Move PDFHistory from viewer.js to its own file

web/pdf_history.js

@@ -0,0 +1,338 @@
+/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set shiftwidth=2 tabstop=2 autoindent cindent expandtab: */
+/* Copyright 2012 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.
+ */
+/* globals PDFJS, PDFView */
+
+'use strict';
+
+var PDFHistory = {
+  initialized: false,
+  initialDestination: null,
+
+  initialize: function pdfHistoryInitialize(fingerprint) {
+    if (PDFJS.disableHistory || window.parent !== window) {
+      // The browsing history is only enabled when the viewer is standalone,
+      // i.e. not when it is embedded in a page.
+      return;
+    }
+    this.initialized = true;
+    this.reInitialized = false;
+    this.allowHashChange = true;
+    this.historyUnlocked = true;
+
+    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)) {
+      // This corresponds to navigating back to the document
+      // from another page in the browser history.
+      if (state.target.dest) {
+        this.initialDestination = state.target.dest;
+      } else {
+        PDFView.initialBookmark = state.target.hash;
+      }
+      this.currentUid = state.uid;
+      this.uid = state.uid + 1;
+      this.current = state.target;
+    } else {
+      // This corresponds to the loading of a new document.
+      if (state && state.fingerprint &&
+          this.fingerprint !== state.fingerprint) {
+        // Reinitialize the browsing history when a new document
+        // is opened in the web viewer.
+        this.reInitialized = true;
+      }
+      window.history.replaceState({ fingerprint: this.fingerprint }, '', '');
+    }
+
+    var self = this;
+    window.addEventListener('popstate', function pdfHistoryPopstate(evt) {
+      evt.preventDefault();
+      evt.stopPropagation();
+
+      if (!self.historyUnlocked) {
+        return;
+      }
+      if (evt.state) {
+        // Move back/forward in the history.
+        self._goTo(evt.state);
+      } else {
+        // Handle the user modifying the hash of a loaded document.
+        self.previousHash = window.location.hash.substring(1);
+
+        // If the history is empty when the hash changes,
+        // update the previous entry in the browser history.
+        if (self.uid === 0) {
+          var previousParams = (self.previousHash && self.currentBookmark &&
+                                self.previousHash !== self.currentBookmark) ?
+            { hash: self.currentBookmark, page: self.currentPage } :
+            { page: 1 };
+          self.historyUnlocked = false;
+          self.allowHashChange = false;
+          window.history.back();
+          self._pushToHistory(previousParams, false, true);
+          window.history.forward();
+          self.historyUnlocked = true;
+        }
+        self._pushToHistory({ hash: self.previousHash }, false, true);
+        self._updatePreviousBookmark();
+      }
+    }, false);
+
+    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();
+      }
+      // Remove the event listener when navigating away from the document,
+      // since 'beforeunload' prevents Firefox from caching the document.
+      window.removeEventListener('beforeunload', pdfHistoryBeforeUnload, false);
+    }
+    window.addEventListener('beforeunload', pdfHistoryBeforeUnload, false);
+
+    window.addEventListener('pageshow', function pdfHistoryPageShow(evt) {
+      // If the entire viewer (including the PDF file) is cached in the browser,
+      // we need to reattach the 'beforeunload' event listener since
+      // the 'DOMContentLoaded' event is not fired on 'pageshow'.
+      window.addEventListener('beforeunload', pdfHistoryBeforeUnload, false);
+    }, false);
+  },
+
+  _isStateObjectDefined: function pdfHistory_isStateObjectDefined(state) {
+    return (state && state.uid >= 0 &&
+            state.fingerprint && this.fingerprint === state.fingerprint &&
+            state.target && state.target.hash) ? true : false;
+  },
+
+  get isHashChangeUnlocked() {
+    if (!this.initialized) {
+      return true;
+    }
+    // If the current hash changes when moving back/forward in the history,
+    // this will trigger a 'popstate' event *as well* as a 'hashchange' event.
+    // Since the hash generally won't correspond to the exact the position
+    // stored in the history's state object, triggering the 'hashchange' event
+    // can thus corrupt the browser history.
+    //
+    // When the hash changes during a 'popstate' event, we *only* prevent the
+    // first 'hashchange' event and immediately reset allowHashChange.
+    // If it is not reset, the user would not be able to change the hash.
+
+    var temp = this.allowHashChange;
+    this.allowHashChange = true;
+    return temp;
+  },
+
+  _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 :
+        PDFView.getDestinationHash(params.dest).split('#')[1];
+    }
+    if (params.page) {
+      params.page |= 0;
+    }
+    if (isInitialBookmark) {
+      var target = window.history.state.target;
+      if (!target) {
+        // Invoked when the user specifies an initial bookmark,
+        // thus setting PDFView.initialBookmark, when the document is loaded.
+        this._pushToHistory(params, false);
+        this.previousHash = window.location.hash.substring(1);
+      }
+      this.updatePreviousBookmark = this.nextHashParam ? false : true;
+      if (target) {
+        // If the current document is reloaded,
+        // avoid creating duplicate entries in the history.
+        this._updatePreviousBookmark();
+      }
+      return;
+    }
+    if (this.nextHashParam && this.nextHashParam === params.hash) {
+      this.nextHashParam = null;
+      this.updatePreviousBookmark = true;
+      return;
+    }
+
+    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;
+    }
+    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 (PDFView.isPresentationMode) {
+      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.hash !== this.previousHash);
+        this._pushToHistory(previousParams, false, replacePrevious);
+      }
+    }
+    if (overwrite || this.uid === 0) {
+      window.history.replaceState(this._stateObj(params), '', '');
+    } else {
+      window.history.pushState(this._stateObj(params), '', '');
+    }
+    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) {
+      PDFView.navigateTo(state.target.dest);
+    } else {
+      PDFView.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();
+      }
+    }
+  }
+};

web/viewer.html

@@ -83,6 +83,7 @@
     <script type="text/javascript" src="text_layer_builder.js"></script>
     <script type="text/javascript" src="pdf_find_bar.js"></script>
     <script type="text/javascript" src="pdf_find_controller.js"></script>
+    <script type="text/javascript" src="pdf_history.js"></script>
 <!--#endif-->
 
     <script type="text/javascript" src="debugger.js"></script>