import { type ReactNode, type RefObject } from 'react';
import { type ViewportCoords } from './coords';
/**
 * Viewport state + derived bounds + imperative api surface, exposed via
 * React context so ruler, playhead, tree column, every lane, and all
 * interaction handlers read from a single source of truth.
 */
export interface TimelineViewport extends ViewportCoords {
    /** Derived: first visible second. */
    viewStart: number;
    /** Derived: last visible second. */
    viewEnd: number;
    setPxPerSecond(v: number): void;
    setScrollSec(v: number): void;
    zoomAtCursor(factor: number, cursorX: number): void;
    fit(): void;
    /** Scroll so that `time` sits at the horizontal center of the viewport. */
    centerOn(time: number): void;
    setContainerWidth(w: number): void;
}
export declare function useTimelineViewport(): TimelineViewport;
export interface TimelineViewportProviderProps {
    duration: number;
    children: ReactNode;
    /** Initial zoom level; defaults to 36 px/s (matches screenshot baseline). */
    initialPxPerSec?: number;
}
export declare function TimelineViewportProvider({ duration, initialPxPerSec, children, }: TimelineViewportProviderProps): import("react/jsx-runtime").JSX.Element;
/**
 * Wire up a ref to report its measured width back to the viewport. Install
 * once on the lane-area container; the Provider keeps `containerWidth` in
 * sync as the element resizes.
 */
export declare function useObservedWidth(ref: RefObject<HTMLElement | null>): void;
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