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.ChecksumException;
21 import com.google.zxing.FormatException;
22 import com.google.zxing.NotFoundException;
23 import com.google.zxing.Result;
24 import com.google.zxing.ResultPoint;
25 import com.google.zxing.common.BitArray;
27 import java.util.Hashtable;
30 * <p>Decodes Code 128 barcodes.</p>
34 public final class Code128Reader extends OneDReader {
36 static final int[][] CODE_PATTERNS = {
37 {2, 1, 2, 2, 2, 2}, // 0
42 {1, 3, 1, 2, 2, 2}, // 5
47 {2, 2, 1, 3, 1, 2}, // 10
52 {1, 1, 3, 2, 2, 2}, // 15
57 {2, 2, 1, 2, 3, 1}, // 20
62 {3, 2, 1, 1, 2, 2}, // 25
67 {2, 1, 2, 1, 2, 3}, // 30
72 {1, 3, 1, 3, 2, 1}, // 35
77 {2, 3, 1, 1, 1, 3}, // 40
82 {1, 1, 3, 1, 2, 3}, // 45
87 {2, 3, 1, 1, 3, 1}, // 50
92 {3, 1, 1, 3, 2, 1}, // 55
97 {3, 1, 4, 1, 1, 1}, // 60
102 {1, 2, 1, 1, 2, 4}, // 65
107 {1, 1, 2, 4, 1, 2}, // 70
112 {2, 4, 1, 2, 1, 1}, // 75
117 {1, 1, 1, 2, 4, 2}, // 80
122 {1, 2, 4, 2, 1, 1}, // 85
127 {2, 1, 4, 1, 2, 1}, // 90
132 {1, 1, 4, 1, 1, 3}, // 95
137 {1, 1, 4, 1, 3, 1}, // 100
142 {2, 1, 1, 2, 3, 2}, // 105
143 {2, 3, 3, 1, 1, 1, 2}
146 private static final int MAX_AVG_VARIANCE = (int) (PATTERN_MATCH_RESULT_SCALE_FACTOR * 0.25f);
147 private static final int MAX_INDIVIDUAL_VARIANCE = (int) (PATTERN_MATCH_RESULT_SCALE_FACTOR * 0.7f);
149 private static final int CODE_SHIFT = 98;
151 private static final int CODE_CODE_C = 99;
152 private static final int CODE_CODE_B = 100;
153 private static final int CODE_CODE_A = 101;
155 private static final int CODE_FNC_1 = 102;
156 private static final int CODE_FNC_2 = 97;
157 private static final int CODE_FNC_3 = 96;
158 private static final int CODE_FNC_4_A = 101;
159 private static final int CODE_FNC_4_B = 100;
161 private static final int CODE_START_A = 103;
162 private static final int CODE_START_B = 104;
163 private static final int CODE_START_C = 105;
164 private static final int CODE_STOP = 106;
166 private static int[] findStartPattern(BitArray row) throws NotFoundException {
167 int width = row.getSize();
169 while (rowOffset < width) {
170 if (row.get(rowOffset)) {
176 int counterPosition = 0;
177 int[] counters = new int[6];
178 int patternStart = rowOffset;
179 boolean isWhite = false;
180 int patternLength = counters.length;
182 for (int i = rowOffset; i < width; i++) {
183 boolean pixel = row.get(i);
184 if (pixel ^ isWhite) {
185 counters[counterPosition]++;
187 if (counterPosition == patternLength - 1) {
188 int bestVariance = MAX_AVG_VARIANCE;
190 for (int startCode = CODE_START_A; startCode <= CODE_START_C; startCode++) {
191 int variance = patternMatchVariance(counters, CODE_PATTERNS[startCode],
192 MAX_INDIVIDUAL_VARIANCE);
193 if (variance < bestVariance) {
194 bestVariance = variance;
195 bestMatch = startCode;
198 if (bestMatch >= 0) {
199 // Look for whitespace before start pattern, >= 50% of width of start pattern
200 if (row.isRange(Math.max(0, patternStart - (i - patternStart) / 2), patternStart,
202 return new int[]{patternStart, i, bestMatch};
205 patternStart += counters[0] + counters[1];
206 for (int y = 2; y < patternLength; y++) {
207 counters[y - 2] = counters[y];
209 counters[patternLength - 2] = 0;
210 counters[patternLength - 1] = 0;
215 counters[counterPosition] = 1;
219 throw NotFoundException.getNotFoundInstance();
222 private static int decodeCode(BitArray row, int[] counters, int rowOffset) throws NotFoundException {
223 recordPattern(row, rowOffset, counters);
224 int bestVariance = MAX_AVG_VARIANCE; // worst variance we'll accept
226 for (int d = 0; d < CODE_PATTERNS.length; d++) {
227 int[] pattern = CODE_PATTERNS[d];
228 int variance = patternMatchVariance(counters, pattern, MAX_INDIVIDUAL_VARIANCE);
229 if (variance < bestVariance) {
230 bestVariance = variance;
234 // TODO We're overlooking the fact that the STOP pattern has 7 values, not 6.
235 if (bestMatch >= 0) {
238 throw NotFoundException.getNotFoundInstance();
242 public Result decodeRow(int rowNumber, BitArray row, Hashtable hints)
243 throws NotFoundException, FormatException, ChecksumException {
245 int[] startPatternInfo = findStartPattern(row);
246 int startCode = startPatternInfo[2];
250 codeSet = CODE_CODE_A;
253 codeSet = CODE_CODE_B;
256 codeSet = CODE_CODE_C;
259 throw FormatException.getFormatInstance();
262 boolean done = false;
263 boolean isNextShifted = false;
265 StringBuffer result = new StringBuffer(20);
266 int lastStart = startPatternInfo[0];
267 int nextStart = startPatternInfo[1];
268 int[] counters = new int[6];
272 int checksumTotal = startCode;
274 boolean lastCharacterWasPrintable = true;
278 boolean unshift = isNextShifted;
279 isNextShifted = false;
281 // Save off last code
284 // Decode another code from image
285 code = decodeCode(row, counters, nextStart);
287 // Remember whether the last code was printable or not (excluding CODE_STOP)
288 if (code != CODE_STOP) {
289 lastCharacterWasPrintable = true;
292 // Add to checksum computation (if not CODE_STOP of course)
293 if (code != CODE_STOP) {
295 checksumTotal += multiplier * code;
298 // Advance to where the next code will to start
299 lastStart = nextStart;
300 for (int i = 0; i < counters.length; i++) {
301 nextStart += counters[i];
304 // Take care of illegal start codes
309 throw FormatException.getFormatInstance();
316 result.append((char) (' ' + code));
317 } else if (code < 96) {
318 result.append((char) (code - 64));
320 // Don't let CODE_STOP, which always appears, affect whether whether we think the last
321 // code was printable or not.
322 if (code != CODE_STOP) {
323 lastCharacterWasPrintable = false;
333 isNextShifted = true;
334 codeSet = CODE_CODE_B;
337 codeSet = CODE_CODE_B;
340 codeSet = CODE_CODE_C;
350 result.append((char) (' ' + code));
352 if (code != CODE_STOP) {
353 lastCharacterWasPrintable = false;
363 isNextShifted = true;
364 codeSet = CODE_CODE_C;
367 codeSet = CODE_CODE_A;
370 codeSet = CODE_CODE_C;
385 if (code != CODE_STOP) {
386 lastCharacterWasPrintable = false;
393 codeSet = CODE_CODE_A;
396 codeSet = CODE_CODE_B;
406 // Unshift back to another code set if we were shifted
410 codeSet = CODE_CODE_C;
413 codeSet = CODE_CODE_A;
416 codeSet = CODE_CODE_B;
423 // Check for ample whitespace following pattern, but, to do this we first need to remember that
424 // we fudged decoding CODE_STOP since it actually has 7 bars, not 6. There is a black bar left
425 // to read off. Would be slightly better to properly read. Here we just skip it:
426 int width = row.getSize();
427 while (nextStart < width && row.get(nextStart)) {
430 if (!row.isRange(nextStart, Math.min(width, nextStart + (nextStart - lastStart) / 2),
432 throw NotFoundException.getNotFoundInstance();
435 // Pull out from sum the value of the penultimate check code
436 checksumTotal -= multiplier * lastCode;
437 // lastCode is the checksum then:
438 if (checksumTotal % 103 != lastCode) {
439 throw ChecksumException.getChecksumInstance();
442 // Need to pull out the check digits from string
443 int resultLength = result.length();
444 // Only bother if the result had at least one character, and if the checksum digit happened to
445 // be a printable character. If it was just interpreted as a control code, nothing to remove.
446 if (resultLength > 0 && lastCharacterWasPrintable) {
447 if (codeSet == CODE_CODE_C) {
448 result.delete(resultLength - 2, resultLength);
450 result.delete(resultLength - 1, resultLength);
454 String resultString = result.toString();
456 if (resultString.length() == 0) {
457 // Almost surely a false positive
458 throw FormatException.getFormatInstance();
461 float left = (float) (startPatternInfo[1] + startPatternInfo[0]) / 2.0f;
462 float right = (float) (nextStart + lastStart) / 2.0f;
467 new ResultPoint(left, (float) rowNumber),
468 new ResultPoint(right, (float) rowNumber)},
469 BarcodeFormat.CODE_128);