Add tablet map-to-output setting

resources/default-config.kdl

@@ -18,13 +18,20 @@ input {
         // repeat-rate 25
     }
 
-    // Next sections contain libinput settings.
+    // Next sections include libinput settings.
     // Omitting settings disables them, or leaves them at their default values.
     touchpad {
         tap
         natural-scroll
         // accel-speed 0.2
     }
+
+    tablet {
+        // Set the name of the output (see below) which the tablet will map to.
+        // If this is unset or the output doesn't exist, the tablet maps to one of the
+        // existing outputs.
+        map-to-output "eDP-1"
+    }
 }
 
 // You can configure outputs by their name, which you can find with wayland-info(1).

src/config.rs

@@ -35,6 +35,8 @@ pub struct Input {
     pub keyboard: Keyboard,
     #[knuffel(child, default)]
     pub touchpad: Touchpad,
+    #[knuffel(child, default)]
+    pub tablet: Tablet,
 }
 
 #[derive(knuffel::Decode, Debug, Default, PartialEq, Eq)]
@@ -73,6 +75,12 @@ pub struct Touchpad {
     pub accel_speed: f64,
 }
 
+#[derive(knuffel::Decode, Debug, Default, PartialEq)]
+pub struct Tablet {
+    #[knuffel(child, unwrap(argument))]
+    pub map_to_output: Option<String>,
+}
+
 #[derive(knuffel::Decode, Debug, Clone, PartialEq)]
 pub struct Output {
     #[knuffel(argument)]
@@ -478,6 +486,10 @@ mod tests {
                     tap
                     accel-speed 0.2
                 }
+
+                tablet {
+                    map-to-output "eDP-1"
+                }
             }
 
             output "eDP-1" {
@@ -530,6 +542,9 @@ mod tests {
                         natural_scroll: false,
                         accel_speed: 0.2,
                     },
+                    tablet: Tablet {
+                        map_to_output: Some("eDP-1".to_owned()),
+                    },
                 },
                 outputs: vec![Output {
                     name: "eDP-1".to_owned(),

src/input.rs

@@ -472,8 +472,7 @@ impl State {
                 pointer.frame(self);
             }
             InputEvent::TabletToolAxis { event, .. } => {
-                // FIXME: allow mapping tablet to different outputs.
-                let Some(output) = self.niri.global_space.outputs().next() else {
+                let Some(output) = self.niri.output_for_tablet() else {
                     return;
                 };
 
@@ -560,8 +559,7 @@ impl State {
                 }
             }
             InputEvent::TabletToolProximity { event, .. } => {
-                // FIXME: allow mapping tablet to different outputs.
-                let Some(output) = self.niri.global_space.outputs().next() else {
+                let Some(output) = self.niri.output_for_tablet() else {
                     return;
                 };
 

src/niri.rs

@@ -105,6 +105,7 @@ pub struct Niri {
     pub unmapped_windows: HashMap<WlSurface, Window>,
 
     pub output_state: HashMap<Output, OutputState>,
+    pub output_by_name: HashMap<String, Output>,
 
     // Smithay state.
     pub compositor_state: CompositorState,
@@ -679,6 +680,7 @@ impl Niri {
             monitor_set: MonitorSet::new(),
             global_space: Space::default(),
             output_state: HashMap::new(),
+            output_by_name: HashMap::new(),
             unmapped_windows: HashMap::new(),
 
             compositor_state,
@@ -787,7 +789,9 @@ impl Niri {
             frame_clock: FrameClock::new(refresh_interval),
             current_estimated_sequence: None,
         };
-        let rv = self.output_state.insert(output, state);
+        let rv = self.output_state.insert(output.clone(), state);
+        assert!(rv.is_none(), "output was already tracked");
+        let rv = self.output_by_name.insert(name, output);
         assert!(rv.is_none(), "output was already tracked");
     }
 
@@ -797,6 +801,8 @@ impl Niri {
         // FIXME: reposition outputs so they are adjacent.
 
         let state = self.output_state.remove(output).unwrap();
+        self.output_by_name.remove(&output.name()).unwrap();
+
         match state.redraw_state {
             RedrawState::Idle => (),
             RedrawState::Queued(idle) => idle.cancel(),
@@ -950,6 +956,14 @@ impl Niri {
             .cloned()
     }
 
+    pub fn output_for_tablet(&self) -> Option<&Output> {
+        let config = self.config.borrow();
+        let map_to_output = config.input.tablet.map_to_output.as_ref();
+        map_to_output
+            .and_then(|name| self.output_by_name.get(name))
+            .or_else(|| self.global_space.outputs().next())
+    }
+
     fn layer_surface_focus(&self) -> Option<WlSurface> {
         let output = self.monitor_set.active_output()?;
         let layers = layer_map_for_output(output);