com.google.zxing.oned.UPCEANReader Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of core Show documentation
Show all versions of core Show documentation
Core barcode encoding/decoding library
/*
* 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.
* 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.ReaderException;
import com.google.zxing.Result;
import com.google.zxing.ResultMetadataType;
import com.google.zxing.ResultPoint;
import com.google.zxing.ResultPointCallback;
import com.google.zxing.common.BitArray;
import java.util.Arrays;
import java.util.Map;
/**
* Encapsulates functionality and implementation that is common to UPC and EAN families
* of one-dimensional barcodes.
*
* @author [email protected] (Daniel Switkin)
* @author Sean Owen
* @author [email protected] (Alasdair Mackintosh)
*/
public abstract class UPCEANReader extends OneDReader {
// These two values are critical for determining how permissive the decoding will be.
// We've arrived at these values through a lot of trial and error. Setting them any higher
// lets false positives creep in quickly.
private static final float MAX_AVG_VARIANCE = 0.48f;
private static final float MAX_INDIVIDUAL_VARIANCE = 0.7f;
/**
* Start/end guard pattern.
*/
static final int[] START_END_PATTERN = {1, 1, 1,};
/**
* Pattern marking the middle of a UPC/EAN pattern, separating the two halves.
*/
static final int[] MIDDLE_PATTERN = {1, 1, 1, 1, 1};
/**
* end guard pattern.
*/
static final int[] END_PATTERN = {1, 1, 1, 1, 1, 1};
/**
* "Odd", or "L" patterns used to encode UPC/EAN digits.
*/
static final int[][] L_PATTERNS = {
{3, 2, 1, 1}, // 0
{2, 2, 2, 1}, // 1
{2, 1, 2, 2}, // 2
{1, 4, 1, 1}, // 3
{1, 1, 3, 2}, // 4
{1, 2, 3, 1}, // 5
{1, 1, 1, 4}, // 6
{1, 3, 1, 2}, // 7
{1, 2, 1, 3}, // 8
{3, 1, 1, 2} // 9
};
/**
* As above but also including the "even", or "G" patterns used to encode UPC/EAN digits.
*/
static final int[][] L_AND_G_PATTERNS;
static {
L_AND_G_PATTERNS = new int[20][];
System.arraycopy(L_PATTERNS, 0, L_AND_G_PATTERNS, 0, 10);
for (int i = 10; i < 20; i++) {
int[] widths = L_PATTERNS[i - 10];
int[] reversedWidths = new int[widths.length];
for (int j = 0; j < widths.length; j++) {
reversedWidths[j] = widths[widths.length - j - 1];
}
L_AND_G_PATTERNS[i] = reversedWidths;
}
}
private final StringBuilder decodeRowStringBuffer;
private final UPCEANExtensionSupport extensionReader;
private final EANManufacturerOrgSupport eanManSupport;
protected UPCEANReader() {
decodeRowStringBuffer = new StringBuilder(20);
extensionReader = new UPCEANExtensionSupport();
eanManSupport = new EANManufacturerOrgSupport();
}
static int[] findStartGuardPattern(BitArray row) throws NotFoundException {
boolean foundStart = false;
int[] startRange = null;
int nextStart = 0;
int[] counters = new int[START_END_PATTERN.length];
while (!foundStart) {
Arrays.fill(counters, 0, START_END_PATTERN.length, 0);
startRange = findGuardPattern(row, nextStart, false, START_END_PATTERN, counters);
int start = startRange[0];
nextStart = startRange[1];
// Make sure there is a quiet zone at least as big as the start pattern before the barcode.
// If this check would run off the left edge of the image, do not accept this barcode,
// as it is very likely to be a false positive.
int quietStart = start - (nextStart - start);
if (quietStart >= 0) {
foundStart = row.isRange(quietStart, start, false);
}
}
return startRange;
}
@Override
public Result decodeRow(int rowNumber, BitArray row, Map hints)
throws NotFoundException, ChecksumException, FormatException {
return decodeRow(rowNumber, row, findStartGuardPattern(row), hints);
}
/**
* Like {@link #decodeRow(int, BitArray, Map)}, but
* allows caller to inform method about where the UPC/EAN start pattern is
* found. This allows this to be computed once and reused across many implementations.
*
* @param rowNumber row index into the image
* @param row encoding of the row of the barcode image
* @param startGuardRange start/end column where the opening start pattern was found
* @param hints optional hints that influence decoding
* @return {@link Result} encapsulating the result of decoding a barcode in the row
* @throws NotFoundException if no potential barcode is found
* @throws ChecksumException if a potential barcode is found but does not pass its checksum
* @throws FormatException if a potential barcode is found but format is invalid
*/
public Result decodeRow(int rowNumber,
BitArray row,
int[] startGuardRange,
Map hints)
throws NotFoundException, ChecksumException, FormatException {
ResultPointCallback resultPointCallback = hints == null ? null :
(ResultPointCallback) hints.get(DecodeHintType.NEED_RESULT_POINT_CALLBACK);
if (resultPointCallback != null) {
resultPointCallback.foundPossibleResultPoint(new ResultPoint(
(startGuardRange[0] + startGuardRange[1]) / 2.0f, rowNumber
));
}
StringBuilder result = decodeRowStringBuffer;
result.setLength(0);
int endStart = decodeMiddle(row, startGuardRange, result);
if (resultPointCallback != null) {
resultPointCallback.foundPossibleResultPoint(new ResultPoint(
endStart, rowNumber
));
}
int[] endRange = decodeEnd(row, endStart);
if (resultPointCallback != null) {
resultPointCallback.foundPossibleResultPoint(new ResultPoint(
(endRange[0] + endRange[1]) / 2.0f, rowNumber
));
}
// Make sure there is a quiet zone at least as big as the end pattern after the barcode. The
// spec might want more whitespace, but in practice this is the maximum we can count on.
int end = endRange[1];
int quietEnd = end + (end - endRange[0]);
if (quietEnd >= row.getSize() || !row.isRange(end, quietEnd, false)) {
throw NotFoundException.getNotFoundInstance();
}
String resultString = result.toString();
// UPC/EAN should never be less than 8 chars anyway
if (resultString.length() < 8) {
throw FormatException.getFormatInstance();
}
if (!checkChecksum(resultString)) {
throw ChecksumException.getChecksumInstance();
}
float left = (startGuardRange[1] + startGuardRange[0]) / 2.0f;
float right = (endRange[1] + endRange[0]) / 2.0f;
BarcodeFormat format = getBarcodeFormat();
Result decodeResult = new Result(resultString,
null, // no natural byte representation for these barcodes
new ResultPoint[]{
new ResultPoint(left, rowNumber),
new ResultPoint(right, rowNumber)},
format);
int extensionLength = 0;
try {
Result extensionResult = extensionReader.decodeRow(rowNumber, row, endRange[1]);
decodeResult.putMetadata(ResultMetadataType.UPC_EAN_EXTENSION, extensionResult.getText());
decodeResult.putAllMetadata(extensionResult.getResultMetadata());
decodeResult.addResultPoints(extensionResult.getResultPoints());
extensionLength = extensionResult.getText().length();
} catch (ReaderException re) {
// continue
}
int[] allowedExtensions =
hints == null ? null : (int[]) hints.get(DecodeHintType.ALLOWED_EAN_EXTENSIONS);
if (allowedExtensions != null) {
boolean valid = false;
for (int length : allowedExtensions) {
if (extensionLength == length) {
valid = true;
break;
}
}
if (!valid) {
throw NotFoundException.getNotFoundInstance();
}
}
if (format == BarcodeFormat.EAN_13 || format == BarcodeFormat.UPC_A) {
String countryID = eanManSupport.lookupCountryIdentifier(resultString);
if (countryID != null) {
decodeResult.putMetadata(ResultMetadataType.POSSIBLE_COUNTRY, countryID);
}
}
return decodeResult;
}
/**
* @param s string of digits to check
* @return {@link #checkStandardUPCEANChecksum(CharSequence)}
* @throws FormatException if the string does not contain only digits
*/
boolean checkChecksum(String s) throws FormatException {
return checkStandardUPCEANChecksum(s);
}
/**
* Computes the UPC/EAN checksum on a string of digits, and reports
* whether the checksum is correct or not.
*
* @param s string of digits to check
* @return true iff string of digits passes the UPC/EAN checksum algorithm
* @throws FormatException if the string does not contain only digits
*/
static boolean checkStandardUPCEANChecksum(CharSequence s) throws FormatException {
int length = s.length();
if (length == 0) {
return false;
}
int check = Character.digit(s.charAt(length - 1), 10);
return getStandardUPCEANChecksum(s.subSequence(0, length - 1)) == check;
}
static int getStandardUPCEANChecksum(CharSequence s) throws FormatException {
int length = s.length();
int sum = 0;
for (int i = length - 1; i >= 0; i -= 2) {
int digit = s.charAt(i) - '0';
if (digit < 0 || digit > 9) {
throw FormatException.getFormatInstance();
}
sum += digit;
}
sum *= 3;
for (int i = length - 2; i >= 0; i -= 2) {
int digit = s.charAt(i) - '0';
if (digit < 0 || digit > 9) {
throw FormatException.getFormatInstance();
}
sum += digit;
}
return (1000 - sum) % 10;
}
int[] decodeEnd(BitArray row, int endStart) throws NotFoundException {
return findGuardPattern(row, endStart, false, START_END_PATTERN);
}
static int[] findGuardPattern(BitArray row,
int rowOffset,
boolean whiteFirst,
int[] pattern) throws NotFoundException {
return findGuardPattern(row, rowOffset, whiteFirst, pattern, new int[pattern.length]);
}
/**
* @param row row of black/white values to search
* @param rowOffset position to start search
* @param whiteFirst if true, indicates that the pattern specifies white/black/white/...
* pixel counts, otherwise, it is interpreted as black/white/black/...
* @param pattern pattern of counts of number of black and white pixels that are being
* searched for as a pattern
* @param counters array of counters, as long as pattern, to re-use
* @return start/end horizontal offset of guard pattern, as an array of two ints
* @throws NotFoundException if pattern is not found
*/
private static int[] findGuardPattern(BitArray row,
int rowOffset,
boolean whiteFirst,
int[] pattern,
int[] counters) throws NotFoundException {
int width = row.getSize();
rowOffset = whiteFirst ? row.getNextUnset(rowOffset) : row.getNextSet(rowOffset);
int counterPosition = 0;
int patternStart = rowOffset;
int patternLength = pattern.length;
boolean isWhite = whiteFirst;
for (int x = rowOffset; x < width; x++) {
if (row.get(x) != isWhite) {
counters[counterPosition]++;
} else {
if (counterPosition == patternLength - 1) {
if (patternMatchVariance(counters, pattern, MAX_INDIVIDUAL_VARIANCE) < MAX_AVG_VARIANCE) {
return new int[]{patternStart, x};
}
patternStart += counters[0] + counters[1];
System.arraycopy(counters, 2, counters, 0, counterPosition - 1);
counters[counterPosition - 1] = 0;
counters[counterPosition] = 0;
counterPosition--;
} else {
counterPosition++;
}
counters[counterPosition] = 1;
isWhite = !isWhite;
}
}
throw NotFoundException.getNotFoundInstance();
}
/**
* Attempts to decode a single UPC/EAN-encoded digit.
*
* @param row row of black/white values to decode
* @param counters the counts of runs of observed black/white/black/... values
* @param rowOffset horizontal offset to start decoding from
* @param patterns the set of patterns to use to decode -- sometimes different encodings
* for the digits 0-9 are used, and this indicates the encodings for 0 to 9 that should
* be used
* @return horizontal offset of first pixel beyond the decoded digit
* @throws NotFoundException if digit cannot be decoded
*/
static int decodeDigit(BitArray row, int[] counters, int rowOffset, int[][] patterns)
throws NotFoundException {
recordPattern(row, rowOffset, counters);
float bestVariance = MAX_AVG_VARIANCE; // worst variance we'll accept
int bestMatch = -1;
int max = patterns.length;
for (int i = 0; i < max; i++) {
int[] pattern = patterns[i];
float variance = patternMatchVariance(counters, pattern, MAX_INDIVIDUAL_VARIANCE);
if (variance < bestVariance) {
bestVariance = variance;
bestMatch = i;
}
}
if (bestMatch >= 0) {
return bestMatch;
} else {
throw NotFoundException.getNotFoundInstance();
}
}
/**
* Get the format of this decoder.
*
* @return The 1D format.
*/
abstract BarcodeFormat getBarcodeFormat();
/**
* Subclasses override this to decode the portion of a barcode between the start
* and end guard patterns.
*
* @param row row of black/white values to search
* @param startRange start/end offset of start guard pattern
* @param resultString {@link StringBuilder} to append decoded chars to
* @return horizontal offset of first pixel after the "middle" that was decoded
* @throws NotFoundException if decoding could not complete successfully
*/
protected abstract int decodeMiddle(BitArray row,
int[] startRange,
StringBuilder resultString) throws NotFoundException;
}
© 2015 - 2024 Weber Informatics LLC | Privacy Policy