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.BarcodeFormat;
20 import com.google.zxing.ReaderException;
21 import com.google.zxing.Result;
22 import com.google.zxing.ResultPoint;
23 import com.google.zxing.common.BitArray;
24 import com.google.zxing.common.GenericResultPoint;
26 import java.util.Hashtable;
29 * <p>Decodes Code 39 barcodes. This does not supported "Full ASCII Code 39" yet.</p>
31 * @author srowen@google.com (Sean Owen)
33 public final class Code39Reader extends AbstractOneDReader {
35 private static final String ALPHABET_STRING = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ-. *$/+%";
36 private static final char[] ALPHABET = ALPHABET_STRING.toCharArray();
39 * These represent the encodings of characters, as patterns of wide and narrow bars.
40 * The 9 least-significant bits of each int correspond to the pattern of wide and narrow,
41 * with 1s representing "wide" and 0s representing narrow.
43 private static final int[] CHARACTER_ENCODINGS = {
44 0x034, 0x121, 0x061, 0x160, 0x031, 0x130, 0x070, 0x025, 0x124, 0x064, // 0-9
45 0x109, 0x049, 0x148, 0x019, 0x118, 0x058, 0x00D, 0x10C, 0x04C, 0x01C, // A-J
46 0x103, 0x043, 0x142, 0x013, 0x112, 0x052, 0x007, 0x106, 0x046, 0x016, // K-T
47 0x181, 0x0C1, 0x1C0, 0x091, 0x190, 0x0D0, 0x085, 0x184, 0x0C4, 0x094, // U-*
48 0x0A8, 0x0A2, 0x08A, 0x02A // $-%
51 private static final int ASTERISK_ENCODING = CHARACTER_ENCODINGS[39];
53 private final boolean usingCheckDigit;
54 private final boolean extendedMode;
57 * Creates a reader that assumes all encoded data is data, and does not treat the final
58 * character as a check digit. It will not decoded "extended Code 39" sequences.
60 public Code39Reader() {
61 usingCheckDigit = false;
66 * Creates a reader that can be configured to check the last character as a check digit.
67 * It will not decoded "extended Code 39" sequences.
69 * @param usingCheckDigit if true, treat the last data character as a check digit, not
70 * data, and verify that the checksum passes
72 public Code39Reader(boolean usingCheckDigit) {
73 this.usingCheckDigit = usingCheckDigit;
74 this.extendedMode = false;
78 * Creates a reader that can be configured to check the last character as a check digit,
79 * or optionally attempt to decode "extended Code 39" sequences that are used to encode
80 * the full ASCII character set.
82 * @param usingCheckDigit if true, treat the last data character as a check digit, not
83 * data, and verify that the checksum passes
84 * @param extendedMode if true, willa tetmpt to decode extended Code 39 sequences in the
87 public Code39Reader(boolean usingCheckDigit, boolean extendedMode) {
88 this.usingCheckDigit = usingCheckDigit;
89 this.extendedMode = extendedMode;
92 public Result decodeRow(int rowNumber, BitArray row, Hashtable hints) throws ReaderException {
94 int[] start = findAsteriskPattern(row);
96 int nextStart = start[1];
98 int end = row.getSize();
100 // Read off white space
101 while (nextStart < end && !row.get(nextStart)) {
105 StringBuffer result = new StringBuffer();
106 int[] counters = new int[9];
110 recordPattern(row, nextStart, counters);
111 int pattern = toNarrowWidePattern(counters);
112 decodedChar = patternToChar(pattern);
113 result.append(decodedChar);
114 lastStart = nextStart;
115 for (int i = 0; i < counters.length; i++) {
116 nextStart += counters[i];
118 // Read off white space
119 while (nextStart < end && !row.get(nextStart)) {
122 } while (decodedChar != '*');
123 result.deleteCharAt(result.length() - 1); // remove asterisk
125 if (usingCheckDigit) {
126 int max = result.length() - 1;
128 for (int i = 0; i < max; i++) {
129 total += ALPHABET_STRING.indexOf(result.charAt(i));
131 if (total % 43 != ALPHABET_STRING.indexOf(result.charAt(max))) {
132 throw new ReaderException("Checksum failed");
134 result.deleteCharAt(max);
137 String resultString = result.toString();
139 resultString = decodeExtended(resultString);
144 new GenericResultPoint((float) (start[1] - start[0]) / 2.0f, (float) rowNumber),
145 new GenericResultPoint((float) (nextStart - lastStart) / 2.0f, (float) rowNumber)},
146 BarcodeFormat.CODE_39);
150 private static int[] findAsteriskPattern(BitArray row) throws ReaderException {
151 int width = row.getSize();
153 while (rowOffset < width) {
154 if (row.get(rowOffset)) {
160 int counterPosition = 0;
161 int[] counters = new int[9];
162 int patternStart = rowOffset;
163 boolean isWhite = false;
164 int patternLength = counters.length;
166 for (int i = rowOffset; i < width; i++) {
167 boolean pixel = row.get(i);
168 if ((!pixel && isWhite) || (pixel && !isWhite)) {
169 counters[counterPosition]++;
171 if (counterPosition == patternLength - 1) {
173 if (toNarrowWidePattern(counters) == ASTERISK_ENCODING) {
174 return new int[]{patternStart, i};
176 } catch (ReaderException re) {
177 // no match, continue
179 patternStart += counters[0] + counters[1];
180 for (int y = 2; y < patternLength; y++) {
181 counters[y - 2] = counters[y];
183 counters[patternLength - 2] = 0;
184 counters[patternLength - 1] = 0;
189 counters[counterPosition] = 1;
193 throw new ReaderException("Can't find pattern");
196 private static int toNarrowWidePattern(int[] counters) throws ReaderException {
197 int numCounters = counters.length;
198 int maxNarrowCounter = 0;
201 int minCounter = Integer.MAX_VALUE;
202 for (int i = 0; i < numCounters; i++) {
203 int counter = counters[i];
204 if (counter < minCounter && counter > maxNarrowCounter) {
205 minCounter = counter;
208 maxNarrowCounter = minCounter;
211 for (int i = 0; i < numCounters; i++) {
212 if (counters[i] > maxNarrowCounter) {
213 pattern |= 1 << (numCounters - 1 - i);
217 if (wideCounters == 3) {
220 } while (wideCounters > 3);
221 throw new ReaderException("Can't find 3 wide bars/spaces out of 9");
224 private static char patternToChar(int pattern) throws ReaderException {
225 for (int i = 0; i < CHARACTER_ENCODINGS.length; i++) {
226 if (CHARACTER_ENCODINGS[i] == pattern) {
230 throw new ReaderException("Pattern did not match character encoding");
233 private static String decodeExtended(String encoded) throws ReaderException {
234 int length = encoded.length();
235 StringBuffer decoded = new StringBuffer(length);
236 for (int i = 0; i < length; i++) {
237 char c = encoded.charAt(i);
238 if (c == '+' || c == '$' || c == '%' || c == '/') {
239 char next = encoded.charAt(i + 1);
240 char decodedChar = '\0';
243 // +A to +Z map to a to z
244 if (next >= 'A' && next <= 'Z') {
245 decodedChar = (char) (next + 32);
247 throw new ReaderException("Invalid extended code 39 sequence: " + c + next);
251 // $A to $Z map to control codes SH to SB
252 if (next >= 'A' && next <= 'Z') {
253 decodedChar = (char) (next - 64);
255 throw new ReaderException("Invalid extended code 39 sequence: " + c + next);
259 // %A to %E map to control codes ESC to US
260 if (next >= 'A' && next <= 'E') {
261 decodedChar = (char) (next - 38);
262 } else if (next >= 'F' && next <= 'W') {
263 decodedChar = (char) (next - 11);
265 throw new ReaderException("Invalid extended code 39 sequence: " + c + next);
269 // /A to /O map to ! to , and /Z maps to :
270 if (next >= 'A' && next <= 'O') {
271 decodedChar = (char) (next - 32);
272 } else if (next == 'Z') {
275 throw new ReaderException("Invalid extended sequence: " + c + next);
279 decoded.append(decodedChar);
280 // bump up i again since we read two characters
286 return decoded.toString();