import type { PNG } from 'pngjs';
/** An [r, g, b] colour triple, each channel 0–255. */
export type RGB = [number, number, number];
/** Paint a solid rectangle onto a PNG, clamped to the canvas bounds. */
export declare function fillRect(png: PNG, x: number, y: number, w: number, h: number, [r, g, b]: RGB): void;