PHP - sacar string de documento

function pdf2string($sourcefile) {

    $fp = fopen($sourcefile, 'rb');

    $content = fread($fp, filesize($sourcefile));

    fclose($fp);

    $searchstart = 'stream';

    $searchend = 'endstream';

    $pdfText = '';

    $pos = 0;

    $pos2 = 0;

    $startpos = 0;

    while ($pos !== false && $pos2 !== false) {

        $pos = strpos($content, $searchstart, $startpos);

        $pos2 = strpos($content, $searchend, $startpos + 1);

        if ($pos !== false && $pos2 !== false){

            if ($content[$pos] == 0x0d && $content[$pos + 1] == 0x0a) {

                $pos += 2;

            } else if ($content[$pos] == 0x0a) {

                $pos++;

            }

            if ($content[$pos2 - 2] == 0x0d && $content[$pos2 - 1] == 0x0a) {

                $pos2 -= 2;

            } else if ($content[$pos2 - 1] == 0x0a) {

                $pos2--;

            }

            $textsection = substr(

                $content,

                $pos + strlen($searchstart) + 2,

                $pos2 - $pos - strlen($searchstart) - 1

            );

            $data = @gzuncompress($textsection);

            $pdfText .= pdfExtractText($data);

            $startpos = $pos2 + strlen($searchend) - 1;

        }

    }

    return preg_replace('/(\s)+/', ' ', $pdfText);

}