/**
 * A place where the sky's names must not go, as the property `keepClear` of `<chikyu-space>` and `<chikyu-earth-realistic>` takes it: a rectangle in the element's own CSS pixels from its top left, or an element of the page whose box is read (on a resize, not every frame).
 *
 * @example
 * ```ts
 * import type { SkyKeepClear } from "@johnmorrisdotca/chikyu-earth/realistic";
 *
 * const areas: SkyKeepClear[] = [{ x: 24, y: 40, width: 480, height: 220 }];
 * console.log(areas.length);
 * ```
 */
export type SkyKeepClear = {
    x: number;
    y: number;
    width: number;
    height: number;
} | {
    getBoundingClientRect(): {
        left: number;
        top: number;
        right: number;
        bottom: number;
    };
};
/** A keep-clear area as the layer holds it: its edges, from the picture's top left, in CSS pixels. */
export interface KeepBox {
    l: number;
    t: number;
    r: number;
    b: number;
}
/**
 * The edges of a keep-clear area, from the picture's top left.
 *
 * @param area - A rectangle in the picture's own pixels, or an element of the page.
 * @param own - The picture's box on the page (`getBoundingClientRect`), to read an element's box against.
 * @param into - The box to write, or one is made.
 * @returns The box.
 */
export declare function keepBox(area: SkyKeepClear, own: {
    left: number;
    top: number;
}, into?: KeepBox): KeepBox;
/**
 * Whether a box touches any of the keep-clear areas.
 *
 * @param areas - The areas, from `keepBox`.
 * @param left - The box's left.
 * @param top - The top.
 * @param right - The right.
 * @param bottom - The bottom.
 * @returns True where the box and an area overlap.
 */
export declare function touchesKeep(areas: readonly KeepBox[], left: number, top: number, right: number, bottom: number): boolean;
/**
 * Whether a point is inside any of the keep-clear areas.
 *
 * @param areas - The areas, from `keepBox`.
 * @param x - The point's x.
 * @param y - The point's y.
 * @returns True where the point is in an area.
 */
export declare function inKeep(areas: readonly KeepBox[], x: number, y: number): boolean;