2 * Copyright 2008 ZXing authors
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 128 barcodes.</p>
31 * @author srowen@google.com (Sean Owen)
33 public final class Code128Reader extends AbstractOneDReader {
35 private static final int[][] CODE_PATTERNS = {
36 {2, 1, 2, 2, 2, 2}, // 0
41 {1, 3, 1, 2, 2, 2}, // 5
46 {2, 2, 1, 3, 1, 2}, // 10
51 {1, 1, 3, 2, 2, 2}, // 15
56 {2, 2, 1, 2, 3, 1}, // 20
61 {3, 2, 1, 1, 2, 2}, // 25
66 {2, 1, 2, 1, 2, 3}, // 30
71 {1, 3, 1, 3, 2, 1}, // 35
76 {2, 3, 1, 1, 1, 3}, // 40
81 {1, 1, 3, 1, 2, 3}, // 45
86 {2, 3, 1, 1, 3, 1}, // 50
91 {3, 1, 1, 3, 2, 1}, // 55
96 {3, 1, 4, 1, 1, 1}, // 60
101 {1, 2, 1, 1, 2, 4}, // 65
106 {1, 1, 2, 4, 1, 2}, // 70
111 {2, 4, 1, 2, 1, 1}, // 75
116 {1, 1, 1, 2, 4, 2}, // 80
121 {1, 2, 4, 2, 1, 1}, // 85
126 {2, 1, 4, 1, 2, 1}, // 90
131 {1, 1, 4, 1, 1, 3}, // 95
136 {1, 1, 4, 1, 3, 1}, // 100
141 {2, 1, 1, 2, 3, 2}, // 105
142 {2, 3, 3, 1, 1, 1, 2}
145 private static final int MAX_AVG_VARIANCE = (int) (PATTERN_MATCH_RESULT_SCALE_FACTOR * 0.25f);
146 private static final int MAX_INDIVIDUAL_VARIANCE = (int) (PATTERN_MATCH_RESULT_SCALE_FACTOR * 0.7f);
148 private static final int CODE_SHIFT = 98;
150 private static final int CODE_CODE_C = 99;
151 private static final int CODE_CODE_B = 100;
152 private static final int CODE_CODE_A = 101;
154 private static final int CODE_FNC_1 = 102;
155 private static final int CODE_FNC_2 = 97;
156 private static final int CODE_FNC_3 = 96;
157 private static final int CODE_FNC_4_A = 101;
158 private static final int CODE_FNC_4_B = 100;
160 private static final int CODE_START_A = 103;
161 private static final int CODE_START_B = 104;
162 private static final int CODE_START_C = 105;
163 private static final int CODE_STOP = 106;
165 private static int[] findStartPattern(BitArray row) throws ReaderException {
166 int width = row.getSize();
168 while (rowOffset < width) {
169 if (row.get(rowOffset)) {
175 int counterPosition = 0;
176 int[] counters = new int[6];
177 int patternStart = rowOffset;
178 boolean isWhite = false;
179 int patternLength = counters.length;
181 for (int i = rowOffset; i < width; i++) {
182 boolean pixel = row.get(i);
183 if ((!pixel && isWhite) || (pixel && !isWhite)) {
184 counters[counterPosition]++;
186 if (counterPosition == patternLength - 1) {
187 int bestVariance = MAX_AVG_VARIANCE;
189 for (int startCode = CODE_START_A; startCode <= CODE_START_C; startCode++) {
190 int variance = patternMatchVariance(counters, CODE_PATTERNS[startCode], MAX_INDIVIDUAL_VARIANCE);
191 if (variance < bestVariance) {
192 bestVariance = variance;
193 bestMatch = startCode;
196 if (bestMatch >= 0) {
197 return new int[]{patternStart, i, bestMatch};
199 patternStart += counters[0] + counters[1];
200 for (int y = 2; y < patternLength; y++) {
201 counters[y - 2] = counters[y];
203 counters[patternLength - 2] = 0;
204 counters[patternLength - 1] = 0;
209 counters[counterPosition] = 1;
213 throw new ReaderException("Can't find pattern");
216 private static int decodeCode(BitArray row, int[] counters, int rowOffset) throws ReaderException {
217 recordPattern(row, rowOffset, counters);
218 int bestVariance = MAX_AVG_VARIANCE; // worst variance we'll accept
220 for (int d = 0; d < CODE_PATTERNS.length; d++) {
221 int[] pattern = CODE_PATTERNS[d];
222 int variance = patternMatchVariance(counters, pattern, MAX_INDIVIDUAL_VARIANCE);
223 if (variance < bestVariance) {
224 bestVariance = variance;
228 // TODO We're overlooking the fact that the STOP pattern has 7 values, not 6
229 if (bestMatch >= 0) {
232 throw new ReaderException("Could not match any code pattern");
236 public Result decodeRow(int rowNumber, BitArray row, Hashtable hints) throws ReaderException {
238 int[] startPatternInfo = findStartPattern(row);
239 int startCode = startPatternInfo[2];
243 codeSet = CODE_CODE_A;
246 codeSet = CODE_CODE_B;
249 codeSet = CODE_CODE_C;
252 throw new ReaderException("Illegal start code");
255 boolean done = false;
256 boolean isNextShifted = false;
258 StringBuffer result = new StringBuffer();
259 int lastStart = startPatternInfo[0];
260 int nextStart = startPatternInfo[1];
261 int[] counters = new int[6];
265 int checksumTotal = startCode;
267 boolean lastCharacterWasPrintable = true;
271 // Remember whether the last code was printable or not (excluding CODE_STOP)
272 lastCharacterWasPrintable = true;
274 boolean unshift = isNextShifted;
275 isNextShifted = false;
277 // Save off last code
280 // Decode another code from image
281 code = decodeCode(row, counters, nextStart);
283 // Add to checksum computation (if not CODE_STOP of course)
284 if (code != CODE_STOP) {
286 checksumTotal += multiplier * code;
289 // Advance to where the next code will to start
290 lastStart = nextStart;
291 for (int i = 0; i < counters.length; i++) {
292 nextStart += counters[i];
295 // Take care of illegal start codes
300 throw new ReaderException("Unexpected start code");
307 result.append((char) (' ' + code));
308 } else if (code < 96) {
309 result.append((char) (code - 64));
311 // Don't let CODE_STOP, which always appears, affect whether whether we think the last code
312 // was printable or not
313 if (code != CODE_STOP) {
314 lastCharacterWasPrintable = false;
324 isNextShifted = true;
325 codeSet = CODE_CODE_B;
328 codeSet = CODE_CODE_B;
331 codeSet = CODE_CODE_C;
341 result.append((char) (' ' + code));
343 if (code != CODE_STOP) {
344 lastCharacterWasPrintable = false;
354 isNextShifted = true;
355 codeSet = CODE_CODE_C;
358 codeSet = CODE_CODE_A;
361 codeSet = CODE_CODE_C;
376 if (code != CODE_STOP) {
377 lastCharacterWasPrintable = false;
384 codeSet = CODE_CODE_A;
387 codeSet = CODE_CODE_B;
397 // Unshift back to another code set if we were shifted
401 codeSet = CODE_CODE_C;
404 codeSet = CODE_CODE_A;
407 codeSet = CODE_CODE_B;
414 // Pull out from sum the value of the penultimate check code
415 checksumTotal -= multiplier * lastCode;
416 // lastCode is the checksum then:
417 if (checksumTotal % 103 != lastCode) {
418 throw new ReaderException("Checksum failed");
421 // Need to pull out the check digits from string
422 int resultLength = result.length();
423 // Only bother if, well, the result had at least one character, and if the checksum digit happened
424 // to be a printable character. If it was just interpreted as a control code, nothing to remove
425 if (resultLength > 0 && lastCharacterWasPrintable) {
426 if (codeSet == CODE_CODE_C) {
427 result.delete(resultLength - 2, resultLength);
429 result.delete(resultLength - 1, resultLength);
433 String resultString = result.toString();
435 if (resultString.length() == 0) {
436 // Almost surely a false positive
437 throw new ReaderException("Empty barcode found; assuming a false positive");
440 float left = (float) (startPatternInfo[1] + startPatternInfo[0]) / 2.0f;
441 float right = (float) (nextStart + lastStart) / 2.0f;
446 new GenericResultPoint(left, (float) rowNumber),
447 new GenericResultPoint(right, (float) rowNumber)},
448 BarcodeFormat.CODE_128);