input: Add a scroll_factor config option

This is not a setting handled by libinput; we have to scale the
scrolling ourselves.

This should match the behavior of the `scroll_factor` defined in
sway-input(5).

cosmic-comp-config/src/input.rs

@@ -42,6 +42,7 @@ pub struct ScrollConfig {
     pub method: Option<ScrollMethod>,
     pub natural_scroll: Option<bool>,
     pub scroll_button: Option<u32>,
+    pub scroll_factor: Option<f64>,
 }
 
 #[derive(Copy, Clone, Debug, Serialize, Deserialize)]

src/config/input_config.rs

@@ -64,6 +64,7 @@ pub fn for_device(device: &InputDevice) -> InputConfig {
                 } else {
                     None
                 },
+                scroll_factor: None,
             })
         } else {
             None
@@ -83,7 +84,7 @@ pub fn for_device(device: &InputDevice) -> InputConfig {
 
 // Get setting from `device_config` if present, then `default_config`
 // Returns `is_default` to indicate this is a default value.
-fn get_config<'a, T: 'a, F: Fn(&'a InputConfig) -> Option<T>>(
+pub fn get_config<'a, T: 'a, F: Fn(&'a InputConfig) -> Option<T>>(
     device_config: Option<&'a InputConfig>,
     default_config: &'a InputConfig,
     f: F,

src/config/mod.rs

@@ -412,13 +412,26 @@ impl Config {
     }
 
     pub fn read_device(&self, device: &mut InputDevice) {
+        let (device_config, default_config) = self.get_device_config(device);
+        input_config::update_device(device, device_config, default_config);
+    }
+
+    pub fn scroll_factor(&self, device: &InputDevice) -> f64 {
+        let (device_config, default_config) = self.get_device_config(device);
+        input_config::get_config(device_config, default_config, |x| {
+            x.scroll_config.as_ref()?.scroll_factor
+        })
+        .map_or(1.0, |x| x.0)
+    }
+
+    fn get_device_config(&self, device: &InputDevice) -> (Option<&InputConfig>, &InputConfig) {
         let default_config = if device.config_tap_finger_count() > 0 {
             &self.input_touchpad
         } else {
             &self.input_default
         };
         let device_config = self.input_devices.get(device.name());
-        input_config::update_device(device, device_config, default_config);
+        (device_config, default_config)
     }
 }
 

src/input/mod.rs

@@ -15,6 +15,7 @@ use crate::{
 };
 use calloop::{timer::Timer, RegistrationToken};
 use cosmic_protocols::screencopy::v1::server::zcosmic_screencopy_session_v1::InputType;
+#[allow(deprecated)]
 use smithay::{
     backend::input::{
         Axis, AxisSource, Device, DeviceCapability, InputBackend, InputEvent, KeyState,
@@ -27,7 +28,10 @@ use smithay::{
         Seat, SeatState,
     },
     output::Output,
-    reexports::wayland_server::DisplayHandle,
+    reexports::{
+        input::event::pointer::PointerAxisEvent as LibinputPointerAxisEvent,
+        wayland_server::DisplayHandle,
+    },
     utils::{Logical, Point, Rectangle, Serial, SERIAL_COUNTER},
     wayland::{
         keyboard_shortcuts_inhibit::KeyboardShortcutsInhibitorSeat, seat::WaylandFocus,
@@ -40,6 +44,7 @@ use tracing::info;
 use tracing::{error, trace, warn};
 
 use std::{
+    any::Any,
     cell::RefCell,
     collections::HashMap,
     time::{Duration, Instant},
@@ -171,7 +176,9 @@ impl State {
         &mut self,
         event: InputEvent<B>,
         needs_key_repetition: bool,
-    ) {
+    ) where
+        <B as InputBackend>::PointerAxisEvent: 'static,
+    {
         use smithay::backend::input::Event;
 
         match event {
@@ -737,6 +744,15 @@ impl State {
                 }
             }
             InputEvent::PointerAxis { event, .. } => {
+                #[allow(deprecated)]
+                let scroll_factor = if let Some(event) =
+                    <dyn Any>::downcast_ref::<LibinputPointerAxisEvent>(&event)
+                {
+                    self.common.config.scroll_factor(&event.device())
+                } else {
+                    1.0
+                };
+
                 let device = event.device();
                 for seat in self.common.seats().cloned().collect::<Vec<_>>().iter() {
                     #[cfg(feature = "debug")]
@@ -775,7 +791,8 @@ impl State {
                             let mut frame =
                                 AxisFrame::new(event.time_msec()).source(event.source());
                             if horizontal_amount != 0.0 {
-                                frame = frame.value(Axis::Horizontal, horizontal_amount);
+                                frame = frame
+                                    .value(Axis::Horizontal, scroll_factor * horizontal_amount);
                                 if let Some(discrete) = horizontal_amount_discrete {
                                     frame = frame.discrete(Axis::Horizontal, discrete as i32);
                                 }
@@ -783,7 +800,8 @@ impl State {
                                 frame = frame.stop(Axis::Horizontal);
                             }
                             if vertical_amount != 0.0 {
-                                frame = frame.value(Axis::Vertical, vertical_amount);
+                                frame =
+                                    frame.value(Axis::Vertical, scroll_factor * vertical_amount);
                                 if let Some(discrete) = vertical_amount_discrete {
                                     frame = frame.discrete(Axis::Vertical, discrete as i32);
                                 }