import { LoadingProgressArgs } from "../engine_setup.js";
declare type LoadingStyleOption = "dark" | "light" | "auto";
/** Loading overlay layout. `centered` = bar centered, capped at 50% width, with an (optional) logo above it (default). `minimal` = thin bar pinned to the top. */
declare type LoadingLayoutOption = "minimal" | "centered";
/** @internal */
export declare class LoadingElementOptions {
    className?: string;
    additionalClasses?: string[];
}
/** @internal */
export interface ILoadingViewHandler {
    onLoadingBegin(message?: string): any;
    onLoadingUpdate(progress: LoadingProgressArgs | number, message?: string): any;
    onLoadingFinished(message?: string): any;
    setMessage(string: string): any;
}
/** @internal */
export declare function calculateProgress01(progress: LoadingProgressArgs): number;
/** @internal */
export declare class EngineLoadingView implements ILoadingViewHandler {
    static LoadingContainerClassName: string;
    loadingProgress: number;
    /** Usually the NeedleEngineHTMLElement */
    private _element;
    private _progress;
    private _allowCustomLoadingElement;
    private _loadingElement?;
    private _loadingTextContainer;
    private _loadingBar;
    private _messageContainer;
    private _loadingElementOptions?;
    /**
     * Creates a new loading view
     * @param owner the element that will contain the loading view (should be the NeedleEngineHTMLElement)
     */
    constructor(owner: HTMLElement, opts?: LoadingElementOptions);
    onLoadingBegin(message?: string): Promise<void>;
    onLoadingUpdate(progress: LoadingProgressArgs | ProgressEvent | number, message?: string): void;
    onLoadingFinished(): void;
    setMessage(message: string): void;
    private _progressLoop;
    private smoothProgressLoop;
    private onDoneLoading;
    private updateDisplay;
    private createLoadingElement;
    /**
     * Dev-only: show the loading overlay with a looping fake progress so the loading UI can be
     * previewed and iterated on without loading a scene. Attributes (`loading-style`,
     * `loading-layout`, `loading-logo`, `poster`, ...) are read from `options` or from `target`.
     *
     * Auto-runs when the URL contains `?loadingpreview` (optionally `?loadingpreview=centered`).
     * Can also be called manually, e.g. `document.querySelector("needle-engine")` as target.
     *
     * @returns a function that stops the preview and hides the overlay.
     */
    static preview(target?: HTMLElement, options?: {
        layout?: LoadingLayoutOption;
        theme?: LoadingStyleOption;
        logo?: boolean;
        logoSrc?: string;
        poster?: string;
    }): () => void;
}
export {};