Fix animation retarget and reflow regressions

docs/window-animations-testing.md

@@ -67,7 +67,7 @@ These paths should not be used as evidence of multiphase behavior:
 - tile-to-float and float-to-tile, which deliberately use linear animation
 - command-driven floating move/resize, which may animate but can overlap
 - pointer or tablet drag/resize, which should not animate
-- spawn-in and spawn-out, which are always linear
+- spawn-in and spawn-out, which are single-phase and use the configured curve
 - cross-output or cross-scale movement, which should snap
 - layer-shell, overlay, override-redirect, and fullscreen map/unmap paths
 
@@ -288,9 +288,9 @@ Hard failure:
 
 ## 9. Mixed-Action Phases
 
-This case is easiest to prove with the planner tests because Wry currently has
-few user commands that create a same-batch move for one tiled window and an
-independent resize for another. The canonical geometry is:
+This case is easiest to prove with the planner tests because Wry does not yet
+have a confirmed stock command that reliably creates a same-batch move for one
+tiled window and an independent resize for another. The canonical geometry is:
 
 ```text
 start:  A = (0,0)-(80,80)      B = (200,0)-(280,80)
@@ -306,9 +306,19 @@ To exercise the current proof directly, run:
 cargo test animation::multiphase::tests::mixed_single_phase_accepts_move_and_scale_when_proven
 ```
 
-For visual/manual testing, use any command sequence that can produce the same
-shape in one layout batch: one window changes only x-position, and a separate,
-non-overlapping window changes only height.
+For visual/manual testing, the target shape is:
+
+```text
+before: [ A ]          [ B ]
+after:    [ A ]        [ B ]
+                        [ ]
+```
+
+`A` must move horizontally without resizing. `B` must resize vertically without
+moving. The two motion bounds must remain separate for the whole animation. If a
+normal command sequence cannot produce that in one layout batch, treat the unit
+test as the authority and record the visual test as not applicable rather than a
+failure.
 
 Expected:
 
@@ -344,7 +354,8 @@ Use a long duration, then issue commands mid-animation:
 
 - swap, then reverse before completion
 - resize, then resize in the other direction before completion
-- move a window out of a stack, then back before completion
+- build `[A | [B | C | D]]`, move `C` left to form `[A | C | [B | D]]`,
+  then move `C` back into the stack before completion
 - start a multiphase group, then change only one window's destination if a
   command sequence allows it
 

src/animation.rs

@@ -12,6 +12,7 @@ use {
     ahash::AHashMap,
     std::{
         cell::{Cell, RefCell},
+        collections::VecDeque,
         rc::{Rc, Weak},
     },
 };
@@ -368,6 +369,14 @@ impl AnimationState {
             .into_iter()
             .map(|(from, to)| PhasedSegment { from, to })
             .collect();
+        let mut route_edges = route_edges_from_segments(&segments);
+        if let Some(anim) = self.phased.borrow().get(&node_id)
+            && !anim.done(now_nsec)
+        {
+            for &(from, to) in &anim.route_edges {
+                push_unique_route_edge(&mut route_edges, from, to);
+            }
+        }
         self.windows.borrow_mut().remove(&node_id);
         self.phased.borrow_mut().insert(
             node_id,
@@ -378,6 +387,7 @@ impl AnimationState {
                 curve,
                 last_damage: from,
                 final_rect,
+                route_edges,
                 retained,
             },
         );
@@ -601,6 +611,7 @@ struct PhasedWindowAnimation {
     curve: AnimationCurve,
     last_damage: Rect,
     final_rect: Rect,
+    route_edges: Vec<(Rect, Rect)>,
     retained: Option<Rc<RetainedToplevel>>,
 }
 
@@ -641,36 +652,110 @@ impl PhasedWindowAnimation {
         (phase < self.segments.len()).then_some(phase)
     }
 
-    fn path_points(&self) -> Option<Vec<Rect>> {
-        let first = self.segments.first()?;
-        let mut points = vec![first.from];
-        points.extend(self.segments.iter().map(|segment| segment.to));
-        Some(points)
-    }
-
     fn route_to(&self, target: Rect, now_nsec: u64) -> Option<Vec<(Rect, Rect)>> {
         let phase = self.phase_at(now_nsec)?;
-        let points = self.path_points()?;
-        let target_idx = points.iter().position(|point| *point == target)?;
         let current = self.rect_at(now_nsec);
         if current == target {
             return Some(vec![]);
         }
+        let segment = self.segments.get(phase)?;
+        route_through_edges(current, target, segment.from, segment.to, &self.route_edges)
+    }
+}
 
-        let mut route = vec![];
-        if target_idx <= phase {
-            push_non_empty_segment(&mut route, current, points[phase]);
-            for idx in (target_idx..phase).rev() {
-                push_non_empty_segment(&mut route, points[idx + 1], points[idx]);
-            }
-        } else {
-            push_non_empty_segment(&mut route, current, points[phase + 1]);
-            for idx in (phase + 1)..target_idx {
-                push_non_empty_segment(&mut route, points[idx], points[idx + 1]);
+fn route_edges_from_segments(segments: &[PhasedSegment]) -> Vec<(Rect, Rect)> {
+    let mut edges = vec![];
+    for segment in segments {
+        push_unique_route_edge(&mut edges, segment.from, segment.to);
+    }
+    edges
+}
+
+fn push_unique_route_edge(edges: &mut Vec<(Rect, Rect)>, from: Rect, to: Rect) {
+    if from == to {
+        return;
+    }
+    if edges
+        .iter()
+        .any(|&(a, b)| (a == from && b == to) || (a == to && b == from))
+    {
+        return;
+    }
+    edges.push((from, to));
+}
+
+fn route_through_edges(
+    current: Rect,
+    target: Rect,
+    current_from: Rect,
+    current_to: Rect,
+    known_edges: &[(Rect, Rect)],
+) -> Option<Vec<(Rect, Rect)>> {
+    let mut edges = known_edges.to_vec();
+    push_unique_route_edge(&mut edges, current, current_from);
+    push_unique_route_edge(&mut edges, current, current_to);
+    rect_graph_route(current, target, &edges)
+}
+
+fn rect_graph_route(
+    start: Rect,
+    target: Rect,
+    edges: &[(Rect, Rect)],
+) -> Option<Vec<(Rect, Rect)>> {
+    let mut nodes = vec![];
+    let mut adjacency: Vec<Vec<usize>> = vec![];
+    let start_idx = rect_graph_node(&mut nodes, &mut adjacency, start);
+    let target_idx = rect_graph_node(&mut nodes, &mut adjacency, target);
+    for &(from, to) in edges {
+        let from_idx = rect_graph_node(&mut nodes, &mut adjacency, from);
+        let to_idx = rect_graph_node(&mut nodes, &mut adjacency, to);
+        if !adjacency[from_idx].contains(&to_idx) {
+            adjacency[from_idx].push(to_idx);
+        }
+        if !adjacency[to_idx].contains(&from_idx) {
+            adjacency[to_idx].push(from_idx);
+        }
+    }
+
+    let mut previous = vec![None; nodes.len()];
+    let mut queue = VecDeque::from([start_idx]);
+    previous[start_idx] = Some(start_idx);
+    while let Some(idx) = queue.pop_front() {
+        if idx == target_idx {
+            break;
+        }
+        for &next in &adjacency[idx] {
+            if previous[next].is_none() {
+                previous[next] = Some(idx);
+                queue.push_back(next);
             }
         }
-        Some(route)
     }
+    previous[target_idx]?;
+
+    let mut reversed_nodes = vec![target_idx];
+    let mut idx = target_idx;
+    while idx != start_idx {
+        idx = previous[idx]?;
+        reversed_nodes.push(idx);
+    }
+    reversed_nodes.reverse();
+
+    let mut route = vec![];
+    for pair in reversed_nodes.windows(2) {
+        push_non_empty_segment(&mut route, nodes[pair[0]], nodes[pair[1]]);
+    }
+    Some(route)
+}
+
+fn rect_graph_node(nodes: &mut Vec<Rect>, adjacency: &mut Vec<Vec<usize>>, rect: Rect) -> usize {
+    if let Some(idx) = nodes.iter().position(|&node| node == rect) {
+        return idx;
+    }
+    let idx = nodes.len();
+    nodes.push(rect);
+    adjacency.push(vec![]);
+    idx
 }
 
 fn push_non_empty_segment(route: &mut Vec<(Rect, Rect)>, from: Rect, to: Rect) {
@@ -977,6 +1062,41 @@ mod tests {
         );
     }
 
+    #[test]
+    fn phased_route_remembers_original_path_after_retarget() {
+        let state = AnimationState::default();
+        let id = NodeId(1);
+        let a = Rect::new_sized_saturating(0, 0, 100, 100);
+        let b = Rect::new_sized_saturating(0, 0, 100, 50);
+        let c = Rect::new_sized_saturating(100, 0, 100, 50);
+        assert!(state.set_phased_target(
+            id,
+            vec![(a, b), (b, c)],
+            None,
+            0,
+            100,
+            AnimationCurve::Linear
+        ));
+
+        let current = lerp_rect(b, c, 0.5);
+        let reverse = state.phased_route_to(id, a, 150_000_000).unwrap();
+        assert_eq!(reverse, vec![(current, b), (b, a)]);
+        assert!(state.set_phased_target(
+            id,
+            reverse,
+            None,
+            150_000_000,
+            100,
+            AnimationCurve::Linear
+        ));
+
+        let current = lerp_rect(current, b, 0.5);
+        assert_eq!(
+            state.phased_route_to(id, c, 200_000_000).unwrap(),
+            vec![(current, b), (b, c)]
+        );
+    }
+
     #[test]
     fn linear_retarget_interrupts_phased_animation_from_current_rect() {
         let state = AnimationState::default();

src/animation/multiphase.rs

@@ -1,6 +1,6 @@
 use {crate::rect::Rect, crate::tree::NodeId};
 
-const MIN_SHRINK_DENOMINATOR: i32 = 4;
+const MIN_SHRINK_DENOMINATOR: i32 = 8;
 
 #[derive(Clone, Debug)]
 pub struct MultiphaseRequest {
@@ -2198,6 +2198,23 @@ mod tests {
         assert!(validate_plan_continuous(&req, &planned.plan));
     }
 
+    #[test]
+    fn single_window_one_axis_group_is_still_multiphase_plannable() {
+        let req = request(vec![window(1, rect(0, 0, 100, 100), rect(40, 0, 140, 100))]);
+        let planned = plan_no_overlap_explained(&req).unwrap();
+
+        assert_eq!(planned.explanation.strategy, PlanStrategy::SingleAction);
+        assert_eq!(
+            planned.plan.phases[0].action,
+            MultiphasePhaseAction::Uniform(PhaseAction {
+                kind: PhaseKind::Move,
+                axis: PhaseAxis::Horizontal,
+            })
+        );
+        assert_eq!(planned.explanation.phases[0].nodes, vec![id(1)]);
+        assert!(validate_plan_continuous(&req, &planned.plan));
+    }
+
     #[test]
     fn mixed_single_phase_still_rejects_diagonal_per_window_motion() {
         let req = request(vec![
@@ -2424,6 +2441,61 @@ mod tests {
         assert!(validate_plan_continuous(&req, plan));
     }
 
+    #[test]
+    fn three_child_stack_extraction_plans_without_linear_fallback() {
+        let old = split(
+            10,
+            PhaseAxis::Horizontal,
+            &[1, 1],
+            vec![
+                leaf(1),
+                split(
+                    11,
+                    PhaseAxis::Vertical,
+                    &[1, 1, 1],
+                    vec![leaf(2), leaf(3), leaf(4)],
+                ),
+            ],
+        );
+        let new = split(
+            10,
+            PhaseAxis::Horizontal,
+            &[1, 1, 1],
+            vec![
+                leaf(1),
+                leaf(3),
+                split(11, PhaseAxis::Vertical, &[1, 1], vec![leaf(2), leaf(4)]),
+            ],
+        );
+        let req = generated_request(&old, &new, rect(0, 0, 600, 300));
+        let planned = plan_no_overlap_explained(&req).unwrap();
+
+        assert_eq!(
+            planned.explanation.strategy,
+            PlanStrategy::SpaceThenOrthogonalGrowth {
+                axis: PhaseAxis::Horizontal,
+            }
+        );
+        assert_eq!(
+            actions(&planned.plan),
+            vec![
+                PhaseAction {
+                    kind: PhaseKind::Scale,
+                    axis: PhaseAxis::Horizontal,
+                },
+                PhaseAction {
+                    kind: PhaseKind::Move,
+                    axis: PhaseAxis::Horizontal,
+                },
+                PhaseAction {
+                    kind: PhaseKind::Scale,
+                    axis: PhaseAxis::Vertical,
+                },
+            ]
+        );
+        assert!(validate_plan_continuous(&req, &planned.plan));
+    }
+
     #[test]
     fn validated_phase_paths_accept_interrupted_reverse_route() {
         let a_current = rect(50, 0, 150, 50);
@@ -2793,7 +2865,7 @@ mod tests {
             MultiphasePlanFailure::ShrinkBound {
                 axis: PhaseAxis::Horizontal,
                 available: 10,
-                required: 100,
+                required: 50,
             }
         ));
     }

src/renderer.rs

@@ -553,6 +553,7 @@ impl Renderer<'_> {
             return;
         }
         let bounds = self.base.scale_rect(body);
+        self.render_window_body_background(&bounds);
         self.stretch = if frame.source_body_size != body.size() {
             Some(self.base.scale_point(body.width(), body.height()))
         } else {
@@ -573,6 +574,21 @@ impl Renderer<'_> {
         self.corner_radius = None;
     }
 
+    fn render_window_body_background(&mut self, bounds: &Rect) {
+        if bounds.is_empty() {
+            return;
+        }
+        let color = self.state.theme.colors.background.get();
+        self.base.sync();
+        self.base.fill_scaled_boxes(
+            slice::from_ref(bounds),
+            &color,
+            None,
+            &self.state.color_manager.srgb_gamma22().linear,
+            RenderIntent::Perceptual,
+        );
+    }
+
     fn render_retained_surface_scaled(
         &mut self,
         retained: &RetainedSurface,
@@ -744,6 +760,9 @@ impl Renderer<'_> {
             }
             let body = visual_mb.move_(x, y);
             let body = self.base.scale_rect(body);
+            if !child.node.node_is_container() {
+                self.render_window_body_background(&body);
+            }
             let content = container
                 .mono_content
                 .get()
@@ -818,6 +837,9 @@ impl Renderer<'_> {
                 }
                 let body = body.move_(x, y);
                 let body = self.base.scale_rect(body);
+                if !child.node.node_is_container() {
+                    self.render_window_body_background(&body);
+                }
                 self.render_child_or_snapshot(
                     &child.node,
                     x + content.x1(),
@@ -1087,6 +1109,7 @@ impl Renderer<'_> {
             let inner_cr = self.scale_corner_radius(cr.expanded_by(-(bw as f32)));
             self.corner_radius = Some(inner_cr);
         }
+        self.render_window_body_background(&scissor_body);
         self.render_child_or_snapshot(&child, body.x1(), body.y1(), Some(&scissor_body));
         self.stretch = None;
         self.corner_radius = None;

src/state.rs

@@ -1663,9 +1663,6 @@ impl State {
         group: &[usize],
         now_nsec: u64,
     ) -> bool {
-        if group.len() < 2 {
-            return false;
-        }
         let request_windows: Vec<_> = group.iter().map(|&idx| windows[idx]).collect();
         let Some(first) = request_windows.first() else {
             return false;

src/tree/container.rs

@@ -2303,6 +2303,11 @@ impl ContainingNode for ContainerNode {
         }
         // log::info!("cnode_remove_child2");
         self.rebuild_tab_bar();
+        if self.state.animations.enabled.get()
+            && !self.state.suppress_animations_for_next_layout.get()
+        {
+            self.animate_next_layout.set(true);
+        }
         self.schedule_layout();
         self.cancel_seat_ops();
         self.child_removed.trigger();