mirror of
https://github.com/octoleo/plantuml.git
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172 lines
5.5 KiB
Java
172 lines
5.5 KiB
Java
/*
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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 zext.plantuml.com.google.zxing.qrcode.decoder;
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/**
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* <p>Encapsulates a QR Code's format information, including the data mask used and
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* error correction level.</p>
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*
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* @author Sean Owen
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* @see DataMask
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* @see ErrorCorrectionLevel
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*/
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final class FormatInformation {
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private static final int FORMAT_INFO_MASK_QR = 0x5412;
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/**
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* See ISO 18004:2006, Annex C, Table C.1
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*/
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private static final int[][] FORMAT_INFO_DECODE_LOOKUP = {
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{0x5412, 0x00},
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{0x5125, 0x01},
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{0x5E7C, 0x02},
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{0x5B4B, 0x03},
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{0x45F9, 0x04},
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{0x40CE, 0x05},
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{0x4F97, 0x06},
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{0x4AA0, 0x07},
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{0x77C4, 0x08},
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{0x72F3, 0x09},
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{0x7DAA, 0x0A},
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{0x789D, 0x0B},
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{0x662F, 0x0C},
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{0x6318, 0x0D},
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{0x6C41, 0x0E},
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{0x6976, 0x0F},
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{0x1689, 0x10},
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{0x13BE, 0x11},
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{0x1CE7, 0x12},
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{0x19D0, 0x13},
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{0x0762, 0x14},
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{0x0255, 0x15},
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{0x0D0C, 0x16},
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{0x083B, 0x17},
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{0x355F, 0x18},
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{0x3068, 0x19},
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{0x3F31, 0x1A},
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{0x3A06, 0x1B},
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{0x24B4, 0x1C},
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{0x2183, 0x1D},
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{0x2EDA, 0x1E},
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{0x2BED, 0x1F},
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};
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/**
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* Offset i holds the number of 1 bits in the binary representation of i
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*/
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private static final int[] BITS_SET_IN_HALF_BYTE =
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{0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4};
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private final ErrorCorrectionLevel errorCorrectionLevel;
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private final byte dataMask;
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private FormatInformation(int formatInfo) {
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// Bits 3,4
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errorCorrectionLevel = ErrorCorrectionLevel.forBits((formatInfo >> 3) & 0x03);
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// Bottom 3 bits
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dataMask = (byte) (formatInfo & 0x07);
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}
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static int numBitsDiffering(int a, int b) {
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a ^= b; // a now has a 1 bit exactly where its bit differs with b's
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// Count bits set quickly with a series of lookups:
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return BITS_SET_IN_HALF_BYTE[a & 0x0F] +
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BITS_SET_IN_HALF_BYTE[(a >>> 4 & 0x0F)] +
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BITS_SET_IN_HALF_BYTE[(a >>> 8 & 0x0F)] +
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BITS_SET_IN_HALF_BYTE[(a >>> 12 & 0x0F)] +
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BITS_SET_IN_HALF_BYTE[(a >>> 16 & 0x0F)] +
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BITS_SET_IN_HALF_BYTE[(a >>> 20 & 0x0F)] +
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BITS_SET_IN_HALF_BYTE[(a >>> 24 & 0x0F)] +
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BITS_SET_IN_HALF_BYTE[(a >>> 28 & 0x0F)];
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}
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/**
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* @param maskedFormatInfo1 format info indicator, with mask still applied
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* @param maskedFormatInfo2 second copy of same info; both are checked at the same time
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* to establish best match
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* @return information about the format it specifies, or <code>null</code>
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* if doesn't seem to match any known pattern
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*/
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static FormatInformation decodeFormatInformation(int maskedFormatInfo1, int maskedFormatInfo2) {
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FormatInformation formatInfo = doDecodeFormatInformation(maskedFormatInfo1, maskedFormatInfo2);
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if (formatInfo != null) {
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return formatInfo;
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}
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// Should return null, but, some QR codes apparently
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// do not mask this info. Try again by actually masking the pattern
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// first
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return doDecodeFormatInformation(maskedFormatInfo1 ^ FORMAT_INFO_MASK_QR,
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maskedFormatInfo2 ^ FORMAT_INFO_MASK_QR);
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}
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private static FormatInformation doDecodeFormatInformation(int maskedFormatInfo1, int maskedFormatInfo2) {
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// Find the int in FORMAT_INFO_DECODE_LOOKUP with fewest bits differing
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int bestDifference = Integer.MAX_VALUE;
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int bestFormatInfo = 0;
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for (int i = 0; i < FORMAT_INFO_DECODE_LOOKUP.length; i++) {
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int[] decodeInfo = FORMAT_INFO_DECODE_LOOKUP[i];
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int targetInfo = decodeInfo[0];
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if (targetInfo == maskedFormatInfo1 || targetInfo == maskedFormatInfo2) {
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// Found an exact match
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return new FormatInformation(decodeInfo[1]);
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}
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int bitsDifference = numBitsDiffering(maskedFormatInfo1, targetInfo);
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if (bitsDifference < bestDifference) {
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bestFormatInfo = decodeInfo[1];
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bestDifference = bitsDifference;
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}
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if (maskedFormatInfo1 != maskedFormatInfo2) {
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// also try the other option
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bitsDifference = numBitsDiffering(maskedFormatInfo2, targetInfo);
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if (bitsDifference < bestDifference) {
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bestFormatInfo = decodeInfo[1];
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bestDifference = bitsDifference;
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}
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}
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}
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// Hamming distance of the 32 masked codes is 7, by construction, so <= 3 bits
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// differing means we found a match
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if (bestDifference <= 3) {
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return new FormatInformation(bestFormatInfo);
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}
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return null;
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}
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ErrorCorrectionLevel getErrorCorrectionLevel() {
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return errorCorrectionLevel;
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}
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byte getDataMask() {
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return dataMask;
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}
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public int hashCode() {
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return (errorCorrectionLevel.ordinal() << 3) | (int) dataMask;
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}
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public boolean equals(Object o) {
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if (!(o instanceof FormatInformation)) {
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return false;
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}
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FormatInformation other = (FormatInformation) o;
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return this.errorCorrectionLevel == other.errorCorrectionLevel &&
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this.dataMask == other.dataMask;
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}
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}
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