Add continuous touchpad workspace swiping

compositor/src/gestures.rs

@@ -1,4 +1,4 @@
-//! A swipe commits once on release; cancelled and ambiguous gestures do nothing.
+//! Navigation previews follow finger motion; actions commit once on release.
 
 #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
 #[repr(u32)]
@@ -14,6 +14,8 @@ pub(crate) struct Swipe {
     delta: Option<(f64, f64)>,
     threshold: f64,
     fingers: u32,
+    direction: Option<SwipeDirection>,
+    preview_started: bool,
 }
 
 impl Swipe {
@@ -21,6 +23,8 @@ impl Swipe {
         self.delta = ((3..=5).contains(&fingers) && !blocked).then_some((0.0, 0.0));
         self.threshold = f64::from(threshold);
         self.fingers = fingers;
+        self.direction = None;
+        self.preview_started = false;
     }
 
     pub fn fingers(&self) -> u32 {
@@ -35,30 +39,63 @@ impl Swipe {
         if let Some((x, y)) = &mut self.delta {
             *x += dx;
             *y += dy;
+            if self.direction.is_none() {
+                self.direction = dominant_direction(*x, *y, 6.0);
+            }
         }
     }
 
+    pub fn mark_preview_started(&mut self) {
+        self.preview_started = true;
+    }
+
+    pub fn preview_started(&self) -> bool {
+        self.preview_started
+    }
+
+    pub fn preview(&self) -> Option<(SwipeDirection, f64)> {
+        let (x, y) = self.delta?;
+        if !x.is_finite() || !y.is_finite() {
+            return None;
+        }
+        let direction = self.direction?;
+        let distance = match direction {
+            SwipeDirection::Left => -x,
+            SwipeDirection::Right => x,
+            SwipeDirection::Up => -y,
+            SwipeDirection::Down => y,
+        };
+        Some((direction, (distance / (self.threshold.max(1.0) * 2.0)).clamp(0.0, 1.0)))
+    }
+
     pub fn finish(&mut self, cancelled: bool) -> Option<SwipeDirection> {
         let (x, y) = self.delta.take()?;
-        if cancelled || !x.is_finite() || !y.is_finite() {
+        if cancelled {
             return None;
         }
-        const DOMINANCE: f64 = 1.25;
-        if x.abs() >= self.threshold && x.abs() > y.abs() * DOMINANCE {
-            Some(if x < 0.0 {
-                SwipeDirection::Left
-            } else {
-                SwipeDirection::Right
-            })
-        } else if y.abs() >= self.threshold && y.abs() > x.abs() * DOMINANCE {
-            Some(if y < 0.0 {
-                SwipeDirection::Up
-            } else {
-                SwipeDirection::Down
-            })
+        dominant_direction(x, y, self.threshold).filter(|direction| Some(*direction) == self.direction)
+    }
+}
+
+fn dominant_direction(x: f64, y: f64, threshold: f64) -> Option<SwipeDirection> {
+    if !x.is_finite() || !y.is_finite() {
+        return None;
+    }
+    const DOMINANCE: f64 = 1.25;
+    if x.abs() >= threshold && x.abs() > y.abs() * DOMINANCE {
+        Some(if x < 0.0 {
+            SwipeDirection::Left
         } else {
-            None
-        }
+            SwipeDirection::Right
+        })
+    } else if y.abs() >= threshold && y.abs() > x.abs() * DOMINANCE {
+        Some(if y < 0.0 {
+            SwipeDirection::Up
+        } else {
+            SwipeDirection::Down
+        })
+    } else {
+        None
     }
 }
 
@@ -66,6 +103,53 @@ impl Swipe {
 mod tests {
     use super::*;
 
+    #[test]
+    fn cancellation_and_new_gestures_reset_preview_state() {
+        let mut swipe = Swipe::default();
+        swipe.begin(3, false, 80);
+        swipe.update(0.0, -200.0);
+        swipe.mark_preview_started();
+        assert_eq!(swipe.preview(), Some((SwipeDirection::Up, 1.0)));
+        assert_eq!(swipe.finish(true), None);
+        assert!(
+            swipe.preview_started(),
+            "release must suppress a second action after a preview"
+        );
+        assert_eq!(swipe.preview(), None);
+        swipe.begin(4, false, 80);
+        assert!(!swipe.preview_started());
+        swipe.update(-100.0, 0.0);
+        assert_eq!(swipe.finish(false), Some(SwipeDirection::Left));
+        swipe.begin(3, true, 80);
+        swipe.update(0.0, -200.0);
+        assert!(!swipe.active());
+        assert_eq!(swipe.finish(false), None);
+    }
+
+    #[test]
+    fn preview_tracks_motion_and_reversal_before_release() {
+        let mut swipe = Swipe::default();
+        swipe.begin(3, false, 80);
+        swipe.update(0.0, -40.0);
+        assert_eq!(swipe.preview(), Some((SwipeDirection::Up, 0.25)));
+        swipe.update(0.0, -40.0);
+        assert_eq!(swipe.preview(), Some((SwipeDirection::Up, 0.5)));
+        swipe.update(0.0, 60.0);
+        assert_eq!(swipe.preview(), Some((SwipeDirection::Up, 0.125)));
+        assert_eq!(swipe.finish(false), None);
+        assert_eq!(swipe.preview(), None);
+    }
+
+    #[test]
+    fn reversal_across_the_origin_cancels_instead_of_committing_another_axis() {
+        let mut swipe = Swipe::default();
+        swipe.begin(3, false, 80);
+        swipe.update(0.0, -40.0);
+        swipe.update(0.0, 160.0);
+        assert_eq!(swipe.preview(), Some((SwipeDirection::Up, 0.0)));
+        assert_eq!(swipe.finish(false), None);
+    }
+
     #[test]
     fn a_swipe_accumulates_motion_and_commits_only_once_on_release() {
         let mut swipe = Swipe::default();

compositor/src/input.rs

@@ -160,6 +160,7 @@ impl Ferese {
         match event {
             InputEvent::GestureSwipeBegin { event } => {
                 let pointer = seat.get_pointer().expect("seat has a pointer");
+                self.finish_workspace_swipe(None);
                 self.swipe.begin(
                     event.fingers(),
                     self.swipe_navigation_blocked()
@@ -185,6 +186,17 @@ impl Ferese {
             InputEvent::GestureSwipeUpdate { event } => {
                 if self.swipe.active() {
                     self.swipe.update(event.delta_x(), event.delta_y());
+                    if self.swipe_navigation_blocked() {
+                        self.finish_workspace_swipe(None);
+                    } else if let Some((direction, progress)) = self.swipe.preview()
+                        && let Some(BindingAction::SwitchRelativeWorkspace(next)) = self
+                            .bindings
+                            .iter()
+                            .find(|binding| binding.matches_swipe(self.swipe.fingers(), direction))
+                            .map(|binding| binding.action.clone())
+                    {
+                        self.preview_workspace_swipe(next, direction, progress);
+                    }
                 } else {
                     seat.get_pointer().expect("seat has a pointer").gesture_swipe_update(
                         self,
@@ -199,7 +211,10 @@ impl Ferese {
                 if self.swipe.active() {
                     let fingers = self.swipe.fingers();
                     let cancelled = event.cancelled() || self.swipe_navigation_blocked();
-                    if let Some(direction) = self.swipe.finish(cancelled)
+                    let direction = self.swipe.finish(cancelled);
+                    let handled = self.finish_workspace_swipe(direction) || self.swipe.preview_started();
+                    if !handled
+                        && let Some(direction) = direction
                         && let Some(action) = self
                             .bindings
                             .iter()
@@ -721,55 +736,48 @@ impl Ferese {
     }
 
     fn switch_relative_workspace(&mut self, next: bool, slide: Option<SwipeDirection>) {
-        let Some(output) = self.output_workspaces.focused_output() else {
-            return;
-        };
-        let Some(current) = self.output_workspaces.active_workspace(output) else {
-            return;
-        };
+        if let Some(workspace) = self.relative_workspace_target(next) {
+            if let Some(direction) = slide {
+                self.activate_managed_workspace_from_swipe(workspace, direction);
+            } else {
+                self.activate_managed_workspace(workspace);
+            }
+        }
+    }
+
+    pub(crate) fn relative_workspace_target(&mut self, next: bool) -> Option<ferese_core::WorkspaceId> {
+        let output = self.output_workspaces.focused_output()?;
+        let current = self.output_workspaces.active_workspace(output)?;
         let mut candidates = self.workspaces.ordered();
         candidates.retain(|workspace| {
             self.output_workspaces
                 .output_for_workspace(workspace.id)
                 .is_none_or(|owner| owner == output)
         });
-        let Some(index) = candidates.iter().position(|workspace| workspace.id == current) else {
-            return;
-        };
-        let index = if next {
+        let index = candidates.iter().position(|workspace| workspace.id == current)?;
+        let neighbor = if next {
             index.checked_add(1)
         } else {
             index.checked_sub(1)
         };
-        if let Some(workspace) = index
-            .and_then(|index| candidates.get(index))
-            .map(|workspace| workspace.id)
-        {
-            if let Some(direction) = slide {
-                self.activate_managed_workspace_from_swipe(workspace, direction);
-            } else {
-                self.activate_managed_workspace(workspace);
-            }
-        } else if next
+        if let Some(workspace) = neighbor.and_then(|index| candidates.get(index)) {
+            return Some(workspace.id);
+        }
+        if next
             && self.workspaces.workspace(current).is_some_and(|workspace| {
                 workspace.layout.window_ids().next().is_some() || !workspace.floating.is_empty()
             })
         {
-            let next_number = self
+            let number = self
                 .workspaces
                 .iter()
                 .filter_map(|workspace| workspace.name.parse::<u32>().ok())
                 .max()
                 .unwrap_or(1)
-                .checked_add(1);
-            if let Some(number) = next_number {
-                if let Some(direction) = slide {
-                    self.switch_workspace_from_swipe(number, direction);
-                } else {
-                    self.switch_workspace(number);
-                }
-            }
+                .checked_add(1)?;
+            return self.workspaces.ensure_numeric(number).ok();
         }
+        None
     }
 
     fn focus_window_at(&mut self, position: Point<f64, Logical>, serial: Serial, raise: bool) {

compositor/src/state.rs

@@ -92,6 +92,17 @@ const CLOSE_ANIMATION_DURATION: Duration = Duration::from_millis(140);
 const WORKSPACE_SLIDE_DURATION: Duration = Duration::from_millis(220);
 const WORKSPACE_SLIDE_FIRST_FRAME: Duration = Duration::from_millis(8);
 
+fn workspace_swipe_is_current(
+    outputs: &OutputWorkspaceMap,
+    output: OutputId,
+    from: WorkspaceId,
+    to: WorkspaceId,
+) -> bool {
+    outputs.focused_output() == Some(output)
+        && outputs.active_workspace(output) == Some(from)
+        && outputs.output_for_workspace(to).is_none_or(|owner| owner == output)
+}
+
 #[derive(Clone, Copy, Debug, Default, PartialEq)]
 struct SlideOffset {
     x: f64,
@@ -129,6 +140,8 @@ struct WorkspaceSlideItem {
 struct WorkspaceSlide {
     items: Vec<WorkspaceSlideItem>,
     elapsed: Duration,
+    held_progress: Option<f64>,
+    gesture: Option<(WorkspaceId, WorkspaceId, SwipeDirection)>,
 }
 
 impl WorkspaceSlide {
@@ -170,11 +183,33 @@ impl WorkspaceSlide {
         Self {
             items,
             elapsed: WORKSPACE_SLIDE_FIRST_FRAME,
+            held_progress: None,
+            gesture: None,
         }
     }
 
     fn progress(&self) -> f64 {
-        smoothstep((self.elapsed.as_secs_f64() / WORKSPACE_SLIDE_DURATION.as_secs_f64()).min(1.0))
+        self.held_progress.unwrap_or_else(|| {
+            smoothstep((self.elapsed.as_secs_f64() / WORKSPACE_SLIDE_DURATION.as_secs_f64()).min(1.0))
+        })
+    }
+
+    fn release(&mut self, committed: bool) {
+        let progress = self.progress();
+        for item in &mut self.items {
+            let position = item.start.between(item.target, progress);
+            if !committed && let Some((from, to, direction)) = self.gesture {
+                if item.workspace == from {
+                    item.target = SlideOffset::default();
+                } else if item.workspace == to {
+                    item.target = SlideOffset::for_swipe(direction).opposite();
+                }
+            }
+            item.start = position;
+        }
+        self.held_progress = None;
+        self.gesture = None;
+        self.elapsed = Duration::ZERO;
     }
 
     fn advance(&mut self, delta: Duration) -> bool {
@@ -1071,7 +1106,12 @@ impl Ferese {
         let Some(workspace) = self.workspaces.workspace_for_window(window) else {
             return (0.0, 0.0);
         };
-        let Some(output_id) = self.output_workspaces.output_for_workspace(workspace) else {
+        let Some(output_id) = self
+            .workspace_slides
+            .iter()
+            .find_map(|(output, slide)| slide.contains(workspace).then_some(*output))
+            .or_else(|| self.output_workspaces.output_for_workspace(workspace))
+        else {
             return (0.0, 0.0);
         };
         let Some(slide) = self.workspace_slides.get(&output_id) else {
@@ -1878,6 +1918,9 @@ impl Ferese {
         let mut active_animation = false;
         let mut completed_slides = Vec::new();
         for (output, slide) in &mut self.workspace_slides {
+            if slide.held_progress.is_some() {
+                continue;
+            }
             if slide.advance(delta) {
                 active_animation = true;
             } else {
@@ -2790,10 +2833,6 @@ impl Ferese {
         }
     }
 
-    pub(crate) fn switch_workspace_from_swipe(&mut self, index: u32, direction: SwipeDirection) {
-        self.switch_workspace_internal(index, Some(direction), false);
-    }
-
     fn switch_workspace_internal(
         &mut self,
         index: u32,
@@ -2833,6 +2872,70 @@ impl Ferese {
         self.restore_keyboard_focus();
     }
 
+    pub(crate) fn preview_workspace_swipe(&mut self, next: bool, direction: SwipeDirection, progress: f64) {
+        if !self.animations_enabled || self.overview.is_presenting() {
+            return;
+        }
+        if let Some((output, (from, to, _))) = self
+            .workspace_slides
+            .iter()
+            .find_map(|(output, slide)| slide.gesture.map(|gesture| (*output, gesture)))
+        {
+            if !workspace_swipe_is_current(&self.output_workspaces, output, from, to) {
+                self.finish_workspace_swipe(None);
+                return;
+            }
+            self.workspace_slides
+                .get_mut(&output)
+                .expect("gesture output exists")
+                .held_progress = Some(progress);
+            self.backdrop_generation = self.backdrop_generation.wrapping_add(1);
+            self.cursor_redraw_pending = true;
+            return;
+        }
+        if self.swipe.preview_started() {
+            return;
+        }
+        let Some(output) = self.output_workspaces.focused_output() else {
+            return;
+        };
+        let Some(from) = self.output_workspaces.active_workspace(output) else {
+            return;
+        };
+        let Some(to) = self.relative_workspace_target(next) else {
+            return;
+        };
+        let previous = self.workspace_slides.remove(&output);
+        let mut slide = WorkspaceSlide::new(previous, from, to, direction);
+        slide.held_progress = Some(progress);
+        slide.gesture = Some((from, to, direction));
+        self.workspace_slides.insert(output, slide);
+        self.swipe.mark_preview_started();
+        self.backdrop_generation = self.backdrop_generation.wrapping_add(1);
+        self.relayout();
+    }
+
+    pub(crate) fn finish_workspace_swipe(&mut self, direction: Option<SwipeDirection>) -> bool {
+        let Some((output, (from, to, expected))) = self
+            .workspace_slides
+            .iter()
+            .find_map(|(output, slide)| slide.gesture.map(|gesture| (*output, gesture)))
+        else {
+            return false;
+        };
+        let committed = direction == Some(expected)
+            && workspace_swipe_is_current(&self.output_workspaces, output, from, to)
+            && self.activate_managed_workspace_from_swipe(to, expected);
+        if !committed {
+            if let Some(slide) = self.workspace_slides.get_mut(&output) {
+                slide.release(false);
+            }
+            self.last_animation_tick = Instant::now();
+            self.relayout();
+        }
+        true
+    }
+
     fn update_workspace_slide(
         &mut self,
         requested_output: OutputId,
@@ -2841,7 +2944,18 @@ impl Ferese {
         workspace: WorkspaceId,
         slide_direction: Option<SwipeDirection>,
     ) {
-        let previous_slide = self.workspace_slides.remove(&owner);
+        let mut previous_slide = self.workspace_slides.remove(&owner);
+        if owner == requested_output
+            && let Some(slide) = previous_slide.as_mut()
+            && slide
+                .gesture
+                .is_some_and(|(_, to, direction)| to == workspace && Some(direction) == slide_direction)
+        {
+            slide.release(true);
+            self.last_animation_tick = Instant::now();
+            self.workspace_slides.insert(owner, previous_slide.unwrap());
+            return;
+        }
         if owner == requested_output
             && let (Some(from), Some(direction)) = (previous, slide_direction)
             && from != workspace
@@ -3188,6 +3302,31 @@ impl ClientData for ClientState {
 
 #[cfg(test)]
 mod tests {
+    #[test]
+    fn workspace_drag_cancels_when_focus_or_target_ownership_changes() {
+        let mut outputs = OutputWorkspaceMap::default();
+        let left = OutputId(1);
+        let right = OutputId(2);
+        let from = WorkspaceId(1);
+        let to = WorkspaceId(3);
+        outputs
+            .connect(left, OutputGeometry::new(0, 0, 1000, 1000), from)
+            .unwrap();
+        outputs
+            .connect(right, OutputGeometry::new(1000, 0, 1000, 1000), WorkspaceId(2))
+            .unwrap();
+        assert!(workspace_swipe_is_current(&outputs, left, from, to));
+        outputs.focus_output(right).unwrap();
+        assert!(!workspace_swipe_is_current(&outputs, left, from, to));
+        outputs.focus_output(left).unwrap();
+        outputs.assign_workspace(right, to).unwrap();
+        assert!(!workspace_swipe_is_current(&outputs, left, from, to));
+        assert_eq!(outputs.active_workspace(left), Some(from));
+        assert_eq!(outputs.output_for_workspace(to), Some(right));
+        outputs.switch_workspace(left, WorkspaceId(4)).unwrap();
+        assert!(!workspace_swipe_is_current(&outputs, left, from, WorkspaceId(5)));
+    }
+
     #[test]
     fn selecting_a_window_activates_its_workspace_on_its_owner() {
         for assignment in [None, Some(OutputId(1)), Some(OutputId(2))] {
@@ -3251,6 +3390,43 @@ mod tests {
         assert_eq!(workspaces.active().last_focused, Some(WindowId(2)));
     }
 
+    #[test]
+    fn workspace_drag_tracks_progress_and_releases_without_a_jump() {
+        for committed in [false, true] {
+            let from = WorkspaceId(1);
+            let to = WorkspaceId(2);
+            let mut slide = WorkspaceSlide::new(None, from, to, SwipeDirection::Up);
+            slide.gesture = Some((from, to, SwipeDirection::Up));
+            slide.held_progress = Some(0.4);
+            slide.advance(Duration::from_secs(10));
+            assert_eq!(slide.offset(from, 1000.0, 1000.0), (0.0, -400.0));
+            assert_eq!(slide.offset(to, 1000.0, 1000.0), (0.0, 600.0));
+            slide.release(committed);
+            assert_eq!(slide.offset(from, 1000.0, 1000.0), (0.0, -400.0));
+            assert_eq!(slide.offset(to, 1000.0, 1000.0), (0.0, 600.0));
+            assert!(!slide.advance(WORKSPACE_SLIDE_DURATION));
+            let active = if committed { to } else { from };
+            assert_eq!(slide.offset(active, 1000.0, 1000.0), (0.0, 0.0));
+        }
+    }
+
+    #[test]
+    fn cancelling_a_chained_drag_returns_to_the_active_workspace() {
+        let first = WorkspaceId(1);
+        let second = WorkspaceId(2);
+        let third = WorkspaceId(3);
+        let mut previous = WorkspaceSlide::new(None, first, second, SwipeDirection::Up);
+        previous.advance(WORKSPACE_SLIDE_DURATION / 3);
+        let mut slide = WorkspaceSlide::new(Some(previous), second, third, SwipeDirection::Up);
+        slide.gesture = Some((second, third, SwipeDirection::Up));
+        slide.held_progress = Some(0.25);
+        let position = slide.offset(second, 1000.0, 1000.0);
+        slide.release(false);
+        assert_eq!(slide.offset(second, 1000.0, 1000.0), position);
+        slide.advance(WORKSPACE_SLIDE_DURATION);
+        assert_eq!(slide.offset(second, 1000.0, 1000.0), (0.0, 0.0));
+    }
+
     #[test]
     fn workspace_slide_moves_both_workspaces_without_a_gap() {
         let width = 1600.0;

docs/configuration.md

@@ -255,11 +255,11 @@ The touchpad device keys are booleans, all defaulting to `true`: `tap`,
 `natural-scroll` and `disable-while-typing`. These apply to DRM devices; nested
 previews use the host's physical input settings.
 
-Three-finger swipes navigate on release: up goes to the next workspace on the
+Workspace swipes follow your fingers and settle when released. Up goes to the next workspace on the
 current monitor, down to the previous; left focuses the window to the right,
 and right focuses the window to the left. Workspace swipes skip workspaces owned
-by other monitors and stop at the first/last workspace. Cancelled, short and
-diagonal swipes do nothing. Navigation pauses while locked, during
+by other monitors and stop at the first/last workspace. Short or cancelled workspace
+swipes slide back; diagonal swipes do not navigate. Navigation pauses while locked, during
 window grabs, or when an application inhibits shortcuts.
 
 Assign swipes in **Settings → Shortcuts** using the same actions and arguments as

docs/shortcuts.md

@@ -83,10 +83,11 @@ for dependencies and custom screenshot commands.
 
 | Three-finger swipe | Action on release |
 | --- | --- |
-| Up / down | Next / previous workspace on this monitor |
+| Up / down | Drag to the next / previous workspace on this monitor; release to settle |
 | Left / right | Focus the window to the right / left |
 
-Short, diagonal, or cancelled swipes do nothing. Gestures can use the same actions
+Short or cancelled workspace swipes slide back. Diagonal swipes do not navigate.
+Gestures can use the same actions
 as keyboard bindings, including overview or moving a window. Four- and five-finger
 bindings are supported too.