Trích xuất văn bản và hình ảnh từ tệp PDF bằng PHP

<?php
/*
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;
	}
}
?>

<?php
	include ( 'class.pdf2text.php' ) ;

	function  output ( $message )
	   {
		if  ( php_sapi_name ( )  ==  'cli' )
			echo ( $message ) ;
		else
			echo ( nl2br ( $message ) ) ;
	    }

	$file	=  'sample' ; // name of pdf file without .pdf extenstion, sample.pdf
	$pdf	=  new PdfToText ( "$file.pdf" ) ;

	
	output ( "Extracted file contents :\n" ) ;
	output ( $pdf -> Text ) ;
?>

<?php
	// This example saves all images found in the 'sample.pdf' file, after having put the string
	// "Hello world" in blue color, using the largest stock font
	include ( 'class.pdf2text.php' ) ;

	function  output ( $message )
	   {
		if  ( php_sapi_name ( )  ==  'cli' )
			echo ( $message ) ;
		else
			echo ( nl2br ( $message ) ) ;
	    }

	$file		=  'sample' ; // name of pdf file without .pdf extenstion, sample.pdf
	$pdf		=  new PdfToText ( "$file.pdf", PdfToText::PDFOPT_DECODE_IMAGE_DATA ) ;
	$image_count 	=  count ( $pdf -> Images ) ;
	
	if  ( $image_count )
	   {
		for  ( $i = 0 ; $i  <  $image_count ; $i ++ )
		   {
			// Get next image and generate a filename for it (there will be a file named "sample.x.jpg"
			// for each image found in file "sample.pdf")
			$img		=  $pdf -> Images [$i] ;			// This is an object of type PdfImage
			$imgindex 	=  sprintf ( "%02d", $i + 1 ) ;
			$output_image	=  "$file.$imgindex.jpg" ;
			
			// Allocate a color entry for "white". Note that the ImageResource property of every PdfImage object
			// is a real image resource that can be specified to any of the image*() Php functions
			$textcolor	=  imagecolorallocate ( $img -> ImageResource, 0, 0, 255 ) ;
			
			// Put the string "Hello world" on top of the image. 
			imagestring ( $img -> ImageResource, 5, 0, 0, "Hello world #$imgindex", $textcolor ) ;
			
			// Save the image (the default is IMG_JPG, but you can specify another IMG_* image type by specifying it
			// as the second parameter)
			$img -> SaveAs ( $output_image ) ;
			
			output ( "Generated image file \"$output_image\"" ) ;
		    }
	    }
	else
		echo "No image was found in sample file \"$file.pdf\"" ;

<?php
	include ( 'class.pdf2text.php' ) ;


	$file	=  'sample' ; // name of pdf file without .pdf extenstion, sample.pdf
	$pdf	=  new PdfToText ( "file.pdf" ) ;

	
	$search = 'john'; // keyword to search goes here 
	 
	    $result		=  $pdf -> text_strpos  ( $search, $start = 0 ) ; // $start is the start offset in the pdf text contents
	    
   echo "<pre>";
print_r($result); // the result will give you the position of searched string and thus indicating its presence in PDF file
?>