From 55838303c7f2ee945dfe6e8a2e08579b5960f772 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Tue, 5 Apr 2022 13:56:51 +0200
Subject: [PATCH] Tweak the `pdfOpenParams` parameter, in the "updateviewarea"
 event, in PresentationMode

The `pdfOpenParams` parameter has never really made sense in PresentationMode, since e.g. the zoom-value doesn't (generally) agree with the value chosen by the user prior to entering PresentationMode.
This has never mattered all that much, since the `viewBookmark`-button isn't visible in PresentationMode (nor is any other toolbar button for that matter). However, in the `PDFHistory`-implementation we're currently forced to handle this case specifically since we don't want to populate the browser history with nonsensical state.
Hence it makes overall sense, as far as I'm concerned, to tweak the "updateviewarea" event to include a *simplified* `pdfOpenParams` parameter when PresentationMode is active. Given that the `viewer components` don't include PresentationMode functionality, this change thus shouldn't matter for third-party users.
---
 web/base_viewer.js |  8 +++++---
 web/pdf_history.js | 19 ++++---------------
 2 files changed, 9 insertions(+), 18 deletions(-)

diff --git a/web/base_viewer.js b/web/base_viewer.js
index f055122b2..3ba5d3a9d 100644
--- a/web/base_viewer.js
+++ b/web/base_viewer.js
@@ -1321,8 +1321,6 @@ class BaseViewer {
         : currentScaleValue;
 
     const pageNumber = firstPage.id;
-    let pdfOpenParams = "#page=" + pageNumber;
-    pdfOpenParams += "&zoom=" + normalizedScaleValue;
     const currentPageView = this._pages[pageNumber - 1];
     const container = this.container;
     const topLeft = currentPageView.getPagePoint(
@@ -1331,7 +1329,11 @@ class BaseViewer {
     );
     const intLeft = Math.round(topLeft[0]);
     const intTop = Math.round(topLeft[1]);
-    pdfOpenParams += "," + intLeft + "," + intTop;
+
+    let pdfOpenParams = `#page=${pageNumber}`;
+    if (!this.isInPresentationMode) {
+      pdfOpenParams += `&zoom=${normalizedScaleValue},${intLeft},${intTop}`;
+    }
 
     this._location = {
       pageNumber,
diff --git a/web/pdf_history.js b/web/pdf_history.js
index c6ef42cc7..b7dec87af 100644
--- a/web/pdf_history.js
+++ b/web/pdf_history.js
@@ -16,11 +16,7 @@
 /** @typedef {import("./event_utils").EventBus} EventBus */
 /** @typedef {import("./interfaces").IPDFLinkService} IPDFLinkService */
 
-import {
-  isValidRotation,
-  parseQueryString,
-  PresentationModeState,
-} from "./ui_utils.js";
+import { isValidRotation, parseQueryString } from "./ui_utils.js";
 import { waitOnEventOrTimeout } from "./event_utils.js";
 
 // Heuristic value used when force-resetting `this._blockHashChange`.
@@ -69,13 +65,8 @@ class PDFHistory {
     this.reset();
 
     this._boundEvents = null;
-    this._isViewerInPresentationMode = false;
-    // Ensure that we don't miss either a 'presentationmodechanged' or a
-    // 'pagesinit' event, by registering the listeners immediately.
-    this.eventBus._on("presentationmodechanged", evt => {
-      this._isViewerInPresentationMode =
-        evt.state !== PresentationModeState.NORMAL;
-    });
+    // Ensure that we don't miss a "pagesinit" event,
+    // by registering the listener immediately.
     this.eventBus._on("pagesinit", () => {
       this._isPagesLoaded = false;
 
@@ -566,9 +557,7 @@ class PDFHistory {
     }
 
     this._position = {
-      hash: this._isViewerInPresentationMode
-        ? `page=${location.pageNumber}`
-        : location.pdfOpenParams.substring(1),
+      hash: location.pdfOpenParams.substring(1),
       page: this.linkService.page,
       first: location.pageNumber,
       rotation: location.rotation,