Get raw bytes from QR Code with zxing lib (or convert from BitMatrix)

I need to get byte[] array from a QR Code encoded into a BitMatrix. Here's my code:

// imports
import com.google.zxing.BarcodeFormat;
import com.google.zxing.ChecksumException;
import com.google.zxing.FormatException;
import com.google.zxing.Writer;
import com.google.zxing.WriterException;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.common.DecoderResult;
import com.google.zxing.qrcode.QRCodeWriter;
import com.google.zxing.datamatrix.decoder.Decoder;

The function to generate QR Code:

public byte[] createQRCode() {
    String qrCodeData = "Hello world";
    String charset = "UTF-8";
    BitMatrix matrix = null;
    Writer writer = new QRCodeWriter();

    try {
        matrix = writer.encode(new String(qrCodeData.getBytes(charset), charset), BarcodeFormat.QR_CODE, qrCodeheight, qrCodewidth);
    } catch (UnsupportedEncodingException e) {
        return;
    }
    catch (WriterException e) {
        return;
    }

    DecoderResult decoderResult = null;
    try {
        decoderResult = new Decoder().decode(matrix);
    } catch (ChecksumException e) {
        return;
    } catch (FormatException e) {
        // Always this exception is throwed
    }

    byte[] cmd = decoderResult.getRawBytes();`
    return cmd;
}

Always the execution stop on FormatException, even the parameter on Decode().decode() requested is BitMatrix.

Someone can tell me what's wrong or show me other way to get the QR Code byte array?

Solution 1:

I found the solution using a library to decode Bitmap: https://github.com/imrankst1221/Thermal-Printer-in-Android

Function to encode String into QR Code Bitmap:

public Bitmap encodeToQrCode(String text, int width, int height){
    QRCodeWriter writer = new QRCodeWriter();
    BitMatrix matrix = null;
    try {
        matrix = writer.encode(text, BarcodeFormat.QR_CODE, width, height);
    } catch (WriterException ex) {
        //
    }
    Bitmap bmp = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);
    for (int x = 0; x < width; x++){
        for (int y = 0; y < height; y++){
            bmp.setPixel(x, y, matrix.get(x,y) ? Color.BLACK : Color.WHITE);
        }
    }
    return bmp;
}

Then I decode bitmap to bytes using Utils from the found library:

try {
    Bitmap bmp = encodeToQrCode("Hello world", 200, 200);
    if (bmp != null ) {
        byte[] command = Utils.decodeBitmap(bmp);
        BluetoothPrintDriver.BT_Write(command);
    } else {
        Log.e("Print Photo error", "file not found");
    }
} catch (Exception e) {
    e.printStackTrace();
    Log.e("PrintTools", "file not found");
}