src/core/oned/AbstractUPCEANReader.ts
/*
* 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.
*/
import BitArray from '../common/BitArray';
import DecodeHintType from '../DecodeHintType';
import Result from '../Result';
import OneDReader from './OneDReader';
import NotFoundException from '../NotFoundException';
import FormatException from '../FormatException';
import { int } from '../../customTypings';
/**
* <p>Encapsulates functionality and implementation that is common to UPC and EAN families
* of one-dimensional barcodes.</p>
*
* @author dswitkin@google.com (Daniel Switkin)
* @author Sean Owen
* @author alasdair@google.com (Alasdair Mackintosh)
*/
export default abstract class AbstractUPCEANReader 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 MAX_AVG_VARIANCE = 0.48;
private static MAX_INDIVIDUAL_VARIANCE = 0.7;
/**
* Start/end guard pattern.
*/
public static START_END_PATTERN: Int32Array = Int32Array.from([1, 1, 1]);
/**
* Pattern marking the middle of a UPC/EAN pattern, separating the two halves.
*/
public static MIDDLE_PATTERN: Int32Array = Int32Array.from([1, 1, 1, 1, 1]);
/**
* end guard pattern.
*/
public static END_PATTERN: Int32Array = Int32Array.from([1, 1, 1, 1, 1, 1]);
/**
* "Odd", or "L" patterns used to encode UPC/EAN digits.
*/
public static L_PATTERNS: Int32Array[] = [
Int32Array.from([3, 2, 1, 1]), // 0
Int32Array.from([2, 2, 2, 1]), // 1
Int32Array.from([2, 1, 2, 2]), // 2
Int32Array.from([1, 4, 1, 1]), // 3
Int32Array.from([1, 1, 3, 2]), // 4
Int32Array.from([1, 2, 3, 1]), // 5
Int32Array.from([1, 1, 1, 4]), // 6
Int32Array.from([1, 3, 1, 2]), // 7
Int32Array.from([1, 2, 1, 3]), // 8
Int32Array.from([3, 1, 1, 2]), // 9
];
/**
* As above but also including the "even", or "G" patterns used to encode UPC/EAN digits.
*/
public static L_AND_G_PATTERNS: Int32Array[];
protected decodeRowStringBuffer = '';
// private final UPCEANExtensionSupport extensionReader;
// private final EANManufacturerOrgSupport eanManSupport;
/*
protected UPCEANReader() {
decodeRowStringBuffer = new StringBuilder(20);
extensionReader = new UPCEANExtensionSupport();
eanManSupport = new EANManufacturerOrgSupport();
}
*/
static findStartGuardPattern(row: BitArray): Int32Array {
let foundStart = false;
let startRange: Int32Array;
let nextStart = 0;
let counters = Int32Array.from([0, 0, 0]);
while (!foundStart) {
counters = Int32Array.from([0, 0, 0]);
startRange = AbstractUPCEANReader.findGuardPattern(row, nextStart, false, this.START_END_PATTERN, counters);
let start = startRange[0];
nextStart = startRange[1];
let quietStart = start - (nextStart - start);
if (quietStart >= 0) {
foundStart = row.isRange(quietStart, start, false);
}
}
return startRange;
}
public abstract decodeRow(rowNumber: number, row: BitArray, hints?: Map<DecodeHintType, any>): Result;
static checkChecksum(s: string): boolean {
return AbstractUPCEANReader.checkStandardUPCEANChecksum(s);
}
static checkStandardUPCEANChecksum(s: string): boolean {
let length = s.length;
if (length === 0) return false;
let check = parseInt(s.charAt(length - 1), 10);
return AbstractUPCEANReader.getStandardUPCEANChecksum(s.substring(0, length - 1)) === check;
}
static getStandardUPCEANChecksum(s: string): number {
let length = s.length;
let sum = 0;
for (let i = length - 1; i >= 0; i -= 2) {
let digit = s.charAt(i).charCodeAt(0) - '0'.charCodeAt(0);
if (digit < 0 || digit > 9) {
throw new FormatException();
}
sum += digit;
}
sum *= 3;
for (let i = length - 2; i >= 0; i -= 2) {
let digit = s.charAt(i).charCodeAt(0) - '0'.charCodeAt(0);
if (digit < 0 || digit > 9) {
throw new FormatException();
}
sum += digit;
}
return (1000 - sum) % 10;
}
static decodeEnd(row: BitArray, endStart: number): Int32Array {
return AbstractUPCEANReader.findGuardPattern(row, endStart, false, AbstractUPCEANReader.START_END_PATTERN, new Int32Array(AbstractUPCEANReader.START_END_PATTERN.length).fill(0));
}
/**
* @throws NotFoundException
*/
static findGuardPatternWithoutCounters(
row: BitArray,
rowOffset: int,
whiteFirst: boolean,
pattern: Int32Array,
): Int32Array {
return this.findGuardPattern(row, rowOffset, whiteFirst, pattern, new Int32Array(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
*/
static findGuardPattern(row: BitArray, rowOffset: number, whiteFirst: boolean, pattern: Int32Array, counters: Int32Array): Int32Array {
let width = row.getSize();
rowOffset = whiteFirst ? row.getNextUnset(rowOffset) : row.getNextSet(rowOffset);
let counterPosition = 0;
let patternStart = rowOffset;
let patternLength = pattern.length;
let isWhite = whiteFirst;
for (let x = rowOffset; x < width; x++) {
if (row.get(x) !== isWhite) {
counters[counterPosition]++;
} else {
if (counterPosition === patternLength - 1) {
if (OneDReader.patternMatchVariance(counters, pattern, AbstractUPCEANReader.MAX_INDIVIDUAL_VARIANCE) < AbstractUPCEANReader.MAX_AVG_VARIANCE) {
return Int32Array.from([patternStart, x]);
}
patternStart += counters[0] + counters[1];
let slice = counters.slice(2, counters.length);
for (let i = 0; i < counterPosition - 1; i++) {
counters[i] = slice[i];
}
counters[counterPosition - 1] = 0;
counters[counterPosition] = 0;
counterPosition--;
} else {
counterPosition++;
}
counters[counterPosition] = 1;
isWhite = !isWhite;
}
}
throw new NotFoundException();
}
static decodeDigit(row: BitArray, counters: Int32Array, rowOffset: int, patterns: Int32Array[]) {
this.recordPattern(row, rowOffset, counters);
let bestVariance = this.MAX_AVG_VARIANCE;
let bestMatch = -1;
let max = patterns.length;
for (let i = 0; i < max; i++) {
let pattern = patterns[i];
let variance = OneDReader.patternMatchVariance(counters, pattern, AbstractUPCEANReader.MAX_INDIVIDUAL_VARIANCE);
if (variance < bestVariance) {
bestVariance = variance;
bestMatch = i;
}
}
if (bestMatch >= 0) {
return bestMatch;
} else {
throw new NotFoundException();
}
}
/**
* Get the format of this decoder.
*
* @return The 1D format.
*/
public abstract 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
*/
public abstract decodeMiddle(row: BitArray, startRange: Int32Array, resultString: /*StringBuilder*/string);
}