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1 <?php 2 //============================================================+ 3 // File name : tcpdf_filters.php 4 // Version : 1.0.000 5 // Begin : 2011-05-23 6 // Last Update : 2012-01-28 7 // Author : Nicola Asuni - Tecnick.com LTD - Manor Coach House, Church Hill, Aldershot, Hants, GU12 4RQ, UK - www.tecnick.com - [email protected] 8 // License : http://www.tecnick.com/pagefiles/tcpdf/LICENSE.TXT GNU-LGPLv3 9 // ------------------------------------------------------------------- 10 // Copyright (C) 2011-2012 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 1.0.000 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 1.0.000 49 * @author Nicola Asuni - [email protected] 50 */ 51 class TCPDF_FILTERS { 52 53 /** 54 * Define a list of available filter decoders. 55 * @private 56 */ 57 private $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 * @public 65 * @since 1.0.000 (2011-05-23) 66 */ 67 public function getAvailableFilters() { 68 return $this->available_filters; 69 } 70 71 /** 72 * Decode data using the specified filter type. 73 * @param $filter (string) Filter name. 74 * @param $data (string) Data to decode. 75 * @return Decoded data string. 76 * @public 77 * @since 1.0.000 (2011-05-23) 78 */ 79 public function decodeFilter($filter, $data) { 80 switch ($filter) { 81 case 'ASCIIHexDecode': { 82 return $this->decodeFilterASCIIHexDecode($data); 83 break; 84 } 85 case 'ASCII85Decode': { 86 return $this->decodeFilterASCII85Decode($data); 87 break; 88 } 89 case 'LZWDecode': { 90 return $this->decodeFilterLZWDecode($data); 91 break; 92 } 93 case 'FlateDecode': { 94 return $this->decodeFilterFlateDecode($data); 95 break; 96 } 97 case 'RunLengthDecode': { 98 return $this->decodeFilterRunLengthDecode($data); 99 break; 100 } 101 case 'CCITTFaxDecode': { 102 return $this->decodeFilterCCITTFaxDecode($data); 103 break; 104 } 105 case 'JBIG2Decode': { 106 return $this->decodeFilterJBIG2Decode($data); 107 break; 108 } 109 case 'DCTDecode': { 110 return $this->decodeFilterDCTDecode($data); 111 break; 112 } 113 case 'JPXDecode': { 114 return $this->decodeFilterJPXDecode($data); 115 break; 116 } 117 case 'Crypt': { 118 return $this->decodeFilterCrypt($data); 119 break; 120 } 121 default: { 122 return 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 $data (string) Data to decode. 134 * @return Decoded data string. 135 * @public 136 * @since 1.0.000 (2011-05-23) 137 */ 138 public function decodeFilterStandard($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 $data (string) Data to decode. 146 * @return Decoded data string. 147 * @public 148 * @since 1.0.000 (2011-05-23) 149 */ 150 public function decodeFilterASCIIHexDecode($data) { 151 // intialize 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 $this->Error('decodeASCIIHex: invalid code'); 171 } 172 } 173 // check for invalid characters 174 if (preg_match('/[^a-fA-F\d]/', $data) > 0) { 175 $this->Error('decodeASCIIHex: 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 $data (string) Data to decode. 186 * @return Decoded data string. 187 * @public 188 * @since 1.0.000 (2011-05-23) 189 */ 190 public function decodeFilterASCII85Decode($data) { 191 // intialize 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 $this->Error('decodeASCII85: 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 $this->Error('decodeASCII85: 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 $this->Error('decodeASCII85: 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 $data (string) Data to decode. 270 * @return Decoded data string. 271 * @public 272 * @since 1.0.000 (2011-05-23) 273 */ 274 public function decodeFilterLZWDecode($data) { 275 // intialize 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 $data (string) Data to decode. 351 * @return Decoded data string. 352 * @public 353 * @since 1.0.000 (2011-05-23) 354 */ 355 public function decodeFilterFlateDecode($data) { 356 // intialize string to return 357 $decoded = gzuncompress($data); 358 if ($decoded === false) { 359 $this->Error('decodeFlate: 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 $data (string) Data to decode. 368 * @public 369 * @since 1.0.000 (2011-05-23) 370 */ 371 public function decodeFilterRunLengthDecode($data) { 372 // intialize 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) 402 * Decompresses data encoded using the CCITT facsimile standard, reproducing the original data (typically monochrome image data at 1 bit per pixel). 403 * @param $data (string) Data to decode. 404 * @return Decoded data string. 405 * @public 406 * @since 1.0.000 (2011-05-23) 407 */ 408 public function decodeFilterCCITTFaxDecode($data) { 409 return $data; 410 } 411 412 /** 413 * JBIG2Decode (NOT IMPLEMETED) 414 * Decompresses data encoded using the JBIG2 standard, reproducing the original monochrome (1 bit per pixel) image data (or an approximation of that data). 415 * @param $data (string) Data to decode. 416 * @return Decoded data string. 417 * @public 418 * @since 1.0.000 (2011-05-23) 419 */ 420 public function decodeFilterJBIG2Decode($data) { 421 return $data; 422 } 423 424 /** 425 * DCTDecode (NOT IMPLEMETED) 426 * Decompresses data encoded using a DCT (discrete cosine transform) technique based on the JPEG standard, reproducing image sample data that approximates the original data. 427 * @param $data (string) Data to decode. 428 * @return Decoded data string. 429 * @public 430 * @since 1.0.000 (2011-05-23) 431 */ 432 public function decodeFilterDCTDecode($data) { 433 return $data; 434 } 435 436 /** 437 * JPXDecode (NOT IMPLEMETED) 438 * Decompresses data encoded using the wavelet-based JPEG2000 standard, reproducing the original image data. 439 * @param $data (string) Data to decode. 440 * @return Decoded data string. 441 * @public 442 * @since 1.0.000 (2011-05-23) 443 */ 444 public function decodeFilterJPXDecode($data) { 445 return $data; 446 } 447 448 /** 449 * Crypt (NOT IMPLEMETED) 450 * Decrypts data encrypted by a security handler, reproducing the data as it was before encryption. 451 * @param $data (string) Data to decode. 452 * @return Decoded data string. 453 * @public 454 * @since 1.0.000 (2011-05-23) 455 */ 456 public function decodeFilterCrypt($data) { 457 return $data; 458 } 459 460 // --- END FILTERS SECTION ------------------------------------------------- 461 462 /** 463 * This method is automatically called in case of fatal error; it simply outputs the message and halts the execution. 464 * @param $msg (string) The error message 465 * @public 466 * @since 1.0.000 (2011-05-23) 467 */ 468 public function Error($msg) { 469 // exit program and print error 470 die('<strong>TCPDF_FILTERS ERROR: </strong>'.$msg); 471 } 472 473 } // END OF TCPDF_FILTERS CLASS 474 475 //============================================================+ 476 // END OF FILE 477 //============================================================+
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