SDL: evdev: Fix vertical high-resolution mouse wheel scaling

SDL Commits
1 
From b640b804a8cfe9f998ac82650a32c5e6e6cd4571 Mon Sep 17 00:00:00 2001
From: Revincx <[EMAIL REDACTED]>
Date: Mon, 10 Aug 2026 22:12:18 +0800
Subject: [PATCH] evdev: Fix vertical high-resolution mouse wheel scaling

This commit fixes a regression introduced by c44fa5bb

The evdev backend currently uses high_res_hwheel to select the
normalization denominator for both horizontal and vertical wheel
events.

This causes devices which advertise REL_WHEEL_HI_RES but not
REL_HWHEEL_HI_RES to report vertical wheel movement 120 times
larger than intended.

Use the corresponding high-resolution capability independently for
each axis, restoring the behavior before c44fa5bb.
---
 src/core/linux/SDL_evdev.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/core/linux/SDL_evdev.c b/src/core/linux/SDL_evdev.c
index a6ef26e54d32b..fa43ee6c574b1 100644
--- a/src/core/linux/SDL_evdev.c
+++ b/src/core/linux/SDL_evdev.c
@@ -516,11 +516,10 @@ void SDL_EVDEV_Poll(void)
 
                         if (item->mouse_wheel != 0 || item->mouse_hwheel != 0) {
                             Uint64 timestamp = SDL_EVDEV_GetEventTimestamp(event);
-                            const float denom = (item->high_res_hwheel ? 120.0f : 1.0f);
                             SDL_SendMouseWheel(timestamp,
                                                mouse->focus, (SDL_MouseID)item->fd,
-                                               item->mouse_hwheel / denom,
-                                               item->mouse_wheel / denom,
+                                               item->mouse_hwheel / (item->high_res_hwheel ? 120.0f : 1.0f),
+                                               item->mouse_wheel / (item->high_res_wheel ? 120.0f : 1.0f),
                                                SDL_MOUSEWHEEL_NORMAL);
                             item->mouse_wheel = item->mouse_hwheel = 0;
                         }