import type { PageCaptureResponseMessage } from "./_vendor/replo-utils/lib/pageCapture";
interface PageCaptureMessageListener {
    (event: {
        data: unknown;
        source: unknown;
        origin: string;
    }): void;
}
/** The slice of `window` the responder touches, so specs can pass a fake. */
export interface PageCaptureWindow {
    readonly innerWidth: number;
    readonly parent: {
        postMessage(message: PageCaptureResponseMessage, targetOrigin: string, transfer: Transferable[]): void;
    };
    readonly document: {
        readonly fonts?: {
            readonly ready: Promise<unknown>;
        };
    };
    requestIdleCallback?(callback: () => void, options: {
        timeout: number;
    }): number;
    addEventListener(type: "message", listener: PageCaptureMessageListener): void;
    removeEventListener(type: "message", listener: PageCaptureMessageListener): void;
}
/**
 * Answers Site Builder's page-capture requests with a JPEG of this page's
 * first screen. Requests run one at a time so concurrent captures never
 * fight over the page's temporary video posters.
 */
export declare function startPageCaptureResponder(targetWindow: PageCaptureWindow): () => void;
export {};