import { logger, LogLevels } from "../lib/logger"; import VisibilityIntersector, { OnVisibilityChange } from "./visibilityIntersector"; type LazyLoadElementBase = { load: () => Promise }; type LazyLoadElement = Omit & { load: (target?: HTMLElement) => Promise, div: HTMLElement wasSeen?: boolean, }; const PARALLEL_LIMIT = Infinity; export class LazyLoadQueueBase { public queueId = 0; protected queue: Array = []; protected inProcess: Set = new Set(); protected lockPromise: Promise = null; protected unlockResolve: () => void = null; protected log = logger('LL', LogLevels.error); constructor(protected parallelLimit = PARALLEL_LIMIT) { } public clear() { this.inProcess.clear(); // ацтеки забьются, будет плохо this.queue.length = 0; // unreachable code /* for(let item of this.inProcess) { this.lazyLoadMedia.push(item); } */ } public lock() { if(this.lockPromise) return; const perf = performance.now(); this.lockPromise = new Promise((resolve, reject) => { this.unlockResolve = resolve; }); this.lockPromise.then(() => { this.log('was locked for:', performance.now() - perf); }); } public unlock() { if(!this.unlockResolve) return; this.unlockResolve(); this.unlockResolve = this.lockPromise = null; this.processQueue(); } public async processItem(item: LazyLoadElementBase) { if(this.lockPromise) { return; } this.inProcess.add(item); this.log('will load media', this.lockPromise, item); try { //await new Promise((resolve) => setTimeout(resolve, 2e3)); //await new Promise((resolve, reject) => window.requestAnimationFrame(() => window.requestAnimationFrame(resolve))); //await item.load(item.div); await this.loadItem(item); } catch(err) { this.log.error('loadMediaQueue error:', err/* , item */); } this.inProcess.delete(item); this.log('loaded media', item); this.processQueue(); } protected loadItem(item: LazyLoadElementBase) { return item.load(); } protected getItem() { return this.queue.shift(); } protected addElement(method: 'push' | 'unshift', el: LazyLoadElementBase) { this.queue[method](el); this.processQueue(); } public async processQueue(item?: LazyLoadElementBase) { if(!this.queue.length || this.lockPromise || (this.parallelLimit > 0 && this.inProcess.size >= this.parallelLimit)) return; do { if(item) { this.queue.findAndSplice(i => i == item); } else { item = this.getItem(); } if(item) { this.processItem(item); } else { break; } item = null; } while(this.inProcess.size < this.parallelLimit && this.queue.length); } public push(el: LazyLoadElementBase) { this.addElement('push', el); } public unshift(el: LazyLoadElementBase) { this.addElement('unshift', el); } } export class LazyLoadQueueIntersector extends LazyLoadQueueBase { protected queue: Array = []; protected inProcess: Set = new Set(); public intersector: VisibilityIntersector; protected intersectorTimeout: number; constructor(protected parallelLimit = PARALLEL_LIMIT) { super(parallelLimit); } public lock() { super.lock(); this.intersector.lock(); } public unlock() { super.unlock(); this.intersector.unlock(); } public unlockAndRefresh() { super.unlock(); this.intersector.unlockAndRefresh(); } public clear() { super.clear(); this.intersector.disconnect(); } public refresh() { this.intersector.refresh(); } protected loadItem(item: LazyLoadElement) { return item.load(item.div); } protected addElement(method: 'push' | 'unshift', el: LazyLoadElement) { const item = this.queue.find(i => i.div == el.div); if(item) { return false; } else { for(const item of this.inProcess) { if(item.div == el.div) { return false; } } } this.queue[method](el); return true; } protected setProcessQueueTimeout() { if(!this.intersectorTimeout) { this.intersectorTimeout = window.setTimeout(() => { this.intersectorTimeout = 0; this.processQueue(); }, 0); } } public push(el: LazyLoadElement) { super.push(el); } public unshift(el: LazyLoadElement) { super.unshift(el); } } export default class LazyLoadQueue extends LazyLoadQueueIntersector { constructor(protected parallelLimit = PARALLEL_LIMIT) { super(parallelLimit); this.intersector = new VisibilityIntersector(this.onVisibilityChange); } private onVisibilityChange = (target: HTMLElement, visible: boolean) => { if(visible) { this.log('isIntersecting', target); // need for set element first if scrolled const item = this.queue.findAndSplice(i => i.div == target); if(item) { item.wasSeen = true; this.queue.unshift(item); //this.processQueue(item); } this.setProcessQueueTimeout(); } }; protected getItem() { return this.queue.findAndSplice(item => item.wasSeen); } public async processItem(item: LazyLoadElement) { await super.processItem(item); this.intersector.unobserve(item.div); } protected addElement(method: 'push' | 'unshift', el: LazyLoadElement) { const inserted = super.addElement(method, el); if(!inserted) return false; this.intersector.observe(el.div); if(el.wasSeen) { this.processQueue(el); } else if(!el.hasOwnProperty('wasSeen')) { el.wasSeen = false; } return true; } } export class LazyLoadQueueRepeat extends LazyLoadQueueIntersector { private _queue: Map = new Map(); constructor(protected parallelLimit = PARALLEL_LIMIT, protected onVisibilityChange?: OnVisibilityChange) { super(parallelLimit); this.intersector = new VisibilityIntersector((target, visible) => { if(visible) { const item = this.queue.findAndSplice(i => i.div == target); this.queue.unshift(item || this._queue.get(target)); } else { this.queue.findAndSplice(i => i.div == target); } this.onVisibilityChange && this.onVisibilityChange(target, visible); this.setProcessQueueTimeout(); }); } public clear() { super.clear(); this._queue.clear(); } /* public async processItem(item: LazyLoadElement) { //await super.processItem(item); await LazyLoadQueueBase.prototype.processItem.call(this, item); if(this.lazyLoadMedia.length) { this.processQueue(); } } */ public observe(el: LazyLoadElement) { this._queue.set(el.div, el); this.intersector.observe(el.div); } } export class LazyLoadQueueRepeat2 extends LazyLoadQueueIntersector { constructor(protected parallelLimit = PARALLEL_LIMIT, protected onVisibilityChange?: OnVisibilityChange) { super(parallelLimit); this.intersector = new VisibilityIntersector((target, visible) => { const item = this.queue.findAndSplice(i => i.div == target); if(visible && item) { this.queue.unshift(item); } this.onVisibilityChange && this.onVisibilityChange(target, visible); this.setProcessQueueTimeout(); }); } public observe(el: HTMLElement) { this.intersector.observe(el); } }