@zxing/library
Version:
TypeScript port of ZXing multi-format 1D/2D barcode image processing library.
124 lines (123 loc) • 4.15 kB
JavaScript
/*
* 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.
*/
/*namespace com.google.zxing.oned {*/
import BarcodeFormat from '../BarcodeFormat';
import NotFoundException from '../NotFoundException';
import OneDReader from './OneDReader';
import Result from '../Result';
import ResultPoint from '../ResultPoint';
/**
* <p>Decodes CodaBar barcodes. </p>
*
* @author Evan @dodobelieve
* @see CodaBarReader
*/
export default class CodaBarReader extends OneDReader {
constructor() {
super(...arguments);
this.CODA_BAR_CHAR_SET = {
nnnnnww: '0',
nnnnwwn: '1',
nnnwnnw: '2',
wwnnnnn: '3',
nnwnnwn: '4',
wnnnnwn: '5',
nwnnnnw: '6',
nwnnwnn: '7',
nwwnnnn: '8',
wnnwnnn: '9',
nnnwwnn: '-',
nnwwnnn: '$',
wnnnwnw: ':',
wnwnnnw: '/',
wnwnwnn: '.',
nnwwwww: '+',
nnwwnwn: 'A',
nwnwnnw: 'B',
nnnwnww: 'C',
nnnwwwn: 'D'
};
}
decodeRow(rowNumber, row, hints) {
let validRowData = this.getValidRowData(row);
if (!validRowData)
throw new NotFoundException();
let retStr = this.codaBarDecodeRow(validRowData.row);
if (!retStr)
throw new NotFoundException();
return new Result(retStr, null, 0, [new ResultPoint(validRowData.left, rowNumber), new ResultPoint(validRowData.right, rowNumber)], BarcodeFormat.CODABAR, new Date().getTime());
}
/**
* converts bit array to valid data array(lengths of black bits and white bits)
* @param row bit array to convert
*/
getValidRowData(row) {
let booleanArr = row.toArray();
let startIndex = booleanArr.indexOf(true);
if (startIndex === -1)
return null;
let lastIndex = booleanArr.lastIndexOf(true);
if (lastIndex <= startIndex)
return null;
booleanArr = booleanArr.slice(startIndex, lastIndex + 1);
let result = [];
let lastBit = booleanArr[0];
let bitLength = 1;
for (let i = 1; i < booleanArr.length; i++) {
if (booleanArr[i] === lastBit) {
bitLength++;
}
else {
lastBit = booleanArr[i];
result.push(bitLength);
bitLength = 1;
}
}
result.push(bitLength);
// CodaBar code data valid
if (result.length < 23 && (result.length + 1) % 8 !== 0)
return null;
return { row: result, left: startIndex, right: lastIndex };
}
/**
* decode codabar code
* @param row row to cecode
*/
codaBarDecodeRow(row) {
const code = [];
const barThreshold = Math.ceil(row.reduce((pre, item) => (pre + item) / 2, 0));
// Read one encoded character at a time.
while (row.length > 0) {
const seg = row.splice(0, 8).splice(0, 7);
const key = seg.map(len => (len < barThreshold ? 'n' : 'w')).join('');
if (this.CODA_BAR_CHAR_SET[key] === undefined)
return null;
code.push(this.CODA_BAR_CHAR_SET[key]);
}
let strCode = code.join('');
if (this.validCodaBarString(strCode))
return strCode;
return null;
}
/**
* check if the string is a CodaBar string
* @param src string to determine
*/
validCodaBarString(src) {
let reg = /^[A-D].{1,}[A-D]$/;
return reg.test(src);
}
}