSourcePreview mPreview;
private GraphicOverlay<BarcodeGraphic> mGraphicOverlay;

// helper objects for detecting taps and pinches.
private ScaleGestureDetector scaleGestureDetector;
private GestureDetector gestureDetector;

/**
 * Initializes the UI and creates the detector pipeline.
 */
@Override
public void onCreate(Bundle icicle) {
    super.onCreate(icicle);
    setContentView(R.layout.barcode_capture2d);
    initToolbar();

    ActivitySource.caller = this;
    mPreview = (CameraSourcePreview) findViewById(R.id.preview);
    mGraphicOverlay = (GraphicOverlay<BarcodeGraphic>) findViewById(R.id.graphicOverlay);

    boolean autoFocus = true;
    boolean useFlash = false;

    // Check for the camera permission before accessing the camera.  If the
    // permission is not granted yet, request permission.
    int rc = ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA);
    if (rc == PackageManager.PERMISSION_GRANTED) {
        createCameraSource(autoFocus, useFlash);
    } else {
        requestCameraPermission();
    }

    gestureDetector = new GestureDetector(this, new CaptureGestureListener());
    scaleGestureDetector = new ScaleGestureDetector(this, new ScaleListener());

    /*Snackbar.make(mGraphicOverlay, "Tap to capture. Pinch/Stretch to zoom",
            Snackbar.LENGTH_LONG)
            .show();*/
}

private void initToolbar() {

    final Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    final ActionBar actionBar = getSupportActionBar();

    if (actionBar != null) {


        actionBar.setHomeButtonEnabled(true);
        actionBar.setHomeAsUpIndicator(ContextCompat.getDrawable(this, R.drawable.abc_ic_ab_back_mtrl_am_alpha));

        actionBar.setDisplayHomeAsUpEnabled(true);
    }
}

private Camera.Size getBestPreviewSize(int width, int height, Camera.Parameters parameters){
    Camera.Size bestSize = null;
    List<Camera.Size> sizeList = parameters.getSupportedPreviewSizes();

    bestSize = sizeList.get(0);

    for(int i = 1; i < sizeList.size(); i++){
        if((sizeList.get(i).width * sizeList.get(i).height) >
                (bestSize.width * bestSize.height)){
            bestSize = sizeList.get(i);
        }
    }
    return bestSize;
}
/**
 * Handles the requesting of the camera permission.  This includes
 * showing a "Snackbar" message of why the permission is needed then
 * sending the request.
 */
private void requestCameraPermission() {
    Log.w(TAG, "Camera permission is not granted. Requesting permission");

    final String[] permissions = new String[]{Manifest.permission.CAMERA};

    if (!ActivityCompat.shouldShowRequestPermissionRationale(this,
            Manifest.permission.CAMERA)) {
        ActivityCompat.requestPermissions(this, permissions, RC_HANDLE_CAMERA_PERM);
        return;
    }

    final Activity thisActivity = this;

    View.OnClickListener listener = new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            ActivityCompat.requestPermissions(thisActivity, permissions,
                    RC_HANDLE_CAMERA_PERM);
        }
    };

    Snackbar.make(mGraphicOverlay, R.string.permission_camera_rationale,
            Snackbar.LENGTH_INDEFINITE)
            .setAction(R.string.ok, listener)
            .show();
}

@Override
public boolean onTouchEvent(MotionEvent e) {
    boolean b = scaleGestureDetector.onTouchEvent(e);

    boolean c = gestureDetector.onTouchEvent(e);

    return b || c || super.onTouchEvent(e);
}

/**
 * Creates and starts the camera.  Note that this uses a higher resolution in comparison
 * to other detection examples to enable the barcode detector to detect small barcodes
 * at long distances.
 *
 * Suppressing InlinedApi since there is a check that the minimum version is met before using
 * the constant.
 */
@SuppressLint("InlinedApi")
private void createCameraSource(boolean autoFocus, boolean useFlash) {
    Context context = getApplicationContext();

    // A barcode detector is created to track barcodes.  An associated multi-processor instance
    // is set to receive the barcode detection results, track the barcodes, and maintain
    // graphics for each barcode on screen.  The factory is used by the multi-processor to
    // create a separate tracker instance for each barcode.

    BarcodeDetector barcodeDetector = new BarcodeDetector.Builder(context).setBarcodeFormats(Barcode.CODE_128 | Barcode.DATA_MATRIX | Barcode.QR_CODE).build();
    BarcodeTrackerFactory barcodeFactory = new BarcodeTrackerFactory(mGraphicOverlay);
    barcodeDetector.setProcessor(
            new MultiProcessor.Builder<>(barcodeFactory).build());

    if (!barcodeDetector.isOperational()) {
        // Note: The first time that an app using the barcode or face API is installed on a
        // device, GMS will download a native libraries to the device in order to do detection.
        // Usually this completes before the app is run for the first time.  But if that
        // download has not yet completed, then the above call will not detect any barcodes
        // and/or faces.
        //
        // isOperational() can be used to check if the required native libraries are currently
        // available.  The detectors will automatically become operational once the library
        // downloads complete on device.
        Log.w(TAG, "Detector dependencies are not yet available.");

        // Check for low storage.  If there is low storage, the native library will not be
        // downloaded, so detection will not become operational.
        IntentFilter lowstorageFilter = new IntentFilter(Intent.ACTION_DEVICE_STORAGE_LOW);
        boolean hasLowStorage = registerReceiver(null, lowstorageFilter) != null;

        if (hasLowStorage) {
            Toast.makeText(this, R.string.low_storage_error, Toast.LENGTH_LONG).show();
            Log.w(TAG, getString(R.string.low_storage_error));
        }
    }

    // Creates and starts the camera.  Note that this uses a higher resolution in comparison
    // to other detection examples to enable the barcode detector to detect small barcodes
    // at long distances.
    CameraSource.Builder builder = new CameraSource.Builder(getApplicationContext(), barcodeDetector)
            .setFacing(CameraSource.CAMERA_FACING_BACK)
            .setRequestedPreviewSize(1100, 844)
            .setRequestedFps(15.0f);
    // make sure that auto focus is an available option
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
        builder = builder.setFocusMode(
                autoFocus ? Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE : null);
    }

    mCameraSource = builder
            .setFlashMode(useFlash ? Camera.Parameters.FLASH_MODE_TORCH : null)
            .build();
}


/**
 * Restarts the camera.
 */
@Override
protected void onResume() {
    super.onResume();
    startCameraSource();
}

/**
 * Stops the camera.
 */
@Override
protected void onPause() {
    super.onPause();
    if (mPreview != null) {
        mPreview.stop();
    }
}

/**
 * Releases the resources associated with the camera source, the associated detectors, and the
 * rest of the processing pipeline.
 */
@Override
protected void onDestroy() {
    super.onDestroy();
    if (mPreview != null) {
        mPreview.release();
    }
}


@Override
public void onRequestPermissionsResult(int requestCode,
                                       @NonNull String[] permissions,
                                       @NonNull int[] grantResults) {
    if (requestCode != RC_HANDLE_CAMERA_PERM) {
        Log.d(TAG, "Got unexpected permission result: " + requestCode);
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        return;
    }

    if (grantResults.length != 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
        Log.d(TAG, "Camera permission granted - initialize the camera source");
        // we have permission, so create the camerasource
        boolean autoFocus = getIntent().getBooleanExtra(AutoFocus,false);
        boolean useFlash = getIntent().getBooleanExtra(UseFlash, false);
        createCameraSource(autoFocus, useFlash);
        return;
    }

    Log.e(TAG, "Permission not granted: results len = " + grantResults.length +
            " Result code = " + (grantResults.length > 0 ? grantResults[0] : "(empty)"));

    DialogInterface.OnClickListener listener = new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int id) {
            finish();
        }
    };

    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setTitle("Multitracker sample")
            .setMessage(R.string.no_camera_permission)
            .setPositiveButton(R.string.ok, listener)
            .show();
}

/**
 * Starts or restarts the camera source, if it exists.  If the camera source doesn't exist yet
 * (e.g., because onResume was called before the camera source was created), this will be called
 * again when the camera source is created.
 */
private void startCameraSource() throws SecurityException {
    // check that the device has play services available.
    int code = GoogleApiAvailability.getInstance().isGooglePlayServicesAvailable(
            getApplicationContext());
    if (code != ConnectionResult.SUCCESS) {
        Dialog dlg =
                GoogleApiAvailability.getInstance().getErrorDialog(this, code, RC_HANDLE_GMS);
        dlg.show();
    }

    if (mCameraSource != null) {
        try {
            mPreview.start(mCameraSource, mGraphicOverlay);
        } catch (IOException e) {
            Log.e(TAG, "Unable to start camera source.", e);
            mCameraSource.release();
            mCameraSource = null;
        }
    }
}

/**
 * onTap is called to capture the oldest barcode currently detected and
 * return it to the caller.
 *
 * @param rawX - the raw position of the tap
 * @param rawY - the raw position of the tap.
 * @return true if the activity is ending.
 */

private boolean onTap(float rawX, float rawY) {
    //TODO: use the tap position to select the barcode.
    BarcodeGraphic graphic = mGraphicOverlay.getFirstGraphic();
    Barcode barcode = null;
    if (graphic != null) {
        barcode = graphic.getBarcode();
        if (barcode != null) {
            Intent data = new Intent();
            data.putExtra(BarcodeObject, barcode);
            setResult(CommonStatusCodes.SUCCESS, data);
            finish();
        }
        else {
            Log.d(TAG, "barcode data is null");
        }
    }
    else {
        Log.d(TAG,"no barcode detected");
    }
    return barcode != null;
}

private class CaptureGestureListener extends GestureDetector.SimpleOnGestureListener {

    @Override
    public boolean onSingleTapConfirmed(MotionEvent e) {

        return onTap(e.getRawX(), e.getRawY()) || super.onSingleTapConfirmed(e);
    }
}

private class ScaleListener implements ScaleGestureDetector.OnScaleGestureListener {

    /**
     * Responds to scaling events for a gesture in progress.
     * Reported by pointer motion.
     *
     * @param detector The detector reporting the event - use this to
     *                 retrieve extended info about event state.
     * @return Whether or not the detector should consider this event
     * as handled. If an event was not handled, the detector
     * will continue to accumulate movement until an event is
     * handled. This can be useful if an application, for example,
     * only wants to update scaling factors if the change is
     * greater than 0.01.
     */
    @Override
    public boolean onScale(ScaleGestureDetector detector) {
        return false;
    }

    /**
     * Responds to the beginning of a scaling gesture. Reported by
     * new pointers going down.
     *
     * @param detector The detector reporting the event - use this to
     *                 retrieve extended info about event state.
     * @return Whether or not the detector should continue recognizing
     * this gesture. For example, if a gesture is beginning
     * with a focal point outside of a region where it makes
     * sense, onScaleBegin() may return false to ignore the
     * rest of the gesture.
     */
    @Override
    public boolean onScaleBegin(ScaleGestureDetector detector) {
        return true;
    }

    /**
     * Responds to the end of a scale gesture. Reported by existing
     * pointers going up.
     * <p/>
     * Once a scale has ended, {@link ScaleGestureDetector#getFocusX()}
     * and {@link ScaleGestureDetector#getFocusY()} will return focal point
     * of the pointers remaining on the screen.
     *
     * @param detector The detector reporting the event - use this to
     *                 retrieve extended info about event state.
     */
    @Override
    public void onScaleEnd(ScaleGestureDetector detector) {
        mCameraSource.doZoom(detector.getScaleFactor());
    }
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    int id = item.getItemId();

    if (id == android.R.id.home) {
        onBackPressed();
        return true;
    }
    return super.onOptionsItemSelected(item);
}
}

回答1:

When scanning a GS1-128 symbol the FNC1 in first position acts as a flag character to indicate the presence of GS1 Application Identifier standard format data and is intentionally omitted from the scanned data, whilst any inter-field FNC1 formatting character is transmitted at GS (ASCII 29).

The implicit, leading FNC1 can be inferred if your reader is configured to emit symbology identifiers at the start of the scanned data. In this case your GS1-128 scanned data will begin with ]C1 rather than ]C0 for generic Code 128.

Unfortunately it does not appear as though either the ZBar library or Google Vision Library can be configured to return symbology identifiers which is a disappointing limitation. Additionally the Google Vision Library erroneously returns a leading GS1 representing the FNC1 in first position.

Reading of GS1 formatted data is described in detail by this answer.

Specifically the ISO/IEC 15417 - Code 128 bar code symbology specification says:

"Any application which utilizes Code 128 symbols with FNC1 in the first or second data position should require the transmission of symbology identifiers to be enabled. When FNC1 is used in the first or second position it shall not be represented in the transmitted message, although its presence is indicated by the use of modifier values 1 or 2 respectively in the symbology identifier."



标签： android barcode-scanner zbar-sdk code128
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