csharp/datamatrix/DataMatrixReader.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 using BarcodeFormat = com.google.zxing.BarcodeFormat;\r
  18 using DecodeHintType = com.google.zxing.DecodeHintType;\r
  19 using BinaryBitmap = com.google.zxing.BinaryBitmap;\r
  20 using Reader = com.google.zxing.Reader;\r
  21 using ReaderException = com.google.zxing.ReaderException;\r
  22 using Result = com.google.zxing.Result;\r
  23 using ResultPoint = com.google.zxing.ResultPoint;\r
  24 using ResultMetadataType = com.google.zxing.ResultMetadataType;\r
  25 using BitMatrix = com.google.zxing.common.BitMatrix;\r
  26 using DecoderResult = com.google.zxing.common.DecoderResult;\r
  27 using DetectorResult = com.google.zxing.common.DetectorResult;\r
  28 using Decoder = com.google.zxing.datamatrix.decoder.Decoder;\r
  29 using Detector = com.google.zxing.datamatrix.detector.Detector;\r
  30 namespace com.google.zxing.datamatrix\r
  31 {\r
  32         \r
  33         /// <summary> This implementation can detect and decode Data Matrix codes in an image.\r
  34         /// \r
  35         /// </summary>\r
  36         /// <author>  bbrown@google.com (Brian Brown)\r
  37         /// </author>\r
  38         /// <author>www.Redivivus.in (suraj.supekar@redivivus.in) - Ported from ZXING Java Source \r
  39         /// </author>\r
  40         public sealed class DataMatrixReader : Reader\r
  41         {\r
  42                 \r
  43                 //UPGRADE_NOTE: Final was removed from the declaration of 'NO_POINTS '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"\r
  44                 private static readonly ResultPoint[] NO_POINTS = new ResultPoint[0];\r
  45                 \r
  46                 //UPGRADE_NOTE: Final was removed from the declaration of 'decoder '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"\r
  47                 private Decoder decoder = new Decoder();\r
  48                 \r
  49                 /// <summary> Locates and decodes a Data Matrix code in an image.\r
  50                 /// \r
  51                 /// </summary>\r
  52                 /// <returns> a String representing the content encoded by the Data Matrix code\r
  53                 /// </returns>\r
  54                 /// <throws>  ReaderException if a Data Matrix code cannot be found, or cannot be decoded </throws>\r
  55                 public Result decode(BinaryBitmap image)\r
  56                 {\r
  57                         return decode(image, null);\r
  58                 }\r
  59                 \r
  60                 public Result decode(BinaryBitmap image, System.Collections.Hashtable hints)\r
  61                 {\r
  62                         DecoderResult decoderResult;\r
  63                         ResultPoint[] points;\r
  64                         if (hints != null && hints.ContainsKey(DecodeHintType.PURE_BARCODE))\r
  65                         {\r
  66                                 BitMatrix bits = extractPureBits(image.BlackMatrix);\r
  67                                 decoderResult = decoder.decode(bits);\r
  68                                 points = NO_POINTS;\r
  69                         }\r
  70                         else\r
  71                         {\r
  72                                 DetectorResult detectorResult = new Detector(image.BlackMatrix).detect();\r
  73                                 decoderResult = decoder.decode(detectorResult.Bits);\r
  74                                 points = detectorResult.Points;\r
  75                         }\r
  76                         Result result = new Result(decoderResult.Text, decoderResult.RawBytes, points, BarcodeFormat.DATAMATRIX);\r
  77                         if (decoderResult.ByteSegments != null)\r
  78                         {\r
  79                                 result.putMetadata(ResultMetadataType.BYTE_SEGMENTS, decoderResult.ByteSegments);\r
  80                         }\r
  81                         if (decoderResult.ECLevel != null)\r
  82                         {\r
  83                                 result.putMetadata(ResultMetadataType.ERROR_CORRECTION_LEVEL, decoderResult.ECLevel.ToString());\r
  84                         }\r
  85                         return result;\r
  86                 }\r
  87                 \r
  88                 /// <summary> This method detects a Data Matrix code in a "pure" image -- that is, pure monochrome image\r
  89                 /// which contains only an unrotated, unskewed, image of a Data Matrix code, with some white border\r
  90                 /// around it. This is a specialized method that works exceptionally fast in this special\r
  91                 /// case.\r
  92                 /// </summary>\r
  93                 private static BitMatrix extractPureBits(BitMatrix image)\r
  94                 {\r
  95                         // Now need to determine module size in pixels\r
  96                         \r
  97                         int height = image.Height;\r
  98                         int width = image.Width;\r
  99                         int minDimension = System.Math.Min(height, width);\r
 100                         \r
 101                         // First, skip white border by tracking diagonally from the top left down and to the right:\r
 102                         int borderWidth = 0;\r
 103                         while (borderWidth < minDimension && !image.get_Renamed(borderWidth, borderWidth))\r
 104                         {\r
 105                                 borderWidth++;\r
 106                         }\r
 107                         if (borderWidth == minDimension)\r
 108                         {\r
 109                                 throw ReaderException.Instance;\r
 110                         }\r
 111                         \r
 112                         // And then keep tracking across the top-left black module to determine module size\r
 113                         int moduleEnd = borderWidth + 1;\r
 114                         while (moduleEnd < width && image.get_Renamed(moduleEnd, borderWidth))\r
 115                         {\r
 116                                 moduleEnd++;\r
 117                         }\r
 118                         if (moduleEnd == width)\r
 119                         {\r
 120                                 throw ReaderException.Instance;\r
 121                         }\r
 122                         \r
 123                         int moduleSize = moduleEnd - borderWidth;\r
 124                         \r
 125                         // And now find where the bottommost black module on the first column ends\r
 126                         int columnEndOfSymbol = height - 1;\r
 127                         while (columnEndOfSymbol >= 0 && !image.get_Renamed(borderWidth, columnEndOfSymbol))\r
 128                         {\r
 129                                 columnEndOfSymbol--;\r
 130                         }\r
 131                         if (columnEndOfSymbol < 0)\r
 132                         {\r
 133                                 throw ReaderException.Instance;\r
 134                         }\r
 135                         columnEndOfSymbol++;\r
 136                         \r
 137                         // Make sure width of barcode is a multiple of module size\r
 138                         if ((columnEndOfSymbol - borderWidth) % moduleSize != 0)\r
 139                         {\r
 140                                 throw ReaderException.Instance;\r
 141                         }\r
 142                         int dimension = (columnEndOfSymbol - borderWidth) / moduleSize;\r
 143                         \r
 144                         // Push in the "border" by half the module width so that we start\r
 145                         // sampling in the middle of the module. Just in case the image is a\r
 146                         // little off, this will help recover.\r
 147                         borderWidth += (moduleSize >> 1);\r
 148                         \r
 149                         int sampleDimension = borderWidth + (dimension - 1) * moduleSize;\r
 150                         if (sampleDimension >= width || sampleDimension >= height)\r
 151                         {\r
 152                                 throw ReaderException.Instance;\r
 153                         }\r
 154                         \r
 155                         // Now just read off the bits\r
 156                         BitMatrix bits = new BitMatrix(dimension);\r
 157                         for (int i = 0; i < dimension; i++)\r
 158                         {\r
 159                                 int iOffset = borderWidth + i * moduleSize;\r
 160                                 for (int j = 0; j < dimension; j++)\r
 161                                 {\r
 162                                         if (image.get_Renamed(borderWidth + j * moduleSize, iOffset))\r
 163                                         {\r
 164                                                 bits.set_Renamed(j, i);\r
 165                                         }\r
 166                                 }\r
 167                         }\r
 168                         return bits;\r
 169                 }\r
 170         }\r
 171 }