export interface TTIMetric {
    name: 'TTI';
    value: number;
}
export interface TTIReportOpts {
    /**
     * Enabling frames per second (FPS) tracking (@code{fpsEnabled: true}) may
     * provide more accurate TTI, while incurring a small performance impact to
     * the application.
     *
     * We expect that in most cases using FPS tracking is unnecessary. A period
     * with no long tasks (which ARE tracked) will typically have a high FPS.
     */
    fpsEnabled: boolean;
}
export type TTIReportCallback = (metric: TTIMetric, opts?: TTIReportOpts) => void;
export declare function onTTI(onReport: TTIReportCallback, opts: TTIReportOpts): void;
/**
 * This class measures the "time to interactive" web vital. Time to interactive
 * is a measure of how long it takes for a page to become interactive for the
 * user.
 * <p>
 * This class implements the TTI algorithm used by Boomerang, with modifications.
 * (Ref: https://akamai.github.io/boomerang/oss/BOOMR.plugins.Continuity.html)
 * <p>
 * Steps to TTI calculation:
 * 1) Find visually ready timestamp (highest of domcontentLoadedEnd, FCP or LCP).
 * 2) Starting from the visually ready timestamp, find a 500ms quiet window. A
 *    quiet window has the following characteristics:
 *      a) No Long Tasks
 *      b) FPS is above 20 (if enabled)
 * 3) TTI is recorded as visually ready timestamp + time from visually ready to the start of the quiet window.
 * <p>
 * This class measures TTI only when running in a browser that supports Long Tasks.
 */
export declare class TimeToInteractive {
    private onReport;
    private quietWindowSearch;
    private visuallyReadySearch;
    constructor(onReport: TTIReportCallback, opts: TTIReportOpts);
}