class.pdf2text.php

<?php
/*
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

This code is an improved version of what can be found at:
http://www.webcheatsheet.com/php/reading_clean_text_from_pdf.php

Related information:
http://www.adobe.com/devnet/acrobat/pdfs/PDF32000_2008.pdf

AUTHOR:
- Webcheatsheet.com (Original code)
- Joeri Stegeman (joeri210 [at] yahoo [dot] com) (Class conversion and fixes/adjustments)

DESCRIPTION:
This is a class to convert PDF files into ASCII text or so called PDF text extraction.
It will ignore anything that is not addressed as text within the PDF and any layout.
Currently supported filters are: ASCIIHexDecode, ASCII85Decode, FlateDecode

HISTORY:
v1.01 2014-02-03: Fixed some word concatenation issues
v1.00 2010-04-17: Initial release of PDF2Text

PURPOSE(S):
Most likely for people that want their PDF to be searchable.

SYNTAX:
include('class.pdf2text.php');
$a = new PDF2Text();
$a->setFilename('test.pdf');
$a->decodePDF();
echo $a->output();

ALTERNATIVES:
Other excellent options to search within a PDF:
- Apache PDFbox (http://pdfbox.apache.org/). An open source Java solution
- pdflib TET (http://www.pdflib.com/products/tet/)
- Online converter: http://snowtide.com/PDFTextStream
*/

class PDF2Text {
    // Some settings
    var $multibyte = 4; // Use setUnicode(TRUE|FALSE)
    var $convertquotes = ENT_QUOTES; // ENT_COMPAT (double-quotes), ENT_QUOTES (Both), ENT_NOQUOTES (None)
    var $showprogress = true; // TRUE if you have problems with time-out

    // Variables
    var $filename = '';
    var $decodedtext = '';

    function setFilename($filename) {
        // Reset
        $this->decodedtext = '';
        $this->filename = $filename;
    }

    function output($echo = false) {
        if($echo) echo $this->decodedtext;
        else return $this->decodedtext;
    }

    function setUnicode($input) {
        // 4 for unicode. But 2 should work in most cases just fine
        if($input == true) $this->multibyte = 4;
        else $this->multibyte = 2;
    }

    function decodePDF() {
        // Read the data from pdf file
        $infile = @file_get_contents($this->filename, FILE_BINARY);
        if (empty($infile))
            return "";

        // Get all text data.
        $transformations = array();
        $texts = array();

        // Get the list of all objects.
        preg_match_all("#obj[\n|\r](.*)endobj[\n|\r]#ismU", $infile . "endobj\r", $objects);
        $objects = @$objects[1];

        // Select objects with streams.
        for ($i = 0; $i < count($objects); $i++) {
            $currentObject = $objects[$i];

            // Prevent time-out
            @set_time_limit ();
            if($this->showprogress) {
//              echo ". ";
                flush(); ob_flush();
            }

            // Check if an object includes data stream.
            if (preg_match("#stream[\n|\r](.*)endstream[\n|\r]#ismU", $currentObject . "endstream\r", $stream )) {
                $stream = ltrim($stream[1]);
                // Check object parameters and look for text data.
                $options = $this->getObjectOptions($currentObject);

                if (!(empty($options["Length1"]) && empty($options["Type"]) && empty($options["Subtype"])) )
//              if ( $options["Image"] && $options["Subtype"] )
//              if (!(empty($options["Length1"]) &&  empty($options["Subtype"])) )
                    continue;

                // Hack, length doesnt always seem to be correct
                unset($options["Length"]);

                // So, we have text data. Decode it.
                $data = $this->getDecodedStream($stream, $options);

                if (strlen($data)) {
                    if (preg_match_all("#BT[\n|\r](.*)ET[\n|\r]#ismU", $data . "ET\r", $textContainers)) {
                        $textContainers = @$textContainers[1];
                        $this->getDirtyTexts($texts, $textContainers);
                    } else
                        $this->getCharTransformations($transformations, $data);
                }
            }
        }

        // Analyze text blocks taking into account character transformations and return results.
        $this->decodedtext = $this->getTextUsingTransformations($texts, $transformations);
    }


    function decodeAsciiHex($input) {
        $output = "";

        $isOdd = true;
        $isComment = false;

        for($i = 0, $codeHigh = -1; $i < strlen($input) && $input[$i] != '>'; $i++) {
            $c = $input[$i];

            if($isComment) {
                if ($c == '\r' || $c == '\n')
                    $isComment = false;
                continue;
            }

            switch($c) {
                case '\0': case '\t': case '\r': case '\f': case '\n': case ' ': break;
                case '%':
                    $isComment = true;
                break;

                default:
                    $code = hexdec($c);
                    if($code === 0 && $c != '0')
                        return "";

                    if($isOdd)
                        $codeHigh = $code;
                    else
                        $output .= chr($codeHigh * 16 + $code);

                    $isOdd = !$isOdd;
                break;
            }
        }

        if($input[$i] != '>')
            return "";

        if($isOdd)
            $output .= chr($codeHigh * 16);

        return $output;
    }

    function decodeAscii85($input) {
        $output = "";

        $isComment = false;
        $ords = array();

        for($i = 0, $state = 0; $i < strlen($input) && $input[$i] != '~'; $i++) {
            $c = $input[$i];

            if($isComment) {
                if ($c == '\r' || $c == '\n')
                    $isComment = false;
                continue;
            }

            if ($c == '\0' || $c == '\t' || $c == '\r' || $c == '\f' || $c == '\n' || $c == ' ')
                continue;
            if ($c == '%') {
                $isComment = true;
                continue;
            }
            if ($c == 'z' && $state === 0) {
                $output .= str_repeat(chr(0), 4);
                continue;
            }
            if ($c < '!' || $c > 'u')
                return "";

            $code = ord($input[$i]) & 0xff;
            $ords[$state++] = $code - ord('!');

            if ($state == 5) {
                $state = 0;
                for ($sum = 0, $j = 0; $j < 5; $j++)
                    $sum = $sum * 85 + $ords[$j];
                for ($j = 3; $j >= 0; $j--)
                    $output .= chr($sum >> ($j * 8));
            }
        }
        if ($state === 1)
            return "";
        elseif ($state > 1) {
            for ($i = 0, $sum = 0; $i < $state; $i++)
                $sum += ($ords[$i] + ($i == $state - 1)) * pow(85, 4 - $i);
            for ($i = 0; $i < $state - 1; $i++) {
                try {
                    if(false == ($o = chr($sum >> ((3 - $i) * 8)))) {
                        throw new Exception('Error');
                    }
                    $output .= $o;
                } catch (Exception $e) { /*Dont do anything*/ }
            }
        }

        return $output;
    }

    function decodeFlate($data) {
        return @gzuncompress($data);
    }

    function getObjectOptions($object) {
        $options = array();

        if (preg_match("#<<(.*)>>#ismU", $object, $options)) {
            $options = explode("/", $options[1]);
            @array_shift($options);

            $o = array();
            for ($j = 0; $j < @count($options); $j++) {
                $options[$j] = preg_replace("#\s+#", " ", trim($options[$j]));
                if (strpos($options[$j], " ") !== false) {
                    $parts = explode(" ", $options[$j]);
                    $o[$parts[0]] = $parts[1];
                } else
                    $o[$options[$j]] = true;
            }
            $options = $o;
            unset($o);
        }

        return $options;
    }

    function getDecodedStream($stream, $options) {
        $data = "";
        if (empty($options["Filter"]))
            $data = $stream;
        else {
            $length = !empty($options["Length"]) ? $options["Length"] : strlen($stream);
            $_stream = substr($stream, 0, $length);

            foreach ($options as $key => $value) {
                if ($key == "ASCIIHexDecode")
                    $_stream = $this->decodeAsciiHex($_stream);
                elseif ($key == "ASCII85Decode")
                    $_stream = $this->decodeAscii85($_stream);
                elseif ($key == "FlateDecode")
                    $_stream = $this->decodeFlate($_stream);
                elseif ($key == "Crypt") { // TO DO
                }
            }
            $data = $_stream;
        }
        return $data;
    }

    function getDirtyTexts(&$texts, $textContainers) {
        for ($j = 0; $j < count($textContainers); $j++) {
            if (preg_match_all("#\[(.*)\]\s*TJ[\n|\r]#ismU", $textContainers[$j], $parts))
                $texts = array_merge($texts, array(@implode('', $parts[1])));
            elseif (preg_match_all("#T[d|w|m|f]\s*(\(.*\))\s*Tj[\n|\r]#ismU", $textContainers[$j], $parts))
                $texts = array_merge($texts, array(@implode('', $parts[1])));
            elseif (preg_match_all("#T[d|w|m|f]\s*(\[.*\])\s*Tj[\n|\r]#ismU", $textContainers[$j], $parts))
                $texts = array_merge($texts, array(@implode('', $parts[1])));
        }

    }

    function getCharTransformations(&$transformations, $stream) {
        preg_match_all("#([0-9]+)\s+beginbfchar(.*)endbfchar#ismU", $stream, $chars, PREG_SET_ORDER);
        preg_match_all("#([0-9]+)\s+beginbfrange(.*)endbfrange#ismU", $stream, $ranges, PREG_SET_ORDER);

        for ($j = 0; $j < count($chars); $j++) {
            $count = $chars[$j][1];
            $current = explode("\n", trim($chars[$j][2]));
            for ($k = 0; $k < $count && $k < count($current); $k++) {
                if (preg_match("#<([0-9a-f]{2,4})>\s+<([0-9a-f]{4,512})>#is", trim($current[$k]), $map))
                    $transformations[str_pad($map[1], 4, "0")] = $map[2];
            }
        }
        for ($j = 0; $j < count($ranges); $j++) {
            $count = $ranges[$j][1];
            $current = explode("\n", trim($ranges[$j][2]));
            for ($k = 0; $k < $count && $k < count($current); $k++) {
                if (preg_match("#<([0-9a-f]{4})>\s+<([0-9a-f]{4})>\s+<([0-9a-f]{4})>#is", trim($current[$k]), $map)) {
                    $from = hexdec($map[1]);
                    $to = hexdec($map[2]);
                    $_from = hexdec($map[3]);

                    for ($m = $from, $n = 0; $m <= $to; $m++, $n++)
                        $transformations[sprintf("%04X", $m)] = sprintf("%04X", $_from + $n);
                } elseif (preg_match("#<([0-9a-f]{4})>\s+<([0-9a-f]{4})>\s+\[(.*)\]#ismU", trim($current[$k]), $map)) {
                    $from = hexdec($map[1]);
                    $to = hexdec($map[2]);
                    $parts = preg_split("#\s+#", trim($map[3]));

                    for ($m = $from, $n = 0; $m <= $to && $n < count($parts); $m++, $n++)
                        $transformations[sprintf("%04X", $m)] = sprintf("%04X", hexdec($parts[$n]));
                }
            }
        }
    }
    function getTextUsingTransformations($texts, $transformations) {
        $document = "";
        for ($i = 0; $i < count($texts); $i++) {
            $isHex = false;
            $isPlain = false;

            $hex = "";
            $plain = "";
            for ($j = 0; $j < strlen($texts[$i]); $j++) {
                $c = $texts[$i][$j];
                switch($c) {
                    case "<":
                        $hex = "";
                        $isHex = true;
                        $isPlain = false;
                    break;
                    case ">":
                        $hexs = str_split($hex, $this->multibyte); // 2 or 4 (UTF8 or ISO)
                        for ($k = 0; $k < count($hexs); $k++) {

                            $chex = str_pad($hexs[$k], 4, "0"); // Add tailing zero
                            if (isset($transformations[$chex]))
                                $chex = $transformations[$chex];
                            $document .= html_entity_decode("&#x".$chex.";");
                        }
                        $isHex = false;
                    break;
                    case "(":
                        $plain = "";
                        $isPlain = true;
                        $isHex = false;
                    break;
                    case ")":
                        $document .= $plain;
                        $isPlain = false;
                    break;
                    case "\\":
                        $c2 = $texts[$i][$j + 1];
                        if (in_array($c2, array("\\", "(", ")"))) $plain .= $c2;
                        elseif ($c2 == "n") $plain .= '\n';
                        elseif ($c2 == "r") $plain .= '\r';
                        elseif ($c2 == "t") $plain .= '\t';
                        elseif ($c2 == "b") $plain .= '\b';
                        elseif ($c2 == "f") $plain .= '\f';
                        elseif ($c2 >= '0' && $c2 <= '9') {
                            $oct = preg_replace("#[^0-9]#", "", substr($texts[$i], $j + 1, 3));
                            $j += strlen($oct) - 1;
                            $plain .= html_entity_decode("&#".octdec($oct).";", $this->convertquotes);
                        }
                        $j++;
                    break;

                    default:
                        if ($isHex)
                            $hex .= $c;
                        elseif ($isPlain)
                            $plain .= $c;
                    break;
                }
            }
            $document .= "\n";
        }

        return $document;
    }
}
?>