/**
 * Shared gradient rasterisation primitives.
 *
 * Canvas 2D has no repeating gradients and no native elliptical radial
 * gradients, so every gradient painter (background, mask, border-image) needs
 * the same two building blocks:
 *
 * 1. periodic stop stacking — the one-cycle stop list re-added k·period + s
 *    for k = 0..cycles-1, clamped to the [0, 1] gradient range;
 * 2. ellipse rasterisation — a circle of radius rx scaled vertically by
 *    ry / rx, painted on a 2rx × 2ry offscreen canvas.
 *
 * Centralising them keeps the subtle invariants in one place:
 * - stop positions are normalised against rx (the canvas gradient radius),
 *   NOT the diameter — normalising against the diameter halves every
 *   absolute-px stop;
 * - the fill must cover the pre-scale circle (fillRect of the rx*2 square),
 *   not the post-scale ellipse box — a user-space (2rx × 2ry) rect shrinks
 *   vertically under the y-scale and clips the ellipse whenever ry < rx;
 * - outside the ending shape a radial gradient continues with its last
 *   colour, which callers must paint across the full area first.
 */
import { UnprocessedGradientColorStop, GradientColorStop } from '../../css/types/image';
export interface StringColorStop {
    stop: number;
    color: string;
}
/**
 * Stack the one-cycle stop list periodically across [0, 1]. Returns null for
 * a degenerate period (all stops clamped to one point) — CSS renders the
 * last colour across the whole area in that case, and callers should paint
 * the last colour instead of stacking.
 */
export declare const stackRepeatingStops: (processed: GradientColorStop[]) => StringColorStop[] | null;
/** Map parsed stops to string-colour stops clamped into the canvas [0, 1] range. */
export declare const toCanvasStops: (processed: GradientColorStop[]) => StringColorStop[];
export interface RasterizedRadialGradient {
    /** 2rx × 2ry device-pixel canvas holding the gradient ellipse. */
    canvas: HTMLCanvasElement;
    /** Colour beyond the ending shape (the last stop's colour). */
    lastColor: string;
    rx: number;
    ry: number;
}
/**
 * Rasterise a radial gradient's ending-shape ellipse to an offscreen canvas.
 *
 * The ellipse is a circle of radius rx scaled vertically by ry / rx around
 * the canvas centre, so the offscreen canvas is the ellipse's full 2rx × 2ry
 * bounding box and callers draw it at (centre - rx, centre - ry). Handles the
 * repeating variant by stacking stops across the [0, 1] gradient range.
 */
export declare const rasterizeRadialGradient: (ownerDocument: Document, rx: number, ry: number, stops: UnprocessedGradientColorStop[], repeating?: boolean) => RasterizedRadialGradient | null;