pdf_viewer.php

<?php
define('WP_USE_THEMES', false);
require('../../../wp-blog-header.php'); #modify to match path of that file on your server
include_once('url_path_config.php');
global $wpdb;
$charset_collate	=	$wpdb->get_charset_collate();
$tableName			=	$wpdb->prefix . 'pdffiles';
$query 		= 	'SELECT * FROM ' . $tableName . ' WHERE file_token="' . trim($_REQUEST['pdfFile']) . '"';
$getData	=	$wpdb->get_results($query);
$fileName	=	explode("-", trim($getData[0]->filename));
$count		=	count($getData);
if ($count == 1) {
?>
	<!doctype html>
	<html>

	<head>
		<meta charset="utf-8">
		<title>PDF | <?php echo trim($fileName[0]); ?></title>
	</head>
	<style>
		iframe {
			width: 98%;
			margin: 0px auto;
			height: 100%;
		}
	</style>

	<body>
		<iframe src="https://docs.google.com/gview?url=<?php echo zPDFpopupViewer_UPLOADS_URL . trim($getData[0]->filename); ?>&embedded=true" frameborder="0"></iframe>
	</body>

	</html>
<?php } else { ?>
	<div style="padding:30px; text-align:center; position: relative; top: 40%; background: #ccc; box-shadow:0px 0px 2px #333333 inset;"><strong>We did not find any file for view!</strong></div>
<?php } ?>