import type { MarkShape } from "./layers.types.ts";
/** A place, `[x, y]`, in the drawing's frame. */
export type P = readonly [number, number];
/**
 * A colour a fraction `t` (0 to 1) of the way through `stops`, as a hex colour, or the nearest stop when one cannot be read without a
 * browser (`var(--x)`, a name that is not a common one). Stops that are not colours are ignored; with none left, `undefined`.
 */
export declare function rampColour(stops: readonly string[], t: number): string | undefined;
/**
 * The path of a polygon shape of width `width` centred on `(cx, cy)`. When the surface is turned a quarter, the corners are turned
 * back so that the shape stands upright as the eye sees it.
 */
export declare function shapePath(shape: Exclude<MarkShape, "circle">, cx: number, cy: number, width: number, turned: boolean): string;
/** True for a shape drawn as a polygon, not a circle. */
export declare const isPolygon: (shape: string) => shape is Exclude<MarkShape, "circle">;
/** A line from one place to another, straight or bowed, that can be walked by distance. */
export interface Curve {
    from: P;
    to: P;
    /** The control point of the bow, or `undefined` for a straight line. */
    control?: P;
    /** The length of the line. */
    length: number;
    /** The place a distance `s` along the line. */
    at(s: number): P;
    /** The unit direction of the line a distance `s` along it. */
    tangent(s: number): P;
    /** The same line with its last `by` cut off (so that an arrowhead's tip can stand where the line was to end). */
    trim(by: number): Curve;
}
/** A line from `from` to `to` bowed by `bow` times its length (zero for straight). Positive bows to the right of the way it goes as the surface is drawn wide. */
export declare function curveBetween(from: P, to: P, bow: number): Curve;
/** The path of a straight or bowed line. */
export declare function curvePath(curve: Curve): string;
/**
 * A wave along a line: a chain of quadratic curves, each half a wavelength long, that leans to one side and then the other, so
 * that it starts and ends on the line. The wavelength is stretched a little so that a whole number of waves fits.
 */
export declare function wavePath(curve: Curve, amplitude: number, wavelength: number): string;
/** The path of a head at `tip`, pointing along the unit direction `u`: a filled triangle (closed) or an open chevron. */
export declare function headPath(tip: P, u: P, headLength: number, halfWidth: number, open: boolean): string;
/** The outline of a comet along a line: a shape that grows from a point at the start to `widest` wide at the end. */
export declare function taperPath(curve: Curve, widest: number, steps?: number): string;
/** A polyline's path. */
export declare const polylinePath: (points: readonly P[], last?: P) => string;