1<?php 2//============================================================+ 3// File name : tcpdf_filters.php 4// Version : 1.0.001 5// Begin : 2011-05-23 6// Last Update : 2014-04-25 7// Author : Nicola Asuni - Tecnick.com LTD - www.tecnick.com - info@tecnick.com 8// License : GNU-LGPL v3 (http://www.gnu.org/copyleft/lesser.html) 9// ------------------------------------------------------------------- 10// Copyright (C) 2011-2013 Nicola Asuni - Tecnick.com LTD 11// 12// This file is part of TCPDF software library. 13// 14// TCPDF is free software: you can redistribute it and/or modify it 15// under the terms of the GNU Lesser General Public License as 16// published by the Free Software Foundation, either version 3 of the 17// License, or (at your option) any later version. 18// 19// TCPDF is distributed in the hope that it will be useful, but 20// WITHOUT ANY WARRANTY; without even the implied warranty of 21// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 22// See the GNU Lesser General Public License for more details. 23// 24// You should have received a copy of the License 25// along with TCPDF. If not, see 26// <http://www.tecnick.com/pagefiles/tcpdf/LICENSE.TXT>. 27// 28// See LICENSE.TXT file for more information. 29// ------------------------------------------------------------------- 30// 31// Description : This is a PHP class for decoding common PDF filters (PDF 32000-2008 - 7.4 Filters). 32// 33//============================================================+ 34 35/** 36 * @file 37 * This is a PHP class for decoding common PDF filters (PDF 32000-2008 - 7.4 Filters).<br> 38 * @package com.tecnick.tcpdf 39 * @author Nicola Asuni 40 * @version 1.0.001 41 */ 42 43/** 44 * @class TCPDF_FILTERS 45 * This is a PHP class for decoding common PDF filters (PDF 32000-2008 - 7.4 Filters).<br> 46 * @package com.tecnick.tcpdf 47 * @brief This is a PHP class for decoding common PDF filters. 48 * @version 1.0.001 49 * @author Nicola Asuni - info@tecnick.com 50 */ 51class TCPDF_FILTERS { 52 53 /** 54 * Define a list of available filter decoders. 55 * @private static 56 */ 57 private static $available_filters = array('ASCIIHexDecode', 'ASCII85Decode', 'LZWDecode', 'FlateDecode', 'RunLengthDecode'); 58 59// ----------------------------------------------------------------------------- 60 61 /** 62 * Get a list of available decoding filters. 63 * @return array Array of available filter decoders. 64 * @since 1.0.000 (2011-05-23) 65 * @public static 66 */ 67 public static function getAvailableFilters() { 68 return self::$available_filters; 69 } 70 71 /** 72 * Decode data using the specified filter type. 73 * @param string $filter Filter name. 74 * @param string $data Data to decode. 75 * @return string Decoded data string. 76 * @since 1.0.000 (2011-05-23) 77 * @public static 78 */ 79 public static function decodeFilter($filter, $data) { 80 switch ($filter) { 81 case 'ASCIIHexDecode': { 82 return self::decodeFilterASCIIHexDecode($data); 83 break; 84 } 85 case 'ASCII85Decode': { 86 return self::decodeFilterASCII85Decode($data); 87 break; 88 } 89 case 'LZWDecode': { 90 return self::decodeFilterLZWDecode($data); 91 break; 92 } 93 case 'FlateDecode': { 94 return self::decodeFilterFlateDecode($data); 95 break; 96 } 97 case 'RunLengthDecode': { 98 return self::decodeFilterRunLengthDecode($data); 99 break; 100 } 101 case 'CCITTFaxDecode': { 102 return self::decodeFilterCCITTFaxDecode($data); 103 break; 104 } 105 case 'JBIG2Decode': { 106 return self::decodeFilterJBIG2Decode($data); 107 break; 108 } 109 case 'DCTDecode': { 110 return self::decodeFilterDCTDecode($data); 111 break; 112 } 113 case 'JPXDecode': { 114 return self::decodeFilterJPXDecode($data); 115 break; 116 } 117 case 'Crypt': { 118 return self::decodeFilterCrypt($data); 119 break; 120 } 121 default: { 122 return self::decodeFilterStandard($data); 123 break; 124 } 125 } 126 } 127 128 // --- FILTERS (PDF 32000-2008 - 7.4 Filters) ------------------------------ 129 130 /** 131 * Standard 132 * Default decoding filter (leaves data unchanged). 133 * @param string $data Data to decode. 134 * @return string Decoded data string. 135 * @since 1.0.000 (2011-05-23) 136 * @public static 137 */ 138 public static function decodeFilterStandard($data) { 139 return $data; 140 } 141 142 /** 143 * ASCIIHexDecode 144 * Decodes data encoded in an ASCII hexadecimal representation, reproducing the original binary data. 145 * @param string $data Data to decode. 146 * @return string Decoded data string. 147 * @since 1.0.000 (2011-05-23) 148 * @public static 149 */ 150 public static function decodeFilterASCIIHexDecode($data) { 151 // initialize string to return 152 $decoded = ''; 153 // all white-space characters shall be ignored 154 $data = preg_replace('/[\s]/', '', $data); 155 // check for EOD character: GREATER-THAN SIGN (3Eh) 156 $eod = strpos($data, '>'); 157 if ($eod !== false) { 158 // remove EOD and extra data (if any) 159 $data = substr($data, 0, $eod); 160 $eod = true; 161 } 162 // get data length 163 $data_length = strlen($data); 164 if (($data_length % 2) != 0) { 165 // odd number of hexadecimal digits 166 if ($eod) { 167 // EOD shall behave as if a 0 (zero) followed the last digit 168 $data = substr($data, 0, -1).'0'.substr($data, -1); 169 } else { 170 self::Error('decodeFilterASCIIHexDecode: invalid code'); 171 } 172 } 173 // check for invalid characters 174 if (preg_match('/[^a-fA-F\d]/', $data) > 0) { 175 self::Error('decodeFilterASCIIHexDecode: invalid code'); 176 } 177 // get one byte of binary data for each pair of ASCII hexadecimal digits 178 $decoded = pack('H*', $data); 179 return $decoded; 180 } 181 182 /** 183 * ASCII85Decode 184 * Decodes data encoded in an ASCII base-85 representation, reproducing the original binary data. 185 * @param string $data Data to decode. 186 * @return string Decoded data string. 187 * @since 1.0.000 (2011-05-23) 188 * @public static 189 */ 190 public static function decodeFilterASCII85Decode($data) { 191 // initialize string to return 192 $decoded = ''; 193 // all white-space characters shall be ignored 194 $data = preg_replace('/[\s]/', '', $data); 195 // remove start sequence 2-character sequence <~ (3Ch)(7Eh) 196 if (strpos($data, '<~') !== false) { 197 // remove EOD and extra data (if any) 198 $data = substr($data, 2); 199 } 200 // check for EOD: 2-character sequence ~> (7Eh)(3Eh) 201 $eod = strpos($data, '~>'); 202 if ($eod !== false) { 203 // remove EOD and extra data (if any) 204 $data = substr($data, 0, $eod); 205 } 206 // data length 207 $data_length = strlen($data); 208 // check for invalid characters 209 if (preg_match('/[^\x21-\x75,\x74]/', $data) > 0) { 210 self::Error('decodeFilterASCII85Decode: invalid code'); 211 } 212 // z sequence 213 $zseq = chr(0).chr(0).chr(0).chr(0); 214 // position inside a group of 4 bytes (0-3) 215 $group_pos = 0; 216 $tuple = 0; 217 $pow85 = array((85*85*85*85), (85*85*85), (85*85), 85, 1); 218 $last_pos = ($data_length - 1); 219 // for each byte 220 for ($i = 0; $i < $data_length; ++$i) { 221 // get char value 222 $char = ord($data[$i]); 223 if ($char == 122) { // 'z' 224 if ($group_pos == 0) { 225 $decoded .= $zseq; 226 } else { 227 self::Error('decodeFilterASCII85Decode: invalid code'); 228 } 229 } else { 230 // the value represented by a group of 5 characters should never be greater than 2^32 - 1 231 $tuple += (($char - 33) * $pow85[$group_pos]); 232 if ($group_pos == 4) { 233 $decoded .= chr($tuple >> 24).chr($tuple >> 16).chr($tuple >> 8).chr($tuple); 234 $tuple = 0; 235 $group_pos = 0; 236 } else { 237 ++$group_pos; 238 } 239 } 240 } 241 if ($group_pos > 1) { 242 $tuple += $pow85[($group_pos - 1)]; 243 } 244 // last tuple (if any) 245 switch ($group_pos) { 246 case 4: { 247 $decoded .= chr($tuple >> 24).chr($tuple >> 16).chr($tuple >> 8); 248 break; 249 } 250 case 3: { 251 $decoded .= chr($tuple >> 24).chr($tuple >> 16); 252 break; 253 } 254 case 2: { 255 $decoded .= chr($tuple >> 24); 256 break; 257 } 258 case 1: { 259 self::Error('decodeFilterASCII85Decode: invalid code'); 260 break; 261 } 262 } 263 return $decoded; 264 } 265 266 /** 267 * LZWDecode 268 * Decompresses data encoded using the LZW (Lempel-Ziv-Welch) adaptive compression method, reproducing the original text or binary data. 269 * @param string $data Data to decode. 270 * @return string Decoded data string. 271 * @since 1.0.000 (2011-05-23) 272 * @public static 273 */ 274 public static function decodeFilterLZWDecode($data) { 275 // initialize string to return 276 $decoded = ''; 277 // data length 278 $data_length = strlen($data); 279 // convert string to binary string 280 $bitstring = ''; 281 for ($i = 0; $i < $data_length; ++$i) { 282 $bitstring .= sprintf('%08b', ord($data[$i])); 283 } 284 // get the number of bits 285 $data_length = strlen($bitstring); 286 // initialize code length in bits 287 $bitlen = 9; 288 // initialize dictionary index 289 $dix = 258; 290 // initialize the dictionary (with the first 256 entries). 291 $dictionary = array(); 292 for ($i = 0; $i < 256; ++$i) { 293 $dictionary[$i] = chr($i); 294 } 295 // previous val 296 $prev_index = 0; 297 // while we encounter EOD marker (257), read code_length bits 298 while (($data_length > 0) AND (($index = bindec(substr($bitstring, 0, $bitlen))) != 257)) { 299 // remove read bits from string 300 $bitstring = substr($bitstring, $bitlen); 301 // update number of bits 302 $data_length -= $bitlen; 303 if ($index == 256) { // clear-table marker 304 // reset code length in bits 305 $bitlen = 9; 306 // reset dictionary index 307 $dix = 258; 308 $prev_index = 256; 309 // reset the dictionary (with the first 256 entries). 310 $dictionary = array(); 311 for ($i = 0; $i < 256; ++$i) { 312 $dictionary[$i] = chr($i); 313 } 314 } elseif ($prev_index == 256) { 315 // first entry 316 $decoded .= $dictionary[$index]; 317 $prev_index = $index; 318 } else { 319 // check if index exist in the dictionary 320 if ($index < $dix) { 321 // index exist on dictionary 322 $decoded .= $dictionary[$index]; 323 $dic_val = $dictionary[$prev_index].$dictionary[$index][0]; 324 // store current index 325 $prev_index = $index; 326 } else { 327 // index do not exist on dictionary 328 $dic_val = $dictionary[$prev_index].$dictionary[$prev_index][0]; 329 $decoded .= $dic_val; 330 } 331 // update dictionary 332 $dictionary[$dix] = $dic_val; 333 ++$dix; 334 // change bit length by case 335 if ($dix == 2047) { 336 $bitlen = 12; 337 } elseif ($dix == 1023) { 338 $bitlen = 11; 339 } elseif ($dix == 511) { 340 $bitlen = 10; 341 } 342 } 343 } 344 return $decoded; 345 } 346 347 /** 348 * FlateDecode 349 * Decompresses data encoded using the zlib/deflate compression method, reproducing the original text or binary data. 350 * @param string $data Data to decode. 351 * @return string Decoded data string. 352 * @since 1.0.000 (2011-05-23) 353 * @public static 354 */ 355 public static function decodeFilterFlateDecode($data) { 356 // initialize string to return 357 $decoded = @gzuncompress($data); 358 if ($decoded === false) { 359 self::Error('decodeFilterFlateDecode: invalid code'); 360 } 361 return $decoded; 362 } 363 364 /** 365 * RunLengthDecode 366 * Decompresses data encoded using a byte-oriented run-length encoding algorithm. 367 * @param string $data Data to decode. 368 * @since 1.0.000 (2011-05-23) 369 * @public static 370 */ 371 public static function decodeFilterRunLengthDecode($data) { 372 // initialize string to return 373 $decoded = ''; 374 // data length 375 $data_length = strlen($data); 376 $i = 0; 377 while($i < $data_length) { 378 // get current byte value 379 $byte = ord($data[$i]); 380 if ($byte == 128) { 381 // a length value of 128 denote EOD 382 break; 383 } elseif ($byte < 128) { 384 // if the length byte is in the range 0 to 127 385 // the following length + 1 (1 to 128) bytes shall be copied literally during decompression 386 $decoded .= substr($data, ($i + 1), ($byte + 1)); 387 // move to next block 388 $i += ($byte + 2); 389 } else { 390 // if length is in the range 129 to 255, 391 // the following single byte shall be copied 257 - length (2 to 128) times during decompression 392 $decoded .= str_repeat($data[($i + 1)], (257 - $byte)); 393 // move to next block 394 $i += 2; 395 } 396 } 397 return $decoded; 398 } 399 400 /** 401 * CCITTFaxDecode (NOT IMPLEMETED - RETURN AN EXCEPTION) 402 * Decompresses data encoded using the CCITT facsimile standard, reproducing the original data (typically monochrome image data at 1 bit per pixel). 403 * @param string $data Data to decode. 404 * @return string Decoded data string. 405 * @since 1.0.000 (2011-05-23) 406 * @public static 407 */ 408 public static function decodeFilterCCITTFaxDecode($data) { 409 self::Error('~decodeFilterCCITTFaxDecode: this method has not been yet implemented'); 410 //return $data; 411 } 412 413 /** 414 * JBIG2Decode (NOT IMPLEMETED - RETURN AN EXCEPTION) 415 * Decompresses data encoded using the JBIG2 standard, reproducing the original monochrome (1 bit per pixel) image data (or an approximation of that data). 416 * @param string $data Data to decode. 417 * @return string Decoded data string. 418 * @since 1.0.000 (2011-05-23) 419 * @public static 420 */ 421 public static function decodeFilterJBIG2Decode($data) { 422 self::Error('~decodeFilterJBIG2Decode: this method has not been yet implemented'); 423 //return $data; 424 } 425 426 /** 427 * DCTDecode (NOT IMPLEMETED - RETURN AN EXCEPTION) 428 * Decompresses data encoded using a DCT (discrete cosine transform) technique based on the JPEG standard, reproducing image sample data that approximates the original data. 429 * @param string $data Data to decode. 430 * @return string Decoded data string. 431 * @since 1.0.000 (2011-05-23) 432 * @public static 433 */ 434 public static function decodeFilterDCTDecode($data) { 435 self::Error('~decodeFilterDCTDecode: this method has not been yet implemented'); 436 //return $data; 437 } 438 439 /** 440 * JPXDecode (NOT IMPLEMETED - RETURN AN EXCEPTION) 441 * Decompresses data encoded using the wavelet-based JPEG2000 standard, reproducing the original image data. 442 * @param string $data Data to decode. 443 * @return string Decoded data string. 444 * @since 1.0.000 (2011-05-23) 445 * @public static 446 */ 447 public static function decodeFilterJPXDecode($data) { 448 self::Error('~decodeFilterJPXDecode: this method has not been yet implemented'); 449 //return $data; 450 } 451 452 /** 453 * Crypt (NOT IMPLEMETED - RETURN AN EXCEPTION) 454 * Decrypts data encrypted by a security handler, reproducing the data as it was before encryption. 455 * @param string $data Data to decode. 456 * @return string Decoded data string. 457 * @since 1.0.000 (2011-05-23) 458 * @public static 459 */ 460 public static function decodeFilterCrypt($data) { 461 self::Error('~decodeFilterCrypt: this method has not been yet implemented'); 462 //return $data; 463 } 464 465 // --- END FILTERS SECTION ------------------------------------------------- 466 467 /** 468 * Throw an exception. 469 * @param string $msg The error message 470 * @since 1.0.000 (2011-05-23) 471 * @public static 472 */ 473 public static function Error($msg) { 474 throw new Exception('TCPDF_PARSER ERROR: '.$msg); 475 } 476 477} // END OF TCPDF_FILTERS CLASS 478 479//============================================================+ 480// END OF FILE 481//============================================================+ 482