From b50e8d5683dbf36170be3c52c61d39c83d90081b Mon Sep 17 00:00:00 2001
From: atagen <boss@atagen.co>
Date: Thu, 21 May 2026 18:27:01 +1000
Subject: [PATCH] Batch layout animation candidates

---
 src/compositor.rs     |  1 +
 src/state.rs          | 53 +++++++++++++++++++++++++++++++++++++++----
 src/tree/container.rs |  6 +++++
 3 files changed, 55 insertions(+), 5 deletions(-)

diff --git a/src/compositor.rs b/src/compositor.rs
index 93600f27..fdb0f282 100644
--- a/src/compositor.rs
+++ b/src/compositor.rs
@@ -364,6 +364,7 @@ fn start_compositor2(
         layout_animations_requested: Default::default(),
         layout_animations_active: Default::default(),
         layout_animation_curve_override: Default::default(),
+        layout_animation_batch: Default::default(),
         suppress_animations_for_next_layout: Default::default(),
         toplevels: Default::default(),
         const_40hz_latch: Default::default(),
diff --git a/src/state.rs b/src/state.rs
index adf7b2ca..303a63c5 100644
--- a/src/state.rs
+++ b/src/state.rs
@@ -157,6 +157,14 @@ use {
     uapi::{OwnedFd, c},
 };
 
+pub(crate) struct LayoutAnimationCandidate {
+    node_id: NodeId,
+    old: Rect,
+    new: Rect,
+    retained: Option<Rc<RetainedToplevel>>,
+    curve: AnimationCurve,
+}
+
 pub struct State {
     pub pid: c::pid_t,
     pub kb_ctx: KbvmContext,
@@ -271,6 +279,7 @@ pub struct State {
     pub layout_animations_requested: Cell<bool>,
     pub layout_animations_active: Cell<bool>,
     pub layout_animation_curve_override: Cell<Option<AnimationCurve>>,
+    pub(crate) layout_animation_batch: RefCell<Option<Vec<LayoutAnimationCandidate>>>,
     pub suppress_animations_for_next_layout: Cell<bool>,
     pub toplevels: CopyHashMap<ToplevelIdentifier, Weak<dyn ToplevelNode>>,
     pub const_40hz_latch: EventSource<dyn LatchListener>,
@@ -1526,25 +1535,59 @@ impl State {
         if old_output != new_output || old_scale != new_scale {
             return;
         }
-        let now = self.now_nsec();
-        let started = self.animations.set_target(
+        let candidate = LayoutAnimationCandidate {
             node_id,
             old,
             new,
             retained,
-            now,
-            self.animations.duration_ms.get(),
             curve,
+        };
+        if let Some(batch) = self.layout_animation_batch.borrow_mut().as_mut() {
+            batch.push(candidate);
+            return;
+        }
+        self.start_layout_animation_candidate(candidate, self.now_nsec());
+    }
+
+    fn start_layout_animation_candidate(
+        self: &Rc<Self>,
+        candidate: LayoutAnimationCandidate,
+        now_nsec: u64,
+    ) {
+        let started = self.animations.set_target(
+            candidate.node_id,
+            candidate.old,
+            candidate.new,
+            candidate.retained,
+            now_nsec,
+            self.animations.duration_ms.get(),
+            candidate.curve,
         );
         if started {
             self.damage(expand_damage_rect(
-                old.union(new),
+                candidate.old.union(candidate.new),
                 self.theme.sizes.border_width.get().max(0),
             ));
             self.ensure_animation_tick();
         }
     }
 
+    pub fn begin_layout_animation_batch(&self) {
+        self.layout_animation_batch
+            .borrow_mut()
+            .get_or_insert_with(Vec::new);
+    }
+
+    pub fn finish_layout_animation_batch(self: &Rc<Self>) {
+        let Some(candidates) = self.layout_animation_batch.borrow_mut().take() else {
+            return;
+        };
+        let now = self.now_nsec();
+        for candidate in candidates {
+            self.start_layout_animation_candidate(candidate, now);
+        }
+    }
+
     pub fn queue_spawn_in_animation(
         self: &Rc<Self>,
         node_id: NodeId,
diff --git a/src/tree/container.rs b/src/tree/container.rs
index 3a6db3a2..8670125c 100644
--- a/src/tree/container.rs
+++ b/src/tree/container.rs
@@ -1771,7 +1771,13 @@ pub async fn container_layout(state: Rc<State>) {
             let animate = container.animate_next_layout.replace(false)
                 && !state.suppress_animations_for_next_layout.get();
             let prev_active = state.layout_animations_active.replace(animate);
+            if animate {
+                state.begin_layout_animation_batch();
+            }
             container.perform_layout();
+            if animate {
+                state.finish_layout_animation_batch();
+            }
             state.layout_animations_active.set(prev_active);
         }
         state.suppress_animations_for_next_layout.set(false);