input: add basic touch support

niri-config/src/lib.rs

@@ -62,6 +62,8 @@ pub struct Input {
     pub trackpoint: Trackpoint,
     #[knuffel(child, default)]
     pub tablet: Tablet,
+    #[knuffel(child, default)]
+    pub touch: Touch,
     #[knuffel(child)]
     pub disable_power_key_handling: bool,
 }
@@ -201,6 +203,12 @@ pub struct Tablet {
     pub map_to_output: Option<String>,
 }
 
+#[derive(knuffel::Decode, Debug, Default, PartialEq)]
+pub struct Touch {
+    #[knuffel(child, unwrap(argument))]
+    pub map_to_output: Option<String>,
+}
+
 #[derive(knuffel::Decode, Debug, Clone, PartialEq)]
 pub struct Output {
     #[knuffel(child)]
@@ -1005,6 +1013,10 @@ mod tests {
                     map-to-output "eDP-1"
                 }
 
+                touch {
+                    map-to-output "eDP-1"
+                }
+
                 disable-power-key-handling
             }
 
@@ -1136,6 +1148,9 @@ mod tests {
                     tablet: Tablet {
                         map_to_output: Some("eDP-1".to_owned()),
                     },
+                    touch: Touch {
+                        map_to_output: Some("eDP-1".to_owned()),
+                    },
                     disable_power_key_handling: true,
                 },
                 outputs: vec![Output {

resources/default-config.kdl

@@ -54,6 +54,13 @@ input {
         map-to-output "eDP-1"
     }
 
+    touch {
+        // Set the name of the output (see below) which touch input will map to.
+        // If this is unset or the output doesn't exist, touch input maps to one of the
+        // existing outputs.
+        map-to-output "eDP-1"
+    }
+
     // By default, niri will take over the power button to make it sleep
     // instead of power off.
     // Uncomment this if you would like to configure the power button elsewhere

src/input.rs

@@ -8,7 +8,7 @@ use smithay::backend::input::{
     GestureBeginEvent, GestureEndEvent, GesturePinchUpdateEvent as _, GestureSwipeUpdateEvent as _,
     InputBackend, InputEvent, KeyState, KeyboardKeyEvent, PointerAxisEvent, PointerButtonEvent,
     PointerMotionEvent, ProximityState, TabletToolButtonEvent, TabletToolEvent,
-    TabletToolProximityEvent, TabletToolTipEvent, TabletToolTipState,
+    TabletToolProximityEvent, TabletToolTipEvent, TabletToolTipState, TouchEvent,
 };
 use smithay::backend::libinput::LibinputInputBackend;
 use smithay::input::keyboard::{keysyms, FilterResult, Keysym, ModifiersState};
@@ -17,6 +17,7 @@ use smithay::input::pointer::{
     GesturePinchBeginEvent, GesturePinchEndEvent, GesturePinchUpdateEvent, GestureSwipeBeginEvent,
     GestureSwipeEndEvent, GestureSwipeUpdateEvent, MotionEvent, RelativeMotionEvent,
 };
+use smithay::input::touch::{DownEvent, MotionEvent as TouchMotionEvent, UpEvent};
 use smithay::utils::{Logical, Point, SERIAL_COUNTER};
 use smithay::wayland::pointer_constraints::{with_pointer_constraint, PointerConstraint};
 use smithay::wayland::tablet_manager::{TabletDescriptor, TabletSeatTrait};
@@ -101,11 +102,11 @@ impl State {
             GesturePinchEnd { event } => self.on_gesture_pinch_end::<I>(event),
             GestureHoldBegin { event } => self.on_gesture_hold_begin::<I>(event),
             GestureHoldEnd { event } => self.on_gesture_hold_end::<I>(event),
-            TouchDown { .. } => (),
-            TouchMotion { .. } => (),
-            TouchUp { .. } => (),
-            TouchCancel { .. } => (),
-            TouchFrame { .. } => (),
+            TouchDown { event } => self.on_touch_down::<I>(event),
+            TouchMotion { event } => self.on_touch_motion::<I>(event),
+            TouchUp { event } => self.on_touch_up::<I>(event),
+            TouchCancel { event } => self.on_touch_cancel::<I>(event),
+            TouchFrame { event } => self.on_touch_frame::<I>(event),
             SwitchToggle { .. } => (),
             Special(_) => (),
         }
@@ -171,6 +172,9 @@ impl State {
             let desc = TabletDescriptor::from(&device);
             tablet_seat.add_tablet::<Self>(&self.niri.display_handle, &desc);
         }
+        if device.has_capability(DeviceCapability::Touch) && self.niri.seat.get_touch().is_none() {
+            self.niri.seat.add_touch();
+        }
     }
 
     fn on_device_removed(&mut self, device: impl Device) {
@@ -283,6 +287,10 @@ impl State {
             return;
         }
 
+        if let Some(touch) = self.niri.seat.get_touch() {
+            touch.cancel(self);
+        }
+
         match action {
             Action::Quit(skip_confirmation) => {
                 if !skip_confirmation {
@@ -1354,6 +1362,94 @@ impl State {
             },
         );
     }
+
+    /// Computes the cursor position for the touch event.
+    ///
+    /// This function handles the touch output mapping, as well as coordinate transform
+    fn compute_touch_location<I: InputBackend, E: AbsolutePositionEvent<I>>(
+        &self,
+        evt: &E,
+    ) -> Option<Point<f64, Logical>> {
+        let output = self.niri.output_for_touch()?;
+        let output_geo = self.niri.global_space.output_geometry(output).unwrap();
+        let transform = output.current_transform();
+        let size = transform.invert().transform_size(output_geo.size);
+        Some(
+            transform.transform_point_in(evt.position_transformed(size), &size.to_f64())
+                + output_geo.loc.to_f64(),
+        )
+    }
+
+    fn on_touch_down<I: InputBackend>(&mut self, evt: I::TouchDownEvent) {
+        let Some(handle) = self.niri.seat.get_touch() else {
+            return;
+        };
+        let Some(touch_location) = self.compute_touch_location(&evt) else {
+            return;
+        };
+        let serial = SERIAL_COUNTER.next_serial();
+        let under = self
+            .niri
+            .surface_under_and_global_space(touch_location)
+            .map(|under| under.surface);
+        handle.down(
+            self,
+            under,
+            &DownEvent {
+                slot: evt.slot(),
+                location: touch_location,
+                serial,
+                time: evt.time_msec(),
+            },
+        );
+    }
+    fn on_touch_up<I: InputBackend>(&mut self, evt: I::TouchUpEvent) {
+        let Some(handle) = self.niri.seat.get_touch() else {
+            return;
+        };
+        let serial = SERIAL_COUNTER.next_serial();
+        handle.up(
+            self,
+            &UpEvent {
+                slot: evt.slot(),
+                serial,
+                time: evt.time_msec(),
+            },
+        )
+    }
+    fn on_touch_motion<I: InputBackend>(&mut self, evt: I::TouchMotionEvent) {
+        let Some(handle) = self.niri.seat.get_touch() else {
+            return;
+        };
+        let Some(touch_location) = self.compute_touch_location(&evt) else {
+            return;
+        };
+        let under = self
+            .niri
+            .surface_under_and_global_space(touch_location)
+            .map(|under| under.surface);
+        handle.motion(
+            self,
+            under,
+            &TouchMotionEvent {
+                slot: evt.slot(),
+                location: touch_location,
+                time: evt.time_msec(),
+            },
+        );
+    }
+    fn on_touch_frame<I: InputBackend>(&mut self, _evt: I::TouchFrameEvent) {
+        let Some(handle) = self.niri.seat.get_touch() else {
+            return;
+        };
+        handle.frame(self);
+    }
+    fn on_touch_cancel<I: InputBackend>(&mut self, _evt: I::TouchCancelEvent) {
+        let Some(handle) = self.niri.seat.get_touch() else {
+            return;
+        };
+        handle.cancel(self);
+    }
 }
 
 /// Check whether the key should be intercepted and mark intercepted

src/niri.rs

@@ -702,6 +702,10 @@ impl State {
             self.niri.reposition_outputs(None);
 
             self.backend.on_output_config_changed(&mut self.niri);
+
+            if let Some(touch) = self.niri.seat.get_touch() {
+                touch.cancel(self);
+            }
         }
 
         // Can't really update xdg-decoration settings since we have to hide the globals for CSD
@@ -1602,6 +1606,14 @@ impl Niri {
             .or_else(|| self.global_space.outputs().next())
     }
 
+    pub fn output_for_touch(&self) -> Option<&Output> {
+        let config = self.config.borrow();
+        let map_to_output = config.input.touch.map_to_output.as_ref();
+        map_to_output
+            .and_then(|name| self.output_by_name.get(name))
+            .or_else(|| self.global_space.outputs().next())
+    }
+
     pub fn output_for_root(&self, root: &WlSurface) -> Option<&Output> {
         // Check the main layout.
         let win_out = self.layout.find_window_and_output(root);