482 lines
14 KiB
PHP
482 lines
14 KiB
PHP
<?php
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//============================================================+
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// File name : tcpdf_filters.php
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// Version : 1.0.001
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// Begin : 2011-05-23
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// Last Update : 2014-04-25
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// Author : Nicola Asuni - Tecnick.com LTD - www.tecnick.com - info@tecnick.com
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// License : GNU-LGPL v3 (http://www.gnu.org/copyleft/lesser.html)
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// -------------------------------------------------------------------
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// Copyright (C) 2011-2013 Nicola Asuni - Tecnick.com LTD
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//
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// This file is part of TCPDF software library.
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//
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// TCPDF is free software: you can redistribute it and/or modify it
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// under the terms of the GNU Lesser General Public License as
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// published by the Free Software Foundation, either version 3 of the
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// License, or (at your option) any later version.
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//
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// TCPDF is distributed in the hope that it will be useful, but
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// WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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// See the GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the License
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// along with TCPDF. If not, see
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// <http://www.tecnick.com/pagefiles/tcpdf/LICENSE.TXT>.
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//
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// See LICENSE.TXT file for more information.
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// -------------------------------------------------------------------
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//
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// Description : This is a PHP class for decoding common PDF filters (PDF 32000-2008 - 7.4 Filters).
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//
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//============================================================+
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/**
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* @file
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* This is a PHP class for decoding common PDF filters (PDF 32000-2008 - 7.4 Filters).<br>
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* @package com.tecnick.tcpdf
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* @author Nicola Asuni
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* @version 1.0.001
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*/
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/**
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* @class TCPDF_FILTERS
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* This is a PHP class for decoding common PDF filters (PDF 32000-2008 - 7.4 Filters).<br>
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* @package com.tecnick.tcpdf
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* @brief This is a PHP class for decoding common PDF filters.
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* @version 1.0.001
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* @author Nicola Asuni - info@tecnick.com
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*/
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class TCPDF_FILTERS {
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/**
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* Define a list of available filter decoders.
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* @private static
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*/
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private static $available_filters = array('ASCIIHexDecode', 'ASCII85Decode', 'LZWDecode', 'FlateDecode', 'RunLengthDecode');
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// -----------------------------------------------------------------------------
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/**
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* Get a list of available decoding filters.
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* @return (array) Array of available filter decoders.
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* @since 1.0.000 (2011-05-23)
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* @public static
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*/
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public static function getAvailableFilters() {
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return self::$available_filters;
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}
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/**
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* Decode data using the specified filter type.
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* @param $filter (string) Filter name.
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* @param $data (string) Data to decode.
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* @return Decoded data string.
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* @since 1.0.000 (2011-05-23)
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* @public static
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*/
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public static function decodeFilter($filter, $data) {
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switch ($filter) {
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case 'ASCIIHexDecode': {
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return self::decodeFilterASCIIHexDecode($data);
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break;
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}
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case 'ASCII85Decode': {
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return self::decodeFilterASCII85Decode($data);
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break;
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}
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case 'LZWDecode': {
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return self::decodeFilterLZWDecode($data);
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break;
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}
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case 'FlateDecode': {
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return self::decodeFilterFlateDecode($data);
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break;
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}
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case 'RunLengthDecode': {
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return self::decodeFilterRunLengthDecode($data);
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break;
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}
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case 'CCITTFaxDecode': {
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return self::decodeFilterCCITTFaxDecode($data);
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break;
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}
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case 'JBIG2Decode': {
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return self::decodeFilterJBIG2Decode($data);
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break;
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}
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case 'DCTDecode': {
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return self::decodeFilterDCTDecode($data);
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break;
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}
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case 'JPXDecode': {
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return self::decodeFilterJPXDecode($data);
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break;
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}
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case 'Crypt': {
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return self::decodeFilterCrypt($data);
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break;
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}
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default: {
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return self::decodeFilterStandard($data);
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break;
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}
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}
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}
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// --- FILTERS (PDF 32000-2008 - 7.4 Filters) ------------------------------
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/**
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* Standard
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* Default decoding filter (leaves data unchanged).
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* @param $data (string) Data to decode.
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* @return Decoded data string.
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* @since 1.0.000 (2011-05-23)
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* @public static
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*/
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public static function decodeFilterStandard($data) {
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return $data;
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}
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/**
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* ASCIIHexDecode
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* Decodes data encoded in an ASCII hexadecimal representation, reproducing the original binary data.
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* @param $data (string) Data to decode.
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* @return Decoded data string.
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* @since 1.0.000 (2011-05-23)
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* @public static
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*/
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public static function decodeFilterASCIIHexDecode($data) {
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// initialize string to return
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$decoded = '';
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// all white-space characters shall be ignored
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$data = preg_replace('/[\s]/', '', $data);
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// check for EOD character: GREATER-THAN SIGN (3Eh)
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$eod = strpos($data, '>');
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if ($eod !== false) {
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// remove EOD and extra data (if any)
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$data = substr($data, 0, $eod);
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$eod = true;
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}
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// get data length
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$data_length = strlen($data);
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if (($data_length % 2) != 0) {
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// odd number of hexadecimal digits
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if ($eod) {
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// EOD shall behave as if a 0 (zero) followed the last digit
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$data = substr($data, 0, -1).'0'.substr($data, -1);
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} else {
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self::Error('decodeFilterASCIIHexDecode: invalid code');
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}
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}
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// check for invalid characters
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if (preg_match('/[^a-fA-F\d]/', $data) > 0) {
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self::Error('decodeFilterASCIIHexDecode: invalid code');
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}
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// get one byte of binary data for each pair of ASCII hexadecimal digits
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$decoded = pack('H*', $data);
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return $decoded;
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}
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/**
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* ASCII85Decode
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* Decodes data encoded in an ASCII base-85 representation, reproducing the original binary data.
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* @param $data (string) Data to decode.
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* @return Decoded data string.
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* @since 1.0.000 (2011-05-23)
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* @public static
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*/
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public static function decodeFilterASCII85Decode($data) {
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// initialize string to return
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$decoded = '';
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// all white-space characters shall be ignored
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$data = preg_replace('/[\s]/', '', $data);
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// remove start sequence 2-character sequence <~ (3Ch)(7Eh)
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if (strpos($data, '<~') !== false) {
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// remove EOD and extra data (if any)
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$data = substr($data, 2);
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}
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// check for EOD: 2-character sequence ~> (7Eh)(3Eh)
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$eod = strpos($data, '~>');
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if ($eod !== false) {
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// remove EOD and extra data (if any)
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$data = substr($data, 0, $eod);
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}
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// data length
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$data_length = strlen($data);
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// check for invalid characters
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if (preg_match('/[^\x21-\x75,\x74]/', $data) > 0) {
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self::Error('decodeFilterASCII85Decode: invalid code');
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}
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// z sequence
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$zseq = chr(0).chr(0).chr(0).chr(0);
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// position inside a group of 4 bytes (0-3)
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$group_pos = 0;
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$tuple = 0;
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$pow85 = array((85*85*85*85), (85*85*85), (85*85), 85, 1);
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$last_pos = ($data_length - 1);
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// for each byte
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for ($i = 0; $i < $data_length; ++$i) {
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// get char value
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$char = ord($data[$i]);
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if ($char == 122) { // 'z'
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if ($group_pos == 0) {
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$decoded .= $zseq;
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} else {
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self::Error('decodeFilterASCII85Decode: invalid code');
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}
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} else {
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// the value represented by a group of 5 characters should never be greater than 2^32 - 1
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$tuple += (($char - 33) * $pow85[$group_pos]);
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if ($group_pos == 4) {
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$decoded .= chr($tuple >> 24).chr($tuple >> 16).chr($tuple >> 8).chr($tuple);
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$tuple = 0;
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$group_pos = 0;
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} else {
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++$group_pos;
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}
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}
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}
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if ($group_pos > 1) {
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$tuple += $pow85[($group_pos - 1)];
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}
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// last tuple (if any)
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switch ($group_pos) {
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case 4: {
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$decoded .= chr($tuple >> 24).chr($tuple >> 16).chr($tuple >> 8);
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break;
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}
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case 3: {
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$decoded .= chr($tuple >> 24).chr($tuple >> 16);
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break;
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}
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case 2: {
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$decoded .= chr($tuple >> 24);
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break;
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}
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case 1: {
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self::Error('decodeFilterASCII85Decode: invalid code');
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break;
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}
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}
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return $decoded;
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}
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/**
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* LZWDecode
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* Decompresses data encoded using the LZW (Lempel-Ziv-Welch) adaptive compression method, reproducing the original text or binary data.
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* @param $data (string) Data to decode.
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* @return Decoded data string.
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* @since 1.0.000 (2011-05-23)
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* @public static
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*/
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public static function decodeFilterLZWDecode($data) {
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// initialize string to return
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$decoded = '';
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// data length
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$data_length = strlen($data);
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// convert string to binary string
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$bitstring = '';
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for ($i = 0; $i < $data_length; ++$i) {
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$bitstring .= sprintf('%08b', ord($data[$i]));
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}
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// get the number of bits
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$data_length = strlen($bitstring);
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// initialize code length in bits
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$bitlen = 9;
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// initialize dictionary index
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$dix = 258;
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// initialize the dictionary (with the first 256 entries).
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$dictionary = array();
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for ($i = 0; $i < 256; ++$i) {
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$dictionary[$i] = chr($i);
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}
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// previous val
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$prev_index = 0;
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// while we encounter EOD marker (257), read code_length bits
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while (($data_length > 0) AND (($index = bindec(substr($bitstring, 0, $bitlen))) != 257)) {
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// remove read bits from string
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$bitstring = substr($bitstring, $bitlen);
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// update number of bits
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$data_length -= $bitlen;
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if ($index == 256) { // clear-table marker
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// reset code length in bits
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$bitlen = 9;
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// reset dictionary index
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$dix = 258;
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$prev_index = 256;
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// reset the dictionary (with the first 256 entries).
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$dictionary = array();
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for ($i = 0; $i < 256; ++$i) {
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$dictionary[$i] = chr($i);
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}
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} elseif ($prev_index == 256) {
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// first entry
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$decoded .= $dictionary[$index];
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$prev_index = $index;
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} else {
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// check if index exist in the dictionary
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if ($index < $dix) {
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// index exist on dictionary
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$decoded .= $dictionary[$index];
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$dic_val = $dictionary[$prev_index].$dictionary[$index][0];
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// store current index
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$prev_index = $index;
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} else {
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// index do not exist on dictionary
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$dic_val = $dictionary[$prev_index].$dictionary[$prev_index][0];
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$decoded .= $dic_val;
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}
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// update dictionary
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$dictionary[$dix] = $dic_val;
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++$dix;
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// change bit length by case
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if ($dix == 2047) {
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$bitlen = 12;
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} elseif ($dix == 1023) {
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$bitlen = 11;
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} elseif ($dix == 511) {
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$bitlen = 10;
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}
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}
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}
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return $decoded;
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}
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/**
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* FlateDecode
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* Decompresses data encoded using the zlib/deflate compression method, reproducing the original text or binary data.
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* @param $data (string) Data to decode.
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* @return Decoded data string.
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* @since 1.0.000 (2011-05-23)
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* @public static
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*/
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public static function decodeFilterFlateDecode($data) {
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// initialize string to return
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$decoded = @gzuncompress($data);
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if ($decoded === false) {
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self::Error('decodeFilterFlateDecode: invalid code');
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}
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return $decoded;
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}
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/**
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* RunLengthDecode
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* Decompresses data encoded using a byte-oriented run-length encoding algorithm.
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* @param $data (string) Data to decode.
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* @since 1.0.000 (2011-05-23)
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* @public static
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*/
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public static function decodeFilterRunLengthDecode($data) {
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// initialize string to return
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$decoded = '';
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// data length
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$data_length = strlen($data);
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$i = 0;
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while($i < $data_length) {
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// get current byte value
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$byte = ord($data[$i]);
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if ($byte == 128) {
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// a length value of 128 denote EOD
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break;
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} elseif ($byte < 128) {
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// if the length byte is in the range 0 to 127
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// the following length + 1 (1 to 128) bytes shall be copied literally during decompression
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$decoded .= substr($data, ($i + 1), ($byte + 1));
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// move to next block
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$i += ($byte + 2);
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} else {
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// if length is in the range 129 to 255,
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// the following single byte shall be copied 257 - length (2 to 128) times during decompression
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$decoded .= str_repeat($data[($i + 1)], (257 - $byte));
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// move to next block
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$i += 2;
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}
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}
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return $decoded;
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}
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/**
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* CCITTFaxDecode (NOT IMPLEMETED - RETURN AN EXCEPTION)
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* Decompresses data encoded using the CCITT facsimile standard, reproducing the original data (typically monochrome image data at 1 bit per pixel).
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* @param $data (string) Data to decode.
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* @return Decoded data string.
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* @since 1.0.000 (2011-05-23)
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* @public static
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*/
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public static function decodeFilterCCITTFaxDecode($data) {
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self::Error('~decodeFilterCCITTFaxDecode: this method has not been yet implemented');
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//return $data;
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}
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/**
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* JBIG2Decode (NOT IMPLEMETED - RETURN AN EXCEPTION)
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* Decompresses data encoded using the JBIG2 standard, reproducing the original monochrome (1 bit per pixel) image data (or an approximation of that data).
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* @param $data (string) Data to decode.
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* @return Decoded data string.
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* @since 1.0.000 (2011-05-23)
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* @public static
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*/
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public static function decodeFilterJBIG2Decode($data) {
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self::Error('~decodeFilterJBIG2Decode: this method has not been yet implemented');
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//return $data;
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}
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/**
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* DCTDecode (NOT IMPLEMETED - RETURN AN EXCEPTION)
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* Decompresses data encoded using a DCT (discrete cosine transform) technique based on the JPEG standard, reproducing image sample data that approximates the original data.
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* @param $data (string) Data to decode.
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* @return Decoded data string.
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* @since 1.0.000 (2011-05-23)
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* @public static
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*/
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public static function decodeFilterDCTDecode($data) {
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self::Error('~decodeFilterDCTDecode: this method has not been yet implemented');
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//return $data;
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}
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/**
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* JPXDecode (NOT IMPLEMETED - RETURN AN EXCEPTION)
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* Decompresses data encoded using the wavelet-based JPEG2000 standard, reproducing the original image data.
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* @param $data (string) Data to decode.
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* @return Decoded data string.
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* @since 1.0.000 (2011-05-23)
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* @public static
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*/
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public static function decodeFilterJPXDecode($data) {
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self::Error('~decodeFilterJPXDecode: this method has not been yet implemented');
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//return $data;
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}
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/**
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* Crypt (NOT IMPLEMETED - RETURN AN EXCEPTION)
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* Decrypts data encrypted by a security handler, reproducing the data as it was before encryption.
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* @param $data (string) Data to decode.
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* @return Decoded data string.
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* @since 1.0.000 (2011-05-23)
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* @public static
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*/
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public static function decodeFilterCrypt($data) {
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self::Error('~decodeFilterCrypt: this method has not been yet implemented');
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//return $data;
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}
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// --- END FILTERS SECTION -------------------------------------------------
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/**
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* Throw an exception.
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* @param $msg (string) The error message
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* @since 1.0.000 (2011-05-23)
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* @public static
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*/
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public static function Error($msg) {
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throw new Exception('TCPDF_PARSER ERROR: '.$msg);
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}
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} // END OF TCPDF_FILTERS CLASS
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//============================================================+
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// END OF FILE
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//============================================================+
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