csharp/pdf417/PDF417Reader.cs

   1 /*\r
   2 * Copyright 2009 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 BinaryBitmap = com.google.zxing.BinaryBitmap;\r
  19 using DecodeHintType = com.google.zxing.DecodeHintType;\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 BitMatrix = com.google.zxing.common.BitMatrix;\r
  25 using DecoderResult = com.google.zxing.common.DecoderResult;\r
  26 using DetectorResult = com.google.zxing.common.DetectorResult;\r
  27 using Decoder = com.google.zxing.pdf417.decoder.Decoder;\r
  28 using Detector = com.google.zxing.pdf417.detector.Detector;\r
  29 namespace com.google.zxing.pdf417\r
  30 {\r
  31         \r
  32         /// <summary> This implementation can detect and decode PDF417 codes in an image.\r
  33         /// \r
  34         /// </summary>\r
  35         /// <author>  SITA Lab (kevin.osullivan@sita.aero)\r
  36         /// </author>\r
  37         /// <author>www.Redivivus.in (suraj.supekar@redivivus.in) - Ported from ZXING Java Source \r
  38         /// </author>\r
  39         public sealed class PDF417Reader : Reader\r
  40         {\r
  41                 \r
  42                 //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
  43                 private static readonly ResultPoint[] NO_POINTS = new ResultPoint[0];\r
  44                 \r
  45                 //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
  46                 private Decoder decoder = new Decoder();\r
  47                 \r
  48                 /// <summary> Locates and decodes a PDF417 code in an image.\r
  49                 /// \r
  50                 /// </summary>\r
  51                 /// <returns> a String representing the content encoded by the PDF417 code\r
  52                 /// </returns>\r
  53                 /// <throws>  ReaderException if a PDF417 code cannot be found, or cannot be decoded </throws>\r
  54                 public Result decode(BinaryBitmap image)\r
  55                 {\r
  56                         return decode(image, null);\r
  57                 }\r
  58                 \r
  59                 public Result decode(BinaryBitmap image, System.Collections.Hashtable hints)\r
  60                 {\r
  61                         DecoderResult decoderResult;\r
  62                         ResultPoint[] points;\r
  63                         if (hints != null && hints.ContainsKey(DecodeHintType.PURE_BARCODE))\r
  64                         {\r
  65                                 BitMatrix bits = extractPureBits(image);\r
  66                                 decoderResult = decoder.decode(bits);\r
  67                                 points = NO_POINTS;\r
  68                         }\r
  69                         else\r
  70                         {\r
  71                                 DetectorResult detectorResult = new Detector(image).detect();\r
  72                                 decoderResult = decoder.decode(detectorResult.Bits);\r
  73                                 points = detectorResult.Points;\r
  74                         }\r
  75                         return new Result(decoderResult.Text, decoderResult.RawBytes, points, BarcodeFormat.PDF417);\r
  76                 }\r
  77                 \r
  78                 /// <summary> This method detects a barcode in a "pure" image -- that is, pure monochrome image\r
  79                 /// which contains only an unrotated, unskewed, image of a barcode, with some white border\r
  80                 /// around it. This is a specialized method that works exceptionally fast in this special\r
  81                 /// case.\r
  82                 /// </summary>\r
  83                 private static BitMatrix extractPureBits(BinaryBitmap image)\r
  84                 {\r
  85                         // Now need to determine module size in pixels\r
  86                         BitMatrix matrix = image.BlackMatrix;\r
  87                         int height = matrix.Height;\r
  88                         int width = matrix.Width;\r
  89                         int minDimension = System.Math.Min(height, width);\r
  90                         \r
  91                         // First, skip white border by tracking diagonally from the top left down and to the right:\r
  92                         int borderWidth = 0;\r
  93                         while (borderWidth < minDimension && !matrix.get_Renamed(borderWidth, borderWidth))\r
  94                         {\r
  95                                 borderWidth++;\r
  96                         }\r
  97                         if (borderWidth == minDimension)\r
  98                         {\r
  99                                 throw ReaderException.Instance;\r
 100                         }\r
 101                         \r
 102                         // And then keep tracking across the top-left black module to determine module size\r
 103                         int moduleEnd = borderWidth;\r
 104                         while (moduleEnd < minDimension && matrix.get_Renamed(moduleEnd, moduleEnd))\r
 105                         {\r
 106                                 moduleEnd++;\r
 107                         }\r
 108                         if (moduleEnd == minDimension)\r
 109                         {\r
 110                                 throw ReaderException.Instance;\r
 111                         }\r
 112                         \r
 113                         int moduleSize = moduleEnd - borderWidth;\r
 114                         \r
 115                         // And now find where the rightmost black module on the first row ends\r
 116                         int rowEndOfSymbol = width - 1;\r
 117                         while (rowEndOfSymbol >= 0 && !matrix.get_Renamed(rowEndOfSymbol, borderWidth))\r
 118                         {\r
 119                                 rowEndOfSymbol--;\r
 120                         }\r
 121                         if (rowEndOfSymbol < 0)\r
 122                         {\r
 123                                 throw ReaderException.Instance;\r
 124                         }\r
 125                         rowEndOfSymbol++;\r
 126                         \r
 127                         // Make sure width of barcode is a multiple of module size\r
 128                         if ((rowEndOfSymbol - borderWidth) % moduleSize != 0)\r
 129                         {\r
 130                                 throw ReaderException.Instance;\r
 131                         }\r
 132                         int dimension = (rowEndOfSymbol - borderWidth) / moduleSize;\r
 133                         \r
 134                         // Push in the "border" by half the module width so that we start\r
 135                         // sampling in the middle of the module. Just in case the image is a\r
 136                         // little off, this will help recover.\r
 137                         borderWidth += (moduleSize >> 1);\r
 138                         \r
 139                         int sampleDimension = borderWidth + (dimension - 1) * moduleSize;\r
 140                         if (sampleDimension >= width || sampleDimension >= height)\r
 141                         {\r
 142                                 throw ReaderException.Instance;\r
 143                         }\r
 144                         \r
 145                         // Now just read off the bits\r
 146                         BitMatrix bits = new BitMatrix(dimension);\r
 147                         for (int y = 0; y < dimension; y++)\r
 148                         {\r
 149                                 int iOffset = borderWidth + y * moduleSize;\r
 150                                 for (int x = 0; x < dimension; x++)\r
 151                                 {\r
 152                                         if (matrix.get_Renamed(borderWidth + x * moduleSize, iOffset))\r
 153                                         {\r
 154                                                 bits.set_Renamed(x, y);\r
 155                                         }\r
 156                                 }\r
 157                         }\r
 158                         return bits;\r
 159                 }\r
 160         }\r
 161 }