css.js

define(["require"], function(moduleRequire){
"use strict";
/*
 * AMD css! plugin
 * This plugin will load and wait for css files. This allows JavaScript resources to 
 * fully there dependencies on stylesheets. This can also be used when
 * loading css files as part of a layer or as a way to apply a run-time theme. This
 * module checks to see if the CSS is already loaded before incurring the cost
 * of loading the full CSS loader codebase
 */
 	function testElementStyle(tag, id, property){
 		// test an element's style
		var docElement = document.documentElement;
		var testDiv = docElement.insertBefore(document.createElement(tag), docElement.firstChild);
		testDiv.id = id;
		var styleValue = (testDiv.currentStyle || getComputedStyle(testDiv, null) || {})[property];
		docElement.removeChild(testDiv);
 		return styleValue;
 	} 
 	return {
		load: function(resourceDef, require, callback, config) {
			var url = require.toUrl(resourceDef);
			var options;
			if(url.match(/!$/)){
				// a final ! can be used to indicate not to wait for the stylesheet to load
				options = {
					wait: false
				};
				url = url.slice(0, -1);
			}
			var cachedCss = require.cache && require.cache['url:' + url];
			if(cachedCss != null){
				// we have CSS cached inline in the build
				if(cachedCss.xCss){
					var parser = cachedCss.parser;
					var xCss =cachedCss.xCss;
					cachedCss = cachedCss.cssText;
				}
				// cachedCss might be {}, indicating this CSS was part of a built stylesheet. Assume the built
				// stylesheet is already loaded, so no need to inject this CSS again.
				if (typeof cachedCss == 'string') {
					moduleRequire(['./core/load-css'],function(load){
						checkForParser(load.insertCss(cachedCss));
					});
				} else {
					checkForParser();
				}
				if(xCss){
					//require([parsed], callback);
				}
				return;
			}
			function checkForParser(styleSheetElement){
				var parser = testElementStyle('x-parse', null, 'content');
				var sheet = styleSheetElement && 
					(styleSheetElement.sheet || styleSheetElement.styleSheet);
				if(parser && parser != 'none' && parser != 'normal'){
					// TODO: wait for parser to load
					require([eval(parser)], function(parser){
						if(styleSheetElement){
							parser.process(styleSheetElement, callback);
						}else{
							parser.processAll();
							callback(sheet);
						}
					});
				}else{
					callback(sheet);
				}
			}
			
			// if there is an id test available, see if the referenced rule is already loaded,
			// and if so we can completely avoid any dynamic CSS loading. If it is
			// not present, we need to use the dynamic CSS loader.
			var displayStyle = testElementStyle('div', resourceDef.replace(/\//g,'-').replace(/\..*/,'') + "-loaded", 'display');
			if(displayStyle == "none"){
				return checkForParser();
			}
			// use dynamic loader
			moduleRequire(["./core/load-css"], function(load){
				load(url, checkForParser, options);
			});
		}
	};
});