Merge "STL decay animation should only play if decayOffset exceeds targetOffset" into main

2 files changed, 41 insertions, 4 deletions

diff --git a/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/SwipeAnimation.kt b/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/SwipeAnimation.kt
index cb0d33cf5205..90c45eec9630 100644
--- a/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/SwipeAnimation.kt
+++ b/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/SwipeAnimation.kt
@@ -403,11 +403,14 @@ internal class SwipeAnimation<T : ContentKey>(
                 initialValue = initialOffset,
             )
 
+        // The decay animation should only play if decayOffset exceeds targetOffset.
+        val lowerBound = checkNotNull(animatable.lowerBound) { "No lower bound" }
+        val upperBound = checkNotNull(animatable.upperBound) { "No upper bound" }
         val willDecayReachBounds =
-            when {
-                targetOffset > initialOffset -> decayOffset >= targetOffset
-                targetOffset < initialOffset -> decayOffset <= targetOffset
-                else -> true
+            when (targetOffset) {
+                lowerBound -> decayOffset <= lowerBound
+                upperBound -> decayOffset >= upperBound
+                else -> error("Target $targetOffset should be $lowerBound or $upperBound")
             }
 
         if (willDecayReachBounds) {
@@ -421,6 +424,10 @@ internal class SwipeAnimation<T : ContentKey>(
                     appendLine("  targetOffset=$targetOffset")
                     appendLine("  initialVelocity=$initialVelocity")
                     appendLine("  decayOffset=$decayOffset")
+                    appendLine(
+                        "  animateDecay result: reason=${result.endReason} " +
+                            "value=${result.endState.value} velocity=${result.endState.velocity}"
+                    )
                 }
             }
             return initialVelocity - result.endState.velocity
diff --git a/packages/SystemUI/compose/scene/tests/src/com/android/compose/animation/scene/DraggableHandlerTest.kt b/packages/SystemUI/compose/scene/tests/src/com/android/compose/animation/scene/DraggableHandlerTest.kt
index 969003cb92f3..06e76d470a08 100644
--- a/packages/SystemUI/compose/scene/tests/src/com/android/compose/animation/scene/DraggableHandlerTest.kt
+++ b/packages/SystemUI/compose/scene/tests/src/com/android/compose/animation/scene/DraggableHandlerTest.kt
@@ -773,6 +773,36 @@ class DraggableHandlerTest {
     }
 
     @Test
+    fun startSwipeAnimationFromBound() = runGestureTest {
+        // Swipe down to go to SceneC.
+        mutableUserActionsA = mapOf(Swipe.Down to SceneC)
+
+        val dragController =
+            onDragStarted(
+                position = Offset(SCREEN_SIZE / 2f, SCREEN_SIZE / 2f),
+                // Swipe up.
+                overSlop = up(0.5f),
+                // Should be ignored.
+                expectedConsumedOverSlop = 0f,
+            )
+
+        val transition = assertThat(transitionState).isSceneTransition()
+        assertThat(transition).hasFromScene(SceneA)
+        assertThat(transition).hasToScene(SceneC)
+        assertThat(transition).hasProgress(0f)
+
+        // Swipe down, but not enough to go to SceneC.
+        dragController.onDragStoppedAnimateNow(
+            velocity = velocityThreshold - 0.01f,
+            onAnimationStart = {
+                assertTransition(fromScene = SceneA, toScene = SceneC, progress = 0f)
+            },
+        )
+
+        assertIdle(SceneA)
+    }
+
+    @Test
     fun requireFullDistanceSwipe() = runGestureTest {
         mutableUserActionsA +=
             Swipe.Up to UserActionResult(SceneB, requiresFullDistanceSwipe = true)