/*
* Copyright 2010 ZXing authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.zxing.oned;
import com.google.zxing.BarcodeFormat;
import com.google.zxing.ChecksumException;
import com.google.zxing.DecodeHintType;
import com.google.zxing.FormatException;
import com.google.zxing.NotFoundException;
import com.google.zxing.Result;
import com.google.zxing.ResultPoint;
import com.google.zxing.common.BitArray;
import java.util.Map;
/**
* <p>Decodes Code 93 barcodes.</p>
*
* @author Sean Owen
* @see Code39Reader
*/
public final class Code93Reader extends OneDReader {
// Note that 'abcd' are dummy characters in place of control characters.
private static final String ALPHABET_STRING = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ-. $/+%abcd*";
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.
*/
private static final int[] CHARACTER_ENCODINGS = {
0x114, 0x148, 0x144, 0x142, 0x128, 0x124, 0x122, 0x150, 0x112, 0x10A, // 0-9
0x1A8, 0x1A4, 0x1A2, 0x194, 0x192, 0x18A, 0x168, 0x164, 0x162, 0x134, // A-J
0x11A, 0x158, 0x14C, 0x146, 0x12C, 0x116, 0x1B4, 0x1B2, 0x1AC, 0x1A6, // K-T
0x196, 0x19A, 0x16C, 0x166, 0x136, 0x13A, // U-Z
0x12E, 0x1D4, 0x1D2, 0x1CA, 0x16E, 0x176, 0x1AE, // - - %
0x126, 0x1DA, 0x1D6, 0x132, 0x15E, // Control chars? $-*
};
private static final int ASTERISK_ENCODING = CHARACTER_ENCODINGS[47];
@Override
public Result decodeRow(int rowNumber, BitArray row, Map<DecodeHintType,?> hints)
throws NotFoundException, ChecksumException, FormatException {
int[] start = findAsteriskPattern(row);
// Read off white space
int nextStart = row.getNextSet(start[1]);
int end = row.getSize();
StringBuilder result = new StringBuilder(20);
int[] counters = new int[6];
char decodedChar;
int lastStart;
do {
recordPattern(row, nextStart, counters);
int pattern = toPattern(counters);
if (pattern < 0) {
throw NotFoundException.getNotFoundInstance();
}
decodedChar = patternToChar(pattern);
result.append(decodedChar);
lastStart = nextStart;
for (int counter : counters) {
nextStart += counter;
}
// Read off white space
nextStart = row.getNextSet(nextStart);
} while (decodedChar != '*');
result.deleteCharAt(result.length() - 1); // remove asterisk
// Should be at least one more black module
if (nextStart == end || !row.get(nextStart)) {
throw NotFoundException.getNotFoundInstance();
}
if (result.length() < 2) {
// false positive -- need at least 2 checksum digits
throw NotFoundException.getNotFoundInstance();
}
checkChecksums(result);
// Remove checksum digits
result.setLength(result.length() - 2);
String resultString = decodeExtended(result);
float left = (float) (start[1] + start[0]) / 2.0f;
float right = (float) (nextStart + lastStart) / 2.0f;
return new Result(
resultString,
null,
new ResultPoint[]{
new ResultPoint(left, (float) rowNumber),
new ResultPoint(right, (float) rowNumber)},
BarcodeFormat.CODE_93);
}
private static int[] findAsteriskPattern(BitArray row) throws NotFoundException {
int width = row.getSize();
int rowOffset = row.getNextSet(0);
int counterPosition = 0;
int[] counters = new int[6];
int patternStart = rowOffset;
boolean isWhite = false;
int patternLength = counters.length;
for (int i = rowOffset; i < width; i++) {
if (row.get(i) ^ isWhite) {
counters[counterPosition]++;
} else {
if (counterPosition == patternLength - 1) {
if (toPattern(counters) == ASTERISK_ENCODING) {
return new int[]{patternStart, i};
}
patternStart += counters[0] + counters[1];
System.arraycopy(counters, 2, counters, 0, patternLength - 2);
counters[patternLength - 2] = 0;
counters[patternLength - 1] = 0;
counterPosition--;
} else {
counterPosition++;
}
counters[counterPosition] = 1;
isWhite = !isWhite;
}
}
throw NotFoundException.getNotFoundInstance();
}
private static int toPattern(int[] counters) {
int max = counters.length;
int sum = 0;
for (int counter : counters) {
sum += counter;
}
int pattern = 0;
for (int i = 0; i < max; i++) {
int scaledShifted = (counters[i] << INTEGER_MATH_SHIFT) * 9 / sum;
int scaledUnshifted = scaledShifted >> INTEGER_MATH_SHIFT;
if ((scaledShifted & 0xFF) > 0x7F) {
scaledUnshifted++;
}
if (scaledUnshifted < 1 || scaledUnshifted > 4) {
return -1;
}
if ((i & 0x01) == 0) {
for (int j = 0; j < scaledUnshifted; j++) {
pattern = (pattern << 1) | 0x01;
}
} else {
pattern <<= scaledUnshifted;
}
}
return pattern;
}
private static char patternToChar(int pattern) throws NotFoundException {
for (int i = 0; i < CHARACTER_ENCODINGS.length; i++) {
if (CHARACTER_ENCODINGS[i] == pattern) {
return ALPHABET[i];
}
}
throw NotFoundException.getNotFoundInstance();
}
private static String decodeExtended(CharSequence encoded) throws FormatException {
int length = encoded.length();
StringBuilder decoded = new StringBuilder(length);
for (int i = 0; i < length; i++) {
char c = encoded.charAt(i);
if (c >= 'a' && c <= 'd') {
if (i >= length - 1) {
throw FormatException.getFormatInstance();
}
char next = encoded.charAt(i + 1);
char decodedChar = '\0';
switch (c) {
case 'd':
// +A to +Z map to a to z
if (next >= 'A' && next <= 'Z') {
decodedChar = (char) (next + 32);
} else {
throw FormatException.getFormatInstance();
}
break;
case 'a':
// $A to $Z map to control codes SH to SB
if (next >= 'A' && next <= 'Z') {
decodedChar = (char) (next - 64);
} else {
throw FormatException.getFormatInstance();
}
break;
case 'b':
// %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 FormatException.getFormatInstance();
}
break;
case 'c':
// /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 FormatException.getFormatInstance();
}
break;
}
decoded.append(decodedChar);
// bump up i again since we read two characters
i++;
} else {
decoded.append(c);
}
}
return decoded.toString();
}
private static void checkChecksums(CharSequence result) throws ChecksumException {
int length = result.length();
checkOneChecksum(result, length - 2, 20);
checkOneChecksum(result, length - 1, 15);
}
private static void checkOneChecksum(CharSequence result, int checkPosition, int weightMax)
throws ChecksumException {
int weight = 1;
int total = 0;
for (int i = checkPosition - 1; i >= 0; i--) {
total += weight * ALPHABET_STRING.indexOf(result.charAt(i));
if (++weight > weightMax) {
weight = 1;
}
}
if (result.charAt(checkPosition) != ALPHABET[total % 47]) {
throw ChecksumException.getChecksumInstance();
}
}
}