C:/xampp/htdocs/moodle/lib/tcpdf/tcpdf_filters.php

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<?php
//============================================================+
// File name   : tcpdf_filters.php
// Version     : 1.0.000
// Begin       : 2011-05-23
// Last Update : 2011-06-26
// Author      : Nicola Asuni - Tecnick.com S.r.l - Via Della Pace, 11 - 09044 - Quartucciu (CA) - ITALY - www.tecnick.com - info@tecnick.com
// License     : http://www.tecnick.com/pagefiles/tcpdf/LICENSE.TXT GNU-LGPLv3 + YOU CAN'T REMOVE ANY TCPDF COPYRIGHT NOTICE OR LINK FROM THE GENERATED PDF DOCUMENTS.
// -------------------------------------------------------------------
// Copyright (C) 2011-2011  Nicola Asuni - Tecnick.com S.r.l.
//
// This file is part of TCPDF software library.
//
// TCPDF is free software: you can redistribute it and/or modify it
// under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version. Additionally,
// YOU CAN'T REMOVE ANY TCPDF COPYRIGHT NOTICE OR LINK FROM THE
// GENERATED PDF DOCUMENTS.
//
// TCPDF is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
// See the GNU Lesser General Public License for more details.
//
// You should have received a copy of the License
// along with TCPDF. If not, see
// <http://www.tecnick.com/pagefiles/tcpdf/LICENSE.TXT>.
//
// See LICENSE.TXT file for more information.
// -------------------------------------------------------------------
//
// Description : This is a PHP class for decoding common PDF filters (PDF 32000-2008 - 7.4 Filters).
//
//============================================================+

class TCPDF_FILTERS {

        private $available_filters = array('ASCIIHexDecode', 'ASCII85Decode', 'LZWDecode', 'FlateDecode', 'RunLengthDecode');

// -----------------------------------------------------------------------------

        public function getAvailableFilters() {
                return $this->available_filters;
        }

        public function decodeFilter($filter, $data) {
                switch ($filter) {
                        case 'ASCIIHexDecode': {
                                return $this->decodeFilterASCIIHexDecode($data);
                                break;
                        }
                        case 'ASCII85Decode': {
                                return $this->decodeFilterASCII85Decode($data);
                                break;
                        }
                        case 'LZWDecode': {
                                return $this->decodeFilterLZWDecode($data);
                                break;
                        }
                        case 'FlateDecode': {
                                return $this->decodeFilterFlateDecode($data);
                                break;
                        }
                        case 'RunLengthDecode': {
                                return $this->decodeFilterRunLengthDecode($data);
                                break;
                        }
                        case 'CCITTFaxDecode': {
                                return $this->decodeFilterCCITTFaxDecode($data);
                                break;
                        }
                        case 'JBIG2Decode': {
                                return $this->decodeFilterJBIG2Decode($data);
                                break;
                        }
                        case 'DCTDecode': {
                                return $this->decodeFilterDCTDecode($data);
                                break;
                        }
                        case 'JPXDecode': {
                                return $this->decodeFilterJPXDecode($data);
                                break;
                        }
                        case 'Crypt': {
                                return $this->decodeFilterCrypt($data);
                                break;
                        }
                        default: {
                                return decodeFilterStandard($data);
                                break;
                        }
                }
        }

        // --- FILTERS (PDF 32000-2008 - 7.4 Filters) ------------------------------

        public function decodeFilterStandard($data) {
                return $data;
        }

        public function decodeFilterASCIIHexDecode($data) {
                // intialize string to return
                $decoded = '';
                // all white-space characters shall be ignored
                $data = preg_replace('/[\s]/', '', $data);
                // check for EOD character: GREATER-THAN SIGN (3Eh)
                $eod = strpos($data, '>');
                if ($eod !== false) {
                        // remove EOD and extra data (if any)
                        $data = substr($data, 0, $eod);
                        $eod = true;
                }
                // get data length
                $data_length = strlen($data);
                if (($data_length % 2) != 0) {
                        // odd number of hexadecimal digits
                        if ($eod) {
                                // EOD shall behave as if a 0 (zero) followed the last digit
                                $data = substr($data, 0, -1).'0'.substr($data, -1);
                        } else {
                                $this->Error('decodeASCIIHex: invalid code');
                        }
                }
                // check for invalid characters
                if (preg_match('/[^a-fA-F\d]/', $data) > 0) {
                        $this->Error('decodeASCIIHex: invalid code');
                }
                // get one byte of binary data for each pair of ASCII hexadecimal digits
                $decoded = pack('H*', $data);
                return $decoded;
        }

        public function decodeFilterASCII85Decode($data) {
                // intialize string to return
                $decoded = '';
                // all white-space characters shall be ignored
                $data = preg_replace('/[\s]/', '', $data);
                // remove start sequence 2-character sequence <~ (3Ch)(7Eh)
                if (strpos($data, '<~') !== false) {
                        // remove EOD and extra data (if any)
                        $data = substr($data, 2);
                }
                // check for EOD: 2-character sequence ~> (7Eh)(3Eh)
                $eod = strpos($data, '~>');
                if ($eod !== false) {
                        // remove EOD and extra data (if any)
                        $data = substr($data, 0, $eod);
                }
                // data length
                $data_length = strlen($data);
                // check for invalid characters
                if (preg_match('/[^\x21-\x75,\x74]/', $data) > 0) {
                        $this->Error('decodeASCII85: invalid code');
                }
                // z sequence
                $zseq = chr(0).chr(0).chr(0).chr(0);
                // position inside a group of 4 bytes (0-3)
                $group_pos = 0;
                $tuple = 0;
                $pow85 = array((85*85*85*85), (85*85*85), (85*85), 85, 1);
                $last_pos = ($data_length - 1);
                // for each byte
                for ($i = 0; $i < $data_length; ++$i) {
                        // get char value
                        $char = ord($data[$i]);
                        if ($char == 122) { // 'z'
                                if ($group_pos == 0) {
                                        $decoded .= $zseq;
                                } else {
                                        $this->Error('decodeASCII85: invalid code');
                                }
                        } else {
                                // the value represented by a group of 5 characters should never be greater than 2^32 - 1
                                $tuple += (($char - 33) * $pow85[$group_pos]);
                                if ($group_pos == 4) {
                                        $decoded .= chr($tuple >> 24).chr($tuple >> 16).chr($tuple >> 8).chr($tuple);
                                        $tuple = 0;
                                        $group_pos = 0;
                                } else {
                                        ++$group_pos;
                                }
                        }
                }
                if ($group_pos > 1) {
                        $tuple += $pow85[($group_pos - 1)];
                }
                // last tuple (if any)
                switch ($group_pos) {
                        case 4: {
                                $decoded .= chr($tuple >> 24).chr($tuple >> 16).chr($tuple >> 8);
                                break;
                        }
                        case 3: {
                                $decoded .= chr($tuple >> 24).chr($tuple >> 16);
                                break;
                        }
                        case 2: {
                                $decoded .= chr($tuple >> 24);
                                break;
                        }
                        case 1: {
                                $this->Error('decodeASCII85: invalid code');
                                break;
                        }
                }
                return $decoded;
        }

        public function decodeFilterLZWDecode($data) {
                // intialize string to return
                $decoded = '';
                // data length
                $data_length = strlen($data);
                // convert string to binary string
                $bitstring = '';
                for ($i = 0; $i < $data_length; ++$i) {
                        $bitstring .= sprintf('%08b', ord($data{$i}));
                }
                // get the number of bits
                $data_length = strlen($bitstring);
                // initialize code length in bits
                $bitlen = 9;
                // initialize dictionary index
                $dix = 258;
                // initialize the dictionary (with the first 256 entries).
                $dictionary = array();
                for ($i = 0; $i < 256; ++$i) {
                        $dictionary[$i] = chr($i);
                }
                // previous val
                $prev_index = 0;
                // while we encounter EOD marker (257), read code_length bits
                while (($data_length > 0) AND (($index = bindec(substr($bitstring, 0, $bitlen))) != 257)) {
                        // remove read bits from string
                        $bitstring = substr($bitstring, $bitlen);
                        // update number of bits
                        $data_length -= $bitlen;
                        if ($index == 256) { // clear-table marker
                                // reset code length in bits
                                $bitlen = 9;
                                // reset dictionary index
                                $dix = 258;
                                $prev_index = 256;
                                // reset the dictionary (with the first 256 entries).
                                $dictionary = array();
                                for ($i = 0; $i < 256; ++$i) {
                                        $dictionary[$i] = chr($i);
                                }
                        } elseif ($prev_index == 256) {
                                // first entry
                                $decoded .= $dictionary[$index];
                                $prev_index = $index;
                        } else {
                                // check if index exist in the dictionary
                                if ($index < $dix) {
                                        // index exist on dictionary
                                        $decoded .= $dictionary[$index];
                                        $dic_val = $dictionary[$prev_index].$dictionary[$index]{0};
                                        // store current index
                                        $prev_index = $index;
                                } else {
                                        // index do not exist on dictionary
                                        $dic_val = $dictionary[$prev_index].$dictionary[$prev_index]{0};
                                        $decoded .= $dic_val;
                                }
                                // update dictionary
                                $dictionary[$dix] = $dic_val;
                                ++$dix;
                                // change bit length by case
                                if ($dix == 2047) {
                                        $bitlen = 12;
                                } elseif ($dix == 1023) {
                                        $bitlen = 11;
                                } elseif ($dix == 511) {
                                        $bitlen = 10;
                                }
                        }
                }
                return $decoded;
        }

        public function decodeFilterFlateDecode($data) {
                // intialize string to return
                $decoded = gzuncompress($data);
                if ($decoded === false) {
                        $this->Error('decodeFlate: invalid code');
                }
                return $decoded;
        }

        public function decodeFilterRunLengthDecode($data) {
                // intialize string to return
                $decoded = '';
                // data length
                $data_length = strlen($data);
                $i = 0;
                while($i < $data_length) {
                        // get current byte value
                        $byte = ord($data{$i});
                        if ($byte == 128) {
                                // a length value of 128 denote EOD
                                break;
                        } elseif ($byte < 128) {
                                // if the length byte is in the range 0 to 127
                                // the following length + 1 (1 to 128) bytes shall be copied literally during decompression
                                $decoded .= substr($data, ($i + 1), ($byte + 1));
                                // move to next block
                                $i += ($byte + 2);
                        } else {
                                // if length is in the range 129 to 255,
                                // the following single byte shall be copied 257 - length (2 to 128) times during decompression
                                $decoded .= str_repeat($data{($i + 1)}, (257 - $byte));
                                // move to next block
                                $i += 2;
                        }
                }
                return $decoded;
        }

        public function decodeFilterCCITTFaxDecode($data) {
                return $data;
        }

        public function decodeFilterJBIG2Decode($data) {
                return $data;
        }

        public function decodeFilterDCTDecode($data) {
                return $data;
        }

        public function decodeFilterJPXDecode($data) {
                return $data;
        }

        public function decodeFilterCrypt($data) {
                return $data;
        }

        // --- END FILTERS SECTION -------------------------------------------------

        public function Error($msg) {
                // exit program and print error
                die('<strong>TCPDF_FILTERS ERROR: </strong>'.$msg);
        }

} // END OF TCPDF_FILTERS CLASS

//============================================================+
// END OF FILE
//============================================================+