pdfjs-dist/lib/web/pdf_history.js

/* Copyright 2017 Mozilla Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
'use strict';

var domEvents = require('./dom_events.js');
function PDFHistory(options) {
  this.linkService = options.linkService;
  this.eventBus = options.eventBus || domEvents.getGlobalEventBus();
  this.initialized = false;
  this.initialDestination = null;
  this.initialBookmark = null;
}
PDFHistory.prototype = {
  initialize: function pdfHistoryInitialize(fingerprint) {
    this.initialized = true;
    this.reInitialized = false;
    this.allowHashChange = true;
    this.historyUnlocked = true;
    this.isViewerInPresentationMode = false;
    this.previousHash = window.location.hash.substring(1);
    this.currentBookmark = '';
    this.currentPage = 0;
    this.updatePreviousBookmark = false;
    this.previousBookmark = '';
    this.previousPage = 0;
    this.nextHashParam = '';
    this.fingerprint = fingerprint;
    this.currentUid = this.uid = 0;
    this.current = {};
    var state = window.history.state;
    if (this._isStateObjectDefined(state)) {
      if (state.target.dest) {
        this.initialDestination = state.target.dest;
      } else {
        this.initialBookmark = state.target.hash;
      }
      this.currentUid = state.uid;
      this.uid = state.uid + 1;
      this.current = state.target;
    } else {
      if (state && state.fingerprint && this.fingerprint !== state.fingerprint) {
        this.reInitialized = true;
      }
      this._pushOrReplaceState({ fingerprint: this.fingerprint }, true);
    }
    var self = this;
    window.addEventListener('popstate', function pdfHistoryPopstate(evt) {
      if (!self.historyUnlocked) {
        return;
      }
      if (evt.state) {
        self._goTo(evt.state);
        return;
      }
      if (self.uid === 0) {
        var previousParams = self.previousHash && self.currentBookmark && self.previousHash !== self.currentBookmark ? {
          hash: self.currentBookmark,
          page: self.currentPage
        } : { page: 1 };
        replacePreviousHistoryState(previousParams, function () {
          updateHistoryWithCurrentHash();
        });
      } else {
        updateHistoryWithCurrentHash();
      }
    });
    function updateHistoryWithCurrentHash() {
      self.previousHash = window.location.hash.slice(1);
      self._pushToHistory({ hash: self.previousHash }, false, true);
      self._updatePreviousBookmark();
    }
    function replacePreviousHistoryState(params, callback) {
      self.historyUnlocked = false;
      self.allowHashChange = false;
      window.addEventListener('popstate', rewriteHistoryAfterBack);
      history.back();
      function rewriteHistoryAfterBack() {
        window.removeEventListener('popstate', rewriteHistoryAfterBack);
        window.addEventListener('popstate', rewriteHistoryAfterForward);
        self._pushToHistory(params, false, true);
        history.forward();
      }
      function rewriteHistoryAfterForward() {
        window.removeEventListener('popstate', rewriteHistoryAfterForward);
        self.allowHashChange = true;
        self.historyUnlocked = true;
        callback();
      }
    }
    function pdfHistoryBeforeUnload() {
      var previousParams = self._getPreviousParams(null, true);
      if (previousParams) {
        var replacePrevious = !self.current.dest && self.current.hash !== self.previousHash;
        self._pushToHistory(previousParams, false, replacePrevious);
        self._updatePreviousBookmark();
      }
      window.removeEventListener('beforeunload', pdfHistoryBeforeUnload);
    }
    window.addEventListener('beforeunload', pdfHistoryBeforeUnload);
    window.addEventListener('pageshow', function pdfHistoryPageShow(evt) {
      window.addEventListener('beforeunload', pdfHistoryBeforeUnload);
    });
    self.eventBus.on('presentationmodechanged', function (e) {
      self.isViewerInPresentationMode = e.active;
    });
  },
  clearHistoryState: function pdfHistory_clearHistoryState() {
    this._pushOrReplaceState(null, true);
  },
  _isStateObjectDefined: function pdfHistory_isStateObjectDefined(state) {
    return state && state.uid >= 0 && state.fingerprint && this.fingerprint === state.fingerprint && state.target && state.target.hash ? true : false;
  },
  _pushOrReplaceState: function pdfHistory_pushOrReplaceState(stateObj, replace) {
    if (replace) {
      window.history.replaceState(stateObj, '', document.URL);
    } else {
      window.history.pushState(stateObj, '', document.URL);
    }
  },
  get isHashChangeUnlocked() {
    if (!this.initialized) {
      return true;
    }
    return this.allowHashChange;
  },
  _updatePreviousBookmark: function pdfHistory_updatePreviousBookmark() {
    if (this.updatePreviousBookmark && this.currentBookmark && this.currentPage) {
      this.previousBookmark = this.currentBookmark;
      this.previousPage = this.currentPage;
      this.updatePreviousBookmark = false;
    }
  },
  updateCurrentBookmark: function pdfHistoryUpdateCurrentBookmark(bookmark, pageNum) {
    if (this.initialized) {
      this.currentBookmark = bookmark.substring(1);
      this.currentPage = pageNum | 0;
      this._updatePreviousBookmark();
    }
  },
  updateNextHashParam: function pdfHistoryUpdateNextHashParam(param) {
    if (this.initialized) {
      this.nextHashParam = param;
    }
  },
  push: function pdfHistoryPush(params, isInitialBookmark) {
    if (!(this.initialized && this.historyUnlocked)) {
      return;
    }
    if (params.dest && !params.hash) {
      params.hash = this.current.hash && this.current.dest && this.current.dest === params.dest ? this.current.hash : this.linkService.getDestinationHash(params.dest).split('#')[1];
    }
    if (params.page) {
      params.page |= 0;
    }
    if (isInitialBookmark) {
      var target = window.history.state.target;
      if (!target) {
        this._pushToHistory(params, false);
        this.previousHash = window.location.hash.substring(1);
      }
      this.updatePreviousBookmark = this.nextHashParam ? false : true;
      if (target) {
        this._updatePreviousBookmark();
      }
      return;
    }
    if (this.nextHashParam) {
      if (this.nextHashParam === params.hash) {
        this.nextHashParam = null;
        this.updatePreviousBookmark = true;
        return;
      }
      this.nextHashParam = null;
    }
    if (params.hash) {
      if (this.current.hash) {
        if (this.current.hash !== params.hash) {
          this._pushToHistory(params, true);
        } else {
          if (!this.current.page && params.page) {
            this._pushToHistory(params, false, true);
          }
          this.updatePreviousBookmark = true;
        }
      } else {
        this._pushToHistory(params, true);
      }
    } else if (this.current.page && params.page && this.current.page !== params.page) {
      this._pushToHistory(params, true);
    }
  },
  _getPreviousParams: function pdfHistory_getPreviousParams(onlyCheckPage, beforeUnload) {
    if (!(this.currentBookmark && this.currentPage)) {
      return null;
    } else if (this.updatePreviousBookmark) {
      this.updatePreviousBookmark = false;
    }
    if (this.uid > 0 && !(this.previousBookmark && this.previousPage)) {
      return null;
    }
    if (!this.current.dest && !onlyCheckPage || beforeUnload) {
      if (this.previousBookmark === this.currentBookmark) {
        return null;
      }
    } else if (this.current.page || onlyCheckPage) {
      if (this.previousPage === this.currentPage) {
        return null;
      }
    } else {
      return null;
    }
    var params = {
      hash: this.currentBookmark,
      page: this.currentPage
    };
    if (this.isViewerInPresentationMode) {
      params.hash = null;
    }
    return params;
  },
  _stateObj: function pdfHistory_stateObj(params) {
    return {
      fingerprint: this.fingerprint,
      uid: this.uid,
      target: params
    };
  },
  _pushToHistory: function pdfHistory_pushToHistory(params, addPrevious, overwrite) {
    if (!this.initialized) {
      return;
    }
    if (!params.hash && params.page) {
      params.hash = 'page=' + params.page;
    }
    if (addPrevious && !overwrite) {
      var previousParams = this._getPreviousParams();
      if (previousParams) {
        var replacePrevious = !this.current.dest && this.current.hash !== this.previousHash;
        this._pushToHistory(previousParams, false, replacePrevious);
      }
    }
    this._pushOrReplaceState(this._stateObj(params), overwrite || this.uid === 0);
    this.currentUid = this.uid++;
    this.current = params;
    this.updatePreviousBookmark = true;
  },
  _goTo: function pdfHistory_goTo(state) {
    if (!(this.initialized && this.historyUnlocked && this._isStateObjectDefined(state))) {
      return;
    }
    if (!this.reInitialized && state.uid < this.currentUid) {
      var previousParams = this._getPreviousParams(true);
      if (previousParams) {
        this._pushToHistory(this.current, false);
        this._pushToHistory(previousParams, false);
        this.currentUid = state.uid;
        window.history.back();
        return;
      }
    }
    this.historyUnlocked = false;
    if (state.target.dest) {
      this.linkService.navigateTo(state.target.dest);
    } else {
      this.linkService.setHash(state.target.hash);
    }
    this.currentUid = state.uid;
    if (state.uid > this.uid) {
      this.uid = state.uid;
    }
    this.current = state.target;
    this.updatePreviousBookmark = true;
    var currentHash = window.location.hash.substring(1);
    if (this.previousHash !== currentHash) {
      this.allowHashChange = false;
    }
    this.previousHash = currentHash;
    this.historyUnlocked = true;
  },
  back: function pdfHistoryBack() {
    this.go(-1);
  },
  forward: function pdfHistoryForward() {
    this.go(1);
  },
  go: function pdfHistoryGo(direction) {
    if (this.initialized && this.historyUnlocked) {
      var state = window.history.state;
      if (direction === -1 && state && state.uid > 0) {
        window.history.back();
      } else if (direction === 1 && state && state.uid < this.uid - 1) {
        window.history.forward();
      }
    }
  }
};
exports.PDFHistory = PDFHistory;