0d58bb5512
This patch attempts to address an issue in the old `PDFHistory` implementation, where the current position wouldn't be correctly saved when the browser was closed. In theory this *should* already be working, however as the discussion in https://bugzilla.mozilla.org/show_bug.cgi?id=1153393 showed, it seems that both `pagehide` and `beforeunload` arrive to late to successfully update the history during closing. Hence a timeout is used to *temporarily* add the current position to the browser history when the viewer is idle. Note that we need to take care not to update the browser history too often, since that would render the viewer more or unusable. Furthermore, if the timeout is *too* long it may end up effectively disable this whole functionality. The `UPDATE_VIEWAREA_TIMEOUT` constant is thus a heuristic value, which we may need to tweak taking the above into account.
567 lines
19 KiB
JavaScript
567 lines
19 KiB
JavaScript
/* Copyright 2017 Mozilla Foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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import { cloneObj, parseQueryString, waitOnEventOrTimeout } from './ui_utils';
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import { getGlobalEventBus } from './dom_events';
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// Heuristic value used when force-resetting `this._blockHashChange`.
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const HASH_CHANGE_TIMEOUT = 1000; // milliseconds
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// Heuristic value used when adding a temporary position to the browser history.
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const UPDATE_VIEWAREA_TIMEOUT = 2000; // milliseconds
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/**
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* @typedef {Object} PDFHistoryOptions
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* @property {IPDFLinkService} linkService - The navigation/linking service.
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* @property {EventBus} eventBus - The application event bus.
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*/
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/**
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* @typedef {Object} PushParameters
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* @property {string} namedDest - (optional) The named destination. If absent,
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* a stringified version of `explicitDest` is used.
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* @property {Array} explicitDest - The explicit destination array.
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* @property {number} pageNumber - The page to which the destination points.
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*/
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function getCurrentHash() {
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return document.location.hash;
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}
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function parseCurrentHash(linkService) {
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let hash = unescape(getCurrentHash()).substring(1);
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let params = parseQueryString(hash);
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let page = params.page | 0;
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if (!(Number.isInteger(page) && page > 0 && page <= linkService.pagesCount)) {
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page = null;
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}
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return { hash, page, };
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}
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class PDFHistory {
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/**
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* @param {PDFHistoryOptions} options
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*/
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constructor({ linkService, eventBus, }) {
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this.linkService = linkService;
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this.eventBus = eventBus || getGlobalEventBus();
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this.initialized = false;
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this.initialBookmark = null;
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this._boundEvents = Object.create(null);
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this._isViewerInPresentationMode = false;
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// Ensure that we don't miss a 'presentationmodechanged' event, by
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// registering the listener immediately.
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this.eventBus.on('presentationmodechanged', (evt) => {
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this._isViewerInPresentationMode = evt.active || evt.switchInProgress;
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});
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}
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/**
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* Initialize the history for the PDF document, using either the current
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* browser history entry or the document hash, whichever is present.
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* @param {string} fingerprint - The PDF document's unique fingerprint.
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* @param {boolean} resetHistory - (optional) Reset the browsing history.
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*/
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initialize(fingerprint, resetHistory = false) {
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if (!fingerprint || typeof fingerprint !== 'string') {
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console.error(
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'PDFHistory.initialize: The "fingerprint" must be a non-empty string.');
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return;
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}
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let reInitialized = this.initialized && this.fingerprint !== fingerprint;
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this.fingerprint = fingerprint;
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if (!this.initialized) {
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this._bindEvents();
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}
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let state = window.history.state;
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this.initialized = true;
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this.initialBookmark = null;
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this._popStateInProgress = false;
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this._blockHashChange = 0;
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this._currentHash = getCurrentHash();
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this._currentUid = this._uid = 0;
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this._destination = null;
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this._position = null;
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if (!this._isValidState(state) || resetHistory) {
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let { hash, page, } = parseCurrentHash(this.linkService);
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if (!hash || reInitialized || resetHistory) {
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// Ensure that the browser history is reset on PDF document load.
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this._pushOrReplaceState(null, /* forceReplace = */ true);
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return;
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}
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// Ensure that the browser history is initialized correctly when
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// the document hash is present on PDF document load.
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this._pushOrReplaceState({ hash, page, }, /* forceReplace = */ true);
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return;
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}
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// The browser history contains a valid entry, ensure that the history is
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// initialized correctly on PDF document load.
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let destination = state.destination;
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this._updateInternalState(destination, state.uid,
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/* removeTemporary = */ true);
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if (destination.dest) {
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this.initialBookmark = JSON.stringify(destination.dest);
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// If the history is updated, e.g. through the user changing the hash,
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// before the initial destination has become visible, then we do *not*
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// want to potentially add `this._position` to the browser history.
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this._destination.page = null;
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} else if (destination.hash) {
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this.initialBookmark = destination.hash;
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} else if (destination.page) {
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// Fallback case; shouldn't be necessary, but better safe than sorry.
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this.initialBookmark = `page=${destination.page}`;
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}
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}
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/**
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* Push an internal destination to the browser history.
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* @param {PushParameters}
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*/
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push({ namedDest, explicitDest, pageNumber, }) {
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if (!this.initialized) {
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return;
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}
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if ((namedDest && typeof namedDest !== 'string') ||
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!(explicitDest instanceof Array) ||
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!(Number.isInteger(pageNumber) &&
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pageNumber > 0 && pageNumber <= this.linkService.pagesCount)) {
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console.error('PDFHistory.push: Invalid parameters.');
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return;
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}
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let hash = namedDest || JSON.stringify(explicitDest);
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if (!hash) {
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// The hash *should* never be undefined, but if that were to occur,
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// avoid any possible issues by not updating the browser history.
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return;
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}
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let forceReplace = false;
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if (this._destination &&
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(this._destination.hash === hash ||
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isDestsEqual(this._destination.dest, explicitDest))) {
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// When the new destination is identical to `this._destination`, and
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// its `page` is undefined, replace the current browser history entry.
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// NOTE: This can only occur if `this._destination` was set either:
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// - through the document hash being specified on load.
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// - through the user changing the hash of the document.
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if (this._destination.page) {
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return;
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}
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forceReplace = true;
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}
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if (this._popStateInProgress && !forceReplace) {
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return;
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}
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this._pushOrReplaceState({
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dest: explicitDest,
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hash,
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page: pageNumber,
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}, forceReplace);
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}
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/**
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* Push the current position to the browser history.
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*/
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pushCurrentPosition() {
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if (!this.initialized || this._popStateInProgress) {
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return;
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}
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this._tryPushCurrentPosition();
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}
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/**
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* Go back one step in the browser history.
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* NOTE: Avoids navigating away from the document, useful for "named actions".
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*/
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back() {
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if (!this.initialized || this._popStateInProgress) {
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return;
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}
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let state = window.history.state;
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if (this._isValidState(state) && state.uid > 0) {
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window.history.back();
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}
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}
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/**
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* Go forward one step in the browser history.
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* NOTE: Avoids navigating away from the document, useful for "named actions".
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*/
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forward() {
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if (!this.initialized || this._popStateInProgress) {
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return;
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}
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let state = window.history.state;
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if (this._isValidState(state) && state.uid < (this._uid - 1)) {
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window.history.forward();
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}
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}
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/**
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* @returns {boolean} Indicating if the user is currently moving through the
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* browser history, useful e.g. for skipping the next 'hashchange' event.
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*/
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get popStateInProgress() {
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return this.initialized &&
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(this._popStateInProgress || this._blockHashChange > 0);
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}
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/**
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* @private
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*/
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_pushOrReplaceState(destination, forceReplace = false) {
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let shouldReplace = forceReplace || !this._destination;
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let newState = {
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fingerprint: this.fingerprint,
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uid: shouldReplace ? this._currentUid : this._uid,
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destination,
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};
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if (typeof PDFJSDev !== 'undefined' && PDFJSDev.test('CHROME') &&
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window.history.state && window.history.state.chromecomState) {
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// history.state.chromecomState is managed by chromecom.js.
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newState.chromecomState = window.history.state.chromecomState;
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}
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this._updateInternalState(destination, newState.uid);
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if (shouldReplace) {
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if (typeof PDFJSDev !== 'undefined' &&
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PDFJSDev.test('FIREFOX || MOZCENTRAL')) {
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// Providing the third argument causes a SecurityError for file:// URLs.
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window.history.replaceState(newState, '');
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} else {
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window.history.replaceState(newState, '', document.URL);
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}
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} else {
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if (typeof PDFJSDev !== 'undefined' &&
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PDFJSDev.test('FIREFOX || MOZCENTRAL')) {
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// Providing the third argument causes a SecurityError for file:// URLs.
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window.history.pushState(newState, '');
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} else {
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window.history.pushState(newState, '', document.URL);
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}
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}
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if (typeof PDFJSDev !== 'undefined' && PDFJSDev.test('CHROME') &&
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top === window) {
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// eslint-disable-next-line no-undef
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chrome.runtime.sendMessage('showPageAction');
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}
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}
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/**
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* @private
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*/
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_tryPushCurrentPosition(temporary = false) {
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if (!this._position) {
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return;
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}
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let position = this._position;
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if (temporary) {
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position = cloneObj(this._position);
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position.temporary = true;
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}
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if (!this._destination) {
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this._pushOrReplaceState(position);
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return;
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}
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if (this._destination.temporary) {
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// Always replace a previous *temporary* position.
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this._pushOrReplaceState(position, /* forceReplace = */ true);
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return;
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}
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if (this._destination.hash === position.hash) {
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return; // The current document position has not changed.
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}
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if (!this._destination.page) {
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// `this._destination` was set through the user changing the hash of
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// the document. Do not add `this._position` to the browser history,
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// to avoid "flooding" it with lots of (nearly) identical entries,
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// since we cannot ensure that the document position has changed.
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return;
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}
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let forceReplace = false;
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if (this._destination.page === position.first ||
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this._destination.page === position.page) {
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// When the `page` of `this._destination` is still visible, do not
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// update the browsing history when `this._destination` either:
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// - contains an internal destination, since in this case we
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// cannot ensure that the document position has actually changed.
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// - was set through the user changing the hash of the document.
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if (this._destination.dest || !this._destination.first) {
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return;
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}
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// To avoid "flooding" the browser history, replace the current entry.
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forceReplace = true;
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}
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this._pushOrReplaceState(position, forceReplace);
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}
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/**
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* @private
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*/
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_isValidState(state) {
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if (!state) {
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return false;
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}
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if (state.fingerprint !== this.fingerprint) {
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// This should only occur in viewers with support for opening more than
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// one PDF document, e.g. the GENERIC viewer.
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return false;
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}
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if (!Number.isInteger(state.uid) || state.uid < 0) {
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return false;
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}
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if (state.destination === null || typeof state.destination !== 'object') {
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return false;
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}
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return true;
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}
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/**
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* @private
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*/
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_updateInternalState(destination, uid, removeTemporary = false) {
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if (removeTemporary && destination && destination.temporary) {
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// When the `destination` comes from the browser history,
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// we no longer treat it as a *temporary* position.
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delete destination.temporary;
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}
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this._destination = destination;
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this._currentUid = uid;
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this._uid = this._currentUid + 1;
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}
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/**
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* @private
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*/
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_updateViewarea({ location, }) {
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if (this._updateViewareaTimeout) {
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clearTimeout(this._updateViewareaTimeout);
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this._updateViewareaTimeout = null;
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}
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this._position = {
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hash: this._isViewerInPresentationMode ?
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`page=${location.pageNumber}` : location.pdfOpenParams.substring(1),
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page: this.linkService.page,
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first: location.pageNumber,
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};
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if (this._popStateInProgress) {
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return;
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}
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if (UPDATE_VIEWAREA_TIMEOUT > 0) {
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// When closing the browser, a 'pagehide' event will be dispatched which
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// *should* allow us to push the current position to the browser history.
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// In practice, it seems that the event is arriving too late in order for
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// the session history to be successfully updated.
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// (For additional details, please refer to the discussion in
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// https://bugzilla.mozilla.org/show_bug.cgi?id=1153393.)
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//
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// To workaround this we attempt to *temporarily* add the current position
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// to the browser history only when the viewer is *idle*,
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// i.e. when scrolling and/or zooming does not occur.
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//
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// PLEASE NOTE: It's absolutely imperative that the browser history is
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// *not* updated too often, since that would render the viewer more or
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// less unusable. Hence the use of a timeout to delay the update until
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// the viewer has been idle for `UPDATE_VIEWAREA_TIMEOUT` milliseconds.
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this._updateViewareaTimeout = setTimeout(() => {
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if (!this._popStateInProgress) {
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this._tryPushCurrentPosition(/* temporary = */ true);
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}
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this._updateViewareaTimeout = null;
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}, UPDATE_VIEWAREA_TIMEOUT);
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}
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}
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/**
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* @private
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*/
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_popState({ state, }) {
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let newHash = getCurrentHash(), hashChanged = this._currentHash !== newHash;
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this._currentHash = newHash;
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if (!state ||
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(typeof PDFJSDev !== 'undefined' && PDFJSDev.test('CHROME') &&
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state.chromecomState && !this._isValidState(state))) {
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// This case corresponds to the user changing the hash of the document.
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this._currentUid = this._uid;
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let { hash, page, } = parseCurrentHash(this.linkService);
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this._pushOrReplaceState({ hash, page, }, /* forceReplace */ true);
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return;
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}
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if (!this._isValidState(state)) {
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// This should only occur in viewers with support for opening more than
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// one PDF document, e.g. the GENERIC viewer.
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return;
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}
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// Prevent the browser history from updating until the new destination,
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// as stored in the browser history, has been scrolled into view.
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this._popStateInProgress = true;
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if (hashChanged) {
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// When the hash changed, implying that the 'popstate' event will be
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// followed by a 'hashchange' event, then we do *not* want to update the
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// browser history when handling the 'hashchange' event (in web/app.js)
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// since that would *overwrite* the new destination navigated to below.
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//
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// To avoid accidentally disabling all future user-initiated hash changes,
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// if there's e.g. another 'hashchange' listener that stops the event
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// propagation, we make sure to always force-reset `this._blockHashChange`
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// after `HASH_CHANGE_TIMEOUT` milliseconds have passed.
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this._blockHashChange++;
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waitOnEventOrTimeout({
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target: window,
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name: 'hashchange',
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delay: HASH_CHANGE_TIMEOUT,
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}).then(() => {
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this._blockHashChange--;
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});
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}
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// This case corresponds to navigation backwards in the browser history.
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if (state.uid < this._currentUid && this._position && this._destination) {
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let shouldGoBack = false;
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if (this._destination.temporary) {
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// If the `this._destination` contains a *temporary* position, always
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// push the `this._position` to the browser history before moving back.
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this._pushOrReplaceState(this._position);
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shouldGoBack = true;
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} else if (this._destination.page &&
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this._destination.page !== this._position.first &&
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this._destination.page !== this._position.page) {
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// If the `page` of the `this._destination` is no longer visible,
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// push the `this._position` to the browser history before moving back.
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this._pushOrReplaceState(this._destination);
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this._pushOrReplaceState(this._position);
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shouldGoBack = true;
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}
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if (shouldGoBack) {
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// After `window.history.back()`, we must not enter this block on the
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// resulting 'popstate' event, since that may cause an infinite loop.
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this._currentUid = state.uid;
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window.history.back();
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return;
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}
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}
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// Navigate to the new destination.
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let destination = state.destination;
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this._updateInternalState(destination, state.uid,
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/* removeTemporary = */ true);
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if (destination.dest) {
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this.linkService.navigateTo(destination.dest);
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} else if (destination.hash) {
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this.linkService.setHash(destination.hash);
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} else if (destination.page) {
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// Fallback case; shouldn't be necessary, but better safe than sorry.
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this.linkService.page = destination.page;
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}
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// Since `PDFLinkService.navigateTo` is asynchronous, we thus defer the
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// resetting of `this._popStateInProgress` slightly.
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Promise.resolve().then(() => {
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this._popStateInProgress = false;
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});
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}
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/**
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* @private
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*/
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_bindEvents() {
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let { _boundEvents, eventBus, } = this;
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_boundEvents.updateViewarea = this._updateViewarea.bind(this);
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_boundEvents.popState = this._popState.bind(this);
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_boundEvents.pageHide = (evt) => {
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// Attempt to push the `this._position` into the browser history when
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// navigating away from the document. This is *only* done if the history
|
|
// is currently empty, since otherwise an existing browser history entry
|
|
// will end up being overwritten (given that new entries cannot be pushed
|
|
// into the browser history when the 'unload' event has already fired).
|
|
if (!this._destination) {
|
|
this._tryPushCurrentPosition();
|
|
}
|
|
};
|
|
|
|
eventBus.on('updateviewarea', _boundEvents.updateViewarea);
|
|
window.addEventListener('popstate', _boundEvents.popState);
|
|
window.addEventListener('pagehide', _boundEvents.pageHide);
|
|
}
|
|
}
|
|
|
|
function isDestsEqual(firstDest, secondDest) {
|
|
function isEntryEqual(first, second) {
|
|
if (typeof first !== typeof second) {
|
|
return false;
|
|
}
|
|
if (first instanceof Array || second instanceof Array) {
|
|
return false;
|
|
}
|
|
if (first !== null && typeof first === 'object' && second !== null) {
|
|
if (Object.keys(first).length !== Object.keys(second).length) {
|
|
return false;
|
|
}
|
|
for (var key in first) {
|
|
if (!isEntryEqual(first[key], second[key])) {
|
|
return false;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
return first === second || (Number.isNaN(first) && Number.isNaN(second));
|
|
}
|
|
|
|
if (!(firstDest instanceof Array && secondDest instanceof Array)) {
|
|
return false;
|
|
}
|
|
if (firstDest.length !== secondDest.length) {
|
|
return false;
|
|
}
|
|
for (let i = 0, ii = firstDest.length; i < ii; i++) {
|
|
if (!isEntryEqual(firstDest[i], secondDest[i])) {
|
|
return false;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
export {
|
|
PDFHistory,
|
|
isDestsEqual,
|
|
};
|