Snippet: Get random image (or file) from folder

<?php

//******************************************
// Created by Darren Doyle, Dec. 2010
//******************************************

// ----- PURPOSE -----
// Designed to pull a random image (or file)
// from a sepcified folder. Parent and path are
// mostly there to help minimize typing on
// the snippet calls.

// ----- VARIABLES -----
// $parent = the path to forced parent folder.
// The path should be relative to the base url.
// Include a trailing slash.
   $parent = 'assets/images/';

// $types = the types of file extensions to accept
   $types = array('jpg', 'gif', 'png');

// ----- PROPERTY -----
// Create a property named "path," and set
// it to the default path within the parent folder.
// This can be overridden in the snippet call.
// Do not include a trailing slash.

//******************************************


// get full path/url
$myDir = $parent . $path . '/'; 
$p = $modx->config['base_path'].$myDir;
$u = $modx->config['base_url'].$myDir;

// get a list of each image file in the target folder
$dir = opendir($p);
while($f = readdir($dir)) {
	$ext = pathinfo($f, PATHINFO_EXTENSION);
	if ( in_array($ext, $types) ) $contents[] = $f;
}
closedir($dir);

// if empty, return nothing
if (empty($contents)) return '';

// else return random file
shuffle($contents);
return ($u.$contents[0]);

// strip out thumbnails
function strip_thumbs($item) {
    return !strpos($item,'thumb_');
}
$contents = array_filter($contents, 'strip_thumbs');

// if empty, return nothing
if (empty($contents)) return '';

// else return random file
shuffle($contents);
return ($u.$contents[0]);