/**
 * --------------------------------------------------------------------
 * jQuery-Plugin "preloadCssImages"
 * by Scott Jehl, scott@filamentgroup.com
 * http://www.filamentgroup.com
 * reference article: http://www.filamentgroup.com/lab/automated_image_preloading/
 * demo page: http://www.filamentgroup.com/examples/preloadImages/
 * 
 * Copyright (c) 2008 Filament Group, Inc
 * Dual licensed under the MIT (filamentgroup.com/examples/mit-license.txt) and GPL (filamentgroup.com/examples/gpl-license.txt) licenses.
 *
 * Version: 1.0, 31.05.2007
 * Changelog:
 * 	02.20.2008 initial Version 1.0
 * --------------------------------------------------------------------
 */
$.preloadCssImages = function(settings) {
    //overrideable defaults
    settings = jQuery.extend({
        imgDir: 'images'
    }, settings);

    //dump all the css rules into one string
    var sheets = document.styleSheets;
    var cssPile = '';
    for (var i = 0; i < sheets.length; i++) {
        if (!$.browser.msie) {
            var thisSheetRules = document.styleSheets[i].cssRules;
            for (var j = 0; j < thisSheetRules.length; j++) {
                cssPile += thisSheetRules[j].cssText;
            }
        }
        else {
            cssPile += document.styleSheets[i].cssText;
        }
    }
    //parse string for image urls and load them into the DOM
    var allImgs = []; //new array for all the image urls  
    var imgUrls = cssPile.match(/[^\/]+\.(gif|jpg|jpeg|png)/g); //reg ex to get a string of between a "/" and a ".filename"
    if (imgUrls != null && imgUrls.length > 0 && imgUrls != '') {//loop array
        var arr = jQuery.makeArray(imgUrls); //create array from regex obj	 
        $(arr).each(function(k) {
            allImgs[k] = new Image(); //new img obj
            allImgs[k].src = settings.imgDir + '/' + this;
        });
    }
    return allImgs;
}