How to decode a barcode from camera preview using zxing library in android?

Question

I want to implement standalone scanner in my android application.I'm using zxing's core.jar library in my project.

I need to decode a barcode from camera preview.But i don't know how to implement it.Because there is no official documentation.

Can you provide me a simple example on followings things? 1.Initialize the camera and getting preview. 2.Decode the barcode from preview.

or

Is there any example project to do this?

Answer 1

Take a look at my simple implementation: https://github.com/piobab/code-scanner

I use ZBar library but if you want you can change ZBarScannerView.java implementation to ZXingScannerView (the rest of the code is ok):

public class ZXingScannerView extends ScannerView {
public interface ResultHandler {
    public void handleResult(Result result);
}

private MultiFormatReader mMultiFormatReader;
private ResultHandler mResultHandler;

public ZXingScannerView(Context context) {
    super(context);
    setupScanner(null);
}

public ZXingScannerView(Context context, AttributeSet attributeSet) {
    super(context, attributeSet);
    setupScanner(null);
}

/**
 * Specify recognized codes types.
 * @param codeTypes list of codes types from ZXing library
 */
public void setCodeTypes(List<com.google.zxing.BarcodeFormat> codeTypes) {
    setupScanner(codeTypes);
}

private void setupScanner(List<com.google.zxing.BarcodeFormat> symbols) {
    Map<DecodeHintType,Object> hints = new EnumMap<DecodeHintType,Object>(DecodeHintType.class);
    // Add specific formats
    hints.put(DecodeHintType.POSSIBLE_FORMATS, symbols);
    mMultiFormatReader = new MultiFormatReader();
    mMultiFormatReader.setHints(hints);
}

/**
 * Register callback in order to receive data from scanner.
 * @param resultHandler
 */
public void setResultHandler(ResultHandler resultHandler) {
    mResultHandler = resultHandler;
}

@Override
public void onPreviewFrame(byte[] data, Camera camera) {
    Camera.Parameters parameters = camera.getParameters();
    Camera.Size size = parameters.getPreviewSize();
    int width = size.width;
    int height = size.height;

    Result rawResult = null;
    PlanarYUVLuminanceSource source = buildLuminanceSource(data, width, height);

    if(source != null) {
        BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));
        try {
            rawResult = mMultiFormatReader.decodeWithState(bitmap);
        } catch (ReaderException re) {

        } catch (NullPointerException npe) {

        } catch (ArrayIndexOutOfBoundsException aoe) {

        } finally {
            mMultiFormatReader.reset();
        }
    }

    if (rawResult != null) {
        stopCamera();
        if(mResultHandler != null) {
            mResultHandler.handleResult(rawResult);
        }
    } else {
        camera.setOneShotPreviewCallback(this);
    }
}

public PlanarYUVLuminanceSource buildLuminanceSource(byte[] data, int width, int height) {
    Rect rect = getFramingRectInPreview(width, height);
    if (rect == null) {
        return null;
    }
    // Go ahead and assume it's YUV rather than die.
    PlanarYUVLuminanceSource source = null;

    try {
        source = new PlanarYUVLuminanceSource(data, width, height, rect.left, rect.top,
                rect.width(), rect.height(), false);
    } catch(Exception e) {
    }

    return source;
}

}

If you use gradle add 'com.google.zxing:core:2.2' to your dependencies.