import { loadScript } from '../utils/loader.js' /** * Manages loading and registering of reveal.js plugins. */ export default class Plugins { constructor() { // Flags our current state (idle -> loading -> loaded) this.state = 'idle'; // An id:instance map of currently registed plugins this.registeredPlugins = {}; this.asyncDependencies = []; } /** * Loads the dependencies of reveal.js. Dependencies are * defined via the configuration option 'dependencies' * and will be loaded prior to starting/binding reveal.js. * Some dependencies may have an 'async' flag, if so they * will load after reveal.js has been started up. */ load( dependencies ) { this.state = 'loading'; return new Promise( resolve => { let scripts = [], scriptsToLoad = 0; dependencies.forEach( s => { // Load if there's no condition or the condition is truthy if( !s.condition || s.condition() ) { if( s.async ) { this.asyncDependencies.push( s ); } else { scripts.push( s ); } } } ); if( scripts.length ) { scriptsToLoad = scripts.length; const scriptLoadedCallback = (s) => { if( typeof s.callback === 'function' ) s.callback(); if( --scriptsToLoad === 0 ) { this.initPlugins().then( resolve ); } }; // Load synchronous scripts scripts.forEach( s => { if( s.id ) { this.registerPlugin( s.id, s.plugin ); scriptLoadedCallback( s ); } else { loadScript( s.src, () => scriptLoadedCallback(s) ); } } ); } else { this.initPlugins().then( resolve ); } } ); } /** * Initializes our plugins and waits for them to be ready * before proceeding. */ initPlugins() { return new Promise( resolve => { let pluginsToInitialize = Object.keys( this.registeredPlugins ).length; // If there are no plugins, skip this step if( pluginsToInitialize === 0 ) { this.loadAsync().then( resolve ); } // ... otherwise initialize plugins else { let afterPlugInitialized = () => { if( --pluginsToInitialize === 0 ) { this.loadAsync().then( resolve ); } }; for( let i in this.registeredPlugins ) { let plugin = this.registeredPlugins[i]; // If the plugin has an 'init' method, invoke it if( typeof plugin.init === 'function' ) { let callback = plugin.init(); // If the plugin returned a Promise, wait for it if( callback && typeof callback.then === 'function' ) { callback.then( afterPlugInitialized ); } else { afterPlugInitialized(); } } else { afterPlugInitialized(); } } } } ) } /** * Loads all async reveal.js dependencies. */ loadAsync() { this.state = 'loaded'; if( this.asyncDependencies.length ) { this.asyncDependencies.forEach( s => { if( s.id ) { this.registerPlugin( s.id, s.plugin ); if( typeof s.plugin.init === 'function' ) s.plugin.init(); if( typeof s.callback === 'function' ) s.callback(); } else { loadScript( s.src, s.callback ); } } ); } return Promise.resolve(); } /** * Registers a new plugin with this reveal.js instance. * * reveal.js waits for all regisered plugins to initialize * before considering itself ready, as long as the plugin * is registered before calling `Reveal.initialize()`. */ registerPlugin( id, plugin ) { if( this.registeredPlugins[id] === undefined ) { this.registeredPlugins[id] = plugin; // If a plugin is registered after reveal.js is loaded, // initialize it right away if( this.state === 'loaded' && typeof plugin.init === 'function' ) { plugin.init(); } } else { console.warn( 'reveal.js: "'+ id +'" plugin has already been registered' ); } } /** * Checks if a specific plugin has been registered. * * @param {String} id Unique plugin identifier */ hasPlugin( id ) { return !!this.registeredPlugins[id]; } /** * Returns the specific plugin instance, if a plugin * with the given ID has been registered. * * @param {String} id Unique plugin identifier */ getPlugin( id ) { return this.registeredPlugins[id]; } getRegisteredPlugins() { return this.registeredPlugins; } }