2 files changed, 78 insertions, 13 deletions

diff --git a/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/SwipeToScene.kt b/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/SwipeToScene.kt
index 3f6bce724b1b..f386cf5842e6 100644
--- a/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/SwipeToScene.kt
+++ b/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/SwipeToScene.kt
@@ -37,11 +37,7 @@ internal fun Modifier.swipeToScene(
     draggableHandler: DraggableHandlerImpl,
     swipeDetector: SwipeDetector,
 ): Modifier {
-    return if (draggableHandler.enabled()) {
-        this.then(SwipeToSceneElement(draggableHandler, swipeDetector))
-    } else {
-        this
-    }
+    return then(SwipeToSceneElement(draggableHandler, swipeDetector, draggableHandler.enabled()))
 }
 
 private fun DraggableHandlerImpl.enabled(): Boolean {
@@ -114,31 +110,59 @@ internal fun Content.findActionResultBestMatch(swipe: Swipe.Resolved): UserActio
 private data class SwipeToSceneElement(
     val draggableHandler: DraggableHandlerImpl,
     val swipeDetector: SwipeDetector,
+    val enabled: Boolean,
 ) : ModifierNodeElement<SwipeToSceneRootNode>() {
     override fun create(): SwipeToSceneRootNode =
-        SwipeToSceneRootNode(draggableHandler, swipeDetector)
+        SwipeToSceneRootNode(draggableHandler, swipeDetector, enabled)
 
     override fun update(node: SwipeToSceneRootNode) {
-        node.update(draggableHandler, swipeDetector)
+        node.update(draggableHandler, swipeDetector, enabled)
     }
 }
 
 private class SwipeToSceneRootNode(
     draggableHandler: DraggableHandlerImpl,
     swipeDetector: SwipeDetector,
+    enabled: Boolean,
 ) : DelegatingNode() {
-    private var delegateNode = delegate(SwipeToSceneNode(draggableHandler, swipeDetector))
+    private var delegateNode = if (enabled) create(draggableHandler, swipeDetector) else null
+
+    fun update(
+        draggableHandler: DraggableHandlerImpl,
+        swipeDetector: SwipeDetector,
+        enabled: Boolean,
+    ) {
+        // Disabled.
+        if (!enabled) {
+            delegateNode?.let { undelegate(it) }
+            delegateNode = null
+            return
+        }
+
+        // Disabled => Enabled.
+        val nullableDelegate = delegateNode
+        if (nullableDelegate == null) {
+            delegateNode = create(draggableHandler, swipeDetector)
+            return
+        }
 
-    fun update(draggableHandler: DraggableHandlerImpl, swipeDetector: SwipeDetector) {
-        if (draggableHandler == delegateNode.draggableHandler) {
+        // Enabled => Enabled (update).
+        if (draggableHandler == nullableDelegate.draggableHandler) {
             // Simple update, just update the swipe detector directly and keep the node.
-            delegateNode.swipeDetector = swipeDetector
+            nullableDelegate.swipeDetector = swipeDetector
         } else {
             // The draggableHandler changed, force recreate the underlying SwipeToSceneNode.
-            undelegate(delegateNode)
-            delegateNode = delegate(SwipeToSceneNode(draggableHandler, swipeDetector))
+            undelegate(nullableDelegate)
+            delegateNode = create(draggableHandler, swipeDetector)
         }
     }
+
+    private fun create(
+        draggableHandler: DraggableHandlerImpl,
+        swipeDetector: SwipeDetector,
+    ): SwipeToSceneNode {
+        return delegate(SwipeToSceneNode(draggableHandler, swipeDetector))
+    }
 }
 
 private class SwipeToSceneNode(
diff --git a/packages/SystemUI/compose/scene/tests/src/com/android/compose/animation/scene/SwipeToSceneTest.kt b/packages/SystemUI/compose/scene/tests/src/com/android/compose/animation/scene/SwipeToSceneTest.kt
index 9135fdd15b3a..e80805a4e374 100644
--- a/packages/SystemUI/compose/scene/tests/src/com/android/compose/animation/scene/SwipeToSceneTest.kt
+++ b/packages/SystemUI/compose/scene/tests/src/com/android/compose/animation/scene/SwipeToSceneTest.kt
@@ -936,4 +936,45 @@ class SwipeToSceneTest {
         assertThat(state.transitionState).isIdle()
         assertThat(state.transitionState).hasCurrentScene(SceneC)
     }
+
+    @Test
+    fun swipeToSceneNodeIsKeptWhenDisabled() {
+        var hasHorizontalActions by mutableStateOf(false)
+        val state = rule.runOnUiThread { MutableSceneTransitionLayoutState(SceneA) }
+        var touchSlop = 0f
+        rule.setContent {
+            touchSlop = LocalViewConfiguration.current.touchSlop
+            SceneTransitionLayout(state) {
+                scene(
+                    SceneA,
+                    userActions =
+                        buildList {
+                                add(Swipe.Down to SceneB)
+
+                                if (hasHorizontalActions) {
+                                    add(Swipe.Left to SceneC)
+                                }
+                            }
+                            .toMap(),
+                ) {
+                    Box(Modifier.fillMaxSize())
+                }
+                scene(SceneB) { Box(Modifier.fillMaxSize()) }
+            }
+        }
+
+        // Swipe down to start a transition to B.
+        rule.onRoot().performTouchInput {
+            down(middle)
+            moveBy(Offset(0f, touchSlop))
+        }
+
+        assertThat(state.transitionState).isSceneTransition()
+
+        // Add new horizontal user actions. This should not stop the current transition, even if a
+        // new horizontal Modifier.swipeToScene() handler is introduced where the vertical one was.
+        hasHorizontalActions = true
+        rule.waitForIdle()
+        assertThat(state.transitionState).isSceneTransition()
+    }
 }