input: add support for natural scrolling

Closes #69

src/backend.rs

@@ -119,6 +119,7 @@ pub trait InputDevice {
     fn set_tap_enabled(&self, enabled: bool);
     fn set_drag_enabled(&self, enabled: bool);
     fn set_drag_lock_enabled(&self, enabled: bool);
+    fn set_natural_scrolling_enabled(&self, enabled: bool);
 }
 
 #[derive(Debug, Copy, Clone, Hash, Eq, PartialEq)]

src/backends/metal.rs

@@ -296,6 +296,7 @@ struct MetalInputDevice {
     tap_enabled: Cell<Option<bool>>,
     drag_enabled: Cell<Option<bool>>,
     drag_lock_enabled: Cell<Option<bool>>,
+    natural_scrolling_enabled: Cell<Option<bool>>,
 }
 
 #[derive(Clone)]
@@ -354,6 +355,9 @@ impl MetalInputDevice {
         if let Some(enabled) = self.drag_lock_enabled.get() {
             dev.device().set_drag_lock_enabled(enabled);
         }
+        if let Some(enabled) = self.natural_scrolling_enabled.get() {
+            dev.device().set_natural_scrolling_enabled(enabled);
+        }
     }
 
     fn pre_pause(&self) {
@@ -465,6 +469,13 @@ impl InputDevice for MetalInputDevice {
             dev.device().set_drag_lock_enabled(enabled);
         }
     }
+
+    fn set_natural_scrolling_enabled(&self, enabled: bool) {
+        self.natural_scrolling_enabled.set(Some(enabled));
+        if let Some(dev) = self.inputdev.get() {
+            dev.device().set_natural_scrolling_enabled(enabled);
+        }
+    }
 }
 
 impl MetalInputDevice {

src/backends/metal/monitor.rs

@@ -296,6 +296,7 @@ impl MetalBackend {
             tap_enabled: Default::default(),
             drag_enabled: Default::default(),
             drag_lock_enabled: Default::default(),
+            natural_scrolling_enabled: Default::default(),
         });
         slots[slot] = Some(dev.clone());
         self.device_holder

src/backends/x.rs

@@ -1162,6 +1162,10 @@ impl InputDevice for XSeatKeyboard {
     fn set_drag_lock_enabled(&self, enabled: bool) {
         let _ = enabled;
     }
+
+    fn set_natural_scrolling_enabled(&self, enabled: bool) {
+        let _ = enabled;
+    }
 }
 
 impl InputDevice for XSeatMouse {
@@ -1223,4 +1227,8 @@ impl InputDevice for XSeatMouse {
     fn set_drag_lock_enabled(&self, enabled: bool) {
         let _ = enabled;
     }
+
+    fn set_natural_scrolling_enabled(&self, enabled: bool) {
+        let _ = enabled;
+    }
 }

src/config/handler.rs

@@ -512,6 +512,16 @@ impl ConfigProxyHandler {
         Ok(())
     }
 
+    fn handle_set_natural_scrolling_enabled(
+        &self,
+        device: InputDevice,
+        enabled: bool,
+    ) -> Result<(), CphError> {
+        let dev = self.get_device_handler_data(device)?;
+        dev.device.set_natural_scrolling_enabled(enabled);
+        Ok(())
+    }
+
     fn handle_set_drag_lock_enabled(
         &self,
         device: InputDevice,
@@ -1296,6 +1306,9 @@ impl ConfigProxyHandler {
             ClientMessage::GetWorkspaceCapture { workspace } => self
                 .handle_get_workspace_capture(workspace)
                 .wrn("get_workspace_capture")?,
+            ClientMessage::SetNaturalScrollingEnabled { device, enabled } => self
+                .handle_set_natural_scrolling_enabled(device, enabled)
+                .wrn("set_natural_scrolling_enabled")?,
         }
         Ok(())
     }

src/it/test_backend.rs

@@ -444,6 +444,10 @@ trait TestInputDevice: InputDevice {
     fn set_drag_lock_enabled(&self, enabled: bool) {
         let _ = enabled;
     }
+
+    fn set_natural_scrolling_enabled(&self, enabled: bool) {
+        let _ = enabled;
+    }
 }
 
 impl<T: TestInputDevice> InputDevice for T {
@@ -502,4 +506,8 @@ impl<T: TestInputDevice> InputDevice for T {
     fn set_drag_lock_enabled(&self, enabled: bool) {
         <Self as TestInputDevice>::set_drag_lock_enabled(self, enabled)
     }
+
+    fn set_natural_scrolling_enabled(&self, enabled: bool) {
+        <Self as TestInputDevice>::set_natural_scrolling_enabled(self, enabled)
+    }
 }

src/libinput/device.rs

@@ -9,6 +9,8 @@ use {
         sys::{
             libinput_device, libinput_device_config_accel_set_profile,
             libinput_device_config_accel_set_speed, libinput_device_config_left_handed_set,
+            libinput_device_config_scroll_get_natural_scroll_enabled,
+            libinput_device_config_scroll_set_natural_scroll_enabled,
             libinput_device_config_tap_get_drag_enabled,
             libinput_device_config_tap_get_drag_lock_enabled,
             libinput_device_config_tap_get_enabled, libinput_device_config_tap_set_drag_enabled,
@@ -146,6 +148,17 @@ impl<'a> LibInputDevice<'a> {
             _ => false,
         }
     }
+
+    pub fn set_natural_scrolling_enabled(&self, enabled: bool) {
+        unsafe {
+            libinput_device_config_scroll_set_natural_scroll_enabled(self.dev, enabled as _);
+        }
+    }
+
+    #[allow(dead_code)]
+    pub fn natural_scrolling_enabled(&self) -> bool {
+        unsafe { libinput_device_config_scroll_get_natural_scroll_enabled(self.dev) != 0 }
+    }
 }
 
 impl RegisteredDevice {

src/libinput/sys.rs

@@ -75,6 +75,13 @@ extern "C" {
     pub fn libinput_device_config_tap_get_drag_lock_enabled(
         device: *mut libinput_device,
     ) -> libinput_config_drag_lock_state;
+    pub fn libinput_device_config_scroll_set_natural_scroll_enabled(
+        device: *mut libinput_device,
+        enable: c::c_int,
+    ) -> libinput_config_status;
+    pub fn libinput_device_config_scroll_get_natural_scroll_enabled(
+        device: *mut libinput_device,
+    ) -> c::c_int;
 
     pub fn libinput_event_destroy(event: *mut libinput_event);
     pub fn libinput_event_get_type(event: *mut libinput_event) -> libinput_event_type;