/*
- * Copyright 2008 Google Inc.
+ * Copyright 2008 ZXing authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
package com.google.zxing.oned;
+import com.google.zxing.BarcodeFormat;
import com.google.zxing.ReaderException;
import com.google.zxing.Result;
import com.google.zxing.ResultPoint;
import com.google.zxing.common.BitArray;
import com.google.zxing.common.GenericResultPoint;
+import java.util.Hashtable;
+
/**
- * <p>Decodes Code 39 barcodes. This does not supported "Full ASCII Code 39" yet.</p>
+ * <p>Decodes Code 39 barcodes. This does not support "Full ASCII Code 39" yet.</p>
*
* @author srowen@google.com (Sean Owen)
*/
private static final String ALPHABET_STRING = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ-. *$/+%";
private static final char[] ALPHABET = ALPHABET_STRING.toCharArray();
+ /**
+ * These represent the encodings of characters, as patterns of wide and narrow bars.
+ * The 9 least-significant bits of each int correspond to the pattern of wide and narrow,
+ * with 1s representing "wide" and 0s representing narrow.
+ */
private static final int[] CHARACTER_ENCODINGS = {
- 0x038, 0x121, 0x061, 0x160, 0x031, 0x130, 0x070, 0x025, 0x124, 0x064, // 0-9
- 0x109, 0x049, 0x148, 0x019, 0x118, 0x058, 0x00D, 0x10C, 0x08C, 0x01C, // A-J
- 0x103, 0x043, 0x142, 0x013, 0x112, 0x052, 0x007, 0x106, 0x046, 0x016, // K-T
+ 0x034, 0x121, 0x061, 0x160, 0x031, 0x130, 0x070, 0x025, 0x124, 0x064, // 0-9
+ 0x109, 0x049, 0x148, 0x019, 0x118, 0x058, 0x00D, 0x10C, 0x04C, 0x01C, // A-J
+ 0x103, 0x043, 0x142, 0x013, 0x112, 0x052, 0x007, 0x106, 0x046, 0x016, // K-T
0x181, 0x0C1, 0x1C0, 0x091, 0x190, 0x0D0, 0x085, 0x184, 0x0C4, 0x094, // U-*
0x0A8, 0x0A2, 0x08A, 0x02A // $-%
};
private static final int ASTERISK_ENCODING = CHARACTER_ENCODINGS[39];
private final boolean usingCheckDigit;
+ private final boolean extendedMode;
/**
* Creates a reader that assumes all encoded data is data, and does not treat the final
- * character as a check digit.
+ * character as a check digit. It will not decoded "extended Code 39" sequences.
*/
public Code39Reader() {
usingCheckDigit = false;
+ extendedMode = false;
}
/**
* Creates a reader that can be configured to check the last character as a check digit.
+ * It will not decoded "extended Code 39" sequences.
*
* @param usingCheckDigit if true, treat the last data character as a check digit, not
- * data, and verify that the checksum passes
+ * data, and verify that the checksum passes.
*/
public Code39Reader(boolean usingCheckDigit) {
this.usingCheckDigit = usingCheckDigit;
+ this.extendedMode = false;
}
- public Result decodeRow(final int rowNumber, final BitArray row) throws ReaderException {
+ /**
+ * Creates a reader that can be configured to check the last character as a check digit,
+ * or optionally attempt to decode "extended Code 39" sequences that are used to encode
+ * the full ASCII character set.
+ *
+ * @param usingCheckDigit if true, treat the last data character as a check digit, not
+ * data, and verify that the checksum passes.
+ * @param extendedMode if true, will attempt to decode extended Code 39 sequences in the
+ * text.
+ */
+ public Code39Reader(boolean usingCheckDigit, boolean extendedMode) {
+ this.usingCheckDigit = usingCheckDigit;
+ this.extendedMode = extendedMode;
+ }
- int[] start = findAsteriskPattern(row);
+ public Result decodeRow(int rowNumber, BitArray row, Hashtable hints) throws ReaderException {
+ int[] start = findAsteriskPattern(row);
int nextStart = start[1];
-
int end = row.getSize();
// Read off white space
} while (decodedChar != '*');
result.deleteCharAt(result.length() - 1); // remove asterisk
+ // Look for whitespace after pattern:
+ int lastPatternSize = 0;
+ for (int i = 0; i < counters.length; i++) {
+ lastPatternSize += counters[i];
+ }
+ int whiteSpaceAfterEnd = nextStart - lastStart - lastPatternSize;
+ // If 50% of last pattern size, following last pattern, is not whitespace, fail
+ // (but if it's whitespace to the very end of the image, that's OK)
+ if (nextStart != end && whiteSpaceAfterEnd / 2 < lastPatternSize) {
+ throw new ReaderException("Pattern not followed by whitespace");
+ }
+
if (usingCheckDigit) {
int max = result.length() - 1;
int total = 0;
}
String resultString = result.toString();
- return new Result(resultString,
- new ResultPoint[]{new GenericResultPoint((float) (start[1] - start[0]) / 2.0f, (float) rowNumber),
- new GenericResultPoint((float) (nextStart - lastStart) / 2.0f, (float) rowNumber)});
+ if (extendedMode) {
+ resultString = decodeExtended(resultString);
+ }
+
+ if (resultString.length() == 0) {
+ // Almost surely a false positive
+ throw new ReaderException("Empty barcode found; assuming a false positive");
+ }
+
+ float left = (float) (start[1] + start[0]) / 2.0f;
+ float right = (float) (nextStart + lastStart) / 2.0f;
+ return new Result(
+ resultString,
+ null,
+ new ResultPoint[]{
+ new GenericResultPoint(left, (float) rowNumber),
+ new GenericResultPoint(right, (float) rowNumber)},
+ BarcodeFormat.CODE_39);
}
if (counterPosition == patternLength - 1) {
try {
if (toNarrowWidePattern(counters) == ASTERISK_ENCODING) {
- return new int[] {patternStart, i};
+ // Look for whitespace before start pattern, >= 50% of width of start pattern
+ if (row.isRange(Math.max(0, patternStart - (i - patternStart) / 2), patternStart, false)) {
+ return new int[]{patternStart, i};
+ }
}
} catch (ReaderException re) {
// no match, continue
for (int y = 2; y < patternLength; y++) {
counters[y - 2] = counters[y];
}
+ counters[patternLength - 2] = 0;
+ counters[patternLength - 1] = 0;
counterPosition--;
} else {
counterPosition++;
}
private static int toNarrowWidePattern(int[] counters) throws ReaderException {
- int minCounter = Integer.MAX_VALUE;
- for (int i = 0; i < counters.length; i++) {
- if (counters[i] < minCounter) {
- minCounter = counters[i];
+ int numCounters = counters.length;
+ int maxNarrowCounter = 0;
+ int wideCounters;
+ do {
+ int minCounter = Integer.MAX_VALUE;
+ for (int i = 0; i < numCounters; i++) {
+ int counter = counters[i];
+ if (counter < minCounter && counter > maxNarrowCounter) {
+ minCounter = counter;
+ }
}
- }
- int maxNarrowCounter = (int) (minCounter * 1.5f);
- int wideCounters = 0;
- int pattern = 0;
- for (int i = 0; i < counters.length; i++) {
- if (counters[i] > maxNarrowCounter) {
- pattern |= 1 << (counters.length - 1 - i);
- wideCounters++;
+ maxNarrowCounter = minCounter;
+ wideCounters = 0;
+ int totalWideCountersWidth = 0;
+ int pattern = 0;
+ for (int i = 0; i < numCounters; i++) {
+ int counter = counters[i];
+ if (counters[i] > maxNarrowCounter) {
+ pattern |= 1 << (numCounters - 1 - i);
+ wideCounters++;
+ totalWideCountersWidth += counter;
+ }
}
- }
- if (wideCounters != 3) {
- throw new ReaderException("Can't find 3 wide bars/spaces out of 9");
- }
- return pattern;
+ if (wideCounters == 3) {
+ // Found 3 wide counters, but are they close enough in width?
+ // We can perform a cheap, conservative check to see if any individual
+ // counter is more than 1.5 times the average:
+ for (int i = 0; i < numCounters && wideCounters > 0; i++) {
+ int counter = counters[i];
+ if (counters[i] > maxNarrowCounter) {
+ wideCounters--;
+ // totalWideCountersWidth = 3 * average, so this checks if counter >= 3/2 * average
+ if ((counter << 1) >= totalWideCountersWidth) {
+ throw new ReaderException("Wide bars vary too much in width, rejecting");
+ }
+ }
+ }
+ return pattern;
+ }
+ } while (wideCounters > 3);
+ throw new ReaderException("Can't find 3 wide bars/spaces out of 9");
}
private static char patternToChar(int pattern) throws ReaderException {
throw new ReaderException("Pattern did not match character encoding");
}
-}
\ No newline at end of file
+ private static String decodeExtended(String encoded) throws ReaderException {
+ int length = encoded.length();
+ StringBuffer decoded = new StringBuffer(length);
+ for (int i = 0; i < length; i++) {
+ char c = encoded.charAt(i);
+ if (c == '+' || c == '$' || c == '%' || c == '/') {
+ char next = encoded.charAt(i + 1);
+ char decodedChar = '\0';
+ switch (c) {
+ case '+':
+ // +A to +Z map to a to z
+ if (next >= 'A' && next <= 'Z') {
+ decodedChar = (char) (next + 32);
+ } else {
+ throw new ReaderException("Invalid extended code 39 sequence: " + c + next);
+ }
+ break;
+ case '$':
+ // $A to $Z map to control codes SH to SB
+ if (next >= 'A' && next <= 'Z') {
+ decodedChar = (char) (next - 64);
+ } else {
+ throw new ReaderException("Invalid extended code 39 sequence: " + c + next);
+ }
+ break;
+ case '%':
+ // %A to %E map to control codes ESC to US
+ if (next >= 'A' && next <= 'E') {
+ decodedChar = (char) (next - 38);
+ } else if (next >= 'F' && next <= 'W') {
+ decodedChar = (char) (next - 11);
+ } else {
+ throw new ReaderException("Invalid extended code 39 sequence: " + c + next);
+ }
+ break;
+ case '/':
+ // /A to /O map to ! to , and /Z maps to :
+ if (next >= 'A' && next <= 'O') {
+ decodedChar = (char) (next - 32);
+ } else if (next == 'Z') {
+ decodedChar = ':';
+ } else {
+ throw new ReaderException("Invalid extended sequence: " + c + next);
+ }
+ break;
+ }
+ decoded.append(decodedChar);
+ // bump up i again since we read two characters
+ i++;
+ } else {
+ decoded.append(c);
+ }
+ }
+ return decoded.toString();
+ }
+
+}
projects / zxing.git / blobdiff