From 2594f0c7380332a4e12ceee6a4c32b86c838904f Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Wed, 9 Sep 2020 13:26:38 +0200
Subject: [PATCH 1/2] Revert "[PDFSidebarResizer] Refactor the clamping in
 `_updateWidth`"

This reverts commit 9e4552d7920fcba13b3d74e1e180fc49180f4436 for causing the sidebar to become too narrow when the entire viewer is resized.

**Steps to reproduce:**
 1. Load the viewer.
 2. Open the sidebar.
 3. Resize the sidebar, making it wider.
 4. Resize the entire viewer, i.e. the browser window, making it *narrower* than 400 pixels.

**Expected result:**
 The sidebar width is clamped at 200 pixels.

**Actual result:**
 The sidebar becomes too narrow.

The cause of this bug is, in hindsight, quite obvious since the `clamp` helper function implicitly assumes that the `min`/`max` arguments are correctly sorted. At viewer widths *below* 400 pixels, that assumption is broken which explains the bug.
---
 web/pdf_sidebar_resizer.js | 20 +++++++++++---------
 web/ui_utils.js            |  1 -
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/web/pdf_sidebar_resizer.js b/web/pdf_sidebar_resizer.js
index 668c59dcb..b3f5b178c 100644
--- a/web/pdf_sidebar_resizer.js
+++ b/web/pdf_sidebar_resizer.js
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-import { clamp, NullL10n } from "./ui_utils.js";
+import { NullL10n } from "./ui_utils.js";
 
 const SIDEBAR_WIDTH_VAR = "--sidebar-width";
 const SIDEBAR_MIN_WIDTH = 200; // pixels
@@ -88,17 +88,19 @@ class PDFSidebarResizer {
     }
     // Prevent the sidebar from becoming too narrow, or from occupying more
     // than half of the available viewer width.
-    const newWidth = clamp(
-      width,
-      SIDEBAR_MIN_WIDTH,
-      Math.floor(this.outerContainerWidth / 2)
-    );
+    const maxWidth = Math.floor(this.outerContainerWidth / 2);
+    if (width > maxWidth) {
+      width = maxWidth;
+    }
+    if (width < SIDEBAR_MIN_WIDTH) {
+      width = SIDEBAR_MIN_WIDTH;
+    }
     // Only update the UI when the sidebar width did in fact change.
-    if (newWidth === this._width) {
+    if (width === this._width) {
       return false;
     }
-    this._width = newWidth;
-    this.doc.style.setProperty(SIDEBAR_WIDTH_VAR, `${newWidth}px`);
+    this._width = width;
+    this.doc.style.setProperty(SIDEBAR_WIDTH_VAR, `${width}px`);
     return true;
   }
 
diff --git a/web/ui_utils.js b/web/ui_utils.js
index d08497165..4d007703d 100644
--- a/web/ui_utils.js
+++ b/web/ui_utils.js
@@ -1006,7 +1006,6 @@ export {
   SpreadMode,
   NullL10n,
   EventBus,
-  clamp,
   ProgressBar,
   getPDFFileNameFromURL,
   noContextMenuHandler,

From 01c1d87171cd7d5a72edaedeb86360242d211ddb Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Wed, 9 Sep 2020 13:29:44 +0200
Subject: [PATCH 2/2] Remove CSS variables feature-testing from
 `PDFSidebarResizer`

CSS variables are now supported in all reasonably modern browsers, according to:
 - https://developer.mozilla.org/en-US/docs/Web/CSS/Using_CSS_custom_properties#Browser_compatibility
 - https://caniuse.com/css-variables
---
 web/pdf_sidebar_resizer.js | 25 +------------------------
 web/viewer.html            |  2 +-
 2 files changed, 2 insertions(+), 25 deletions(-)

diff --git a/web/pdf_sidebar_resizer.js b/web/pdf_sidebar_resizer.js
index b3f5b178c..e69c55bf9 100644
--- a/web/pdf_sidebar_resizer.js
+++ b/web/pdf_sidebar_resizer.js
@@ -34,7 +34,6 @@ class PDFSidebarResizer {
    * @param {IL10n} l10n - Localization service.
    */
   constructor(options, eventBus, l10n = NullL10n) {
-    this.enabled = false;
     this.isRTL = false;
     this.sidebarOpen = false;
     this.doc = document.documentElement;
@@ -45,24 +44,8 @@ class PDFSidebarResizer {
     this.outerContainer = options.outerContainer;
     this.resizer = options.resizer;
     this.eventBus = eventBus;
-    this.l10n = l10n;
 
-    if (
-      (typeof PDFJSDev === "undefined" || !PDFJSDev.test("MOZCENTRAL")) &&
-      (typeof CSS === "undefined" ||
-        typeof CSS.supports !== "function" ||
-        !CSS.supports(SIDEBAR_WIDTH_VAR, `calc(-1 * ${SIDEBAR_MIN_WIDTH}px)`))
-    ) {
-      console.warn(
-        "PDFSidebarResizer: " +
-          "The browser does not support resizing of the sidebar."
-      );
-      return;
-    }
-    this.enabled = true;
-    this.resizer.classList.remove("hidden"); // Show the resizer DOM element.
-
-    this.l10n.getDirection().then(dir => {
+    l10n.getDirection().then(dir => {
       this.isRTL = dir === "rtl";
     });
     this._addEventListeners();
@@ -83,9 +66,6 @@ class PDFSidebarResizer {
    * returns {boolean} Indicating if the sidebar width was updated.
    */
   _updateWidth(width = 0) {
-    if (!this.enabled) {
-      return false;
-    }
     // Prevent the sidebar from becoming too narrow, or from occupying more
     // than half of the available viewer width.
     const maxWidth = Math.floor(this.outerContainerWidth / 2);
@@ -134,9 +114,6 @@ class PDFSidebarResizer {
    * @private
    */
   _addEventListeners() {
-    if (!this.enabled) {
-      return;
-    }
     const _boundEvents = this._boundEvents;
     _boundEvents.mouseMove = this._mouseMove.bind(this);
     _boundEvents.mouseUp = this._mouseUp.bind(this);
diff --git a/web/viewer.html b/web/viewer.html
index 1ae684876..0bef5178b 100644
--- a/web/viewer.html
+++ b/web/viewer.html
@@ -101,7 +101,7 @@ See https://github.com/adobe-type-tools/cmap-resources
           <div id="layersView" class="hidden">
           </div>
         </div>
-        <div id="sidebarResizer" class="hidden"></div>
+        <div id="sidebarResizer"></div>
       </div>  <!-- sidebarContainer -->
 
       <div id="mainContainer">