Convert Unicode to Image and Compress for ZPL - Zebra (^GF for ZPL)

textToZ64CompressedImage.java

/**

This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
   ________________________________________________________________________ 
* The purpose of this is to take some unicode text
* and create an image out of it so that we can
* print it on an old Zebra label printer that
* doesn't have enough memory for unicode fonts.
* 
* The string that is returned can be embedded directly into
* a ZPL script and sent to the printer.
* 
* After many searches and scouring of manuals,
* and with the help of others, I finally got this working well.
*
* Hopefully this can help someone else and that they
* find it faster than it took me to piece it together.
*
* Obviously I'm leaving out all the imports and stuff.
*/

public String textToZ64CompressedImage(String input){            
            BufferedImage img = new BufferedImage(1, 1, BufferedImage.TYPE_BYTE_BINARY);

            Graphics2D g2d = img.createGraphics();
            Font font = new Font(g2d.getFont().getName(), Font.PLAIN, 28);
            g2d.setFont(font);

            FontMetrics fm = g2d.getFontMetrics();
            int width = fm.stringWidth(input);
            int height = fm.getHeight();

            img = new BufferedImage(width, height, BufferedImage.TYPE_BYTE_BINARY);
            g2d = img.createGraphics();
            g2d.setColor(Color.BLACK);
            g2d.fillRect(0, 0, width, height);
            g2d.setColor(Color.WHITE);
            g2d.setFont(font);
            g2d.drawString(input, 0, fm.getAscent());
            g2d.dispose();

            // LZ77 compression
            ByteArrayOutputStream compressedImage = new ByteArrayOutputStream();
            DataBufferByte dataBufferByte = (DataBufferByte)img.getRaster().getDataBuffer();
            DeflaterOutputStream deflaterOutputStream = new DeflaterOutputStream(compressedImage);
            try
            {
                deflaterOutputStream.write(dataBufferByte.getData(), 0, dataBufferByte.getData().length);
                deflaterOutputStream.finish();
            }
            catch (IOException e)
            {
                LOG.debug("Couldn't compress image for printing.");
                return "I/O error";
            }

            // without compression
//          byte[] encodedBytesImage = Base64.getMimeEncoder().encode(dataBufferByte.getData());
            byte[] encodedBytesImage = Base64.getMimeEncoder().encode(compressedImage.toByteArray());
            String crcString = getCRCHexString(encodedBytesImage);
            String bytesPerRow = String.valueOf(dataBufferByte.getData().length / height);
            int binaryByteCount = (width * height) / 8;
            String encodedAscii = "^GFA," + binaryByteCount + "," + binaryByteCount + "," + bytesPerRow + ",:Z64:" + new String(encodedBytesImage, Charsets.US_ASCII) + ":" + crcString;

            try
            {
                compressedImage.close();
            }
            catch (IOException e)
            {
                LOG.error("Couldn't close image output stream.");
            }

            return encodedAscii;
}

/**
     *  Reads in a sequence of bytes and prints out its 16 bit
     *  Cylcic Redundancy Check (CRC-CCIIT 0xFFFF).
     *
     *  1 + x + x^5 + x^12 + x^16 is irreducible polynomial.
     *
     */

    private static String getCRCHexString(byte[] bytes)
    {
        int crc = 0x0000;           // initial value
        int polynomial = 0x1021;    // 0001 0000 0010 0001  (0, 5, 12)
        for (byte b : bytes)
        {
            for (int i = 0; i < 8; i++)
            {
                boolean bit = ((b >> (7 - i) & 1) == 1);
                boolean c15 = ((crc >> 15 & 1) == 1);
                crc <<= 1;

                if (c15 ^ bit)
                {
                    crc ^= polynomial;
                }
            }
        }

        crc &= 0xffff;
        return Integer.toHexString(crc);
   }

OK, thanks