[Windows] Reverse horizonal scroll direction in WindowEvent::MouseWheel

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Unreleased
 
 - On X11, add mappings for numpad comma, numpad enter, numlock and pause.
+- On Windows, reversed horizontal scrolling in `WindowEvent::MouseWheel` to match the direction of vertical scrolling.
 
 # 0.26.0 (2021-12-01)
 

examples/mouse_wheel.rs

@@ -1,6 +1,6 @@
 use simple_logger::SimpleLogger;
 use winit::{
-    event::{DeviceEvent, Event, WindowEvent},
+    event::{Event, WindowEvent},
     event_loop::{ControlFlow, EventLoop},
     window::WindowBuilder,
 };
@@ -20,23 +20,20 @@ fn main() {
         match event {
             Event::WindowEvent { event, .. } => match event {
                 WindowEvent::CloseRequested => *control_flow = ControlFlow::Exit,
-                _ => (),
-            },
-            Event::DeviceEvent { event, .. } => match event {
-                DeviceEvent::MouseWheel { delta } => match delta {
+                WindowEvent::MouseWheel { delta, .. } => match delta {
                     winit::event::MouseScrollDelta::LineDelta(x, y) => {
                         println!("mouse wheel Line Delta: ({},{})", x, y);
                         let pixels_per_line = 120.0;
                         let mut pos = window.outer_position().unwrap();
-                        pos.x -= (x * pixels_per_line) as i32;
-                        pos.y -= (y * pixels_per_line) as i32;
+                        pos.x += (x * pixels_per_line) as i32;
+                        pos.y += (y * pixels_per_line) as i32;
                         window.set_outer_position(pos)
                     }
                     winit::event::MouseScrollDelta::PixelDelta(p) => {
                         println!("mouse wheel Pixel Delta: ({},{})", p.x, p.y);
                         let mut pos = window.outer_position().unwrap();
-                        pos.x -= p.x as i32;
-                        pos.y -= p.y as i32;
+                        pos.x += p.x as i32;
+                        pos.y += p.y as i32;
                         window.set_outer_position(pos)
                     }
                 },

src/platform_impl/windows/event_loop.rs

@@ -1200,7 +1200,7 @@ unsafe fn public_window_callback_inner<T: 'static>(
 
             let value = (wparam >> 16) as i16;
             let value = value as i32;
-            let value = value as f32 / winuser::WHEEL_DELTA as f32;
+            let value = -value as f32 / winuser::WHEEL_DELTA as f32;
 
             update_modifiers(window, userdata);