Source: document-library-preview-document/src/main/resources/META-INF/resources/preview/js/DocumentPreviewer.es.js

/**
 * Copyright (c) 2000-present Liferay, Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation; either version 2.1 of the License, or (at your option)
 * any later version.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
 * details.
 */
import ClayButton from '@clayui/button';
import ClayIcon from '@clayui/icon';
import ClayLoadingIndicator from '@clayui/loading-indicator';
import {useIsMounted} from '@liferay/frontend-js-react-web';
import {debounce} from 'frontend-js-web';
import imagePromise from 'image-promise';
import PropTypes from 'prop-types';
import React, {useEffect, useRef, useState} from 'react';
const KEY_CODE_ENTER = 13;
const KEY_CODE_ESC = 27;
/**
 * Valid list of keycodes
 * Includes backspace, tab, arrows, delete and numbers
 * @type {Array<number>}
 */
const VALID_KEY_CODES = [
	8,
	9,
	37,
	38,
	39,
	40,
	46,
	48,
	49,
	50,
	51,
	52,
	53,
	54,
	55,
	56,
	57,
];
/**
 * Milisecons between goToPage calls
 * @type {number}
 */
const WAIT_BETWEEN_GO_TO_PAGE = 250;
/**
 * Component that creates a pdf preview
 * @review
 */
const DocumentPreviewer = ({baseImageURL, initialPage, totalPages}) => {
	const [currentPage, setCurrentPage] = useState(initialPage);
	const [currentPageLoading, setCurrentPageLoading] = useState(false);
	const [expanded, setExpanded] = useState(false);
	const [loadedPages] = useState({
		[currentPage]: {
			loaded: true,
			pagePromise: Promise.resolve(),
		},
	});
	const [nextPageDisabled, setNextPageDisabled] = useState(
		currentPage === totalPages
	);
	const [previousPageDisabled, setPreviousPageDisabled] = useState(
		currentPage === 1
	);
	const [showPageInput, setShowPageInput] = useState(false);
	const imageContainer = useRef();
	const pageInput = useRef();
	const showPageInputButton = useRef();
	const isMounted = useIsMounted();
	if (showPageInput) {
		setTimeout(() => {
			if (isMounted()) {
				pageInput.current.focus();
			}
		}, 100);
	}
	const loadPage = (page) => {
		let pagePromise = loadedPages[page] && loadedPages[page].pagePromise;
		if (!pagePromise) {
			pagePromise = imagePromise(`${baseImageURL}${page}`).then(() => {
				loadedPages[page].loaded = true;
			});
			loadedPages[page] = {
				loaded: false,
				pagePromise,
			};
		}
		return pagePromise;
	};
	const loadAdjacentPages = (page, adjacentPageCount = 2) => {
		for (let i = 1; i <= adjacentPageCount; i++) {
			if (page + i <= totalPages) {
				loadPage(page + i);
			}
			if (page - i > 1) {
				loadPage(page - i);
			}
		}
	};
	const loadCurrentPage = debounce((page) => {
		loadPage(page)
			.then(() => {
				loadAdjacentPages(page);
				setCurrentPageLoading(false);
			})
			.catch(() => {
				setCurrentPageLoading(false);
			});
	}, WAIT_BETWEEN_GO_TO_PAGE);
	const goToPage = (page) => {
		setNextPageDisabled(page === totalPages);
		setPreviousPageDisabled(page === 1);
		if (!loadedPages[page] || !loadedPages[page].loaded) {
			setCurrentPageLoading(true);
			loadCurrentPage(page);
		}
		imageContainer.current.scrollTop = 0;
		setCurrentPage(page);
	};
	const processPageInput = (value) => {
		let pageNumber = Number.parseInt(value, 10);
		pageNumber = pageNumber
			? Math.min(Math.max(1, pageNumber), totalPages)
			: currentPage;
		goToPage(pageNumber);
	};
	const hidePageInput = (returnFocus = true) => {
		setShowPageInput(false);
		if (returnFocus) {
			setTimeout(() => {
				if (isMounted()) {
					showPageInputButton.current.focus();
				}
			}, 100);
		}
	};
	const handleBlurPageInput = (event) => {
		processPageInput(event.currentTarget.value);
		hidePageInput(false);
	};
	const handleKeyDownPageInput = (event) => {
		const code = event.keyCode || event.charCode;
		if (code === KEY_CODE_ENTER) {
			processPageInput(event.currentTarget.value);
			hidePageInput();
		}
		else if (code === KEY_CODE_ESC) {
			hidePageInput();
		}
		else if (VALID_KEY_CODES.indexOf(code) === -1) {
			event.preventDefault();
		}
	};
	useEffect(() => {
		loadAdjacentPages(initialPage);
		// eslint-disable-next-line react-hooks/exhaustive-deps
	}, []);
	return (
		<div className="preview-file">
			<div
				className="preview-file-container preview-file-max-height"
				ref={imageContainer}
			>
				{currentPageLoading ? (
					<ClayLoadingIndicator />
				) : (
					<img
						className={`preview-file-document ${
							!expanded && 'preview-file-document-fit'
						}`}
						src={`${baseImageURL}${currentPage}`}
					/>
				)}
			</div>
			<div className="preview-toolbar-container">
				<ClayButton.Group className="floating-bar">
					<ClayButton.Group>
						<ClayButton
							className="btn-floating-bar btn-floating-bar-text"
							onClick={() => {
								setShowPageInput(true);
							}}
							ref={showPageInputButton}
							title={
								totalPages > 1 &&
								Liferay.Language.get('click-to-jump-to-a-page')
							}
						>
							{`${Liferay.Language.get(
								'page'
							)} ${currentPage} / ${totalPages}`}
						</ClayButton>
						{showPageInput && (
							<div className="floating-bar-input-wrapper">
								<input
									className="floating-bar-input form-control form-control-sm"
									max={totalPages}
									min="1"
									onBlur={handleBlurPageInput}
									onKeyDown={handleKeyDownPageInput}
									placeholder={Liferay.Language.get(
										'page-...'
									)}
									ref={pageInput}
									type="number"
								/>
							</div>
						)}
					</ClayButton.Group>
					<ClayButton
						className="btn-floating-bar"
						disabled={previousPageDisabled}
						monospaced
						onClick={() => {
							goToPage(currentPage - 1);
						}}
						title={Liferay.Language.get('page-above')}
					>
						<ClayIcon symbol="caret-top" />
					</ClayButton>
					<ClayButton
						className="btn-floating-bar"
						disabled={nextPageDisabled}
						monospaced
						onClick={() => {
							goToPage(currentPage + 1);
						}}
						title={Liferay.Language.get('page-below')}
					>
						<ClayIcon symbol="caret-bottom" />
					</ClayButton>
					<div className="separator-floating-bar"></div>
					<ClayButton
						className="btn-floating-bar"
						monospaced
						onClick={() => {
							setExpanded(!expanded);
						}}
						title={
							expanded
								? Liferay.Language.get('zoom-to-fit')
								: Liferay.Language.get('expand')
						}
					>
						<ClayIcon
							symbol={expanded ? 'autosize' : 'full-size'}
						/>
					</ClayButton>
				</ClayButton.Group>
			</div>
		</div>
	);
};
DocumentPreviewer.propTypes = {
	baseImageURL: PropTypes.string,
	initialPage: PropTypes.number,
	totalPages: PropTypes.number,
};
export default DocumentPreviewer;