import { OnDestroy } from '@angular/core';
import { IPDFViewerApplication } from './options/pdf-viewer-application';
import { IPDFViewerApplicationOptions } from './options/pdf-viewer-application-options';
import { PdfCspPolicyService } from './pdf-csp-policy.service';
import * as i0 from "@angular/core";
/** What a loaded copy of the viewer module (`viewer-*.mjs`) hands over in its `ngxViewerFileHasBeenLoaded` event. */
export interface PdfJsModuleCopy {
    PDFViewerApplication: IPDFViewerApplication;
    PDFViewerApplicationOptions: IPDFViewerApplicationOptions;
    webViewerLoad: (cspPolicyService: PdfCspPolicyService, options?: {
        root?: HTMLElement;
    }) => void;
}
/**
 * Multiple viewers on one page: every live viewer needs its own copy of the viewer module.
 *
 * pdf.js keeps its state at module level (PDFViewerApplication, AppOptions, the print
 * service, ...). The browser evaluates a module once per URL, so a different query string
 * gives an independent copy: the first copy loads `viewer-*.mjs` as before, further copies
 * load `viewer-*.mjs?instance=N`.
 *
 * A viewer returns its copy after its cleanup has finished. The next viewer reuses it, the
 * same way a single viewer always reused the one module after a route change. A viewer
 * mounted while another one is still cleaning up gets a copy of its own instead.
 *
 * Loads run one at a time: the module announces itself with a document-wide event that
 * doesn't say which copy sent it.
 *
 * Internal - not part of the public API.
 */
export declare class PdfJsModulePool implements OnDestroy {
    private readonly copies;
    /** serializes the loads */
    private queue;
    /**
     * Hands out a free copy of the module at `path`, or loads a new one.
     * @param load loads the module from the given URL and resolves with what it announced
     */
    acquire(path: string, forceReload: boolean, load: (url: string) => Promise<PdfJsModuleCopy>): Promise<PdfJsModuleCopy>;
    /** Called when a viewer has finished its cleanup. */
    release(copy: PdfJsModuleCopy | undefined): void;
    /** Runs when the application shuts down (this used to be the root PDFScriptLoaderService's ngOnDestroy). */
    ngOnDestroy(): void;
    static ɵfac: i0.ɵɵFactoryDeclaration<PdfJsModulePool, never>;
    static ɵprov: i0.ɵɵInjectableDeclaration<PdfJsModulePool>;
}