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.Result;
21 import com.google.zxing.ResultPoint;
22 import com.google.zxing.common.BitArray;
23 import com.google.zxing.common.GenericResultPoint;
26 * <p>Decodes Code 39 barcodes. This does not supported "Full ASCII Code 39" yet.</p>
28 * @author srowen@google.com (Sean Owen)
30 public final class Code39Reader extends AbstractOneDReader {
32 private static final String ALPHABET_STRING = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ-. *$/+%";
33 private static final char[] ALPHABET = ALPHABET_STRING.toCharArray();
36 * These represent the encodings of characters, as patterns of wide and narrow bars.
37 * The 9 least-significant bits of each int correspond to the pattern of wide and narrow,
38 * with 1s representing "wide" and 0s representing narrow.
40 private static final int[] CHARACTER_ENCODINGS = {
41 0x038, 0x121, 0x061, 0x160, 0x031, 0x130, 0x070, 0x025, 0x124, 0x064, // 0-9
42 0x109, 0x049, 0x148, 0x019, 0x118, 0x058, 0x00D, 0x10C, 0x04C, 0x01C, // A-J
43 0x103, 0x043, 0x142, 0x013, 0x112, 0x052, 0x007, 0x106, 0x046, 0x016, // K-T
44 0x181, 0x0C1, 0x1C0, 0x091, 0x190, 0x0D0, 0x085, 0x184, 0x0C4, 0x094, // U-*
45 0x0A8, 0x0A2, 0x08A, 0x02A // $-%
48 private static final int ASTERISK_ENCODING = CHARACTER_ENCODINGS[39];
50 private final boolean usingCheckDigit;
51 private final boolean extendedMode;
54 * Creates a reader that assumes all encoded data is data, and does not treat the final
55 * character as a check digit. It will not decoded "extended Code 39" sequences.
57 public Code39Reader() {
58 usingCheckDigit = false;
63 * Creates a reader that can be configured to check the last character as a check digit.
64 * It will not decoded "extended Code 39" sequences.
66 * @param usingCheckDigit if true, treat the last data character as a check digit, not
67 * data, and verify that the checksum passes
69 public Code39Reader(boolean usingCheckDigit) {
70 this.usingCheckDigit = usingCheckDigit;
71 this.extendedMode = false;
75 * Creates a reader that can be configured to check the last character as a check digit,
76 * or optionally attempt to decode "extended Code 39" sequences that are used to encode
77 * the full ASCII character set.
79 * @param usingCheckDigit if true, treat the last data character as a check digit, not
80 * data, and verify that the checksum passes
81 * @param extendedMode if true, willa tetmpt to decode extended Code 39 sequences in the
84 public Code39Reader(boolean usingCheckDigit, boolean extendedMode) {
85 this.usingCheckDigit = usingCheckDigit;
86 this.extendedMode = extendedMode;
89 public Result decodeRow(final int rowNumber, final BitArray row) throws ReaderException {
91 int[] start = findAsteriskPattern(row);
93 int nextStart = start[1];
95 int end = row.getSize();
97 // Read off white space
98 while (nextStart < end && !row.get(nextStart)) {
102 StringBuffer result = new StringBuffer();
103 int[] counters = new int[9];
107 recordPattern(row, nextStart, counters);
108 int pattern = toNarrowWidePattern(counters);
109 decodedChar = patternToChar(pattern);
110 result.append(decodedChar);
111 lastStart = nextStart;
112 for (int i = 0; i < counters.length; i++) {
113 nextStart += counters[i];
115 // Read off white space
116 while (nextStart < end && !row.get(nextStart)) {
119 } while (decodedChar != '*');
120 result.deleteCharAt(result.length() - 1); // remove asterisk
122 if (usingCheckDigit) {
123 int max = result.length() - 1;
125 for (int i = 0; i < max; i++) {
126 total += ALPHABET_STRING.indexOf(result.charAt(i));
128 if (total % 43 != ALPHABET_STRING.indexOf(result.charAt(max))) {
129 throw new ReaderException("Checksum failed");
131 result.deleteCharAt(max);
134 String resultString = result.toString();
136 resultString = decodeExtended(resultString);
138 return new Result(resultString,
139 new ResultPoint[]{new GenericResultPoint((float) (start[1] - start[0]) / 2.0f, (float) rowNumber),
140 new GenericResultPoint((float) (nextStart - lastStart) / 2.0f, (float) rowNumber)});
144 private static int[] findAsteriskPattern(BitArray row) throws ReaderException {
145 int width = row.getSize();
147 while (rowOffset < width) {
148 if (row.get(rowOffset)) {
154 int counterPosition = 0;
155 int[] counters = new int[9];
156 int patternStart = rowOffset;
157 boolean isWhite = false;
158 int patternLength = counters.length;
160 for (int i = rowOffset; i < width; i++) {
161 boolean pixel = row.get(i);
162 if ((!pixel && isWhite) || (pixel && !isWhite)) {
163 counters[counterPosition]++;
165 if (counterPosition == patternLength - 1) {
167 if (toNarrowWidePattern(counters) == ASTERISK_ENCODING) {
168 return new int[]{patternStart, i};
170 } catch (ReaderException re) {
171 // no match, continue
173 patternStart += counters[0] + counters[1];
174 for (int y = 2; y < patternLength; y++) {
175 counters[y - 2] = counters[y];
181 counters[counterPosition] = 1;
185 throw new ReaderException("Can't find pattern");
188 private static int toNarrowWidePattern(int[] counters) throws ReaderException {
189 int minCounter = Integer.MAX_VALUE;
190 for (int i = 0; i < counters.length; i++) {
191 if (counters[i] < minCounter) {
192 minCounter = counters[i];
195 int maxNarrowCounter = (int) (minCounter * 1.5f);
196 int wideCounters = 0;
198 for (int i = 0; i < counters.length; i++) {
199 if (counters[i] > maxNarrowCounter) {
200 pattern |= 1 << (counters.length - 1 - i);
204 if (wideCounters != 3) {
205 throw new ReaderException("Can't find 3 wide bars/spaces out of 9");
210 private static char patternToChar(int pattern) throws ReaderException {
211 for (int i = 0; i < CHARACTER_ENCODINGS.length; i++) {
212 if (CHARACTER_ENCODINGS[i] == pattern) {
216 throw new ReaderException("Pattern did not match character encoding");
219 private static String decodeExtended(String encoded) throws ReaderException {
220 int length = encoded.length();
221 StringBuffer decoded = new StringBuffer(length);
222 for (int i = 0; i < length; i++) {
223 char c = encoded.charAt(i);
224 if (c == '+' || c == '$' || c == '%' || c == '/') {
225 char next = encoded.charAt(i + 1);
226 char decodedChar = '\0';
229 // +A to +Z map to a to z
230 if (next >= 'A' && next <= 'Z') {
231 decodedChar = (char) (next + 32);
233 throw new ReaderException("Invalid extended code 39 sequence: " + c + next);
237 // $A to $Z map to control codes SH to SB
238 if (next >= 'A' && next <= 'Z') {
239 decodedChar = (char) (next - 64);
241 throw new ReaderException("Invalid extended code 39 sequence: " + c + next);
245 // %A to %E map to control codes ESC to US
246 if (next >= 'A' && next <= 'E') {
247 decodedChar = (char) (next - 38);
248 } else if (next >= 'F' && next <= 'W') {
249 decodedChar = (char) (next - 11);
251 throw new ReaderException("Invalid extended code 39 sequence: " + c + next);
255 // /A to /O map to ! to , and /Z maps to :
256 if (next >= 'A' && next <= 'O') {
257 decodedChar = (char) (next - 32);
258 } else if (next == 'Z') {
261 throw new ReaderException("Invalid extended sequence: " + c + next);
265 decoded.append(decodedChar);
266 // bump up i again since we read two characters
272 return decoded.toString();