Code128Writer.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 CODE128 code as a {@link BitMatrix}.
 * 
 * @author erik.barbara@gmail.com (Erik Barbara)
 */
public final class Code128Writer extends UPCEANWriter {

    public BitMatrix encode(String contents,
                            BarcodeFormat format,
                            int width,
                            int height,
                            Hashtable hints) throws WriterException {
      if (format != BarcodeFormat.CODE_128) {
        throw new IllegalArgumentException("Can only encode CODE_128, 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 codeWidth = 11 + 11 + 13; //start plus check plus stop character
      //get total code width for this barcode
      for (int i = 0; i < length; i++) {
        int[] patterns = Code128Reader.CODE_PATTERNS[contents.charAt(i) - ' '];
        for (int j = 0; j < patterns.length; j++)  {
          codeWidth += patterns[j];
        }
      }
      byte[] result = new byte[codeWidth];
      int pos = appendPattern(result, 0, Code128Reader.CODE_PATTERNS[104], 1);
      int check = 104;
      //append next character to bytematrix
      for(int i = 0; i < length; i++) {
        check += (contents.charAt(i) - ' ') * (i + 1);
        pos += appendPattern(result, pos, Code128Reader.CODE_PATTERNS[contents.charAt(i) - ' '],1);
      }
      //compute checksum and append it along with end character and quiet space
      check %= 103;
      pos += appendPattern(result,pos,Code128Reader.CODE_PATTERNS[check],1);
      pos += appendPattern(result,pos,Code128Reader.CODE_PATTERNS[106],1);

      return result;
    }

}