QRCodeEncoderDecoder.java

package org.multibit.mbm.core.qrcode;

import com.google.zxing.BinaryBitmap;
import com.google.zxing.LuminanceSource;
import com.google.zxing.ReaderException;
import com.google.zxing.Result;
import com.google.zxing.client.j2se.BufferedImageLuminanceSource;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.common.HybridBinarizer;
import com.google.zxing.qrcode.QRCodeReader;
import com.google.zxing.qrcode.QRCodeWriter;
import com.yammer.dropwizard.logging.Log;


import java.awt.image.BufferedImage;
import java.util.Hashtable;

/**
 * <p>Utility class to encode and decode QR codes. Used by SwatchGenerator</p>
 * <ul>
 * <li>Create a QR code from a bitcoin uri</li>
 * <li>Decode a QR code to a bitcoin uri</li>
 * </p>
 *
 * @since 0.0.1
 */
public class QRCodeEncoderDecoder {
  private static final Log LOG = Log.forClass(QRCodeEncoderDecoder.class);

  private int width;
  private int height;

  public QRCodeEncoderDecoder(int width, int height) {
    this.width = width;
    this.height = height;
  }

  public BufferedImage encode(String data) {
    // get a byte matrix for the data
    BitMatrix matrix;
    com.google.zxing.Writer writer = new QRCodeWriter();
    try {
      matrix = writer.encode(data, com.google.zxing.BarcodeFormat.QR_CODE, width, height);
    } catch (com.google.zxing.WriterException e) {
      // exit the method
      return null;
    }

    // generate an image from the byte matrix
    int width = matrix.getWidth();
    int height = matrix.getHeight();

    // create buffered image to draw to
    BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

    // iterate through the matrix and draw the pixels to the image
    for (int y = 0; y < height; y++) {
      for (int x = 0; x < width; x++) {
        boolean imageValue = matrix.get(x, y);
        image.setRGB(x, y, (imageValue ? 0 : 0xFFFFFF));
      }
    }

    // //write the image to the output stream
    // ImageIO.write(image, "png", outputStream);

    return image;
  }

  public String decode(BufferedImage image) {

    // convert the image to a binary bitmap source
    LuminanceSource source = new BufferedImageLuminanceSource(image);
    BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));

    // decode the barcode
    QRCodeReader reader = new QRCodeReader();

    try {
      @SuppressWarnings("rawtypes")
      Hashtable hints = new Hashtable();
      Result result = reader.decode(bitmap, hints);
      LOG.info("Decoded image successfully, result was : '" + result.getText() + "'");

      return result.getText();
    } catch (ReaderException e) {
      // the data is improperly formatted
      LOG.debug(e.getMessage());
      LOG.error("Error while decoding image", e);
    }

    return "";
  }
}