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com.google.zxing.oned.UPCEANReader Maven / Gradle / Ivy

/*
 * 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; }




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