* @date : 2013-08-08 * * References : * - http://www.mactech.com/articles/mactech/Vol.15/15.09/PDFIntro/index.html * - http://framework.zend.com/issues/secure/attachment/12512/Pdf.php * - http://www.php.net/manual/en/ref.pdf.php#74211 */ class PdfParser { /** * Parse PDF file * * @param string $filename * @return string */ public static function parseFile($filename) { $content = file_get_contents($filename); return self::extractText($content); } /** * Parse PDF content * * @param string $content * @return string */ public static function parseContent($content) { return self::extractText($content); } /** * Convert a PDF into text. * * @param string $filename The filename to extract the data from. * @return string The extracted text from the PDF */ protected static function extractText($data) { /** * Split apart the PDF document into sections. We will address each * section separately. */ $a_obj = self::getDataArray($data, 'obj', 'endobj'); $j = 0; $a_chunks = array(); /** * Attempt to extract each part of the PDF document into a 'filter' * element and a 'data' element. This can then be used to decode the * data. */ foreach ($a_obj as $obj) { $a_filter = self::getDataArray($obj, '<<', '>>'); if (is_array($a_filter) && isset($a_filter[0])) { $a_chunks[$j]['filter'] = $a_filter[0]; $a_data = self::getDataArray($obj, 'stream', 'endstream'); if (is_array($a_data) && isset($a_data[0])) { $a_chunks[$j]['data'] = trim(substr($a_data[0], strlen('stream'), strlen($a_data[0]) - strlen('stream') - strlen('endstream'))); } $j++; } } $result_data = null; // decode the chunks foreach ($a_chunks as $chunk) { // Look at each chunk decide if we can decode it by looking at the contents of the filter if (isset($chunk['data'])) { // look at the filter to find out which encoding has been used if (strpos($chunk['filter'], 'FlateDecode') !== false) { // Use gzuncompress but suppress error messages. $data =@ gzuncompress($chunk['data']); } else { $data = $chunk['data']; } if (trim($data) != '') { // If we got data then attempt to extract it. $result_data .= ' ' . self::extractTextElements($data); } } } /** * Make sure we don't have large blocks of white space before and after * our string. Also extract alphanumerical information to reduce * redundant data. */ if (trim($result_data) == '') { return null; } else { // Optimize hyphened words $result_data = preg_replace('/\s*-[\r\n]+\s*/', '', $result_data); $result_data = preg_replace('/\s+/', ' ', $result_data); return $result_data; } } protected static function extractTextElements($content) { if (strpos($content, '/CIDInit') === 0) { return ''; } $text = ''; $lines = explode("\n", $content); foreach ($lines as $line) { $line = trim($line); $matches = array(); // Parse each lines to extract command and operator values if (preg_match('/^(?.*[\)\] ])(?[a-z]+[\*]?)$/i', $line, $matches)) { $command = trim($matches['command']); // Convert octal encoding $found_octal_values = array(); preg_match_all('/\\\\([0-9]{3})/', $command, $found_octal_values); foreach ($found_octal_values[0] as $value) { $octal = substr($value, 1); if ((int)$octal < 40) { // Skips non printable chars $command = str_replace($value, '', $command); } else { $command = str_replace($value, chr(octdec($octal)), $command); } } // Removes encoded new lines, tabs, ... $command = preg_replace('/\\\\[\r\n]/', '', $command); $command = preg_replace('/\\\\[rnftb ]/', ' ', $command); // Force UTF-8 charset $encoding = mb_detect_encoding($command, array('ASCII', 'UTF-8', 'Windows-1252', 'ISO-8859-1')); if (strtoupper($encoding) != 'UTF-8') { if ($decoded = @iconv('CP1252', 'UTF-8//TRANSLIT//IGNORE', $command)) { $command = $decoded; } } // Removes leading spaces $operator = trim($matches['operator']); } else { $command = $line; $operator = ''; } // Handle main operators switch ($operator) { // Set character spacing. case 'Tc': break; // Move text current point. case 'Td': $values = explode(' ', $command); $y = array_pop($values); $x = array_pop($values); if ($x > 0) { $text .= ' '; } if ($y < 0) { $text .= ' '; } break; // Move text current point and set leading. case 'TD': $values = explode(' ', $command); $y = array_pop($values); if ($y < 0) { $text .= "\n"; } break; // Set font name and size. case 'Tf': $text.= ' '; break; // Display text, allowing individual character positioning case 'TJ': $start = mb_strpos($command, '[', null, 'UTF-8') + 1; $end = mb_strrpos($command, ']', null, 'UTF-8'); $text.= self::parseTextCommand(mb_substr($command, $start, $end - $start, 'UTF-8')); break; // Display text. case 'Tj': $start = mb_strpos($command, '(', null, 'UTF-8') + 1; $end = mb_strrpos($command, ')', null, 'UTF-8'); $text.= mb_substr($command, $start, $end - $start, 'UTF-8'); // Removes round brackets break; // Set leading. case 'TL': // Set text matrix. case 'Tm': // $text.= ' '; break; // Set text rendering mode. case 'Tr': break; // Set super/subscripting text rise. case 'Ts': break; // Set text spacing. case 'Tw': break; // Set horizontal scaling. case 'Tz': break; // Move to start of next line. case 'T*': $text.= "\n"; break; // Internal use case 'g': case 'gs': case 're': case 'f': // Begin text case 'BT': // End text case 'ET': break; case '': break; default: } } $text = str_replace(array('\\(', '\\)'), array('(', ')'), $text); return $text; } /** * Strip out the text from a small chunk of data. * * @param string $text * @param int $font_size Currently not used * * @return string */ protected static function parseTextCommand($text, $font_size = 0) { $result = ''; $cur_start_pos = 0; while (($cur_start_text = mb_strpos($text, '(', $cur_start_pos, 'UTF-8')) !== false) { // New text element found if ($cur_start_text - $cur_start_pos > 8) { $spacing = ' '; } else { $spacing_size = mb_substr($text, $cur_start_pos, $cur_start_text - $cur_start_pos, 'UTF-8'); if ($spacing_size < -50) { $spacing = ' '; } else { $spacing = ''; } } $cur_start_text++; $start_search_end = $cur_start_text; while (($cur_start_pos = mb_strpos($text, ')', $start_search_end, 'UTF-8')) !== false) { if (mb_substr($text, $cur_start_pos - 1, 1, 'UTF-8') != '\\') { break; } $start_search_end = $cur_start_pos + 1; } // something wrong happened if ($cur_start_pos === false) { break; } // Add to result $result .= $spacing . mb_substr($text, $cur_start_text, $cur_start_pos - $cur_start_text, 'UTF-8'); $cur_start_pos++; } return $result; } /** * Convert a section of data into an array, separated by the start and end words. * * @param string $data The data. * @param string $start_word The start of each section of data. * @param string $end_word The end of each section of data. * @return array The array of data. */ protected static function getDataArray($data, $start_word, $end_word) { $start = 0; $end = 0; $a_results = array(); while ($start !== false && $end !== false) { $start = strpos($data, $start_word, $end); $end = strpos($data, $end_word, $start); if ($end !== false && $start !== false) { // data is between start and end $a_results[] = substr($data, $start, $end - $start + strlen($end_word)); } } return $a_results; } }