<?php
/*
 * Plugin Name: Preview Theme
 * Plugin URI: http://dougal.gunters.org/blog/2005/03/09/theme-preview-plugin/
 * Description: Allows themes to be previewed without activation
 * Author: Dougal Campbell
 * Author URI: http://dougal.gunters.org/
 * Version: 1.0
 */

/*
 * USAGE:
 *
 * Add query variables 'preview_theme' and/or 'preview_css' to
 * your query string. Example:
 *  http://example.com/index.php?preview_theme=default&preview_css=my-theme
 */

$gr_preview_theme = $_GET['preview_theme'];
$gr_preview_css = $_GET['preview_css'];

if (! $gr_preview_css ) 
    $gr_preview_css = $gr_preview_theme;

if($gr_preview_theme && file_exists(get_theme_root() . "/$gr_preview_theme")) {
    add_filter('template','use_preview_theme');
}

if($gr_preview_css && file_exists(get_theme_root() . "/$gr_preview_css")) {
    add_filter('stylesheet','use_preview_css');
}

function use_preview_theme($themename) {
    global $gr_preview_theme;

    return $gr_preview_theme;
}

function use_preview_css($cssname) {
    global $gr_preview_css;

    return $gr_preview_css;
}

?>