2 * Copyright 2008 Google Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 package com.google.zxing.oned;
19 import com.google.zxing.ReaderException;
20 import com.google.zxing.common.BitArray;
23 * <p>Implements decoding of the UPC-A format.</p>
25 * @author dswitkin@google.com (Daniel Switkin)
26 * @author srowen@google.com (Sean Owen)
28 public final class UPCAReader extends AbstractUPCEANReader {
30 protected int decodeMiddle(BitArray row, int[] startRange, StringBuffer resultString) throws ReaderException {
31 int middleStart = decodeDigits(row, startRange[1], resultString);
32 int[] middleRange = findGuardPattern(row, middleStart, true, MIDDLE_PATTERN);
33 return decodeDigits(row, middleRange[1], resultString);
37 * @param row row of black/white values to decode
38 * @param start horizontal offset from which decoding starts
39 * @param result {@link StringBuffer} to append decoded digits to
40 * @return horizontal offset of first pixel after the six decoded digits
41 * @throws ReaderException if six digits could not be decoded from the row
43 private static int decodeDigits(BitArray row, int start, StringBuffer result) throws ReaderException {
44 int[] counters = new int[4];
45 int end = row.getSize();
46 int rowOffset = start;
47 for (int x = 0; x < 6 && rowOffset < end; x++) {
48 int bestMatch = decodeDigit(row, counters, rowOffset, L_PATTERNS);
49 result.append((char) ('0' + bestMatch));
50 for (int i = 0; i < counters.length; i++) {
51 rowOffset += counters[i];