csharp/qrcode/decoder/DataBlock.cs

   1 /*\r
   2 * Copyright 2007 ZXing authors\r
   3 *\r
   4 * Licensed under the Apache License, Version 2.0 (the "License");\r
   5 * you may not use this file except in compliance with the License.\r
   6 * You may obtain a copy of the License at\r
   7 *\r
   8 *      http://www.apache.org/licenses/LICENSE-2.0\r
   9 *\r
  10 * Unless required by applicable law or agreed to in writing, software\r
  11 * distributed under the License is distributed on an "AS IS" BASIS,\r
  12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\r
  13 * See the License for the specific language governing permissions and\r
  14 * limitations under the License.\r
  15 */\r
  16 using System;\r
  17 namespace com.google.zxing.qrcode.decoder\r
  18 {\r
  19         \r
  20         /// <summary> <p>Encapsulates a block of data within a QR Code. QR Codes may split their data into\r
  21         /// multiple blocks, each of which is a unit of data and error-correction codewords. Each\r
  22         /// is represented by an instance of this class.</p>\r
  23         /// \r
  24         /// </summary>\r
  25         /// <author>  Sean Owen\r
  26         /// </author>\r
  27         /// <author>www.Redivivus.in (suraj.supekar@redivivus.in) - Ported from ZXING Java Source \r
  28         /// </author>\r
  29         sealed class DataBlock\r
  30         {\r
  31                 internal int NumDataCodewords\r
  32                 {\r
  33                         get\r
  34                         {\r
  35                                 return numDataCodewords;\r
  36                         }\r
  37                         \r
  38                 }\r
  39                 internal sbyte[] Codewords\r
  40                 {\r
  41                         get\r
  42                         {\r
  43                                 return codewords;\r
  44                         }\r
  45                         \r
  46                 }\r
  47                 \r
  48                 //UPGRADE_NOTE: Final was removed from the declaration of 'numDataCodewords '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"\r
  49                 private int numDataCodewords;\r
  50                 //UPGRADE_NOTE: Final was removed from the declaration of 'codewords '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"\r
  51                 private sbyte[] codewords;\r
  52                 \r
  53                 private DataBlock(int numDataCodewords, sbyte[] codewords)\r
  54                 {\r
  55                         this.numDataCodewords = numDataCodewords;\r
  56                         this.codewords = codewords;\r
  57                 }\r
  58                 \r
  59                 /// <summary> <p>When QR Codes use multiple data blocks, they are actually interleaved.\r
  60                 /// That is, the first byte of data block 1 to n is written, then the second bytes, and so on. This\r
  61                 /// method will separate the data into original blocks.</p>\r
  62                 /// \r
  63                 /// </summary>\r
  64                 /// <param name="rawCodewords">bytes as read directly from the QR Code\r
  65                 /// </param>\r
  66                 /// <param name="version">version of the QR Code\r
  67                 /// </param>\r
  68                 /// <param name="ecLevel">error-correction level of the QR Code\r
  69                 /// </param>\r
  70                 /// <returns> {@link DataBlock}s containing original bytes, "de-interleaved" from representation in the\r
  71                 /// QR Code\r
  72                 /// </returns>\r
  73                 internal static DataBlock[] getDataBlocks(sbyte[] rawCodewords, Version version, ErrorCorrectionLevel ecLevel)\r
  74                 {\r
  75                         \r
  76                         if (rawCodewords.Length != version.TotalCodewords)\r
  77                         {\r
  78                                 throw new System.ArgumentException();\r
  79                         }\r
  80                         \r
  81                         // Figure out the number and size of data blocks used by this version and\r
  82                         // error correction level\r
  83                         Version.ECBlocks ecBlocks = version.getECBlocksForLevel(ecLevel);\r
  84                         \r
  85                         // First count the total number of data blocks\r
  86                         int totalBlocks = 0;\r
  87                         Version.ECB[] ecBlockArray = ecBlocks.getECBlocks();\r
  88                         for (int i = 0; i < ecBlockArray.Length; i++)\r
  89                         {\r
  90                                 totalBlocks += ecBlockArray[i].Count;\r
  91                         }\r
  92                         \r
  93                         // Now establish DataBlocks of the appropriate size and number of data codewords\r
  94                         DataBlock[] result = new DataBlock[totalBlocks];\r
  95                         int numResultBlocks = 0;\r
  96                         for (int j = 0; j < ecBlockArray.Length; j++)\r
  97                         {\r
  98                                 Version.ECB ecBlock = ecBlockArray[j];\r
  99                                 for (int i = 0; i < ecBlock.Count; i++)\r
 100                                 {\r
 101                                         int numDataCodewords = ecBlock.DataCodewords;\r
 102                                         int numBlockCodewords = ecBlocks.ECCodewordsPerBlock + numDataCodewords;\r
 103                                         result[numResultBlocks++] = new DataBlock(numDataCodewords, new sbyte[numBlockCodewords]);\r
 104                                 }\r
 105                         }\r
 106                         \r
 107                         // All blocks have the same amount of data, except that the last n\r
 108                         // (where n may be 0) have 1 more byte. Figure out where these start.\r
 109                         int shorterBlocksTotalCodewords = result[0].codewords.Length;\r
 110                         int longerBlocksStartAt = result.Length - 1;\r
 111                         while (longerBlocksStartAt >= 0)\r
 112                         {\r
 113                                 int numCodewords = result[longerBlocksStartAt].codewords.Length;\r
 114                                 if (numCodewords == shorterBlocksTotalCodewords)\r
 115                                 {\r
 116                                         break;\r
 117                                 }\r
 118                                 longerBlocksStartAt--;\r
 119                         }\r
 120                         longerBlocksStartAt++;\r
 121                         \r
 122                         int shorterBlocksNumDataCodewords = shorterBlocksTotalCodewords - ecBlocks.ECCodewordsPerBlock;\r
 123                         // The last elements of result may be 1 element longer;\r
 124                         // first fill out as many elements as all of them have\r
 125                         int rawCodewordsOffset = 0;\r
 126                         for (int i = 0; i < shorterBlocksNumDataCodewords; i++)\r
 127                         {\r
 128                                 for (int j = 0; j < numResultBlocks; j++)\r
 129                                 {\r
 130                                         result[j].codewords[i] = rawCodewords[rawCodewordsOffset++];\r
 131                                 }\r
 132                         }\r
 133                         // Fill out the last data block in the longer ones\r
 134                         for (int j = longerBlocksStartAt; j < numResultBlocks; j++)\r
 135                         {\r
 136                                 result[j].codewords[shorterBlocksNumDataCodewords] = rawCodewords[rawCodewordsOffset++];\r
 137                         }\r
 138                         // Now add in error correction blocks\r
 139                         int max = result[0].codewords.Length;\r
 140                         for (int i = shorterBlocksNumDataCodewords; i < max; i++)\r
 141                         {\r
 142                                 for (int j = 0; j < numResultBlocks; j++)\r
 143                                 {\r
 144                                         int iOffset = j < longerBlocksStartAt?i:i + 1;\r
 145                                         result[j].codewords[iOffset] = rawCodewords[rawCodewordsOffset++];\r
 146                                 }\r
 147                         }\r
 148                         return result;\r
 149                 }\r
 150         }\r
 151 }