/**
 * Used to load a group of assets and fires a callback when all assets are loaded.
 *
 * ```javascript
 * const assets = [
 *     new Asset('model', 'container', { url: `http://example.com/asset.glb` }),
 *     new Asset('styling', 'css', { url: `http://example.com/asset.css` })
 * ];
 * const assetListLoader = new AssetListLoader(assets, app.assets);
 * assetListLoader.load((err, failed) => {
 *     if (err) {
 *         console.error(`${failed.length} assets failed to load`);
 *     } else {
 *         console.log(`${assets.length} assets loaded`);
 *    }
 * });
 * ```
 *
 * @category Asset
 */
export class AssetListLoader extends EventHandler {
    /**
     * Create a new AssetListLoader using a list of assets to load and the asset registry used to load and manage them.
     *
     * @param {Asset[]|number[]} assetList - An array of {@link Asset} objects to load or an array of Asset IDs to load.
     * @param {import('./asset-registry.js').AssetRegistry} assetRegistry - The application's asset registry.
     * @example
     * const assetListLoader = new pc.AssetListLoader([
     *     new pc.Asset("texture1", "texture", { url: 'http://example.com/my/assets/here/texture1.png') }),
     *     new pc.Asset("texture2", "texture", { url: 'http://example.com/my/assets/here/texture2.png') })
     * ], app.assets);
     */
    constructor(assetList: Asset[] | number[], assetRegistry: import("./asset-registry.js").AssetRegistry);
    _assets: Set<any>;
    _loadingAssets: Set<any>;
    _waitingAssets: Set<any>;
    _registry: import("./asset-registry.js").AssetRegistry;
    _loading: boolean;
    _loaded: boolean;
    _failed: any[];
    /**
     * Removes all references to this asset list loader.
     */
    destroy(): void;
    _assetHasDependencies(asset: any): any;
    /**
     * Start loading asset list, call done() when all assets have loaded or failed to load.
     *
     * @param {Function} done - Callback called when all assets in the list are loaded. Passed (err, failed) where err is the undefined if no errors are encountered and failed contains a list of assets that failed to load.
     * @param {object} [scope] - Scope to use when calling callback.
     */
    load(done: Function, scope?: object): void;
    _callback: Function;
    _scope: any;
    /**
     * Sets a callback which will be called when all assets in the list have been loaded.
     *
     * @param {Function} done - Callback called when all assets in the list are loaded.
     * @param {object} [scope] - Scope to use when calling callback.
     */
    ready(done: Function, scope?: object): void;
    _loadingComplete(): void;
    _onLoad(asset: any): void;
    _onError(err: any, asset: any): void;
    _onAddAsset(asset: any): void;
    _waitForAsset(assetId: any): void;
}
import { EventHandler } from '../../core/event-handler.js';
import { Asset } from './asset.js';