win32: account for mouse wheel speed setting

Also adds a method to toggle this behavior during runtime.

winit-win32/src/event_loop.rs

@@ -42,22 +42,23 @@ use windows_sys::Win32::UI::Input::{
 use windows_sys::Win32::UI::WindowsAndMessaging::{
     CreateWindowExW, DefWindowProcW, DestroyWindow, DispatchMessageW, GetClientRect, GetCursorPos,
     GetMenu, LoadCursorW, MsgWaitForMultipleObjectsEx, PeekMessageW, PostMessageW,
-    RegisterClassExW, RegisterWindowMessageA, SetCursor, SetWindowPos, TranslateMessage,
+    RegisterClassExW, RegisterWindowMessageA, SetCursor, SetWindowPos, SystemParametersInfoW,
-    CREATESTRUCTW, GWL_STYLE, GWL_USERDATA, HTCAPTION, HTCLIENT, MINMAXINFO, MNC_CLOSE, MSG,
+    TranslateMessage, CREATESTRUCTW, GWL_STYLE, GWL_USERDATA, HTCAPTION, HTCLIENT, MINMAXINFO,
-    MWMO_INPUTAVAILABLE, NCCALCSIZE_PARAMS, PM_REMOVE, PT_TOUCH, QS_ALLINPUT, RI_MOUSE_HWHEEL,
+    MNC_CLOSE, MSG, MWMO_INPUTAVAILABLE, NCCALCSIZE_PARAMS, PM_REMOVE, PT_TOUCH, QS_ALLINPUT,
-    RI_MOUSE_WHEEL, SC_MINIMIZE, SC_RESTORE, SIZE_MAXIMIZED, SWP_NOACTIVATE, SWP_NOMOVE,
+    RI_MOUSE_HWHEEL, RI_MOUSE_WHEEL, SC_MINIMIZE, SC_RESTORE, SIZE_MAXIMIZED,
-    SWP_NOSIZE, SWP_NOZORDER, WHEEL_DELTA, WINDOWPOS, WMSZ_BOTTOM, WMSZ_BOTTOMLEFT,
+    SPI_GETWHEELSCROLLCHARS, SPI_GETWHEELSCROLLLINES, SWP_NOACTIVATE, SWP_NOMOVE, SWP_NOSIZE,
-    WMSZ_BOTTOMRIGHT, WMSZ_LEFT, WMSZ_RIGHT, WMSZ_TOP, WMSZ_TOPLEFT, WMSZ_TOPRIGHT,
+    SWP_NOZORDER, WHEEL_DELTA, WINDOWPOS, WMSZ_BOTTOM, WMSZ_BOTTOMLEFT, WMSZ_BOTTOMRIGHT,
-    WM_CAPTURECHANGED, WM_CLOSE, WM_CREATE, WM_DESTROY, WM_DPICHANGED, WM_ENTERSIZEMOVE,
+    WMSZ_LEFT, WMSZ_RIGHT, WMSZ_TOP, WMSZ_TOPLEFT, WMSZ_TOPRIGHT, WM_CAPTURECHANGED, WM_CLOSE,
-    WM_EXITSIZEMOVE, WM_GETMINMAXINFO, WM_IME_COMPOSITION, WM_IME_ENDCOMPOSITION,
+    WM_CREATE, WM_DESTROY, WM_DPICHANGED, WM_ENTERSIZEMOVE, WM_EXITSIZEMOVE, WM_GETMINMAXINFO,
-    WM_IME_SETCONTEXT, WM_IME_STARTCOMPOSITION, WM_INPUT, WM_KEYDOWN, WM_KEYUP, WM_KILLFOCUS,
+    WM_IME_COMPOSITION, WM_IME_ENDCOMPOSITION, WM_IME_SETCONTEXT, WM_IME_STARTCOMPOSITION,
-    WM_LBUTTONDOWN, WM_LBUTTONUP, WM_MBUTTONDOWN, WM_MBUTTONUP, WM_MENUCHAR, WM_MOUSEHWHEEL,
+    WM_INPUT, WM_KEYDOWN, WM_KEYUP, WM_KILLFOCUS, WM_LBUTTONDOWN, WM_LBUTTONUP, WM_MBUTTONDOWN,
-    WM_MOUSEMOVE, WM_MOUSEWHEEL, WM_NCACTIVATE, WM_NCCALCSIZE, WM_NCCREATE, WM_NCDESTROY,
+    WM_MBUTTONUP, WM_MENUCHAR, WM_MOUSEHWHEEL, WM_MOUSEMOVE, WM_MOUSEWHEEL, WM_NCACTIVATE,
-    WM_NCLBUTTONDOWN, WM_PAINT, WM_POINTERDOWN, WM_POINTERUP, WM_POINTERUPDATE, WM_RBUTTONDOWN,
+    WM_NCCALCSIZE, WM_NCCREATE, WM_NCDESTROY, WM_NCLBUTTONDOWN, WM_PAINT, WM_POINTERDOWN,
-    WM_RBUTTONUP, WM_SETCURSOR, WM_SETFOCUS, WM_SETTINGCHANGE, WM_SIZE, WM_SIZING, WM_SYSCOMMAND,
+    WM_POINTERUP, WM_POINTERUPDATE, WM_RBUTTONDOWN, WM_RBUTTONUP, WM_SETCURSOR, WM_SETFOCUS,
-    WM_SYSKEYDOWN, WM_SYSKEYUP, WM_TOUCH, WM_WINDOWPOSCHANGED, WM_WINDOWPOSCHANGING,
+    WM_SETTINGCHANGE, WM_SIZE, WM_SIZING, WM_SYSCOMMAND, WM_SYSKEYDOWN, WM_SYSKEYUP, WM_TOUCH,
-    WM_XBUTTONDOWN, WM_XBUTTONUP, WNDCLASSEXW, WS_EX_LAYERED, WS_EX_NOACTIVATE, WS_EX_TOOLWINDOW,
+    WM_WINDOWPOSCHANGED, WM_WINDOWPOSCHANGING, WM_XBUTTONDOWN, WM_XBUTTONUP, WNDCLASSEXW,
-    WS_EX_TRANSPARENT, WS_OVERLAPPED, WS_POPUP, WS_VISIBLE,
+    WS_EX_LAYERED, WS_EX_NOACTIVATE, WS_EX_TOOLWINDOW, WS_EX_TRANSPARENT, WS_OVERLAPPED, WS_POPUP,
+    WS_VISIBLE,
 };
 use winit_core::application::ApplicationHandler;
 use winit_core::cursor::{CustomCursor, CustomCursorSource};
@@ -92,6 +93,13 @@ use crate::window::{InitData, Window};
 use crate::window_state::{CursorFlags, ImeState, WindowFlags, WindowState};
 use crate::{raw_input, util};
 
+// This is defined in `winuser.h` as a macro that expands to `UINT_MAX`
+const WHEEL_PAGESCROLL: u32 = u32::MAX;
+// https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-systemparametersinfoa#:~:text=SPI_GETWHEELSCROLLLINES
+const DEFAULT_SCROLL_LINES_PER_WHEEL_DELTA: isize = 3;
+// https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-systemparametersinfoa#:~:text=SPI_GETWHEELSCROLLCHARS
+const DEFAULT_SCROLL_CHARACTERS_PER_WHEEL_DELTA: isize = 3;
+
 pub(crate) struct WindowData {
     pub window_state: Arc<Mutex<WindowState>>,
     pub event_loop_runner: Rc<EventLoopRunner>,
@@ -1636,9 +1644,26 @@ unsafe fn public_window_callback_inner(
 
             update_modifiers(window, userdata);
 
+            let scroll_lines_multiplier = if userdata.window_state_lock().use_system_wheel_speed {
+                let mut scroll_lines = DEFAULT_SCROLL_LINES_PER_WHEEL_DELTA;
+                let _ = SystemParametersInfoW(
+                    SPI_GETWHEELSCROLLLINES,
+                    0,
+                    &mut scroll_lines as *mut isize as *mut c_void,
+                    0,
+                );
+                if scroll_lines as u32 == WHEEL_PAGESCROLL {
+                    // TODO: figure out how to handle page scrolls
+                    scroll_lines = DEFAULT_SCROLL_LINES_PER_WHEEL_DELTA;
+                }
+                scroll_lines
+            } else {
+                1
+            };
+
             userdata.send_window_event(window, WindowEvent::MouseWheel {
                 device_id: None,
-                delta: LineDelta(0.0, value),
+                delta: LineDelta(0.0, value * scroll_lines_multiplier as f32),
                 phase: TouchPhase::Moved,
             });
 
@@ -1653,9 +1678,23 @@ unsafe fn public_window_callback_inner(
 
             update_modifiers(window, userdata);
 
+            let scroll_characters_multiplier =
+                if userdata.window_state_lock().use_system_wheel_speed {
+                    let mut scroll_characters = DEFAULT_SCROLL_CHARACTERS_PER_WHEEL_DELTA;
+                    let _ = SystemParametersInfoW(
+                        SPI_GETWHEELSCROLLCHARS,
+                        0,
+                        &mut scroll_characters as *mut isize as *mut c_void,
+                        0,
+                    );
+                    scroll_characters
+                } else {
+                    1
+                };
+
             userdata.send_window_event(window, WindowEvent::MouseWheel {
                 device_id: None,
-                delta: LineDelta(value, 0.0),
+                delta: LineDelta(value * scroll_characters_multiplier as f32, 0.0),
                 phase: TouchPhase::Moved,
             });
 

winit-win32/src/lib.rs

@@ -285,6 +285,15 @@ pub trait WindowExtWindows {
     /// Supported starting with Windows 11 Build 22000.
     fn set_corner_preference(&self, preference: CornerPreference);
 
+    /// Sets if the reported [`winit_core::event::WindowEvent::MouseWheel`] event
+    /// should account for scroll speed system settings.
+    ///
+    /// The default scroll speed on Windows is 3 lines/characters per scroll,
+    /// this will be 1 if you set it to false.
+    ///
+    /// The default is `true`.
+    fn set_use_system_scroll_speed(&self, should_use: bool);
+
     /// Get the raw window handle for this [`Window`] without checking for thread affinity.
     ///
     /// Window handles in Win32 have a property called "thread affinity" that ties them to their
@@ -398,6 +407,11 @@ impl WindowExtWindows for dyn CoreWindow + '_ {
         window.set_corner_preference(preference)
     }
 
+    fn set_use_system_scroll_speed(&self, should_use: bool) {
+        let window = self.cast_ref::<Window>().unwrap();
+        window.set_use_system_scroll_speed(should_use)
+    }
+
     unsafe fn window_handle_any_thread(
         &self,
     ) -> Result<rwh_06::WindowHandle<'_>, rwh_06::HandleError> {
@@ -459,6 +473,7 @@ pub struct WindowAttributesWindows {
     pub(crate) title_background_color: Option<Color>,
     pub(crate) title_text_color: Option<Color>,
     pub(crate) corner_preference: Option<CornerPreference>,
+    pub(crate) use_system_wheel_speed: bool,
 }
 
 impl Default for WindowAttributesWindows {
@@ -478,6 +493,7 @@ impl Default for WindowAttributesWindows {
             title_background_color: None,
             title_text_color: None,
             corner_preference: None,
+            use_system_wheel_speed: true,
         }
     }
 }
@@ -610,6 +626,18 @@ impl WindowAttributesWindows {
         self.corner_preference = Some(corners);
         self
     }
+
+    /// Sets if the reported [`winit_core::event::WindowEvent::MouseWheel`] event
+    /// should account for scroll speed system settings.
+    ///
+    /// The default scroll speed on Windows is 3 lines/characters per scroll,
+    /// this will be 1 if you set it to false.
+    ///
+    /// The default is `true`.
+    pub fn with_use_system_scroll_speed(mut self, should_use: bool) -> Self {
+        self.use_system_wheel_speed = should_use;
+        self
+    }
 }
 
 impl PlatformWindowAttributes for WindowAttributesWindows {

winit-win32/src/window.rs

@@ -344,6 +344,11 @@ impl Window {
         }
     }
 
+    #[inline]
+    pub fn set_use_system_scroll_speed(&self, should_use: bool) {
+        self.window_state_lock().use_system_wheel_speed = should_use;
+    }
+
     fn set_icon(&self, mut new_icon: Icon, icon_type: IconType) {
         if let Some(icon) = new_icon.cast_ref::<RgbaIcon>() {
             let icon = match WinIcon::from_rgba(icon) {
@@ -1303,6 +1308,7 @@ impl InitData<'_> {
         win.set_skip_taskbar(self.win_attributes.skip_taskbar);
         win.set_window_icon(self.attributes.window_icon.clone());
         win.set_taskbar_icon(self.win_attributes.taskbar_icon.clone());
+        win.set_use_system_scroll_speed(self.win_attributes.use_system_wheel_speed);
 
         let attributes = self.attributes.clone();
 

winit-win32/src/window_state.rs

@@ -60,6 +60,8 @@ pub(crate) struct WindowState {
     pub dragging: bool,
 
     pub skip_taskbar: bool,
+
+    pub use_system_wheel_speed: bool,
 }
 
 #[derive(Clone)]
@@ -187,6 +189,8 @@ impl WindowState {
             dragging: false,
 
             skip_taskbar: false,
+
+            use_system_wheel_speed: true,
         }
     }
 

winit/src/changelog/unreleased.md

@@ -256,3 +256,4 @@ changelog entry.
 - On macOS, fixed redundant `SurfaceResized` event at window creation.
 - On macOS, don't panic on monitors with unknown bit-depths.
 - On macOS, fixed crash when closing the window on macOS 26+.
+- On Windows, account for mouse wheel lines per scroll setting for `WindowEvent::MouseWheel`.