From 2f783dd6714204c54ba5647a376907f4de6799ff Mon Sep 17 00:00:00 2001
From: Gabriel Vogel <gabriel.vogel@online.de>
Date: Thu, 20 Jan 2022 22:58:22 +0100
Subject: [PATCH] Fix #324840: Ctrl+Scrollwheel zoom on Linux X11

With recent libinput versions zooming with Ctrl+Scrollwheel would zoom
in huge steps. This change enforces the previous behavior for Linux X11
only.

Scrolling is left unchanged for Wayland
---
 src/notation/view/notationviewinputcontroller.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/notation/view/notationviewinputcontroller.cpp b/src/notation/view/notationviewinputcontroller.cpp
index 4518e98fb197..195b5e113ee3 100644
--- a/src/notation/view/notationviewinputcontroller.cpp
+++ b/src/notation/view/notationviewinputcontroller.cpp
@@ -398,6 +398,15 @@ void NotationViewInputController::wheelEvent(QWheelEvent* event)
     qreal stepsX = 0.0;
     qreal stepsY = 0.0;
 
+// pixelDelta is unreliable on X11
+#ifdef Q_OS_LINUX
+    if (std::getenv("WAYLAND_DISPLAY") == NULL) {
+        // Ignore pixelsScrolled unless Wayland is used
+        pixelsScrolled.setX(0);
+        pixelsScrolled.setY(0);
+    }
+#endif
+
     if (!pixelsScrolled.isNull()) {
         dx = pixelsScrolled.x();
         dy = pixelsScrolled.y();