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<?php

//============================================================+

// File name   : tcpdf_filters.php

// Version     : 1.0.000

// Begin       : 2011-05-23

// Last Update : 2013-03-17

// Author      : Nicola Asuni - Tecnick.com LTD - www.tecnick.com - info@tecnick.com

// License     : GNU-LGPL v3 (http://www.gnu.org/copyleft/lesser.html)

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

// Copyright (C) 2011-2013 Nicola Asuni - Tecnick.com LTD

//

// 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.

//

// 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).

//

//============================================================+

/**

 * @file

 * This is a PHP class for decoding common PDF filters (PDF 32000-2008 - 7.4 Filters).<br>

 * @package com.tecnick.tcpdf

 * @author Nicola Asuni

 * @version 1.0.000

 */

/**

 * @class TCPDF_FILTERS

 * This is a PHP class for decoding common PDF filters (PDF 32000-2008 - 7.4 Filters).<br>

 * @package com.tecnick.tcpdf

 * @brief This is a PHP class for decoding common PDF filters.

 * @version 1.0.000

 * @author Nicola Asuni - info@tecnick.com

 */

class TCPDF_FILTERS {

	/**

	 * Define a list of available filter decoders.

	 * @private static

	 */

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

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

	/**

	 * Get a list of available decoding filters.

	 * @return (array) Array of available filter decoders.

	 * @since 1.0.000 (2011-05-23)

	 * @public static

	 */

	public static function getAvailableFilters() {

		return self::$available_filters;

	}

	/**

	 * Decode data using the specified filter type.

	 * @param $filter (string) Filter name.

	 * @param $data (string) Data to decode.

	 * @return Decoded data string.

	 * @since 1.0.000 (2011-05-23)

	 * @public static

	 */

	public static function decodeFilter($filter, $data) {

		switch ($filter) {

			case 'ASCIIHexDecode': {

				return self::decodeFilterASCIIHexDecode($data);

				break;

			}

			case 'ASCII85Decode': {

				return self::decodeFilterASCII85Decode($data);

				break;

			}

			case 'LZWDecode': {

				return self::decodeFilterLZWDecode($data);

				break;

			}

			case 'FlateDecode': {

				return self::decodeFilterFlateDecode($data);

				break;

			}

			case 'RunLengthDecode': {

				return self::decodeFilterRunLengthDecode($data);

				break;

			}

			case 'CCITTFaxDecode': {

				return self::decodeFilterCCITTFaxDecode($data);

				break;

			}

			case 'JBIG2Decode': {

				return self::decodeFilterJBIG2Decode($data);

				break;

			}

			case 'DCTDecode': {

				return self::decodeFilterDCTDecode($data);

				break;

			}

			case 'JPXDecode': {

				return self::decodeFilterJPXDecode($data);

				break;

			}

			case 'Crypt': {

				return self::decodeFilterCrypt($data);

				break;

			}

			default: {

				return self::decodeFilterStandard($data);

				break;

			}

		}

	}

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

	/**

	 * Standard

	 * Default decoding filter (leaves data unchanged).

	 * @param $data (string) Data to decode.

	 * @return Decoded data string.

	 * @since 1.0.000 (2011-05-23)

	 * @public static

	 */

	public static function decodeFilterStandard($data) {

		return $data;

	}

	/**

	 * ASCIIHexDecode

	 * Decodes data encoded in an ASCII hexadecimal representation, reproducing the original binary data.

	 * @param $data (string) Data to decode.

	 * @return Decoded data string.

	 * @since 1.0.000 (2011-05-23)

	 * @public static

	 */

	public static 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 {

				self::Error('decodeASCIIHex: invalid code');

			}

		}

		// check for invalid characters

		if (preg_match('/[^a-fA-F\d]/', $data) > 0) {

			self::Error('decodeASCIIHex: invalid code');

		}

		// get one byte of binary data for each pair of ASCII hexadecimal digits

		$decoded = pack('H*', $data);

		return $decoded;

	}

	/**

	 * ASCII85Decode

	 * Decodes data encoded in an ASCII base-85 representation, reproducing the original binary data.

	 * @param $data (string) Data to decode.

	 * @return Decoded data string.

	 * @since 1.0.000 (2011-05-23)

	 * @public static

	 */

	public static 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) {

			self::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 {

					self::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: {

				self::Error('decodeASCII85: invalid code');

				break;

			}

		}

		return $decoded;

	}

	/**

	 * LZWDecode

	 * Decompresses data encoded using the LZW (Lempel-Ziv-Welch) adaptive compression method, reproducing the original text or binary data.

	 * @param $data (string) Data to decode.

	 * @return Decoded data string.

	 * @since 1.0.000 (2011-05-23)

	 * @public static

	 */

	public static 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;

	}

	/**

	 * FlateDecode

	 * Decompresses data encoded using the zlib/deflate compression method, reproducing the original text or binary data.

	 * @param $data (string) Data to decode.

	 * @return Decoded data string.

	 * @since 1.0.000 (2011-05-23)

	 * @public static

	 */

	public static function decodeFilterFlateDecode($data) {

		// intialize string to return

		$decoded = gzuncompress($data);

		if ($decoded === false) {

			self::Error('decodeFlate: invalid code');

		}

		return $decoded;

	}

	/**

	 * RunLengthDecode

	 * Decompresses data encoded using a byte-oriented run-length encoding algorithm.

	 * @param $data (string) Data to decode.

	 * @since 1.0.000 (2011-05-23)

	 * @public static

	 */

	public static 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;

	}

	/**

	 * CCITTFaxDecode (NOT IMPLEMETED)

	 * Decompresses data encoded using the CCITT facsimile standard, reproducing the original data (typically monochrome image data at 1 bit per pixel).

	 * @param $data (string) Data to decode.

	 * @return Decoded data string.

	 * @since 1.0.000 (2011-05-23)

	 * @public static

	 */

	public static function decodeFilterCCITTFaxDecode($data) {

		return $data;

	}

	/**

	 * JBIG2Decode (NOT IMPLEMETED)

	 * Decompresses data encoded using the JBIG2 standard, reproducing the original monochrome (1 bit per pixel) image data (or an approximation of that data).

	 * @param $data (string) Data to decode.

	 * @return Decoded data string.

	 * @since 1.0.000 (2011-05-23)

	 * @public static

	 */

	public static function decodeFilterJBIG2Decode($data) {

		return $data;

	}

	/**

	 * DCTDecode (NOT IMPLEMETED)

	 * Decompresses data encoded using a DCT (discrete cosine transform) technique based on the JPEG standard, reproducing image sample data that approximates the original data.

	 * @param $data (string) Data to decode.

	 * @return Decoded data string.

	 * @since 1.0.000 (2011-05-23)

	 * @public static

	 */

	public static function decodeFilterDCTDecode($data) {

		return $data;

	}

	/**

	 * JPXDecode (NOT IMPLEMETED)

	 * Decompresses data encoded using the wavelet-based JPEG2000 standard, reproducing the original image data.

	 * @param $data (string) Data to decode.

	 * @return Decoded data string.

	 * @since 1.0.000 (2011-05-23)

	 * @public static

	 */

	public static function decodeFilterJPXDecode($data) {

		return $data;

	}

	/**

	 * Crypt (NOT IMPLEMETED)

	 * Decrypts data encrypted by a security handler, reproducing the data as it was before encryption.

	 * @param $data (string) Data to decode.

	 * @return Decoded data string.

	 * @since 1.0.000 (2011-05-23)

	 * @public static

	 */

	public static function decodeFilterCrypt($data) {

		return $data;

	}

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

	/**

	 * This method is automatically called in case of fatal error; it simply outputs the message and halts the execution.

	 * @param $msg (string) The error message

	 * @since 1.0.000 (2011-05-23)

	 * @public static

	 */

	public static function Error($msg) {

		// exit program and print error

		die('<strong>TCPDF_FILTERS ERROR: </strong>'.$msg);

	}

} // END OF TCPDF_FILTERS CLASS

//============================================================+

// END OF FILE

//============================================================+