import * as React from "react";
import { ConfigConsumerProps } from "../Config";
interface IBacktopProps {
    /**
     * 自定义组件类名
     *
     * @default ""
     **/
    className?: string;
    /**
     * 返回顶部按钮内容
     *
     *
     **/
    children: React.ReactNode;
    /**
     * 滚动高度超过该值时，渲染组件
     *
     * @default 400
     **/
    displayHeight?: number | undefined;
    /**
     * 滚动时长 单位毫秒
     *
     * @default 1000
     **/
    duration?: number;
    /**
     * 点击返回顶部时的回调函数
     *
     * @default (e: Event) => void
     **/
    onClick?: (e: Event) => void;
    /**
     * 组件切换显示或者隐藏时的回调函数
     *
     * @default (isShow: boolean) => void
     **/
    onToggle?: (isShow: boolean) => void;
    /**
     * 是否使用平滑滚动
     *
     * @default true
     **/
    smooth?: boolean;
    /**
     * 默认前缀
     *
     * @default 'lg'
     **/
    prefixCls?: string;
    /**
     * 指定滚动的容器
     *
     * @default  () => window
     **/
    getContainer?: () => HTMLElement | Window;
    /**
     * 自定义样式
     *
     * @default
     **/
    style?: React.CSSProperties;
}
interface IBacktopState {
    show: boolean;
}
declare class Backtop extends React.PureComponent<IBacktopProps, IBacktopState> {
    scrollEvent: any;
    private scrollContainer;
    static defaultProps: {
        className: string;
        displayHeight: number;
        duration: number;
        onClick: () => null;
        onToggle: () => null;
        smooth: boolean;
        style: {};
        getContainer: () => Window & typeof globalThis;
    };
    constructor(props: IBacktopProps);
    componentDidMount(): void;
    componentWillUnmount(): void;
    handleScroll(): void;
    handleClick(e: any): void;
    renderBacktop: ({ getPrefixCls }: ConfigConsumerProps) => false | JSX.Element;
    render(): JSX.Element;
}
export default Backtop;