csharp/oned/Code39Reader.cs

   1 /*\r
   2 * Copyright 2008 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 ReaderException = com.google.zxing.ReaderException;\r
  19 using Result = com.google.zxing.Result;\r
  20 using ResultPoint = com.google.zxing.ResultPoint;\r
  21 using BitArray = com.google.zxing.common.BitArray;\r
  22 namespace com.google.zxing.oned\r
  23 {\r
  24         \r
  25         /// <summary> <p>Decodes Code 39 barcodes. This does not support "Full ASCII Code 39" yet.</p>\r
  26         /// \r
  27         /// </summary>\r
  28         /// <author>  Sean Owen\r
  29         /// </author>\r
  30         /// <author>www.Redivivus.in (suraj.supekar@redivivus.in) - Ported from ZXING Java Source \r
  31         /// </author>\r
  32         public sealed class Code39Reader:OneDReader\r
  33         {\r
  34                 \r
  35                 private const System.String ALPHABET_STRING = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ-. *$/+%";\r
  36                 //UPGRADE_NOTE: Final was removed from the declaration of 'ALPHABET '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"\r
  37                 private static readonly char[] ALPHABET = ALPHABET_STRING.ToCharArray();\r
  38                 \r
  39                 /// <summary> These represent the encodings of characters, as patterns of wide and narrow bars.\r
  40                 /// The 9 least-significant bits of each int correspond to the pattern of wide and narrow,\r
  41                 /// with 1s representing "wide" and 0s representing narrow.\r
  42                 /// </summary>\r
  43                 //UPGRADE_NOTE: Final was removed from the declaration of 'CHARACTER_ENCODINGS'. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"\r
  44                 private static readonly int[] CHARACTER_ENCODINGS = new int[]{0x034, 0x121, 0x061, 0x160, 0x031, 0x130, 0x070, 0x025, 0x124, 0x064, 0x109, 0x049, 0x148, 0x019, 0x118, 0x058, 0x00D, 0x10C, 0x04C, 0x01C, 0x103, 0x043, 0x142, 0x013, 0x112, 0x052, 0x007, 0x106, 0x046, 0x016, 0x181, 0x0C1, 0x1C0, 0x091, 0x190, 0x0D0, 0x085, 0x184, 0x0C4, 0x094, 0x0A8, 0x0A2, 0x08A, 0x02A};\r
  45                 \r
  46                 //UPGRADE_NOTE: Final was removed from the declaration of 'ASTERISK_ENCODING '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"\r
  47                 private static readonly int ASTERISK_ENCODING = CHARACTER_ENCODINGS[39];\r
  48                 \r
  49                 //UPGRADE_NOTE: Final was removed from the declaration of 'usingCheckDigit '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"\r
  50                 private bool usingCheckDigit;\r
  51                 //UPGRADE_NOTE: Final was removed from the declaration of 'extendedMode '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"\r
  52                 private bool extendedMode;\r
  53                 \r
  54                 /// <summary> Creates a reader that assumes all encoded data is data, and does not treat the final\r
  55                 /// character as a check digit. It will not decoded "extended Code 39" sequences.\r
  56                 /// </summary>\r
  57                 public Code39Reader()\r
  58                 {\r
  59                         usingCheckDigit = false;\r
  60                         extendedMode = false;\r
  61                 }\r
  62                 \r
  63                 /// <summary> Creates a reader that can be configured to check the last character as a check digit.\r
  64                 /// It will not decoded "extended Code 39" sequences.\r
  65                 /// \r
  66                 /// </summary>\r
  67                 /// <param name="usingCheckDigit">if true, treat the last data character as a check digit, not\r
  68                 /// data, and verify that the checksum passes.\r
  69                 /// </param>\r
  70                 public Code39Reader(bool usingCheckDigit)\r
  71                 {\r
  72                         this.usingCheckDigit = usingCheckDigit;\r
  73                         this.extendedMode = false;\r
  74                 }\r
  75                 \r
  76                 /// <summary> Creates a reader that can be configured to check the last character as a check digit,\r
  77                 /// or optionally attempt to decode "extended Code 39" sequences that are used to encode\r
  78                 /// the full ASCII character set.\r
  79                 /// \r
  80                 /// </summary>\r
  81                 /// <param name="usingCheckDigit">if true, treat the last data character as a check digit, not\r
  82                 /// data, and verify that the checksum passes.\r
  83                 /// </param>\r
  84                 /// <param name="extendedMode">if true, will attempt to decode extended Code 39 sequences in the\r
  85                 /// text.\r
  86                 /// </param>\r
  87                 public Code39Reader(bool usingCheckDigit, bool extendedMode)\r
  88                 {\r
  89                         this.usingCheckDigit = usingCheckDigit;\r
  90                         this.extendedMode = extendedMode;\r
  91                 }\r
  92                 \r
  93                 public override Result decodeRow(int rowNumber, BitArray row, System.Collections.Hashtable hints)\r
  94                 {\r
  95                         \r
  96                         int[] start = findAsteriskPattern(row);\r
  97                         int nextStart = start[1];\r
  98                         int end = row.Size;\r
  99                         \r
 100                         // Read off white space\r
 101                         while (nextStart < end && !row.get_Renamed(nextStart))\r
 102                         {\r
 103                                 nextStart++;\r
 104                         }\r
 105                         \r
 106                         System.Text.StringBuilder result = new System.Text.StringBuilder(20);\r
 107                         int[] counters = new int[9];\r
 108                         char decodedChar;\r
 109                         int lastStart;\r
 110                         do \r
 111                         {\r
 112                                 recordPattern(row, nextStart, counters);\r
 113                                 int pattern = toNarrowWidePattern(counters);\r
 114                                 if (pattern < 0)\r
 115                                 {\r
 116                                         throw ReaderException.Instance;\r
 117                                 }\r
 118                                 decodedChar = patternToChar(pattern);\r
 119                                 result.Append(decodedChar);\r
 120                                 lastStart = nextStart;\r
 121                                 for (int i = 0; i < counters.Length; i++)\r
 122                                 {\r
 123                                         nextStart += counters[i];\r
 124                                 }\r
 125                                 // Read off white space\r
 126                                 while (nextStart < end && !row.get_Renamed(nextStart))\r
 127                                 {\r
 128                                         nextStart++;\r
 129                                 }\r
 130                         }\r
 131                         while (decodedChar != '*');\r
 132                         result.Remove(result.Length - 1, 1); // remove asterisk\r
 133                         \r
 134                         // Look for whitespace after pattern:\r
 135                         int lastPatternSize = 0;\r
 136                         for (int i = 0; i < counters.Length; i++)\r
 137                         {\r
 138                                 lastPatternSize += counters[i];\r
 139                         }\r
 140                         int whiteSpaceAfterEnd = nextStart - lastStart - lastPatternSize;\r
 141                         // If 50% of last pattern size, following last pattern, is not whitespace, fail\r
 142                         // (but if it's whitespace to the very end of the image, that's OK)\r
 143                         if (nextStart != end && whiteSpaceAfterEnd / 2 < lastPatternSize)\r
 144                         {\r
 145                                 throw ReaderException.Instance;\r
 146                         }\r
 147                         \r
 148                         if (usingCheckDigit)\r
 149                         {\r
 150                                 int max = result.Length - 1;\r
 151                                 int total = 0;\r
 152                                 for (int i = 0; i < max; i++)\r
 153                                 {\r
 154                                         total += ALPHABET_STRING.IndexOf((System.Char) result[i]);\r
 155                                 }\r
 156                                 if (total % 43 != ALPHABET_STRING.IndexOf((System.Char) result[max]))\r
 157                                 {\r
 158                                         throw ReaderException.Instance;\r
 159                                 }\r
 160                                 result.Remove(max, 1);\r
 161                         }\r
 162                         \r
 163                         System.String resultString = result.ToString();\r
 164                         if (extendedMode)\r
 165                         {\r
 166                                 resultString = decodeExtended(resultString);\r
 167                         }\r
 168                         \r
 169                         if (resultString.Length == 0)\r
 170                         {\r
 171                                 // Almost surely a false positive\r
 172                                 throw ReaderException.Instance;\r
 173                         }\r
 174                         \r
 175                         //UPGRADE_WARNING: Data types in Visual C# might be different.  Verify the accuracy of narrowing conversions. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1042'"\r
 176                         float left = (float) (start[1] + start[0]) / 2.0f;\r
 177                         //UPGRADE_WARNING: Data types in Visual C# might be different.  Verify the accuracy of narrowing conversions. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1042'"\r
 178                         float right = (float) (nextStart + lastStart) / 2.0f;\r
 179                         //UPGRADE_WARNING: Data types in Visual C# might be different.  Verify the accuracy of narrowing conversions. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1042'"\r
 180                         return new Result(resultString, null, new ResultPoint[]{new ResultPoint(left, (float) rowNumber), new ResultPoint(right, (float) rowNumber)}, BarcodeFormat.CODE_39);\r
 181                 }\r
 182                 \r
 183                 private static int[] findAsteriskPattern(BitArray row)\r
 184                 {\r
 185                         int width = row.Size;\r
 186                         int rowOffset = 0;\r
 187                         while (rowOffset < width)\r
 188                         {\r
 189                                 if (row.get_Renamed(rowOffset))\r
 190                                 {\r
 191                                         break;\r
 192                                 }\r
 193                                 rowOffset++;\r
 194                         }\r
 195                         \r
 196                         int counterPosition = 0;\r
 197                         int[] counters = new int[9];\r
 198                         int patternStart = rowOffset;\r
 199                         bool isWhite = false;\r
 200                         int patternLength = counters.Length;\r
 201                         \r
 202                         for (int i = rowOffset; i < width; i++)\r
 203                         {\r
 204                                 bool pixel = row.get_Renamed(i);\r
 205                                 if (pixel ^ isWhite)\r
 206                                 {\r
 207                                         counters[counterPosition]++;\r
 208                                 }\r
 209                                 else\r
 210                                 {\r
 211                                         if (counterPosition == patternLength - 1)\r
 212                                         {\r
 213                                                 if (toNarrowWidePattern(counters) == ASTERISK_ENCODING)\r
 214                                                 {\r
 215                                                         // Look for whitespace before start pattern, >= 50% of width of start pattern\r
 216                                                         if (row.isRange(System.Math.Max(0, patternStart - (i - patternStart) / 2), patternStart, false))\r
 217                                                         {\r
 218                                                                 return new int[]{patternStart, i};\r
 219                                                         }\r
 220                                                 }\r
 221                                                 patternStart += counters[0] + counters[1];\r
 222                                                 for (int y = 2; y < patternLength; y++)\r
 223                                                 {\r
 224                                                         counters[y - 2] = counters[y];\r
 225                                                 }\r
 226                                                 counters[patternLength - 2] = 0;\r
 227                                                 counters[patternLength - 1] = 0;\r
 228                                                 counterPosition--;\r
 229                                         }\r
 230                                         else\r
 231                                         {\r
 232                                                 counterPosition++;\r
 233                                         }\r
 234                                         counters[counterPosition] = 1;\r
 235                                         isWhite = !isWhite;\r
 236                                 }\r
 237                         }\r
 238                         throw ReaderException.Instance;\r
 239                 }\r
 240                 \r
 241                 // For efficiency, returns -1 on failure. Not throwing here saved as many as 700 exceptions\r
 242                 // per image when using some of our blackbox images.\r
 243                 private static int toNarrowWidePattern(int[] counters)\r
 244                 {\r
 245                         int numCounters = counters.Length;\r
 246                         int maxNarrowCounter = 0;\r
 247                         int wideCounters;\r
 248                         do \r
 249                         {\r
 250                                 int minCounter = System.Int32.MaxValue;\r
 251                                 for (int i = 0; i < numCounters; i++)\r
 252                                 {\r
 253                                         int counter = counters[i];\r
 254                                         if (counter < minCounter && counter > maxNarrowCounter)\r
 255                                         {\r
 256                                                 minCounter = counter;\r
 257                                         }\r
 258                                 }\r
 259                                 maxNarrowCounter = minCounter;\r
 260                                 wideCounters = 0;\r
 261                                 int totalWideCountersWidth = 0;\r
 262                                 int pattern = 0;\r
 263                                 for (int i = 0; i < numCounters; i++)\r
 264                                 {\r
 265                                         int counter = counters[i];\r
 266                                         if (counters[i] > maxNarrowCounter)\r
 267                                         {\r
 268                                                 pattern |= 1 << (numCounters - 1 - i);\r
 269                                                 wideCounters++;\r
 270                                                 totalWideCountersWidth += counter;\r
 271                                         }\r
 272                                 }\r
 273                                 if (wideCounters == 3)\r
 274                                 {\r
 275                                         // Found 3 wide counters, but are they close enough in width?\r
 276                                         // We can perform a cheap, conservative check to see if any individual\r
 277                                         // counter is more than 1.5 times the average:\r
 278                                         for (int i = 0; i < numCounters && wideCounters > 0; i++)\r
 279                                         {\r
 280                                                 int counter = counters[i];\r
 281                                                 if (counters[i] > maxNarrowCounter)\r
 282                                                 {\r
 283                                                         wideCounters--;\r
 284                                                         // totalWideCountersWidth = 3 * average, so this checks if counter >= 3/2 * average\r
 285                                                         if ((counter << 1) >= totalWideCountersWidth)\r
 286                                                         {\r
 287                                                                 return - 1;\r
 288                                                         }\r
 289                                                 }\r
 290                                         }\r
 291                                         return pattern;\r
 292                                 }\r
 293                         }\r
 294                         while (wideCounters > 3);\r
 295                         return - 1;\r
 296                 }\r
 297                 \r
 298                 private static char patternToChar(int pattern)\r
 299                 {\r
 300                         for (int i = 0; i < CHARACTER_ENCODINGS.Length; i++)\r
 301                         {\r
 302                                 if (CHARACTER_ENCODINGS[i] == pattern)\r
 303                                 {\r
 304                                         return ALPHABET[i];\r
 305                                 }\r
 306                         }\r
 307                         throw ReaderException.Instance;\r
 308                 }\r
 309                 \r
 310                 private static System.String decodeExtended(System.String encoded)\r
 311                 {\r
 312                         int length = encoded.Length;\r
 313                         System.Text.StringBuilder decoded = new System.Text.StringBuilder(length);\r
 314                         for (int i = 0; i < length; i++)\r
 315                         {\r
 316                                 char c = encoded[i];\r
 317                                 if (c == '+' || c == '$' || c == '%' || c == '/')\r
 318                                 {\r
 319                                         char next = encoded[i + 1];\r
 320                                         char decodedChar = '\x0000';\r
 321                                         switch (c)\r
 322                                         {\r
 323                                                 \r
 324                                                 case '+': \r
 325                                                         // +A to +Z map to a to z\r
 326                                                         if (next >= 'A' && next <= 'Z')\r
 327                                                         {\r
 328                                                                 decodedChar = (char) (next + 32);\r
 329                                                         }\r
 330                                                         else\r
 331                                                         {\r
 332                                                                 throw ReaderException.Instance;\r
 333                                                         }\r
 334                                                         break;\r
 335                                                 \r
 336                                                 case '$': \r
 337                                                         // $A to $Z map to control codes SH to SB\r
 338                                                         if (next >= 'A' && next <= 'Z')\r
 339                                                         {\r
 340                                                                 decodedChar = (char) (next - 64);\r
 341                                                         }\r
 342                                                         else\r
 343                                                         {\r
 344                                                                 throw ReaderException.Instance;\r
 345                                                         }\r
 346                                                         break;\r
 347                                                 \r
 348                                                 case '%': \r
 349                                                         // %A to %E map to control codes ESC to US\r
 350                                                         if (next >= 'A' && next <= 'E')\r
 351                                                         {\r
 352                                                                 decodedChar = (char) (next - 38);\r
 353                                                         }\r
 354                                                         else if (next >= 'F' && next <= 'W')\r
 355                                                         {\r
 356                                                                 decodedChar = (char) (next - 11);\r
 357                                                         }\r
 358                                                         else\r
 359                                                         {\r
 360                                                                 throw ReaderException.Instance;\r
 361                                                         }\r
 362                                                         break;\r
 363                                                 \r
 364                                                 case '/': \r
 365                                                         // /A to /O map to ! to , and /Z maps to :\r
 366                                                         if (next >= 'A' && next <= 'O')\r
 367                                                         {\r
 368                                                                 decodedChar = (char) (next - 32);\r
 369                                                         }\r
 370                                                         else if (next == 'Z')\r
 371                                                         {\r
 372                                                                 decodedChar = ':';\r
 373                                                         }\r
 374                                                         else\r
 375                                                         {\r
 376                                                                 throw ReaderException.Instance;\r
 377                                                         }\r
 378                                                         break;\r
 379                                                 }\r
 380                                         decoded.Append(decodedChar);\r
 381                                         // bump up i again since we read two characters\r
 382                                         i++;\r
 383                                 }\r
 384                                 else\r
 385                                 {\r
 386                                         decoded.Append(c);\r
 387                                 }\r
 388                         }\r
 389                         return decoded.ToString();\r
 390                 }\r
 391         }\r
 392 }