import { type Browser } from 'playwright-core';
import type { UiKeyframe } from './hud-state.js';
export declare const CHROME_MISSING_HINT = "Google Chrome could not be launched \u2014 install it from https://www.google.com/chrome/";
/** Headless system Chrome for offscreen rasterization; null (with a warning) when it cannot start. */
export declare function launchRasterBrowser(purpose: string): Promise<Browser | null>;
export interface RasterizeOptions {
    harnessUrl: string;
    /** Overlay PNGs are written here as ui_NNNN.png, one per keyframe. */
    outDir: string;
    /**
     * CSS-pixel viewport the HUD lays out against — the recorded window's
     * aspect-corrected size when the manifest carries one, else the recording
     * resolution (see computeRasterGeometry in hud-state.ts).
     */
    width: number;
    height: number;
    /** PNG pixels per CSS pixel; >1 keeps overlays at/above the recording size. */
    deviceScaleFactor: number;
}
export declare function uiPngPath(outDir: string, index: number): string;
/**
 * Render one transparent PNG per keyframe, reusing a single browser + page.
 * Returns paths in keyframe order — a slot is null when that one keyframe
 * failed (the caller holds the previous overlay across its window) — or null
 * overall when UI must be skipped entirely (no Chrome, harness unreachable, the
 * page died mid-run, or every keyframe failed).
 */
export declare function rasterizeUiKeyframes(keyframes: readonly UiKeyframe[], options: RasterizeOptions): Promise<Array<string | null> | null>;