/**
* jQuery-Plugin "preloadCssImages"
* by Scott Jehl, scott@filamentgroup.com
* http://www.filamentgroup.com
* reference article: http://www.filamentgroup.com/lab/update_automatically_preload_images_from_css_with_jquery/
* demo page: http://www.filamentgroup.com/examples/preloadImages/index_v2.php
*
* 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: 5.0, 10.31.2008
* Changelog:
* 02.20.2008 initial Version 1.0
* 06.04.2008 Version 2.0 : removed need for any passed arguments. Images load from any and all directories.
* 06.21.2008 Version 3.0 : Added options for loading status. Fixed IE abs image path bug (thanks Sam Pohlenz).
* 07.24.2008 Version 4.0 : Added support for @imported CSS (credit: http://marcarea.com/). Fixed support in Opera as well.
* 10.31.2008 Version: 5.0 : Many feature and performance enhancements from trixta
* --------------------------------------------------------------------
*/
;jQuery.preloadCssImages = function(settings){
settings = jQuery.extend({
statusTextEl: null,
statusBarEl: null,
errorDelay: 999, // handles 404-Errors in IE
simultaneousCacheLoading: 2
}, settings);
var allImgs = [],
loaded = 0,
imgUrls = [],
thisSheetRules,
errorTimer;
function onImgComplete(){
clearTimeout(errorTimer);
if (imgUrls && imgUrls.length && imgUrls[loaded]) {
loaded++;
if (settings.statusTextEl) {
var nowloading = (imgUrls[loaded]) ?
'Now Loading: <span>' + imgUrls[loaded].split('/')[imgUrls[loaded].split('/').length - 1] :
'Loading complete'; // wrong status-text bug fixed
jQuery(settings.statusTextEl).html('<span class="numLoaded">' + loaded + '</span> of <span class="numTotal">' + imgUrls.length + '</span> loaded (<span class="percentLoaded">' + (loaded / imgUrls.length * 100).toFixed(0) + '%</span>) <span class="currentImg">' + nowloading + '</span></span>');
}
if (settings.statusBarEl) {
var barWidth = jQuery(settings.statusBarEl).width();
jQuery(settings.statusBarEl).css('background-position', -(barWidth - (barWidth * loaded / imgUrls.length).toFixed(0)) + 'px 50%');
}
loadImgs();
}
}
function loadImgs(){
//only load 1 image at the same time / most browsers can only handle 2 http requests, 1 should remain for user-interaction (Ajax, other images, normal page requests...)
// otherwise set simultaneousCacheLoading to a higher number for simultaneous downloads
if(imgUrls && imgUrls.length && imgUrls[loaded]){
var img = new Image(); //new img obj
img.src = imgUrls[loaded]; //set src either absolute or rel to css dir
if(!img.complete){
jQuery(img).bind('error load onreadystatechange', onImgComplete);
} else {
onImgComplete();
}
errorTimer = setTimeout(onImgComplete, settings.errorDelay); // handles 404-Errors in IE
}
}
function parseCSS(sheets, urls) {
var w3cImport = false,
imported = [],
importedSrc = [],
baseURL;
var sheetIndex = sheets.length;
while(sheetIndex--){//loop through each stylesheet
var cssPile = '';//create large string of all css rules in sheet
if(urls && urls[sheetIndex]){
baseURL = urls[sheetIndex];
} else {
var csshref = (sheets[sheetIndex].href) ? sheets[sheetIndex].href : 'window.location.href';
var baseURLarr = csshref.split('/');//split href at / to make array
baseURLarr.pop();//remove file path from baseURL array
baseURL = baseURLarr.join('/');//create base url for the images in this sheet (css file's dir)
if (baseURL) {
baseURL += '/'; //tack on a / if needed
}
}
if(sheets[sheetIndex].cssRules || sheets[sheetIndex].rules){
thisSheetRules = (sheets[sheetIndex].cssRules) ? //->>> http://www.quirksmode.org/dom/w3c_css.html
sheets[sheetIndex].cssRules : //w3
sheets[sheetIndex].rules; //ie
var ruleIndex = thisSheetRules.length;
while(ruleIndex--){
if(thisSheetRules[ruleIndex].style && thisSheetRules[ruleIndex].style.cssText){
var text = thisSheetRules[ruleIndex].style.cssText;
if(text.toLowerCase().indexOf('url') != -1){ // only add rules to the string if you can assume, to find an image, speed improvement
cssPile += text; // thisSheetRules[ruleIndex].style.cssText instead of thisSheetRules[ruleIndex].cssText is a huge speed improvement
}
} else if(thisSheetRules[ruleIndex].styleSheet) {
imported.push(thisSheetRules[ruleIndex].styleSheet);
w3cImport = true;
}
}
}
//parse cssPile for image urls
var tmpImage = cssPile.match(/[^\("]+\.(gif|jpg|jpeg|png)/g);//reg ex to get a string of between a "(" and a ".filename" / '"' for opera-bugfix
if(tmpImage){
var i = tmpImage.length;
while(i--){ // handle baseUrl here for multiple stylesheets in different folders bug
var imgSrc = (tmpImage[i].charAt(0) == '/' || tmpImage[i].match('://')) ? // protocol-bug fixed
tmpImage[i] :
baseURL + tmpImage[i];
if(jQuery.inArray(imgSrc, imgUrls) == -1){
imgUrls.push(imgSrc);
}
}
}
if(!w3cImport && sheets[sheetIndex].imports && sheets[sheetIndex].imports.length) {
for(var iImport = 0, importLen = sheets[sheetIndex].imports.length; iImport < importLen; iImport++){
var iHref = sheets[sheetIndex].imports[iImport].href;
iHref = iHref.split('/');
iHref.pop();
iHref = iHref.join('/');
if (iHref) {
iHref += '/'; //tack on a / if needed
}
var iSrc = (iHref.charAt(0) == '/' || iHref.match('://')) ? // protocol-bug fixed
iHref :
baseURL + iHref;
importedSrc.push(iSrc);
imported.push(sheets[sheetIndex].imports[iImport]);
}
}
}//loop
if(imported.length){
parseCSS(imported, importedSrc);
return false;
}
var downloads = settings.simultaneousCacheLoading;
while( downloads--){
setTimeout(loadImgs, downloads);
}
}
parseCSS(document.styleSheets);
return imgUrls;
};