import type { TransformLineage } from './transform.js';
import type { Channel, ChannelOutput, ChartKey, ChartMark, ChartMarkMotionOptions, ChartValue, VisualChannel } from './types.js';
export interface DensityContourDatum<TDatum> extends TransformLineage<TDatum> {
    /** Weighted observations per CSS pixel squared at this contour level. */
    readonly density: number;
    readonly group: ChartKey | null;
}
export interface DensityContourOptions<TDatum> extends ChartMarkMotionOptions<never> {
    id?: string;
    x: Channel<TDatum, ChartValue | null | undefined>;
    y: Channel<TDatum, ChartValue | null | undefined>;
    /** Estimates a separate density field for each non-null group. */
    z?: Channel<TDatum, ChartKey | null | undefined>;
    weight?: Channel<TDatum, number | null | undefined>;
    /** Gaussian-kernel bandwidth in final CSS pixels. Defaults to 20. */
    bandwidth?: number;
    /** Density-grid cell size in final CSS pixels. Defaults to 4. */
    cellSize?: number;
    /** Exact density levels or an approximate shared level count. Defaults to 20. */
    thresholds?: number | Iterable<number>;
    color?: Channel<DensityContourDatum<TDatum>, ChartKey | null | undefined>;
    fill?: VisualChannel<DensityContourDatum<TDatum>, string>;
    fillOpacity?: number;
    stroke?: VisualChannel<DensityContourDatum<TDatum>, string>;
    strokeOpacity?: number;
    strokeWidth?: number;
    strokeDasharray?: string;
    opacity?: number;
}
type DensityXOutput<TDatum, TOptions> = ChannelOutput<TDatum, TOptions extends {
    x: infer TChannel;
} ? TChannel : never, number>;
type DensityYOutput<TDatum, TOptions> = ChannelOutput<TDatum, TOptions extends {
    y: infer TChannel;
} ? TChannel : never, number>;
/** Estimates filled density contours after x/y scales reach final screen space. */
export declare function densityContour<TDatum, const TOptions extends DensityContourOptions<NoInfer<TDatum>>>(source: Iterable<TDatum>, options: TOptions): ChartMark<never, never, never, DensityXOutput<TDatum, TOptions>, DensityYOutput<TDatum, TOptions>>;
export {};