Code39Writer.java

/*
 * Copyright 2010 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.zxing.oned;

import java.util.Hashtable;
import com.google.zxing.BarcodeFormat;
import com.google.zxing.WriterException;
import com.google.zxing.common.BitMatrix;

/**
 * This object renders a CODE39 code as a {@link BitMatrix}.
 * 
 * @author erik.barbara@gmail.com (Erik Barbara)
 */
public final class Code39Writer extends UPCEANWriter {

  public BitMatrix encode(String contents,
                          BarcodeFormat format,
                          int width,
                          int height,
                          Hashtable hints) throws WriterException {
    if (format != BarcodeFormat.CODE_39) {
      throw new IllegalArgumentException("Can only encode CODE_39, but got " + format);
    }
    return super.encode(contents, format, width, height, hints);
  }

  public byte[] encode(String contents) {
    int length = contents.length();
    if (length > 80) {
      throw new IllegalArgumentException(
          "Requested contents should be less than 80 digits long, but got " + length);
    }

    int[] widths = new int[9];
    int codeWidth = 24 + 1 + length;
    for (int i = 0; i < length; i++) {
      int indexInString = Code39Reader.ALPHABET_STRING.indexOf(contents.charAt(i));
      toIntArray(Code39Reader.CHARACTER_ENCODINGS[indexInString], widths);
      for(int j = 0; j < widths.length; j++) {
        codeWidth += widths[j];
      }
    }
    byte[] result = new byte[codeWidth];
    toIntArray(Code39Reader.CHARACTER_ENCODINGS[39], widths);
    int pos = appendPattern(result, 0, widths, 1);
    int[] narrowWhite = {1};
    pos += appendPattern(result, pos, narrowWhite, 0);
    //append next character to bytematrix
    for(int i = length-1; i >= 0; i--) {
      int indexInString = Code39Reader.ALPHABET_STRING.indexOf(contents.charAt(i));
      toIntArray(Code39Reader.CHARACTER_ENCODINGS[indexInString], widths);
      pos += appendPattern(result, pos, widths, 1);
      pos += appendPattern(result, pos, narrowWhite, 0);
    }
    toIntArray(Code39Reader.CHARACTER_ENCODINGS[39], widths);
    pos += appendPattern(result, pos, widths, 1);
    return result;
  }

  private static void toIntArray(int a, int[] toReturn) {
    for (int i = 0; i < 9; i++) {
      int temp = a & (1 << i);
      toReturn[i] = (temp == 0) ? 1 : 2;
    }
  }

}