From 9d773c1499dc1dbe90996d16d4f8c24b59d5288b Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Fri, 25 Feb 2022 15:36:45 +0100
Subject: [PATCH] Only support the standard, unprefixed, Fullscreen API in the
 default viewer

At this point in time, after recent rounds of clean-up, the `webkit`-prefixed Fullscreen API is the only remaining *browser-specific* compatibility hack in the `web/`-folder JavaScript code.

The standard, and thus unprefixed, Fullscreen API has been supported for *over three years* in both Mozilla Firefox and Google Chrome. [According to MDN](https://developer.mozilla.org/en-US/docs/Web/API/Fullscreen_API#browser_compatibility), the unprefixed Fullscreen API has been available since:
 - Mozilla Firefox 64, released on 2018-12-11; see https://wiki.mozilla.org/Release_Management/Calendar#Past_branch_dates
 - Google Chrome 71, released on 2018-12-04; see https://en.wikipedia.org/wiki/Google_Chrome_version_history

Hence *only* Safari now requires using a prefixed Fullscreen API, and it's thus (significantly) lagging behind other browsers in this regard.
Considering that the default viewer is written *specifically* to be the UI for the Firefox PDF Viewer, and that we ask users to not just use it as-is[1], I think that we should only support the standard Fullscreen API now.
Furthermore, note also that the FAQ already lists Safari as "Mostly" supported; see https://github.com/mozilla/pdf.js/wiki/Frequently-Asked-Questions#faq-support

---
[1] Note e.g. http://mozilla.github.io/pdf.js/getting_started/#introduction
> The viewer is built on the display layer and is the UI for PDF viewer in Firefox and the other browser extensions within the project. It can be a good starting point for building your own viewer. *However, we do ask if you plan to embed the viewer in your own site, that it not just be an unmodified version. Please re-skin it or build upon it.*
---
 web/app.js                   |  9 +------
 web/pdf_presentation_mode.js | 47 ++++++------------------------------
 2 files changed, 9 insertions(+), 47 deletions(-)

diff --git a/web/app.js b/web/app.js
index f60bf0296..6f6897f54 100644
--- a/web/app.js
+++ b/web/app.js
@@ -671,14 +671,7 @@ const PDFViewerApplication = {
   },
 
   get supportsFullscreen() {
-    if (typeof PDFJSDev !== "undefined" && PDFJSDev.test("MOZCENTRAL")) {
-      return shadow(this, "supportsFullscreen", document.fullscreenEnabled);
-    }
-    return shadow(
-      this,
-      "supportsFullscreen",
-      document.fullscreenEnabled || document.webkitFullscreenEnabled
-    );
+    return shadow(this, "supportsFullscreen", document.fullscreenEnabled);
   },
 
   get supportsIntegratedFind() {
diff --git a/web/pdf_presentation_mode.js b/web/pdf_presentation_mode.js
index 9b590ad81..f94bea021 100644
--- a/web/pdf_presentation_mode.js
+++ b/web/pdf_presentation_mode.js
@@ -63,28 +63,19 @@ class PDFPresentationMode {
    * @returns {boolean} Indicating if the request was successful.
    */
   request() {
-    if (this.switchInProgress || this.active || !this.pdfViewer.pagesCount) {
+    if (
+      this.switchInProgress ||
+      this.active ||
+      !this.pdfViewer.pagesCount ||
+      !this.container.requestFullscreen
+    ) {
       return false;
     }
     this.#addFullscreenChangeListeners();
     this.#setSwitchInProgress();
     this.#notifyStateChange();
 
-    if (typeof PDFJSDev !== "undefined" && PDFJSDev.test("MOZCENTRAL")) {
-      if (this.container.requestFullscreen) {
-        this.container.requestFullscreen();
-      } else {
-        return false;
-      }
-    } else {
-      if (this.container.requestFullscreen) {
-        this.container.requestFullscreen();
-      } else if (this.container.webkitRequestFullscreen) {
-        this.container.webkitRequestFullscreen(Element.ALLOW_KEYBOARD_INPUT);
-      } else {
-        return false;
-      }
-    }
+    this.container.requestFullscreen();
 
     this.args = {
       pageNumber: this.pdfViewer.currentPageNumber,
@@ -92,7 +83,6 @@ class PDFPresentationMode {
       scrollMode: this.pdfViewer.scrollMode,
       spreadMode: this.pdfViewer.spreadMode,
     };
-
     return true;
   }
 
@@ -136,13 +126,6 @@ class PDFPresentationMode {
     }
   }
 
-  get isFullscreen() {
-    if (typeof PDFJSDev !== "undefined" && PDFJSDev.test("MOZCENTRAL")) {
-      return !!document.fullscreenElement;
-    }
-    return !!(document.fullscreenElement || document.webkitIsFullScreen);
-  }
-
   #notifyStateChange() {
     let state = PresentationModeState.NORMAL;
     if (this.switchInProgress) {
@@ -386,7 +369,7 @@ class PDFPresentationMode {
   }
 
   #fullscreenChange() {
-    if (this.isFullscreen) {
+    if (/* isFullscreen = */ document.fullscreenElement) {
       this.#enter();
     } else {
       this.#exit();
@@ -395,25 +378,11 @@ class PDFPresentationMode {
 
   #addFullscreenChangeListeners() {
     this.fullscreenChangeBind = this.#fullscreenChange.bind(this);
-
     window.addEventListener("fullscreenchange", this.fullscreenChangeBind);
-    if (typeof PDFJSDev === "undefined" || !PDFJSDev.test("MOZCENTRAL")) {
-      window.addEventListener(
-        "webkitfullscreenchange",
-        this.fullscreenChangeBind
-      );
-    }
   }
 
   #removeFullscreenChangeListeners() {
     window.removeEventListener("fullscreenchange", this.fullscreenChangeBind);
-    if (typeof PDFJSDev === "undefined" || !PDFJSDev.test("MOZCENTRAL")) {
-      window.removeEventListener(
-        "webkitfullscreenchange",
-        this.fullscreenChangeBind
-      );
-    }
-
     delete this.fullscreenChangeBind;
   }
 }