2 * Copyright 2007 ZXing authors
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4 * Licensed under the Apache License, Version 2.0 (the "License");
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5 * you may not use this file except in compliance with the License.
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6 * You may obtain a copy of the License at
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8 * http://www.apache.org/licenses/LICENSE-2.0
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10 * Unless required by applicable law or agreed to in writing, software
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11 * distributed under the License is distributed on an "AS IS" BASIS,
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12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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13 * See the License for the specific language governing permissions and
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14 * limitations under the License.
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17 using BitMatrix = com.google.zxing.common.BitMatrix;
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18 namespace com.google.zxing.qrcode.decoder
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21 /// <summary> <p>Encapsulates data masks for the data bits in a QR code, per ISO 18004:2006 6.8. Implementations
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22 /// of this class can un-mask a raw BitMatrix. For simplicity, they will unmask the entire BitMatrix,
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23 /// including areas used for finder patterns, timing patterns, etc. These areas should be unused
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24 /// after the point they are unmasked anyway.</p>
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26 /// <p>Note that the diagram in section 6.8.1 is misleading since it indicates that i is column position
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27 /// 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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30 /// <author> Sean Owen
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32 /// <author>www.Redivivus.in (suraj.supekar@redivivus.in) - Ported from ZXING Java Source
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34 abstract class DataMask
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37 /// <summary> See ISO 18004:2006 6.8.1</summary>
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38 //UPGRADE_NOTE: Final was removed from the declaration of 'DATA_MASKS '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
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39 private static readonly DataMask[] DATA_MASKS = new DataMask[]{new DataMask000(), new DataMask001(), new DataMask010(), new DataMask011(), new DataMask100(), new DataMask101(), new DataMask110(), new DataMask111()};
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45 /// <summary> <p>Implementations of this method reverse the data masking process applied to a QR Code and
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46 /// make its bits ready to read.</p>
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49 /// <param name="bits">representation of QR Code bits
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51 /// <param name="dimension">dimension of QR Code, represented by bits, being unmasked
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53 internal void unmaskBitMatrix(BitMatrix bits, int dimension)
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55 for (int i = 0; i < dimension; i++)
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57 for (int j = 0; j < dimension; j++)
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67 internal abstract bool isMasked(int i, int j);
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69 /// <param name="reference">a value between 0 and 7 indicating one of the eight possible
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70 /// data mask patterns a QR Code may use
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72 /// <returns> {@link DataMask} encapsulating the data mask pattern
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74 internal static DataMask forReference(int reference)
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76 if (reference < 0 || reference > 7)
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78 throw new System.ArgumentException();
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80 return DATA_MASKS[reference];
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83 /// <summary> 000: mask bits for which (x + y) mod 2 == 0</summary>
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84 private class DataMask000:DataMask
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86 internal override bool isMasked(int i, int j)
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88 return ((i + j) & 0x01) == 0;
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92 /// <summary> 001: mask bits for which x mod 2 == 0</summary>
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93 private class DataMask001:DataMask
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95 internal override bool isMasked(int i, int j)
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97 return (i & 0x01) == 0;
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101 /// <summary> 010: mask bits for which y mod 3 == 0</summary>
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102 private class DataMask010:DataMask
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104 internal override bool isMasked(int i, int j)
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110 /// <summary> 011: mask bits for which (x + y) mod 3 == 0</summary>
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111 private class DataMask011:DataMask
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113 internal override bool isMasked(int i, int j)
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115 return (i + j) % 3 == 0;
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119 /// <summary> 100: mask bits for which (x/2 + y/3) mod 2 == 0</summary>
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120 private class DataMask100:DataMask
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122 internal override bool isMasked(int i, int j)
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124 return (((SupportClass.URShift(i, 1)) + (j / 3)) & 0x01) == 0;
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128 /// <summary> 101: mask bits for which xy mod 2 + xy mod 3 == 0</summary>
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129 private class DataMask101:DataMask
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131 internal override bool isMasked(int i, int j)
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134 return (temp & 0x01) + (temp % 3) == 0;
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138 /// <summary> 110: mask bits for which (xy mod 2 + xy mod 3) mod 2 == 0</summary>
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139 private class DataMask110:DataMask
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141 internal override bool isMasked(int i, int j)
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144 return (((temp & 0x01) + (temp % 3)) & 0x01) == 0;
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148 /// <summary> 111: mask bits for which ((x+y)mod 2 + xy mod 3) mod 2 == 0</summary>
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149 private class DataMask111:DataMask
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151 internal override bool isMasked(int i, int j)
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153 return ((((i + j) & 0x01) + ((i * j) % 3)) & 0x01) == 0;
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