From 785487c55819faba2b56ef84d8905ddd9e915b54 Mon Sep 17 00:00:00 2001
From: Calixte Denizet <calixte.denizet@gmail.com>
Date: Sun, 6 Dec 2020 20:59:10 +0100
Subject: [PATCH] Fix automatic zoom under spread mode (#12699)

Reset scale when update spread mode
---
 web/base_viewer.js            | 22 ++++++++++++++++++++--
 web/pdf_single_page_viewer.js |  4 ++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/web/base_viewer.js b/web/base_viewer.js
index 3b9b78ca40e1a..240d6b75a2854 100644
--- a/web/base_viewer.js
+++ b/web/base_viewer.js
@@ -725,6 +725,20 @@ class BaseViewer {
     }
   }
 
+  /**
+   * @private
+   */
+  get _pageWidthScaleFactor() {
+    if (
+      this.spreadMode !== SpreadMode.NONE &&
+      this.scrollMode !== ScrollMode.HORIZONTAL &&
+      !this.isInPresentationMode
+    ) {
+      return 2;
+    }
+    return 1;
+  }
+
   _setScale(value, noScroll = false) {
     let scale = parseFloat(value);
 
@@ -743,8 +757,9 @@ class BaseViewer {
         [hPadding, vPadding] = [vPadding, hPadding]; // Swap the padding values.
       }
       const pageWidthScale =
-        ((this.container.clientWidth - hPadding) / currentPage.width) *
-        currentPage.scale;
+        (((this.container.clientWidth - hPadding) / currentPage.width) *
+          currentPage.scale) /
+        this._pageWidthScaleFactor;
       const pageHeightScale =
         ((this.container.clientHeight - vPadding) / currentPage.height) *
         currentPage.scale;
@@ -1473,6 +1488,9 @@ class BaseViewer {
     if (!pageNumber) {
       return;
     }
+    if (this._currentScaleValue && isNaN(this._currentScaleValue)) {
+      this._setScale(this._currentScaleValue, true);
+    }
     this._setCurrentPageNumber(pageNumber, /* resetCurrentPageView = */ true);
     this.update();
   }
diff --git a/web/pdf_single_page_viewer.js b/web/pdf_single_page_viewer.js
index 1e835897d0896..20b340e1336d0 100644
--- a/web/pdf_single_page_viewer.js
+++ b/web/pdf_single_page_viewer.js
@@ -35,6 +35,10 @@ class PDFSinglePageViewer extends BaseViewer {
     return shadow(this, "_viewerElement", this._shadowViewer);
   }
 
+  get _pageWidthScaleFactor() {
+    return 1;
+  }
+
   _resetView() {
     super._resetView();
     this._previousPageNumber = 1;