From c92ba393c2934b0b29b2d6e993484529b281252a Mon Sep 17 00:00:00 2001
From: Calixte Denizet <calixte.denizet@gmail.com>
Date: Wed, 8 Feb 2023 14:31:28 +0100
Subject: [PATCH] Fix pinch-to-zoom on mac for the Firefox builtin viewer

In the mac case we don't want to care about the scaleFactor threshold
because else if too big another move could start and then subsequent
events aren't considered as wheel events.
It isn't really ideal and at some point we'll need to find a way at
least for the Firefox case to get the real events instead of the fake
wheel ones.
---
 src/pdf.js | 2 ++
 web/app.js | 7 ++++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/pdf.js b/src/pdf.js
index a07828441..44a0dfe67 100644
--- a/src/pdf.js
+++ b/src/pdf.js
@@ -32,6 +32,7 @@ import {
   CMapCompressionType,
   createPromiseCapability,
   createValidAbsoluteUrl,
+  FeatureTest,
   InvalidPDFException,
   MissingPDFException,
   OPS,
@@ -89,6 +90,7 @@ export {
   CMapCompressionType,
   createPromiseCapability,
   createValidAbsoluteUrl,
+  FeatureTest,
   getDocument,
   getFilenameFromUrl,
   getPdfFilenameFromUrl,
diff --git a/web/app.js b/web/app.js
index 85759cbb0..243b16cf7 100644
--- a/web/app.js
+++ b/web/app.js
@@ -38,6 +38,7 @@ import {
   AnnotationEditorType,
   build,
   createPromiseCapability,
+  FeatureTest,
   getDocument,
   getFilenameFromUrl,
   getPdfFilenameFromUrl,
@@ -2695,12 +2696,16 @@ function webViewerWheel(evt) {
   // https://searchfox.org/mozilla-central/rev/d62c4c4d5547064487006a1506287da394b64724/widget/InputData.cpp#618-626
   let scaleFactor = Math.exp(-evt.deltaY / 100);
 
+  const isBuiltInMac =
+    typeof PDFJSDev !== "undefined" &&
+    PDFJSDev.test("MOZCENTRAL") &&
+    FeatureTest.platform.isMac;
   const isPinchToZoom =
     evt.ctrlKey &&
     !PDFViewerApplication._isCtrlKeyDown &&
     deltaMode === WheelEvent.DOM_DELTA_PIXEL &&
     evt.deltaX === 0 &&
-    Math.abs(scaleFactor - 1) < 0.05 &&
+    (Math.abs(scaleFactor - 1) < 0.05 || isBuiltInMac) &&
     evt.deltaZ === 0;
 
   if (