From 89a1615cd151d503a4574a51139d523d54d157a2 Mon Sep 17 00:00:00 2001
From: Abishek Jayan <abishekjayan98@gmail.com>
Date: Sun, 25 Jun 2023 14:32:07 +0530
Subject: [PATCH] Reduce the amount scaled when using mouse-wheel zooming in
 Chromium-browsers (issue 16325) So I have found that rather than messing with
 the delta values, the simplest way to solve the problem would be to find a
 clean way to detect if the browser was Chromium or not. I found that chromium
 browsers have a property called windows.chrome which on console logging,
 looks something like this:

{
        app: {
            isInstalled: false,
            InstallState: {
                DISABLED: disabled,
                INSTALLED: installed,
                NOT_INSTALLED: not_installed
            },
            RunningState: {
                CANNOT_RUN: cannot_run,
                READY_TO_RUN: ready_to_run,
                RUNNING: running
            }
        },
        appPinningPrivate: {}
}

Whereas in firefox, logging that property returns undefined. I had searched to see if there were ways that the window.chrome property could be faked (since the navigator.userAgent could be faked) but I couldnt find anything regarding that. Whats more, Edge, Opera, Brave and Chrome all support this property as per https://stackoverflow.com/a/13348618

So the current fix just adds the windows.chrome check to the if condition at line 2762.

I had tested this functionality myself on all these browsers and they work as intended in both desktop and mobile versions.

Update: Added PDFJSDev checks to ensure no unnecessary code ends up in
the built-in Firefox PDF Viewer
---
 web/app.js | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/web/app.js b/web/app.js
index 1ade1c6944975..add5300389405 100644
--- a/web/app.js
+++ b/web/app.js
@@ -2760,6 +2760,9 @@ function webViewerWheel(evt) {
 
       let ticks = 0;
       if (
+        (typeof PDFJSDev !== "undefined" &&
+          PDFJSDev.test("GENERIC || CHROME") &&
+          window.chrome) ||
         deltaMode === WheelEvent.DOM_DELTA_LINE ||
         deltaMode === WheelEvent.DOM_DELTA_PAGE
       ) {