import type { GlyphMetrics, StyleGlyph } from './alpha-image';
import { RGBAImage } from './alpha-image';
/**
 * SDF_SCALE controls the pixel density of locally generated glyphs relative
 * to "normal" SDFs which are generated at 24pt font and a "pixel ratio" of 1.
 * The GlyphManager will generate glyphs SDF_SCALE times as large,
 * but with the same glyph metrics, and the quad generation code will scale them
 * back down so they display at the same size.
 *
 * The choice of SDF_SCALE is a trade-off between performance and quality.
 * Glyph generation time grows quadratically with the the scale, while quality
 * improvements drop off rapidly when the scale is higher than the pixel ratio
 * of the device. The scale of 2 buys noticeable improvements on HDPI screens
 * at acceptable cost.
 */
export declare const SDF_SCALE = 4;
export declare const BASE_FONT_WIDTH: number;
export declare const BASE_FONT_BUFFER: number;
export declare const RADIUS: number;
export declare const glyphPadding = 1;
type Rect = {
    x: number;
    y: number;
    w: number;
    h: number;
};
export type GlyphPosition = {
    rect: Rect;
    metrics: GlyphMetrics;
};
export type GlyphPositions = Record<string, Record<string, GlyphPosition>>;
/**
 * Merge SDFs into a large squared atlas with `potpack`,
 * because on WebGL1 context, all textures are resized to a power of two to produce the best quality.
 *
 * @see https://doc.babylonjs.com/advanced_topics/webGL2#power-of-two-textures
 */
export declare class GlyphAtlas {
    image: RGBAImage;
    positions: GlyphPositions;
    constructor(stacks: Record<string, Record<string, StyleGlyph>>);
}
export {};