/*
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* Copyright 2007 ZXing authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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import Version from './Version';
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import FormatInformation from './FormatInformation';
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import DataMask from './DataMask';
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import FormatException from '../../FormatException';
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/**
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* @author Sean Owen
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*/
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export default class BitMatrixParser {
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/**
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* @param bitMatrix {@link BitMatrix} to parse
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* @throws FormatException if dimension is not >= 21 and 1 mod 4
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*/
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constructor(bitMatrix) {
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const dimension = bitMatrix.getHeight();
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if (dimension < 21 || (dimension & 0x03) !== 1) {
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throw new FormatException();
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}
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this.bitMatrix = bitMatrix;
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}
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/**
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* <p>Reads format information from one of its two locations within the QR Code.</p>
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*
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* @return {@link FormatInformation} encapsulating the QR Code's format info
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* @throws FormatException if both format information locations cannot be parsed as
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* the valid encoding of format information
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*/
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readFormatInformation() {
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if (this.parsedFormatInfo !== null && this.parsedFormatInfo !== undefined) {
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return this.parsedFormatInfo;
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}
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// Read top-left format info bits
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let formatInfoBits1 = 0;
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for (let i = 0; i < 6; i++) {
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formatInfoBits1 = this.copyBit(i, 8, formatInfoBits1);
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}
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// .. and skip a bit in the timing pattern ...
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formatInfoBits1 = this.copyBit(7, 8, formatInfoBits1);
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formatInfoBits1 = this.copyBit(8, 8, formatInfoBits1);
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formatInfoBits1 = this.copyBit(8, 7, formatInfoBits1);
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// .. and skip a bit in the timing pattern ...
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for (let j = 5; j >= 0; j--) {
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formatInfoBits1 = this.copyBit(8, j, formatInfoBits1);
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}
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// Read the top-right/bottom-left pattern too
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const dimension = this.bitMatrix.getHeight();
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let formatInfoBits2 = 0;
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const jMin = dimension - 7;
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for (let j = dimension - 1; j >= jMin; j--) {
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formatInfoBits2 = this.copyBit(8, j, formatInfoBits2);
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}
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for (let i = dimension - 8; i < dimension; i++) {
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formatInfoBits2 = this.copyBit(i, 8, formatInfoBits2);
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}
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this.parsedFormatInfo = FormatInformation.decodeFormatInformation(formatInfoBits1, formatInfoBits2);
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if (this.parsedFormatInfo !== null) {
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return this.parsedFormatInfo;
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}
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throw new FormatException();
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}
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/**
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* <p>Reads version information from one of its two locations within the QR Code.</p>
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*
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* @return {@link Version} encapsulating the QR Code's version
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* @throws FormatException if both version information locations cannot be parsed as
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* the valid encoding of version information
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*/
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readVersion() {
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if (this.parsedVersion !== null && this.parsedVersion !== undefined) {
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return this.parsedVersion;
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}
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const dimension = this.bitMatrix.getHeight();
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const provisionalVersion = Math.floor((dimension - 17) / 4);
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if (provisionalVersion <= 6) {
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return Version.getVersionForNumber(provisionalVersion);
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}
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// Read top-right version info: 3 wide by 6 tall
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let versionBits = 0;
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const ijMin = dimension - 11;
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for (let j = 5; j >= 0; j--) {
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for (let i = dimension - 9; i >= ijMin; i--) {
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versionBits = this.copyBit(i, j, versionBits);
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}
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}
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let theParsedVersion = Version.decodeVersionInformation(versionBits);
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if (theParsedVersion !== null && theParsedVersion.getDimensionForVersion() === dimension) {
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this.parsedVersion = theParsedVersion;
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return theParsedVersion;
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}
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// Hmm, failed. Try bottom left: 6 wide by 3 tall
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versionBits = 0;
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for (let i = 5; i >= 0; i--) {
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for (let j = dimension - 9; j >= ijMin; j--) {
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versionBits = this.copyBit(i, j, versionBits);
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}
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}
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theParsedVersion = Version.decodeVersionInformation(versionBits);
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if (theParsedVersion !== null && theParsedVersion.getDimensionForVersion() === dimension) {
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this.parsedVersion = theParsedVersion;
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return theParsedVersion;
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}
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throw new FormatException();
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}
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copyBit(i /*int*/, j /*int*/, versionBits /*int*/) {
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const bit = this.isMirror ? this.bitMatrix.get(j, i) : this.bitMatrix.get(i, j);
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return bit ? (versionBits << 1) | 0x1 : versionBits << 1;
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}
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/**
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* <p>Reads the bits in the {@link BitMatrix} representing the finder pattern in the
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* correct order in order to reconstruct the codewords bytes contained within the
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* QR Code.</p>
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*
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* @return bytes encoded within the QR Code
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* @throws FormatException if the exact number of bytes expected is not read
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*/
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readCodewords() {
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const formatInfo = this.readFormatInformation();
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const version = this.readVersion();
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// Get the data mask for the format used in this QR Code. This will exclude
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// some bits from reading as we wind through the bit matrix.
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const dataMask = DataMask.values.get(formatInfo.getDataMask());
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const dimension = this.bitMatrix.getHeight();
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dataMask.unmaskBitMatrix(this.bitMatrix, dimension);
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const functionPattern = version.buildFunctionPattern();
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let readingUp = true;
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const result = new Uint8Array(version.getTotalCodewords());
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let resultOffset = 0;
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let currentByte = 0;
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let bitsRead = 0;
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// Read columns in pairs, from right to left
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for (let j = dimension - 1; j > 0; j -= 2) {
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if (j === 6) {
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// Skip whole column with vertical alignment pattern
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// saves time and makes the other code proceed more cleanly
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j--;
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}
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// Read alternatingly from bottom to top then top to bottom
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for (let count = 0; count < dimension; count++) {
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const i = readingUp ? dimension - 1 - count : count;
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for (let col = 0; col < 2; col++) {
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// Ignore bits covered by the function pattern
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if (!functionPattern.get(j - col, i)) {
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// Read a bit
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bitsRead++;
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currentByte <<= 1;
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if (this.bitMatrix.get(j - col, i)) {
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currentByte |= 1;
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}
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// If we've made a whole byte, save it off
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if (bitsRead === 8) {
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result[resultOffset++] = /*(byte) */ currentByte;
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bitsRead = 0;
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currentByte = 0;
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}
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}
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}
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}
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readingUp = !readingUp; // readingUp ^= true; // readingUp = !readingUp; // switch directions
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}
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if (resultOffset !== version.getTotalCodewords()) {
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throw new FormatException();
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}
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return result;
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}
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/**
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* Revert the mask removal done while reading the code words. The bit matrix should revert to its original state.
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*/
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remask() {
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if (this.parsedFormatInfo === null) {
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return; // We have no format information, and have no data mask
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}
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const dataMask = DataMask.values.get(this.parsedFormatInfo.getDataMask());
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const dimension = this.bitMatrix.getHeight();
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dataMask.unmaskBitMatrix(this.bitMatrix, dimension);
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}
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/**
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* Prepare the parser for a mirrored operation.
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* This flag has effect only on the {@link #readFormatInformation()} and the
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* {@link #readVersion()}. Before proceeding with {@link #readCodewords()} the
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* {@link #mirror()} method should be called.
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*
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* @param mirror Whether to read version and format information mirrored.
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*/
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setMirror(isMirror) {
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this.parsedVersion = null;
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this.parsedFormatInfo = null;
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this.isMirror = isMirror;
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}
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/** Mirror the bit matrix in order to attempt a second reading. */
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mirror() {
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const bitMatrix = this.bitMatrix;
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for (let x = 0, width = bitMatrix.getWidth(); x < width; x++) {
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for (let y = x + 1, height = bitMatrix.getHeight(); y < height; y++) {
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if (bitMatrix.get(x, y) !== bitMatrix.get(y, x)) {
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bitMatrix.flip(y, x);
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bitMatrix.flip(x, y);
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}
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}
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}
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}
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}
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