declare type AlphaCallback = (alpha: number) => void;
declare class Alpha {
    protected pareElement: HTMLElement;
    protected barEle: HTMLElement;
    protected cursorEle: HTMLElement;
    root: HTMLElement;
    currentAlpha: number;
    private color;
    protected callback?: AlphaCallback;
    constructor(pareElement: HTMLElement, callback?: AlphaCallback);
    protected createBar(): HTMLDivElement;
    protected createCursorEle(): HTMLDivElement;
    private create;
    setColor(alpha: number, color: string): void;
    private update;
    getCursorLeft(): number;
    setCallback(callback: AlphaCallback): void;
    listen(): void;
}
export default Alpha;