Question

I can successfully create QR Code PNG images with ZXing but there is no easy way to get the output as SVG or EPS.

How can I create a vector image from the BitMatrix object that is created by the QRCodeWriter?

Answer 1

The easiest way I found was to create a PDF with iText and then convert the resulting PDF to EPS or SVG. Here is the code to create the PDF:

   @Test
   public void testQRtoPDF() throws WriterException, FileNotFoundException, DocumentException, UnsupportedEncodingException {
      final int s = 600;
      int r = 1;

      Charset charset = Charset.forName( "UTF-8" );
      CharsetEncoder encoder = charset.newEncoder();
      byte[] b = null;
      try {
         // Convert a string to UTF-8 bytes in a ByteBuffer
         ByteBuffer bbuf = encoder.encode( CharBuffer.wrap(
                     "1éöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùò1" +
                                 "2éöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùò2" +
                                 "3éöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùò3" +
                                 "4éöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùò4" +
                                 "5éöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùò5" +
                                 "6éöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùòïëéöàäèüùò6" ) );
         b = bbuf.array();
      } catch ( CharacterCodingException e ) {
         System.out.println( e.getMessage() );
      }

      String content = new String( b, "UTF-8" );
      QRCodeWriter qrCodeWriter = new QRCodeWriter();
      Hashtable<EncodeHintType, String> hints = new Hashtable<EncodeHintType, String>( 2 );
      hints.put( EncodeHintType.CHARACTER_SET, "UTF-8" );
      BitMatrix qrCode = qrCodeWriter.encode( content, BarcodeFormat.QR_CODE, s, s, hints );

      Document doc = new Document( new Rectangle( s, s ) );
      PdfWriter pdfWriter = PdfWriter.getInstance( doc, new FileOutputStream( "qr-code.pdf" ) );
      doc.open();
      PdfContentByte contentByte = pdfWriter.getDirectContent();
      contentByte.setColorFill( BaseColor.BLACK );

      boolean d = false;
      for ( int x = 0; x < qrCode.getWidth(); x += r ) {
         for ( int y = 0; y < qrCode.getHeight(); y += r ) {
            if ( qrCode.get( x, y ) ) {
               contentByte.rectangle( x, s - y, r, r );
               contentByte.fill();
               contentByte.stroke();
            }
         }
      }

      doc.close();
   }

I then use image magic for the conversion. Like so:

convert qr-code.pdf qr-code.eps

the same can NOT be done for svg

convert qr-code.pdf qr-code.svg

this does not work

I tested this code with some long content and it worked with up to 600 characters. This is probably down to the precision of either camera on the phone or screen.

I hope this helps someone