Babylon.js/Viewer/src/viewer/viewerManager.ts

import { Observable } from 'babylonjs';
import { AbstractViewer } from './viewer';

class ViewerManager {

    private viewers: { [key: string]: AbstractViewer };

    public onViewerAdded: (viewer: AbstractViewer) => void;
    public onViewerAddedObservable: Observable<AbstractViewer>;

    constructor() {
        this.viewers = {};
        this.onViewerAddedObservable = new Observable();
    }

    public addViewer(viewer: AbstractViewer) {
        this.viewers[viewer.getBaseId()] = viewer;
        this._onViewerAdded(viewer);
    }

    public getViewerById(id: string): AbstractViewer {
        return this.viewers[id];
    }

    public getViewerByHTMLElement(element: HTMLElement) {
        for (let id in this.viewers) {
            if (this.viewers[id].containerElement === element) {
                return this.getViewerById(id);
            }
        }
    }

    public getViewerPromiseById(id: string): Promise<AbstractViewer> {
        return new Promise((resolve, reject) => {
            let viewerFunction = (viewer: AbstractViewer) => {
                if (viewer.getBaseId() === id) {
                    resolve(viewer);
                    this.onViewerAddedObservable.removeCallback(viewerFunction);
                }
            }
            this.onViewerAddedObservable.add(viewerFunction);
        });
    }

    private _onViewerAdded(viewer: AbstractViewer) {
        this.onViewerAdded && this.onViewerAdded(viewer);
        this.onViewerAddedObservable.notifyObservers(viewer);
    }
}

export let viewerManager = new ViewerManager();