feat: add smart tiling navigation

compositor/src/input.rs

@@ -1,10 +1,10 @@
 use smithay::{
     backend::input::{
         AbsolutePositionEvent, Axis, AxisSource, ButtonState, Event, InputBackend, InputEvent,
-        KeyboardKeyEvent, PointerAxisEvent, PointerButtonEvent, PointerMotionEvent,
+        KeyState, KeyboardKeyEvent, PointerAxisEvent, PointerButtonEvent, PointerMotionEvent,
     },
     input::{
-        keyboard::FilterResult,
+        keyboard::{FilterResult, keysyms},
         pointer::{AxisFrame, ButtonEvent, MotionEvent, PointerHandle, RelativeMotionEvent},
     },
     reexports::wayland_server::protocol::wl_surface::WlSurface,
@@ -13,19 +13,54 @@ use smithay::{
 };
 
 use crate::Ferese;
+use ferese_layout::Direction;
 
 impl Ferese {
     pub fn process_input_event<I: InputBackend>(&mut self, event: InputEvent<I>) {
         match event {
             InputEvent::Keyboard { event, .. } => {
                 let keyboard = self.seat.get_keyboard().expect("seat has a keyboard");
+                let keycode = event.key_code();
+                let state = event.state();
+
                 keyboard.input::<(), _>(
                     self,
-                    event.key_code(),
+                    keycode,
-                    event.state(),
+                    state,
                     SERIAL_COUNTER.next_serial(),
                     Event::time(&event) as u32,
-                    |_, _, _| FilterResult::Forward,
+                    |data, modifiers, keysym| {
+                        if state == KeyState::Released && data.intercepted_keys.remove(&keycode) {
+                            return FilterResult::Intercept(());
+                        }
+
+                        let direction = if modifiers.logo
+                            && !modifiers.ctrl
+                            && !modifiers.alt
+                            && !modifiers.shift
+                        {
+                            match keysym.modified_sym().raw() {
+                                keysyms::KEY_h | keysyms::KEY_H => Some(Direction::Left),
+                                keysyms::KEY_j | keysyms::KEY_J => Some(Direction::Down),
+                                keysyms::KEY_k | keysyms::KEY_K => Some(Direction::Up),
+                                keysyms::KEY_l | keysyms::KEY_L => Some(Direction::Right),
+                                _ => None,
+                            }
+                        } else {
+                            None
+                        };
+
+                        if let Some(direction) = direction {
+                            if state == KeyState::Pressed {
+                                data.intercepted_keys.insert(keycode);
+                                data.focus_direction(direction);
+                            }
+
+                            FilterResult::Intercept(())
+                        } else {
+                            FilterResult::Forward
+                        }
+                    },
                 );
             }
             InputEvent::PointerMotionAbsolute { event, .. } => {

compositor/src/state.rs

@@ -1,6 +1,12 @@
-use std::{collections::HashMap, error::Error, ffi::OsString, sync::Arc, time::Instant};
+use std::{
+    collections::{HashMap, HashSet},
+    error::Error,
+    ffi::OsString,
+    sync::Arc,
+    time::Instant,
+};
 
-use ferese_layout::{Axis, LayoutTree, Rect, WindowId};
+use ferese_layout::{Axis, Direction, GapConfig, LayoutTree, Rect, WindowId};
 
 use smithay::{
     desktop::{PopupManager, Space, Window, WindowSurfaceType},
@@ -40,6 +46,7 @@ pub struct Ferese {
     pub layout: LayoutTree,
     pub window_ids: HashMap<Window, WindowId>,
     pub focused_window: Option<WindowId>,
+    pub intercepted_keys: HashSet<smithay::input::keyboard::Keycode>,
     next_window_id: u64,
     pub popups: PopupManager,
     pub seat: Seat<Self>,
@@ -94,6 +101,7 @@ impl Ferese {
             layout: LayoutTree::default(),
             window_ids: HashMap::new(),
             focused_window: None,
+            intercepted_keys: HashSet::new(),
             next_window_id: 1,
             popups: PopupManager::default(),
             seat,
@@ -160,10 +168,12 @@ impl Ferese {
         let id = WindowId(self.next_window_id);
         self.next_window_id += 1;
 
-        if let Err(error) = self
+        let axis = self
-            .layout
+            .output_bounds()
-            .insert(id, self.focused_window, Axis::Horizontal, 0.5)
+            .and_then(|bounds| self.layout.automatic_axis(self.focused_window, bounds).ok())
-        {
+            .unwrap_or(Axis::Horizontal);
+
+        if let Err(error) = self.layout.insert(id, self.focused_window, axis, 0.5) {
             tracing::error!(%error, ?id, "failed to insert window into layout");
             return;
         }
@@ -195,19 +205,10 @@ impl Ferese {
     }
 
     pub fn relayout(&mut self) {
-        let Some(output) = self.space.outputs().next() else {
+        let Some(bounds) = self.output_bounds() else {
             return;
         };
-        let Some(output_geometry) = self.space.output_geometry(output) else {
+        let geometry = match self.layout.geometry_with_gaps(bounds, GapConfig::default()) {
-            return;
-        };
-        let bounds = Rect::new(
-            output_geometry.loc.x as f64,
-            output_geometry.loc.y as f64,
-            output_geometry.size.w as f64,
-            output_geometry.size.h as f64,
-        );
-        let geometry = match self.layout.geometry(bounds) {
             Ok(geometry) => geometry,
             Err(error) => {
                 tracing::error!(%error, "failed to compute tiled geometry");
@@ -234,6 +235,60 @@ impl Ferese {
             }
         }
     }
+
+    pub fn focus_direction(&mut self, direction: Direction) {
+        let Some(current) = self.focused_window else {
+            return;
+        };
+        let Some(bounds) = self.output_bounds() else {
+            return;
+        };
+        let Ok(Some(next)) = self.layout.directional_neighbor(current, direction, bounds) else {
+            return;
+        };
+        let Some(window) = self
+            .window_ids
+            .iter()
+            .find_map(|(window, id)| (*id == next).then(|| window.clone()))
+        else {
+            return;
+        };
+        let Some(surface) = window
+            .toplevel()
+            .map(|toplevel| toplevel.wl_surface().clone())
+        else {
+            return;
+        };
+
+        self.focused_window = Some(next);
+        self.space.raise_element(&window, true);
+        self.seat
+            .get_keyboard()
+            .expect("seat has a keyboard")
+            .set_focus(
+                self,
+                Some(surface),
+                smithay::utils::SERIAL_COUNTER.next_serial(),
+            );
+
+        for window in self.space.elements() {
+            if let Some(toplevel) = window.toplevel() {
+                toplevel.send_pending_configure();
+            }
+        }
+    }
+
+    fn output_bounds(&self) -> Option<Rect> {
+        let output = self.space.outputs().next()?;
+        let geometry = self.space.output_geometry(output)?;
+
+        Some(Rect::new(
+            geometry.loc.x as f64,
+            geometry.loc.y as f64,
+            geometry.size.w as f64,
+            geometry.size.h as f64,
+        ))
+    }
 }
 
 #[derive(Default)]

crates/ferese-layout/src/lib.rs

@@ -17,6 +17,14 @@ pub enum Axis {
     Vertical,
 }
 
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub enum Direction {
+    Left,
+    Right,
+    Up,
+    Down,
+}
+
 #[derive(Clone, Debug, PartialEq)]
 pub enum Node {
     Window(WindowId),
@@ -49,6 +57,27 @@ impl Rect {
             height,
         }
     }
+
+    fn center(self) -> (f64, f64) {
+        (self.x + self.width / 2.0, self.y + self.height / 2.0)
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct GapConfig {
+    pub inner: f64,
+    pub outer: f64,
+    pub smart: bool,
+}
+
+impl Default for GapConfig {
+    fn default() -> Self {
+        Self {
+            inner: 10.0,
+            outer: 10.0,
+            smart: true,
+        }
+    }
 }
 
 #[derive(Clone, Debug, Eq, PartialEq)]
@@ -185,6 +214,134 @@ impl LayoutTree {
         Ok(geometry)
     }
 
+    pub fn geometry_with_gaps(
+        &self,
+        bounds: Rect,
+        gaps: GapConfig,
+    ) -> Result<HashMap<WindowId, Rect>, LayoutError> {
+        let mut geometry = self.geometry(bounds)?;
+        let outer = if gaps.smart && geometry.len() == 1 {
+            0.0
+        } else {
+            valid_gap(gaps.outer)
+        };
+        let half_inner = valid_gap(gaps.inner) / 2.0;
+        let right = bounds.x + bounds.width;
+        let bottom = bounds.y + bounds.height;
+
+        for rect in geometry.values_mut() {
+            let left_inset = if nearly_equal(rect.x, bounds.x) {
+                outer
+            } else {
+                half_inner
+            };
+            let top_inset = if nearly_equal(rect.y, bounds.y) {
+                outer
+            } else {
+                half_inner
+            };
+            let right_inset = if nearly_equal(rect.x + rect.width, right) {
+                outer
+            } else {
+                half_inner
+            };
+            let bottom_inset = if nearly_equal(rect.y + rect.height, bottom) {
+                outer
+            } else {
+                half_inner
+            };
+
+            rect.x += left_inset;
+            rect.y += top_inset;
+            rect.width = (rect.width - left_inset - right_inset).max(1.0);
+            rect.height = (rect.height - top_inset - bottom_inset).max(1.0);
+        }
+
+        Ok(geometry)
+    }
+
+    pub fn automatic_axis(
+        &self,
+        focused: Option<WindowId>,
+        bounds: Rect,
+    ) -> Result<Axis, LayoutError> {
+        let Some(root) = self.root else {
+            return Ok(Axis::Horizontal);
+        };
+        let target = match focused {
+            Some(window) => window,
+            None => match self.nodes.get(&self.first_window(root)?) {
+                Some(Node::Window(window)) => *window,
+                _ => return Err(LayoutError::InvalidTree("leaf is not a window")),
+            },
+        };
+        let rect = self
+            .geometry(bounds)?
+            .remove(&target)
+            .ok_or(LayoutError::UnknownWindow(target))?;
+
+        Ok(if rect.width > rect.height {
+            Axis::Horizontal
+        } else {
+            Axis::Vertical
+        })
+    }
+
+    pub fn directional_neighbor(
+        &self,
+        window: WindowId,
+        direction: Direction,
+        bounds: Rect,
+    ) -> Result<Option<WindowId>, LayoutError> {
+        let geometry = self.geometry(bounds)?;
+        let target = geometry
+            .get(&window)
+            .copied()
+            .ok_or(LayoutError::UnknownWindow(window))?;
+        let (target_x, target_y) = target.center();
+
+        Ok(geometry
+            .into_iter()
+            .filter(|(candidate, _)| *candidate != window)
+            .filter_map(|(candidate, rect)| {
+                let (candidate_x, candidate_y) = rect.center();
+                let (primary, secondary, aligned) = match direction {
+                    Direction::Left if candidate_x < target_x => (
+                        target_x - candidate_x,
+                        (target_y - candidate_y).abs(),
+                        intervals_overlap(target.y, target.height, rect.y, rect.height),
+                    ),
+                    Direction::Right if candidate_x > target_x => (
+                        candidate_x - target_x,
+                        (target_y - candidate_y).abs(),
+                        intervals_overlap(target.y, target.height, rect.y, rect.height),
+                    ),
+                    Direction::Up if candidate_y < target_y => (
+                        target_y - candidate_y,
+                        (target_x - candidate_x).abs(),
+                        intervals_overlap(target.x, target.width, rect.x, rect.width),
+                    ),
+                    Direction::Down if candidate_y > target_y => (
+                        candidate_y - target_y,
+                        (target_x - candidate_x).abs(),
+                        intervals_overlap(target.x, target.width, rect.x, rect.width),
+                    ),
+                    _ => return None,
+                };
+
+                Some((candidate, primary, secondary, aligned))
+            })
+            .min_by(|left, right| {
+                right
+                    .3
+                    .cmp(&left.3)
+                    .then_with(|| left.1.total_cmp(&right.1))
+                    .then_with(|| left.2.total_cmp(&right.2))
+                    .then_with(|| left.0.0.cmp(&right.0.0))
+            })
+            .map(|(candidate, _, _, _)| candidate))
+    }
+
     pub fn validate(&self) -> Result<(), LayoutError> {
         let Some(root) = self.root else {
             return if self.nodes.is_empty() && self.parents.is_empty() && self.windows.is_empty() {
@@ -351,6 +508,23 @@ fn normalized_ratio(ratio: f64) -> f64 {
     }
 }
 
+fn valid_gap(gap: f64) -> f64 {
+    if gap.is_finite() { gap.max(0.0) } else { 0.0 }
+}
+
+fn nearly_equal(left: f64, right: f64) -> bool {
+    (left - right).abs() < f64::EPSILON * left.abs().max(right.abs()).max(1.0)
+}
+
+fn intervals_overlap(
+    first_start: f64,
+    first_size: f64,
+    second_start: f64,
+    second_size: f64,
+) -> bool {
+    first_start < second_start + second_size && second_start < first_start + first_size
+}
+
 fn split_rect(bounds: Rect, axis: Axis, ratio: f64) -> (Rect, Rect) {
     match axis {
         Axis::Horizontal => {
@@ -456,4 +630,85 @@ mod tests {
         assert_eq!(normalized_ratio(f64::NAN), 0.5);
         assert_eq!(normalized_ratio(f64::INFINITY), 0.5);
     }
+
+    #[test]
+    fn automatic_axis_follows_focused_tile_shape() {
+        let mut tree = LayoutTree::default();
+        tree.insert(WindowId(1), None, Axis::Horizontal, 0.5)
+            .unwrap();
+
+        let wide = Rect::new(0.0, 0.0, 1_920.0, 1_080.0);
+        assert_eq!(
+            tree.automatic_axis(Some(WindowId(1)), wide).unwrap(),
+            Axis::Horizontal
+        );
+
+        tree.insert(WindowId(2), Some(WindowId(1)), Axis::Horizontal, 0.5)
+            .unwrap();
+        assert_eq!(
+            tree.automatic_axis(Some(WindowId(1)), wide).unwrap(),
+            Axis::Vertical
+        );
+    }
+
+    #[test]
+    fn gaps_preserve_outer_and_shared_spacing() {
+        let mut tree = LayoutTree::default();
+        tree.insert(WindowId(1), None, Axis::Horizontal, 0.5)
+            .unwrap();
+        tree.insert(WindowId(2), Some(WindowId(1)), Axis::Horizontal, 0.5)
+            .unwrap();
+
+        let geometry = tree
+            .geometry_with_gaps(Rect::new(0.0, 0.0, 100.0, 80.0), GapConfig::default())
+            .unwrap();
+        let first = geometry[&WindowId(1)];
+        let second = geometry[&WindowId(2)];
+
+        assert_eq!(first.x, 10.0);
+        assert_eq!(second.x + second.width, 90.0);
+        assert_eq!(second.x - (first.x + first.width), 10.0);
+    }
+
+    #[test]
+    fn smart_gaps_remove_outer_gap_for_one_window() {
+        let mut tree = LayoutTree::default();
+        tree.insert(WindowId(1), None, Axis::Horizontal, 0.5)
+            .unwrap();
+
+        let bounds = Rect::new(0.0, 0.0, 100.0, 80.0);
+        let geometry = tree
+            .geometry_with_gaps(bounds, GapConfig::default())
+            .unwrap();
+
+        assert_eq!(geometry[&WindowId(1)], bounds);
+    }
+
+    #[test]
+    fn directional_neighbor_prefers_primary_distance() {
+        let mut tree = LayoutTree::default();
+        tree.insert(WindowId(1), None, Axis::Horizontal, 0.5)
+            .unwrap();
+        tree.insert(WindowId(2), Some(WindowId(1)), Axis::Horizontal, 0.5)
+            .unwrap();
+        tree.insert(WindowId(3), Some(WindowId(2)), Axis::Vertical, 0.5)
+            .unwrap();
+
+        let bounds = Rect::new(0.0, 0.0, 100.0, 100.0);
+        assert_eq!(
+            tree.directional_neighbor(WindowId(1), Direction::Right, bounds)
+                .unwrap(),
+            Some(WindowId(2))
+        );
+        assert_eq!(
+            tree.directional_neighbor(WindowId(2), Direction::Down, bounds)
+                .unwrap(),
+            Some(WindowId(3))
+        );
+        assert_eq!(
+            tree.directional_neighbor(WindowId(1), Direction::Left, bounds)
+                .unwrap(),
+            None
+        );
+    }
 }