mirror of
https://github.com/octoleo/plantuml.git
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156 lines
4.2 KiB
Java
156 lines
4.2 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 com.google.zxing.qrcode.decoder;
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import com.google.zxing.common.BitMatrix;
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/**
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* <p>Encapsulates data masks for the data bits in a QR code, per ISO 18004:2006 6.8. Implementations
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* of this class can un-mask a raw BitMatrix. For simplicity, they will unmask the entire BitMatrix,
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* including areas used for finder patterns, timing patterns, etc. These areas should be unused
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* after the point they are unmasked anyway.</p>
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*
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* <p>Note that the diagram in section 6.8.1 is misleading since it indicates that i is column position
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* and j is row position. In fact, as the text says, i is row position and j is column position.</p>
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*
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* @author Sean Owen
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*/
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abstract class DataMask {
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/**
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* See ISO 18004:2006 6.8.1
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*/
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private static final DataMask[] DATA_MASKS = {
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new DataMask000(),
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new DataMask001(),
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new DataMask010(),
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new DataMask011(),
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new DataMask100(),
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new DataMask101(),
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new DataMask110(),
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new DataMask111(),
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};
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private DataMask() {
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}
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/**
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* <p>Implementations of this method reverse the data masking process applied to a QR Code and
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* make its bits ready to read.</p>
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*
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* @param bits representation of QR Code bits
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* @param dimension dimension of QR Code, represented by bits, being unmasked
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*/
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final void unmaskBitMatrix(BitMatrix bits, int dimension) {
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for (int i = 0; i < dimension; i++) {
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for (int j = 0; j < dimension; j++) {
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if (isMasked(i, j)) {
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bits.flip(j, i);
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}
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}
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}
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}
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abstract boolean isMasked(int i, int j);
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/**
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* @param reference a value between 0 and 7 indicating one of the eight possible
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* data mask patterns a QR Code may use
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* @return {@link DataMask} encapsulating the data mask pattern
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*/
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static DataMask forReference(int reference) {
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if (reference < 0 || reference > 7) {
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throw new IllegalArgumentException();
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}
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return DATA_MASKS[reference];
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}
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/**
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* 000: mask bits for which (x + y) mod 2 == 0
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*/
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private static class DataMask000 extends DataMask {
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boolean isMasked(int i, int j) {
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return ((i + j) & 0x01) == 0;
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}
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}
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/**
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* 001: mask bits for which x mod 2 == 0
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*/
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private static class DataMask001 extends DataMask {
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boolean isMasked(int i, int j) {
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return (i & 0x01) == 0;
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}
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}
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/**
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* 010: mask bits for which y mod 3 == 0
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*/
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private static class DataMask010 extends DataMask {
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boolean isMasked(int i, int j) {
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return j % 3 == 0;
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}
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}
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/**
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* 011: mask bits for which (x + y) mod 3 == 0
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*/
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private static class DataMask011 extends DataMask {
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boolean isMasked(int i, int j) {
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return (i + j) % 3 == 0;
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}
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}
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/**
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* 100: mask bits for which (x/2 + y/3) mod 2 == 0
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*/
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private static class DataMask100 extends DataMask {
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boolean isMasked(int i, int j) {
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return (((i >>> 1) + (j /3)) & 0x01) == 0;
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}
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}
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/**
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* 101: mask bits for which xy mod 2 + xy mod 3 == 0
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*/
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private static class DataMask101 extends DataMask {
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boolean isMasked(int i, int j) {
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int temp = i * j;
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return (temp & 0x01) + (temp % 3) == 0;
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}
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}
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/**
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* 110: mask bits for which (xy mod 2 + xy mod 3) mod 2 == 0
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*/
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private static class DataMask110 extends DataMask {
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boolean isMasked(int i, int j) {
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int temp = i * j;
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return (((temp & 0x01) + (temp % 3)) & 0x01) == 0;
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}
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}
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/**
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* 111: mask bits for which ((x+y)mod 2 + xy mod 3) mod 2 == 0
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*/
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private static class DataMask111 extends DataMask {
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boolean isMasked(int i, int j) {
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return ((((i + j) & 0x01) + ((i * j) % 3)) & 0x01) == 0;
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}
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}
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}
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