import { ElementRef, OnChanges } from '@angular/core';
/**
 * 创建缩略图
 */
export declare class FileThumbDirective implements OnChanges {
    private el;
    /**
     * 文件对象，必填项
     */
    file: File;
    constructor(el: ElementRef<HTMLElement>);
    private render;
    ngOnChanges(): void;
}