/** Where the engine's assets live, as passed to a worker factory. */
export interface PdfWorkerUrls {
    /** Absolute URL of `pdfium_worker.js`, a classic worker script. */
    workerUrl: string;
    /**
     * Absolute URL of `pdfium.wasm`. The worker script reads it from the global
     * `pdfiumWasmUrl`, which the bootstrap must define before running the script.
     *
     */
    wasmUrl: string;
}
/**
 * The part of the Web Worker API this engine uses. A browser `Worker` satisfies
 * it as is; on hosts without one (Node) the engine wraps their equivalent.
 *
 */
export interface PdfWorkerLike {
    /**
     * Sends a protocol message to the worker.
     *
     * @param message - The structured-cloneable message.
     * @param transfer - Transferable objects whose ownership moves to the worker.
     */
    postMessage(message: unknown, transfer: Transferable[]): void;
    terminate(): void;
    onmessage: ((event: {
        data: unknown;
    }) => void) | null;
    onerror: ((event: {
        message?: string;
    }) => void) | null;
}
/**
 * Where the engine's own `assets/` directory is, relative to this module — the
 * two are shipped side by side in the package, so on a host that can read the
 * package's files there is nothing for the caller to configure.
 *
 * A browser cannot: the assets have to be served, and a bundler will have
 * rewritten `import.meta.url` to point at the bundle by then, so callers there
 * say where they put them.
 * @internal
 *
 */
export declare function defaultWasmModulesUrl(): string;
/**
 * What relative URLs resolve against when the caller does not say: the document
 * base URL in a browser, the current directory on a server runtime.
 * @internal
 *
 */
export declare function defaultBaseUrl(): string;
/**
 * Runs `pdfium_worker.js` on whatever this host offers: a Web Worker in a
 * browser, a module worker on Bun/Deno (no `importScripts` there), or a
 * `node:worker_threads` worker on Node.
 * @internal
 *
 */
export declare function createDefaultWorker(urls: PdfWorkerUrls): PdfWorkerLike | Promise<PdfWorkerLike>;
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