@zxing/library
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TypeScript port of ZXing multi-format 1D/2D barcode image processing library.
143 lines (142 loc) • 5.65 kB
JavaScript
/*
* Copyright 2007 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.qrcode.decoder {*/
import ErrorCorrectionLevel from './ErrorCorrectionLevel';
import Integer from '../../util/Integer';
/**
* <p>Encapsulates a QR Code's format information, including the data mask used and
* error correction level.</p>
*
* @author Sean Owen
* @see DataMask
* @see ErrorCorrectionLevel
*/
export default class FormatInformation {
constructor(formatInfo /*int*/) {
// Bits 3,4
this.errorCorrectionLevel = ErrorCorrectionLevel.forBits((formatInfo >> 3) & 0x03);
// Bottom 3 bits
this.dataMask = /*(byte) */ (formatInfo & 0x07);
}
static numBitsDiffering(a /*int*/, b /*int*/) {
return Integer.bitCount(a ^ b);
}
/**
* @param maskedFormatInfo1 format info indicator, with mask still applied
* @param maskedFormatInfo2 second copy of same info; both are checked at the same time
* to establish best match
* @return information about the format it specifies, or {@code null}
* if doesn't seem to match any known pattern
*/
static decodeFormatInformation(maskedFormatInfo1 /*int*/, maskedFormatInfo2 /*int*/) {
const formatInfo = FormatInformation.doDecodeFormatInformation(maskedFormatInfo1, maskedFormatInfo2);
if (formatInfo !== null) {
return formatInfo;
}
// Should return null, but, some QR codes apparently
// do not mask this info. Try again by actually masking the pattern
// first
return FormatInformation.doDecodeFormatInformation(maskedFormatInfo1 ^ FormatInformation.FORMAT_INFO_MASK_QR, maskedFormatInfo2 ^ FormatInformation.FORMAT_INFO_MASK_QR);
}
static doDecodeFormatInformation(maskedFormatInfo1 /*int*/, maskedFormatInfo2 /*int*/) {
// Find the int in FORMAT_INFO_DECODE_LOOKUP with fewest bits differing
let bestDifference = Number.MAX_SAFE_INTEGER;
let bestFormatInfo = 0;
for (const decodeInfo of FormatInformation.FORMAT_INFO_DECODE_LOOKUP) {
const targetInfo = decodeInfo[0];
if (targetInfo === maskedFormatInfo1 || targetInfo === maskedFormatInfo2) {
// Found an exact match
return new FormatInformation(decodeInfo[1]);
}
let bitsDifference = FormatInformation.numBitsDiffering(maskedFormatInfo1, targetInfo);
if (bitsDifference < bestDifference) {
bestFormatInfo = decodeInfo[1];
bestDifference = bitsDifference;
}
if (maskedFormatInfo1 !== maskedFormatInfo2) {
// also try the other option
bitsDifference = FormatInformation.numBitsDiffering(maskedFormatInfo2, targetInfo);
if (bitsDifference < bestDifference) {
bestFormatInfo = decodeInfo[1];
bestDifference = bitsDifference;
}
}
}
// Hamming distance of the 32 masked codes is 7, by construction, so <= 3 bits
// differing means we found a match
if (bestDifference <= 3) {
return new FormatInformation(bestFormatInfo);
}
return null;
}
getErrorCorrectionLevel() {
return this.errorCorrectionLevel;
}
getDataMask() {
return this.dataMask;
}
/*@Override*/
hashCode() {
return (this.errorCorrectionLevel.getBits() << 3) | this.dataMask;
}
/*@Override*/
equals(o) {
if (!(o instanceof FormatInformation)) {
return false;
}
const other = o;
return this.errorCorrectionLevel === other.errorCorrectionLevel &&
this.dataMask === other.dataMask;
}
}
FormatInformation.FORMAT_INFO_MASK_QR = 0x5412;
/**
* See ISO 18004:2006, Annex C, Table C.1
*/
FormatInformation.FORMAT_INFO_DECODE_LOOKUP = [
Int32Array.from([0x5412, 0x00]),
Int32Array.from([0x5125, 0x01]),
Int32Array.from([0x5E7C, 0x02]),
Int32Array.from([0x5B4B, 0x03]),
Int32Array.from([0x45F9, 0x04]),
Int32Array.from([0x40CE, 0x05]),
Int32Array.from([0x4F97, 0x06]),
Int32Array.from([0x4AA0, 0x07]),
Int32Array.from([0x77C4, 0x08]),
Int32Array.from([0x72F3, 0x09]),
Int32Array.from([0x7DAA, 0x0A]),
Int32Array.from([0x789D, 0x0B]),
Int32Array.from([0x662F, 0x0C]),
Int32Array.from([0x6318, 0x0D]),
Int32Array.from([0x6C41, 0x0E]),
Int32Array.from([0x6976, 0x0F]),
Int32Array.from([0x1689, 0x10]),
Int32Array.from([0x13BE, 0x11]),
Int32Array.from([0x1CE7, 0x12]),
Int32Array.from([0x19D0, 0x13]),
Int32Array.from([0x0762, 0x14]),
Int32Array.from([0x0255, 0x15]),
Int32Array.from([0x0D0C, 0x16]),
Int32Array.from([0x083B, 0x17]),
Int32Array.from([0x355F, 0x18]),
Int32Array.from([0x3068, 0x19]),
Int32Array.from([0x3F31, 0x1A]),
Int32Array.from([0x3A06, 0x1B]),
Int32Array.from([0x24B4, 0x1C]),
Int32Array.from([0x2183, 0x1D]),
Int32Array.from([0x2EDA, 0x1E]),
Int32Array.from([0x2BED, 0x1F]),
];