show all images in directory

<?php

    scanDirectoryImages('.');

    function scanDirectoryImages($directory) {

        if (substr($directory, -1) == '/') {

            $directory = substr($directory, 0, -1);
        }
        if (!file_exists($directory) || !is_dir($directory)) {

            return FALSE;
        }
        else if (is_readable($directory)) {

            $directory_tree = array();
            $directory_list = opendir($directory);

            while($file = readdir($directory_list)) {

                if ($file != '.' && $file != '..') {

                    $path = $directory . '/' . $file;

                    if (is_readable($path)) {

                        $subdirectories = explode('/', $path);

                        if (is_dir($path)) {

                            scanDirectoryImages($path);
                        }
                        else if (is_file($path)) {

                            $extension = end(explode('.', end($subdirectories)));

                            if (in_array($extension, array('jpeg', 'jpg', 'gif', 'png'))) {

                                echo '<a href="' . $path . '"><img src="' . $path . '" style="max-height: 100px; max-width: 100px;" /></a>';
                            }
                        }
                    }
                }
            }

            closedir($directory_list);
        }
        else {

            return FALSE;
        }
    }

?>