Maintain the current position in the document when zooming

web/page_view.js

@@ -400,16 +400,10 @@ var PageView = function pageView(container, id, scale,
       this.viewport.convertToViewportPoint(x, y),
       this.viewport.convertToViewportPoint(x + width, y + height)
     ];
-    setTimeout(function pageViewScrollIntoViewRelayout() {
-      // letting page to re-layout before scrolling
-      var scale = PDFView.currentScale;
-      var x = Math.min(boundingRect[0][0], boundingRect[1][0]);
-      var y = Math.min(boundingRect[0][1], boundingRect[1][1]);
-      var width = Math.abs(boundingRect[0][0] - boundingRect[1][0]);
-      var height = Math.abs(boundingRect[0][1] - boundingRect[1][1]);
-
-      scrollIntoView(div, {left: x, top: y, width: width, height: height});
-    }, 0);
+    var left = Math.min(boundingRect[0][0], boundingRect[1][0]);
+    var top = Math.min(boundingRect[0][1], boundingRect[1][1]);
+
+    scrollIntoView(div, { left: left, top: top });
   };
 
   this.getTextContent = function pageviewGetTextContent() {

web/presentation_mode.js

@@ -20,6 +20,7 @@
 
 var DELAY_BEFORE_HIDING_CONTROLS = 3000; // in ms
 var SELECTOR = 'presentationControls';
+var DELAY_BEFORE_RESETTING_SWITCH_IN_PROGRESS = 1000; // in ms
 
 var PresentationMode = {
   active: false,
@@ -66,11 +67,38 @@ var PresentationMode = {
             document.msFullscreenElement);
   },
 
+  /**
+   * Initialize a timeout that is used to reset PDFView.currentPosition when the
+   * browser transitions to fullscreen mode. Since resize events are triggered
+   * multiple times during the switch to fullscreen mode, this is necessary in
+   * order to prevent the page from being scrolled partially, or completely,
+   * out of view when Presentation Mode is enabled.
+   * Note: This is only an issue at certain zoom levels, e.g. 'page-width'.
+   */
+  _setSwitchInProgress: function presentationMode_setSwitchInProgress() {
+    if (this.switchInProgress) {
+      clearTimeout(this.switchInProgress);
+    }
+    this.switchInProgress = setTimeout(function switchInProgressTimeout() {
+      delete this.switchInProgress;
+    }.bind(this), DELAY_BEFORE_RESETTING_SWITCH_IN_PROGRESS);
+
+    PDFView.currentPosition = null;
+  },
+
+  _resetSwitchInProgress: function presentationMode_resetSwitchInProgress() {
+    if (this.switchInProgress) {
+      clearTimeout(this.switchInProgress);
+      delete this.switchInProgress;
+    }
+  },
+
   request: function presentationModeRequest() {
     if (!PDFView.supportsFullscreen || this.isFullscreen ||
         !this.viewer.hasChildNodes()) {
       return false;
     }
+    this._setSwitchInProgress();
 
     if (this.container.requestFullscreen) {
       this.container.requestFullscreen();
@@ -94,9 +122,15 @@ var PresentationMode = {
 
   enter: function presentationModeEnter() {
     this.active = true;
+    this._resetSwitchInProgress();
 
-    PDFView.page = this.args.page;
-    PDFView.setScale('page-fit', true);
+    // Ensure that the correct page is scrolled into view when entering
+    // Presentation Mode, by waiting until fullscreen mode in enabled.
+    // Note: This is only necessary in non-Mozilla browsers.
+    setTimeout(function enterPresentationModeTimeout() {
+      PDFView.page = this.args.page;
+      PDFView.setScale('page-fit', true);
+    }.bind(this), 0);
 
     window.addEventListener('mousemove', this.mouseMove, false);
     window.addEventListener('mousedown', this.mouseDown, false);
@@ -109,18 +143,25 @@ var PresentationMode = {
   },
 
   exit: function presentationModeExit() {
-    this.active = false;
-
     var page = PDFView.page;
-    PDFView.setScale(this.args.previousScale);
-    PDFView.page = page;
+
+    // Ensure that the correct page is scrolled into view when exiting
+    // Presentation Mode, by waiting until fullscreen mode is disabled.
+    // Note: This is only necessary in non-Mozilla browsers.
+    setTimeout(function exitPresentationModeTimeout() {
+      PDFView.setScale(this.args.previousScale);
+      PDFView.page = page;
+      // Keep Presentation Mode active until the page is scrolled into view,
+      // to prevent issues in non-Mozilla browsers.
+      this.active = false;
+      this.args = null;
+    }.bind(this), 0);
 
     window.removeEventListener('mousemove', this.mouseMove, false);
     window.removeEventListener('mousedown', this.mouseDown, false);
     window.removeEventListener('contextmenu', this.contextMenu, false);
 
     this.hideControls();
-    this.args = null;
     PDFView.clearMouseScrollState();
     HandTool.exitPresentationMode();
     this.container.removeAttribute('contextmenu');

web/viewer.js

@@ -40,6 +40,7 @@ var SCALE_SELECT_PADDING = 22;
 var THUMBNAIL_SCROLL_MARGIN = -19;
 var USE_ONLY_CSS_ZOOM = false;
 var CLEANUP_TIMEOUT = 30000;
+var IGNORE_CURRENT_POSITION_ON_ZOOM = false;
 //#if B2G
 //USE_ONLY_CSS_ZOOM = true;
 //#endif
@@ -111,6 +112,7 @@ var PDFView = {
   previousPageNumber: 1,
   isViewerEmbedded: (window.parent !== window),
   idleTimeout: null,
+  currentPosition: null,
 
   // called once when the document is loaded
   initialize: function pdfViewInitialize() {
@@ -219,7 +221,13 @@ var PDFView = {
     this.currentScale = newScale;
 
     if (!noScroll) {
-      this.pages[this.page - 1].scrollIntoView();
+      var page = this.page, dest;
+      if (this.currentPosition && !IGNORE_CURRENT_POSITION_ON_ZOOM) {
+        page = this.currentPosition.page;
+        dest = [null, { name: 'XYZ' }, this.currentPosition.left,
+                this.currentPosition.top, null];
+      }
+      this.pages[page - 1].scrollIntoView(dest);
     }
     var event = document.createEvent('UIEvents');
     event.initUIEvent('scalechange', false, false, window, 0);
@@ -1049,6 +1057,9 @@ var PDFView = {
     // Reset 'currentPageNumber', since otherwise the page's scale will be wrong
     // if 'currentPageNumber' is larger than the number of pages in the file.
     document.getElementById('pageNumber').value = currentPageNumber = 1;
+    // Reset the current position when loading a new file,
+    // to prevent displaying the wrong position in the document.
+    this.currentPosition = null;
 
     if (PDFHistory.initialDestination) {
       this.navigateTo(PDFHistory.initialDestination);
@@ -1307,7 +1318,7 @@ var PDFView = {
                      Math.max(0, currentHeight + viewHeight - bottom);
       percentHeight = ((viewHeight - hiddenHeight) * 100 / viewHeight) | 0;
 
-      visible.push({ id: view.id, y: currentHeight,
+      visible.push({ id: view.id, x: currentWidth, y: currentHeight,
                      view: view, percent: percentHeight });
     }
 
@@ -1379,7 +1390,7 @@ var PDFView = {
   },
 
   rotatePages: function pdfViewRotatePages(delta) {
-
+    var currentPage = this.pages[this.page - 1];
     this.pageRotation = (this.pageRotation + 360 + delta) % 360;
 
     for (var i = 0, l = this.pages.length; i < l; i++) {
@@ -1392,19 +1403,13 @@ var PDFView = {
       thumb.update(this.pageRotation);
     }
 
-    this.setScale(this.currentScaleValue, true);
+    this.setScale(this.currentScaleValue, true, true);
 
     this.renderHighestPriority();
 
-    var currentPage = this.pages[this.page - 1];
-    if (!currentPage) {
-      return;
-    }
-
-    // Wait for presentation mode to take effect
-    setTimeout(function() {
+    if (currentPage) {
       currentPage.scrollIntoView();
-    }, 0);
+    }
   },
 
   /**
@@ -1615,6 +1620,11 @@ document.addEventListener('DOMContentLoaded', function webViewerLoad(evt) {
     PDFJS.verbosity = hashParams['verbosity'] | 0;
   }
 
+  if ('ignoreCurrentPositionOnZoom' in hashParams) {
+    IGNORE_CURRENT_POSITION_ON_ZOOM =
+      (hashParams['ignoreCurrentPositionOnZoom'] === 'true');
+  }
+
 //#if !(FIREFOX || MOZCENTRAL)
   var locale = navigator.language;
   if ('locale' in hashParams)
@@ -1812,17 +1822,26 @@ function updateViewarea() {
   var pdfOpenParams = '#page=' + pageNumber;
   pdfOpenParams += '&zoom=' + normalizedScaleValue;
   var currentPage = PDFView.pages[pageNumber - 1];
-  var topLeft = currentPage.getPagePoint(PDFView.container.scrollLeft,
-    (PDFView.container.scrollTop - firstPage.y));
-  pdfOpenParams += ',' + Math.round(topLeft[0]) + ',' + Math.round(topLeft[1]);
+  var container = PDFView.container;
+  var topLeft = currentPage.getPagePoint((container.scrollLeft - firstPage.x),
+                                         (container.scrollTop - firstPage.y));
+  var intLeft = Math.round(topLeft[0]);
+  var intTop = Math.round(topLeft[1]);
+  pdfOpenParams += ',' + intLeft + ',' + intTop;
+
+  if (PresentationMode.active || PresentationMode.switchInProgress) {
+    PDFView.currentPosition = null;
+  } else {
+    PDFView.currentPosition = { page: pageNumber, left: intLeft, top: intTop };
+  }
 
   var store = PDFView.store;
   store.initializedPromise.then(function() {
     store.set('exists', true);
     store.set('page', pageNumber);
     store.set('zoom', normalizedScaleValue);
-    store.set('scrollLeft', Math.round(topLeft[0]));
-    store.set('scrollTop', Math.round(topLeft[1]));
+    store.set('scrollLeft', intLeft);
+    store.set('scrollTop', intTop);
   });
   var href = PDFView.getAnchorUrl(pdfOpenParams);
   document.getElementById('viewBookmark').href = href;