mirror of https://github.com/NekoX-Dev/NekoX.git
190 lines
6.6 KiB
Java
Executable File
190 lines
6.6 KiB
Java
Executable File
/*
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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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package com.google.zxing.qrcode.decoder;
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import com.google.zxing.ChecksumException;
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import com.google.zxing.DecodeHintType;
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import com.google.zxing.FormatException;
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import com.google.zxing.common.BitMatrix;
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import com.google.zxing.common.DecoderResult;
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import com.google.zxing.common.reedsolomon.GenericGF;
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import com.google.zxing.common.reedsolomon.ReedSolomonDecoder;
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import com.google.zxing.common.reedsolomon.ReedSolomonException;
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import java.util.Map;
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/**
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* <p>The main class which implements QR Code decoding -- as opposed to locating and extracting
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* the QR Code from an image.</p>
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*
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* @author Sean Owen
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*/
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public final class Decoder {
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private final ReedSolomonDecoder rsDecoder;
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public Decoder() {
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rsDecoder = new ReedSolomonDecoder(GenericGF.QR_CODE_FIELD_256);
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}
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public DecoderResult decode(boolean[][] image) throws ChecksumException, FormatException {
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return decode(image, null);
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}
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/**
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* <p>Convenience method that can decode a QR Code represented as a 2D array of booleans.
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* "true" is taken to mean a black module.</p>
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*
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* @param image booleans representing white/black QR Code modules
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* @param hints decoding hints that should be used to influence decoding
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* @return text and bytes encoded within the QR Code
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* @throws FormatException if the QR Code cannot be decoded
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* @throws ChecksumException if error correction fails
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*/
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public DecoderResult decode(boolean[][] image, Map<DecodeHintType,?> hints)
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throws ChecksumException, FormatException {
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return decode(BitMatrix.parse(image), hints);
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}
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public DecoderResult decode(BitMatrix bits) throws ChecksumException, FormatException {
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return decode(bits, null);
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}
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/**
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* <p>Decodes a QR Code represented as a {@link BitMatrix}. A 1 or "true" is taken to mean a black module.</p>
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*
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* @param bits booleans representing white/black QR Code modules
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* @param hints decoding hints that should be used to influence decoding
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* @return text and bytes encoded within the QR Code
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* @throws FormatException if the QR Code cannot be decoded
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* @throws ChecksumException if error correction fails
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*/
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public DecoderResult decode(BitMatrix bits, Map<DecodeHintType,?> hints)
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throws FormatException, ChecksumException {
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// Construct a parser and read version, error-correction level
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BitMatrixParser parser = new BitMatrixParser(bits);
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FormatException fe = null;
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ChecksumException ce = null;
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try {
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return decode(parser, hints);
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} catch (FormatException e) {
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fe = e;
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} catch (ChecksumException e) {
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ce = e;
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}
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try {
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// Revert the bit matrix
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parser.remask();
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// Will be attempting a mirrored reading of the version and format info.
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parser.setMirror(true);
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// Preemptively read the version.
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parser.readVersion();
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// Preemptively read the format information.
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parser.readFormatInformation();
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/*
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* Since we're here, this means we have successfully detected some kind
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* of version and format information when mirrored. This is a good sign,
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* that the QR code may be mirrored, and we should try once more with a
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* mirrored content.
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*/
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// Prepare for a mirrored reading.
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parser.mirror();
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DecoderResult result = decode(parser, hints);
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// Success! Notify the caller that the code was mirrored.
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result.setOther(new QRCodeDecoderMetaData(true));
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return result;
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} catch (FormatException | ChecksumException e) {
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// Throw the exception from the original reading
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if (fe != null) {
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throw fe;
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}
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throw ce; // If fe is null, this can't be
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}
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}
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private DecoderResult decode(BitMatrixParser parser, Map<DecodeHintType,?> hints)
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throws FormatException, ChecksumException {
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Version version = parser.readVersion();
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ErrorCorrectionLevel ecLevel = parser.readFormatInformation().getErrorCorrectionLevel();
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// Read codewords
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byte[] codewords = parser.readCodewords();
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// Separate into data blocks
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DataBlock[] dataBlocks = DataBlock.getDataBlocks(codewords, version, ecLevel);
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// Count total number of data bytes
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int totalBytes = 0;
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for (DataBlock dataBlock : dataBlocks) {
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totalBytes += dataBlock.getNumDataCodewords();
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}
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byte[] resultBytes = new byte[totalBytes];
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int resultOffset = 0;
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// Error-correct and copy data blocks together into a stream of bytes
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for (DataBlock dataBlock : dataBlocks) {
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byte[] codewordBytes = dataBlock.getCodewords();
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int numDataCodewords = dataBlock.getNumDataCodewords();
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correctErrors(codewordBytes, numDataCodewords);
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for (int i = 0; i < numDataCodewords; i++) {
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resultBytes[resultOffset++] = codewordBytes[i];
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}
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}
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// Decode the contents of that stream of bytes
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return DecodedBitStreamParser.decode(resultBytes, version, ecLevel, hints);
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}
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/**
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* <p>Given data and error-correction codewords received, possibly corrupted by errors, attempts to
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* correct the errors in-place using Reed-Solomon error correction.</p>
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*
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* @param codewordBytes data and error correction codewords
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* @param numDataCodewords number of codewords that are data bytes
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* @throws ChecksumException if error correction fails
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*/
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private void correctErrors(byte[] codewordBytes, int numDataCodewords) throws ChecksumException {
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int numCodewords = codewordBytes.length;
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// First read into an array of ints
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int[] codewordsInts = new int[numCodewords];
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for (int i = 0; i < numCodewords; i++) {
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codewordsInts[i] = codewordBytes[i] & 0xFF;
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}
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try {
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rsDecoder.decode(codewordsInts, codewordBytes.length - numDataCodewords);
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} catch (ReedSolomonException ignored) {
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throw ChecksumException.getChecksumInstance();
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}
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// Copy back into array of bytes -- only need to worry about the bytes that were data
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// We don't care about errors in the error-correction codewords
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for (int i = 0; i < numDataCodewords; i++) {
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codewordBytes[i] = (byte) codewordsInts[i];
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}
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}
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}
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