From 36111a1f40ae800556ab4196f4e7f299939d9e22 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Thu, 21 Jun 2018 17:55:59 +0200
Subject: [PATCH 1/8] [Regression] Remove instances of
 `Element.classList.toggle()` with *two* parameters, since browser support is
 limited

The Secondary Toolbar buttons for, not to mention the actual toggling of, Scroll/Spread modes are currently completely broken in older browsers (such as IE11).

As a follow-up, it'd probably be a good idea to try and find a *feature complete* `classList` polyfill that could be used instead, but this patch at least addresses the immediate regression.

Please refer to the compatibility information in https://developer.mozilla.org/en-US/docs/Web/API/Element/classList#Browser_compatibility
---
 web/base_viewer.js       | 15 +++++++++++---
 web/secondary_toolbar.js | 42 ++++++++++++++++++++++++++++------------
 2 files changed, 42 insertions(+), 15 deletions(-)

diff --git a/web/base_viewer.js b/web/base_viewer.js
index e084512b0..2eee52ac9 100644
--- a/web/base_viewer.js
+++ b/web/base_viewer.js
@@ -1035,9 +1035,18 @@ class BaseViewer {
   }
 
   _updateScrollModeClasses() {
-    const mode = this.scrollMode, { classList, } = this.viewer;
-    classList.toggle('scrollHorizontal', mode === ScrollMode.HORIZONTAL);
-    classList.toggle('scrollWrapped', mode === ScrollMode.WRAPPED);
+    const { scrollMode, viewer, } = this;
+
+    if (scrollMode === ScrollMode.HORIZONTAL) {
+      viewer.classList.add('scrollHorizontal');
+    } else {
+      viewer.classList.remove('scrollHorizontal');
+    }
+    if (scrollMode === ScrollMode.WRAPPED) {
+      viewer.classList.add('scrollWrapped');
+    } else {
+      viewer.classList.remove('scrollWrapped');
+    }
   }
 
   setSpreadMode(mode) {
diff --git a/web/secondary_toolbar.js b/web/secondary_toolbar.js
index a44be0642..233f5f6fa 100644
--- a/web/secondary_toolbar.js
+++ b/web/secondary_toolbar.js
@@ -190,23 +190,41 @@ class SecondaryToolbar {
 
   _bindScrollModeListener(buttons) {
     this.eventBus.on('scrollmodechanged', function(evt) {
-      buttons.scrollVerticalButton.classList.toggle('toggled',
-        evt.mode === ScrollMode.VERTICAL);
-      buttons.scrollHorizontalButton.classList.toggle('toggled',
-        evt.mode === ScrollMode.HORIZONTAL);
-      buttons.scrollWrappedButton.classList.toggle('toggled',
-        evt.mode === ScrollMode.WRAPPED);
+      buttons.scrollVerticalButton.classList.remove('toggled');
+      buttons.scrollHorizontalButton.classList.remove('toggled');
+      buttons.scrollWrappedButton.classList.remove('toggled');
+
+      switch (evt.mode) {
+        case ScrollMode.VERTICAL:
+          buttons.scrollVerticalButton.classList.add('toggled');
+          break;
+        case ScrollMode.HORIZONTAL:
+          buttons.scrollHorizontalButton.classList.add('toggled');
+          break;
+        case ScrollMode.WRAPPED:
+          buttons.scrollWrappedButton.classList.add('toggled');
+          break;
+      }
     });
   }
 
   _bindSpreadModeListener(buttons) {
     this.eventBus.on('spreadmodechanged', function(evt) {
-      buttons.spreadNoneButton.classList.toggle('toggled',
-        evt.mode === SpreadMode.NONE);
-      buttons.spreadOddButton.classList.toggle('toggled',
-        evt.mode === SpreadMode.ODD);
-      buttons.spreadEvenButton.classList.toggle('toggled',
-        evt.mode === SpreadMode.EVEN);
+      buttons.spreadNoneButton.classList.remove('toggled');
+      buttons.spreadOddButton.classList.remove('toggled');
+      buttons.spreadEvenButton.classList.remove('toggled');
+
+      switch (evt.mode) {
+        case SpreadMode.NONE:
+          buttons.spreadNoneButton.classList.add('toggled');
+          break;
+        case SpreadMode.ODD:
+          buttons.spreadOddButton.classList.add('toggled');
+          break;
+        case SpreadMode.EVEN:
+          buttons.spreadEvenButton.classList.add('toggled');
+          break;
+      }
     });
   }
 

From 9b0ed6f821219ee07ca8684b7a99b6dd3b4d03c3 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Thu, 21 Jun 2018 18:15:04 +0200
Subject: [PATCH 2/8] Remove all pages from the DOM at once, rather than using
 a loop, in `PDFViewer._regroupSpreads`

There's no good reason to iterate through an arbitrary number of DOM elements this way, since a document could contain thousands of pages, when everything can be easily removed at once; compare with e.g. `BaseViewer._resetView` and `PDFThumbnailViewer._resetView`.

Furthermore given that it's a `PDFViewer` instance, the `this.viewer` property can be accessed directly. Besides, `_setDocumentViewerElement` only exists as a helper method for `setDocument` in the base class and none of this code applies for `PDFSinglePageViewer` instances either.
---
 web/pdf_viewer.js | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/web/pdf_viewer.js b/web/pdf_viewer.js
index 2a6c46ca8..99757087d 100644
--- a/web/pdf_viewer.js
+++ b/web/pdf_viewer.js
@@ -88,13 +88,13 @@ class PDFViewer extends BaseViewer {
   }
 
   _regroupSpreads() {
-    const container = this._setDocumentViewerElement, pages = this._pages;
-    while (container.firstChild) {
-      container.firstChild.remove();
-    }
+    const viewer = this.viewer, pages = this._pages;
+    // Temporarily remove all the pages from the DOM.
+    viewer.textContent = '';
+
     if (this.spreadMode === SpreadMode.NONE) {
       for (let i = 0, iMax = pages.length; i < iMax; ++i) {
-        container.appendChild(pages[i].div);
+        viewer.appendChild(pages[i].div);
       }
     } else {
       const parity = this.spreadMode - 1;
@@ -103,10 +103,10 @@ class PDFViewer extends BaseViewer {
         if (spread === null) {
           spread = document.createElement('div');
           spread.className = 'spread';
-          container.appendChild(spread);
+          viewer.appendChild(spread);
         } else if (i % 2 === parity) {
           spread = spread.cloneNode(false);
-          container.appendChild(spread);
+          viewer.appendChild(spread);
         }
         spread.appendChild(pages[i].div);
       }

From da52dff04b90e48a2e17d3ebc891bf677c3ed1ec Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Thu, 21 Jun 2018 19:53:13 +0200
Subject: [PATCH 3/8] Add validation of the argument in the
 `BaseViewer.{setScrollMode, setSpreadMode}` methods

Since all the other "public" methods validate the arguments, these (new) ones really ought to do the same.
---
 web/base_viewer.js | 49 +++++++++++++++++++++++++++++-----------------
 1 file changed, 31 insertions(+), 18 deletions(-)

diff --git a/web/base_viewer.js b/web/base_viewer.js
index 2eee52ac9..2ff541905 100644
--- a/web/base_viewer.js
+++ b/web/base_viewer.js
@@ -181,7 +181,9 @@ class BaseViewer {
     if (this.removePageBorders) {
       this.viewer.classList.add('removePageBorders');
     }
-    this._updateScrollModeClasses();
+    if (this.scrollMode !== ScrollMode.VERTICAL) {
+      this._updateScrollModeClasses();
+    }
   }
 
   get pagesCount() {
@@ -1018,20 +1020,26 @@ class BaseViewer {
   }
 
   setScrollMode(mode) {
-    if (mode !== this.scrollMode) {
-      this.scrollMode = mode;
-      this._updateScrollModeClasses();
-      this.eventBus.dispatch('scrollmodechanged', { mode, });
-      const pageNumber = this._currentPageNumber;
-      // Non-numeric scale modes can be sensitive to the scroll orientation.
-      // Call this before re-scrolling to the current page, to ensure that any
-      // changes in scale don't move the current page.
-      if (isNaN(this._currentScaleValue)) {
-        this._setScale(this._currentScaleValue, this.isInPresentationMode);
-      }
-      this.scrollPageIntoView({ pageNumber, });
-      this.update();
+    if (mode === this.scrollMode) {
+      return;
     }
+    if (!Number.isInteger(mode) || !Object.values(ScrollMode).includes(mode)) {
+      throw new Error(`Invalid scroll mode: ${mode}`);
+    }
+
+    this.scrollMode = mode;
+    this._updateScrollModeClasses();
+    this.eventBus.dispatch('scrollmodechanged', { mode, });
+
+    const pageNumber = this._currentPageNumber;
+    // Non-numeric scale modes can be sensitive to the scroll orientation.
+    // Call this before re-scrolling to the current page, to ensure that any
+    // changes in scale don't move the current page.
+    if (isNaN(this._currentScaleValue)) {
+      this._setScale(this._currentScaleValue, this.isInPresentationMode);
+    }
+    this.scrollPageIntoView({ pageNumber, });
+    this.update();
   }
 
   _updateScrollModeClasses() {
@@ -1050,11 +1058,16 @@ class BaseViewer {
   }
 
   setSpreadMode(mode) {
-    if (mode !== this.spreadMode) {
-      this.spreadMode = mode;
-      this.eventBus.dispatch('spreadmodechanged', { mode, });
-      this._regroupSpreads();
+    if (mode === this.spreadMode) {
+      return;
     }
+    if (!Number.isInteger(mode) || !Object.values(SpreadMode).includes(mode)) {
+      throw new Error(`Invalid spread mode: ${mode}`);
+    }
+
+    this.spreadMode = mode;
+    this.eventBus.dispatch('spreadmodechanged', { mode, });
+    this._regroupSpreads();
   }
 
   _regroupSpreads() {}

From 8bd12442985b084dde154dbf7b0f60448c9b26e3 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Thu, 21 Jun 2018 20:30:58 +0200
Subject: [PATCH 4/8] Move `_updateScrollModeClasses` from `BaseViewer` to
 `PDFViewer`

Given that this method is a no-op in `PDFSinglePageViewer`, similar to `_regroupSpreads`, let's improve the general code structure by simply moving the method.
---
 web/base_viewer.js | 17 ++++-------------
 web/pdf_viewer.js  | 15 +++++++++++++++
 2 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/web/base_viewer.js b/web/base_viewer.js
index 2ff541905..11f5432aa 100644
--- a/web/base_viewer.js
+++ b/web/base_viewer.js
@@ -1043,18 +1043,7 @@ class BaseViewer {
   }
 
   _updateScrollModeClasses() {
-    const { scrollMode, viewer, } = this;
-
-    if (scrollMode === ScrollMode.HORIZONTAL) {
-      viewer.classList.add('scrollHorizontal');
-    } else {
-      viewer.classList.remove('scrollHorizontal');
-    }
-    if (scrollMode === ScrollMode.WRAPPED) {
-      viewer.classList.add('scrollWrapped');
-    } else {
-      viewer.classList.remove('scrollWrapped');
-    }
+    // No-op in the base class.
   }
 
   setSpreadMode(mode) {
@@ -1070,7 +1059,9 @@ class BaseViewer {
     this._regroupSpreads();
   }
 
-  _regroupSpreads() {}
+  _regroupSpreads() {
+    // No-op in the base class.
+  }
 }
 
 export {
diff --git a/web/pdf_viewer.js b/web/pdf_viewer.js
index 99757087d..79c3e055b 100644
--- a/web/pdf_viewer.js
+++ b/web/pdf_viewer.js
@@ -87,6 +87,21 @@ class PDFViewer extends BaseViewer {
     });
   }
 
+  _updateScrollModeClasses() {
+    const { scrollMode, viewer, } = this;
+
+    if (scrollMode === ScrollMode.HORIZONTAL) {
+      viewer.classList.add('scrollHorizontal');
+    } else {
+      viewer.classList.remove('scrollHorizontal');
+    }
+    if (scrollMode === ScrollMode.WRAPPED) {
+      viewer.classList.add('scrollWrapped');
+    } else {
+      viewer.classList.remove('scrollWrapped');
+    }
+  }
+
   _regroupSpreads() {
     const viewer = this.viewer, pages = this._pages;
     // Temporarily remove all the pages from the DOM.

From 6a086fa0b9431c7f997a8edd666d9616d6d22c8c Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Thu, 21 Jun 2018 20:54:57 +0200
Subject: [PATCH 5/8] Refactor `setScrollMode`/`setSpreadMode`, in the viewer
 classes, such that they are no-ops in `PDFSinglePageViewer` instances

Since the Scroll/Spread modes doesn't make (any) sense in `PDFSinglePageViewer` instances, the general structure of these methods can be improved to reflect that.
---
 web/base_viewer.js | 22 ----------------------
 web/pdf_viewer.js  | 30 ++++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 22 deletions(-)

diff --git a/web/base_viewer.js b/web/base_viewer.js
index 11f5432aa..d259ef4d3 100644
--- a/web/base_viewer.js
+++ b/web/base_viewer.js
@@ -1020,26 +1020,10 @@ class BaseViewer {
   }
 
   setScrollMode(mode) {
-    if (mode === this.scrollMode) {
-      return;
-    }
     if (!Number.isInteger(mode) || !Object.values(ScrollMode).includes(mode)) {
       throw new Error(`Invalid scroll mode: ${mode}`);
     }
-
     this.scrollMode = mode;
-    this._updateScrollModeClasses();
-    this.eventBus.dispatch('scrollmodechanged', { mode, });
-
-    const pageNumber = this._currentPageNumber;
-    // Non-numeric scale modes can be sensitive to the scroll orientation.
-    // Call this before re-scrolling to the current page, to ensure that any
-    // changes in scale don't move the current page.
-    if (isNaN(this._currentScaleValue)) {
-      this._setScale(this._currentScaleValue, this.isInPresentationMode);
-    }
-    this.scrollPageIntoView({ pageNumber, });
-    this.update();
   }
 
   _updateScrollModeClasses() {
@@ -1047,16 +1031,10 @@ class BaseViewer {
   }
 
   setSpreadMode(mode) {
-    if (mode === this.spreadMode) {
-      return;
-    }
     if (!Number.isInteger(mode) || !Object.values(SpreadMode).includes(mode)) {
       throw new Error(`Invalid spread mode: ${mode}`);
     }
-
     this.spreadMode = mode;
-    this.eventBus.dispatch('spreadmodechanged', { mode, });
-    this._regroupSpreads();
   }
 
   _regroupSpreads() {
diff --git a/web/pdf_viewer.js b/web/pdf_viewer.js
index 79c3e055b..10d11a4c6 100644
--- a/web/pdf_viewer.js
+++ b/web/pdf_viewer.js
@@ -87,6 +87,26 @@ class PDFViewer extends BaseViewer {
     });
   }
 
+  setScrollMode(mode) {
+    if (mode === this.scrollMode) {
+      return;
+    }
+    super.setScrollMode(mode);
+
+    this.eventBus.dispatch('scrollmodechanged', { mode, });
+    this._updateScrollModeClasses();
+
+    const pageNumber = this._currentPageNumber;
+    // Non-numeric scale modes can be sensitive to the scroll orientation.
+    // Call this before re-scrolling to the current page, to ensure that any
+    // changes in scale don't move the current page.
+    if (isNaN(this._currentScaleValue)) {
+      this._setScale(this._currentScaleValue, this.isInPresentationMode);
+    }
+    this.scrollPageIntoView({ pageNumber, });
+    this.update();
+  }
+
   _updateScrollModeClasses() {
     const { scrollMode, viewer, } = this;
 
@@ -102,6 +122,16 @@ class PDFViewer extends BaseViewer {
     }
   }
 
+  setSpreadMode(mode) {
+    if (mode === this.spreadMode) {
+      return;
+    }
+    super.setSpreadMode(mode);
+
+    this.eventBus.dispatch('spreadmodechanged', { mode, });
+    this._regroupSpreads();
+  }
+
   _regroupSpreads() {
     const viewer = this.viewer, pages = this._pages;
     // Temporarily remove all the pages from the DOM.

From 05f682cd4be78b7985dd630a708f17ea752a76dd Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Thu, 21 Jun 2018 21:45:03 +0200
Subject: [PATCH 6/8] [Regression] Ensure that pre-rendering of the
 next/previous page works correctly in Presentation Mode, when horizontal
 scrolling was enabled

Note how in `BaseViewer.forceRendering` the Scroll mode is used to determine how pre-rendering will work. Currently this is broken in Presentation Mode, if horizontal scrolling was enabled prior to entering fullscreen.

Furthermore, there's a few additional cases where the `this.scrollMode === ScrollMode.HORIZONTAL` check is pointless either in Presentation Mode or when a `PDFSinglePageViewer` instance is used.
---
 web/base_viewer.js            | 18 +++++++++++-------
 web/pdf_single_page_viewer.js |  5 +++++
 web/pdf_viewer.js             |  9 ++++++++-
 3 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/web/base_viewer.js b/web/base_viewer.js
index d259ef4d3..79c65c9d4 100644
--- a/web/base_viewer.js
+++ b/web/base_viewer.js
@@ -597,11 +597,11 @@ class BaseViewer {
       if (!currentPage) {
         return;
       }
-      let hPadding = (this.isInPresentationMode || this.removePageBorders) ?
-        0 : SCROLLBAR_PADDING;
-      let vPadding = (this.isInPresentationMode || this.removePageBorders) ?
-        0 : VERTICAL_PADDING;
-      if (this.scrollMode === ScrollMode.HORIZONTAL) {
+      const noPadding = (this.isInPresentationMode || this.removePageBorders);
+      let hPadding = noPadding ? 0 : SCROLLBAR_PADDING;
+      let vPadding = noPadding ? 0 : VERTICAL_PADDING;
+
+      if (!noPadding && this._isScrollModeHorizontal) {
         const temp = hPadding;
         hPadding = vPadding;
         vPadding = temp;
@@ -834,6 +834,10 @@ class BaseViewer {
     this.container.focus();
   }
 
+  get _isScrollModeHorizontal() {
+    throw new Error('Not implemented: _isScrollModeHorizontal');
+  }
+
   get isInPresentationMode() {
     return this.presentationModeState === PresentationModeState.FULLSCREEN;
   }
@@ -906,8 +910,8 @@ class BaseViewer {
 
   forceRendering(currentlyVisiblePages) {
     let visiblePages = currentlyVisiblePages || this._getVisiblePages();
-    let scrollAhead = this.scrollMode === ScrollMode.HORIZONTAL ?
-      this.scroll.right : this.scroll.down;
+    let scrollAhead = (this._isScrollModeHorizontal ?
+                       this.scroll.right : this.scroll.down);
     let pageView = this.renderingQueue.getHighestPriority(visiblePages,
                                                           this._pages,
                                                           scrollAhead);
diff --git a/web/pdf_single_page_viewer.js b/web/pdf_single_page_viewer.js
index 94fb7823e..4a446f457 100644
--- a/web/pdf_single_page_viewer.js
+++ b/web/pdf_single_page_viewer.js
@@ -142,6 +142,11 @@ class PDFSinglePageViewer extends BaseViewer {
       location: this._location,
     });
   }
+
+  get _isScrollModeHorizontal() {
+    // The Scroll/Spread modes are never used in `PDFSinglePageViewer`.
+    return shadow(this, '_isScrollModeHorizontal', false);
+  }
 }
 
 export {
diff --git a/web/pdf_viewer.js b/web/pdf_viewer.js
index 10d11a4c6..78a2ce3a5 100644
--- a/web/pdf_viewer.js
+++ b/web/pdf_viewer.js
@@ -23,7 +23,7 @@ class PDFViewer extends BaseViewer {
   }
 
   _scrollIntoView({ pageDiv, pageSpot = null, }) {
-    if (!pageSpot) {
+    if (!pageSpot && !this.isInPresentationMode) {
       const left = pageDiv.offsetLeft + pageDiv.clientLeft;
       const right = left + pageDiv.clientWidth;
       const { scrollLeft, clientWidth, } = this.container;
@@ -87,6 +87,13 @@ class PDFViewer extends BaseViewer {
     });
   }
 
+  get _isScrollModeHorizontal() {
+    // Used to ensure that pre-rendering of the next/previous page works
+    // correctly, since Scroll/Spread modes are ignored in Presentation Mode.
+    return (this.isInPresentationMode ?
+            false : this.scrollMode === ScrollMode.HORIZONTAL);
+  }
+
   setScrollMode(mode) {
     if (mode === this.scrollMode) {
       return;

From d3cb5e7117fbd112b90fb79e92dba630fdb79f29 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Sat, 23 Jun 2018 10:30:22 +0200
Subject: [PATCH 7/8] Don't attempt to modify the DOM and/or trigger rendering
 when changing Scroll/Spread modes without a PDF document being loaded

---
 web/pdf_viewer.js | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/web/pdf_viewer.js b/web/pdf_viewer.js
index 78a2ce3a5..6e42db779 100644
--- a/web/pdf_viewer.js
+++ b/web/pdf_viewer.js
@@ -103,6 +103,9 @@ class PDFViewer extends BaseViewer {
     this.eventBus.dispatch('scrollmodechanged', { mode, });
     this._updateScrollModeClasses();
 
+    if (!this.pdfDocument) {
+      return;
+    }
     const pageNumber = this._currentPageNumber;
     // Non-numeric scale modes can be sensitive to the scroll orientation.
     // Call this before re-scrolling to the current page, to ensure that any
@@ -140,6 +143,9 @@ class PDFViewer extends BaseViewer {
   }
 
   _regroupSpreads() {
+    if (!this.pdfDocument) {
+      return;
+    }
     const viewer = this.viewer, pages = this._pages;
     // Temporarily remove all the pages from the DOM.
     viewer.textContent = '';

From bfbe2b411c3aa0925fa6b0c35a1eee3614c9ddf6 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Sat, 23 Jun 2018 10:43:07 +0200
Subject: [PATCH 8/8] Simplify the `_setScale` call when changing Scroll modes

Since the current page will be explicitly scrolled into view *directly* afterwards anyway (compare with e.g. the `pagesRotation` code), trying to maintain the current position when re-applying the zoom level during changing of Scroll modes is redundant.
---
 web/pdf_viewer.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/web/pdf_viewer.js b/web/pdf_viewer.js
index 6e42db779..0a7db67ce 100644
--- a/web/pdf_viewer.js
+++ b/web/pdf_viewer.js
@@ -111,7 +111,7 @@ class PDFViewer extends BaseViewer {
     // Call this before re-scrolling to the current page, to ensure that any
     // changes in scale don't move the current page.
     if (isNaN(this._currentScaleValue)) {
-      this._setScale(this._currentScaleValue, this.isInPresentationMode);
+      this._setScale(this._currentScaleValue, true);
     }
     this.scrollPageIntoView({ pageNumber, });
     this.update();