AnimatedValue per-value animation end signal

This change reworks animation end signalling for AnimatedValue; rather
than consuming a top-level Flow to signal that an animation has ended,
each AnimatedValue exposes its own stopAnimating() method that,
critically, only affects that specific AnimatedValue; if a new
AnimatedValue is emitted by the Flow returned from
toAnimatedValueFlow(), then a invoking stopAnimating() on a
previously-emitted AnimatedValue will be ignored.

This helps avoid a common pitfall with modelling animation state, where
a new AnimatedValue is emitted whilst a previous animation is still
occurring. In many cases, we want to cancel() the previous animation,
which without careful management, will result in a cancel signal making
it back to the toAnimatedValueFlow(), *before* the new animation is even
started. This will cause a new AnimatedValue to be emitted with
isAnimating == false, immediately cancelling the new animation.

Bug: 278765923
Test: atest SystemUITests
Change-Id: I3503cbf604d6b85b573987264c0bb7611632b293

10 files changed, 439 insertions, 133 deletions

diff --git a/packages/SystemUI/src/com/android/systemui/complication/ComplicationLayoutEngine.java b/packages/SystemUI/src/com/android/systemui/complication/ComplicationLayoutEngine.java
index 20b2494a6c29..f7b6b0f06a00 100644
--- a/packages/SystemUI/src/com/android/systemui/complication/ComplicationLayoutEngine.java
+++ b/packages/SystemUI/src/com/android/systemui/complication/ComplicationLayoutEngine.java
@@ -652,8 +652,7 @@ public class ComplicationLayoutEngine implements Complication.VisibilityControll
             CrossFadeHelper.fadeOut(
                     mLayout,
                     mFadeOutDuration,
-                    /* delay= */ 0,
-                    /* endRunnable= */ null);
+                    /* delay= */ 0);
         }
     }
 
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/CrossFadeHelper.java b/packages/SystemUI/src/com/android/systemui/statusbar/CrossFadeHelper.java
index 77b095802b00..7d81e55d336a 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/CrossFadeHelper.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/CrossFadeHelper.java
@@ -16,7 +16,9 @@
 
 package com.android.systemui.statusbar;
 
+import android.animation.Animator;
 import android.view.View;
+import android.view.ViewPropertyAnimator;
 
 import androidx.annotation.Nullable;
 
@@ -31,32 +33,58 @@ public class CrossFadeHelper {
     public static final long ANIMATION_DURATION_LENGTH = 210;
 
     public static void fadeOut(final View view) {
-        fadeOut(view, null);
+        fadeOut(view, (Runnable) null);
     }
 
     public static void fadeOut(final View view, final Runnable endRunnable) {
         fadeOut(view, ANIMATION_DURATION_LENGTH, 0, endRunnable);
     }
 
+    public static void fadeOut(final View view, final Animator.AnimatorListener listener) {
+        fadeOut(view, ANIMATION_DURATION_LENGTH, 0, listener);
+    }
+
+    public static void fadeOut(final View view, long duration, int delay) {
+        fadeOut(view, duration, delay, (Runnable) null);
+    }
+
     public static void fadeOut(final View view, long duration, int delay,
-            final Runnable endRunnable) {
+            @Nullable final Runnable endRunnable) {
         view.animate().cancel();
         view.animate()
                 .alpha(0f)
                 .setDuration(duration)
                 .setInterpolator(Interpolators.ALPHA_OUT)
                 .setStartDelay(delay)
-                .withEndAction(new Runnable() {
-                    @Override
-                    public void run() {
-                        if (endRunnable != null) {
-                            endRunnable.run();
-                        }
-                        if (view.getVisibility() != View.GONE) {
-                            view.setVisibility(View.INVISIBLE);
-                        }
+                .withEndAction(() -> {
+                    if (endRunnable != null) {
+                        endRunnable.run();
+                    }
+                    if (view.getVisibility() != View.GONE) {
+                        view.setVisibility(View.INVISIBLE);
+                    }
+                });
+        if (view.hasOverlappingRendering()) {
+            view.animate().withLayer();
+        }
+    }
+
+    public static void fadeOut(final View view, long duration, int delay,
+            @Nullable final Animator.AnimatorListener listener) {
+        view.animate().cancel();
+        ViewPropertyAnimator animator = view.animate()
+                .alpha(0f)
+                .setDuration(duration)
+                .setInterpolator(Interpolators.ALPHA_OUT)
+                .setStartDelay(delay)
+                .withEndAction(() -> {
+                    if (view.getVisibility() != View.GONE) {
+                        view.setVisibility(View.INVISIBLE);
                     }
                 });
+        if (listener != null) {
+            animator.setListener(listener);
+        }
         if (view.hasOverlappingRendering()) {
             view.animate().withLayer();
         }
@@ -119,8 +147,12 @@ public class CrossFadeHelper {
         fadeIn(view, ANIMATION_DURATION_LENGTH, /* delay= */ 0, endRunnable);
     }
 
+    public static void fadeIn(final View view, Animator.AnimatorListener listener) {
+        fadeIn(view, ANIMATION_DURATION_LENGTH, /* delay= */ 0, listener);
+    }
+
     public static void fadeIn(final View view, long duration, int delay) {
-        fadeIn(view, duration, delay, /* endRunnable= */ null);
+        fadeIn(view, duration, delay, /* endRunnable= */ (Runnable) null);
     }
 
     public static void fadeIn(final View view, long duration, int delay,
@@ -141,6 +173,26 @@ public class CrossFadeHelper {
         }
     }
 
+    public static void fadeIn(final View view, long duration, int delay,
+            @Nullable Animator.AnimatorListener listener) {
+        view.animate().cancel();
+        if (view.getVisibility() == View.INVISIBLE) {
+            view.setAlpha(0.0f);
+            view.setVisibility(View.VISIBLE);
+        }
+        ViewPropertyAnimator animator = view.animate()
+                .alpha(1f)
+                .setDuration(duration)
+                .setStartDelay(delay)
+                .setInterpolator(Interpolators.ALPHA_IN);
+        if (listener != null) {
+            animator.setListener(listener);
+        }
+        if (view.hasOverlappingRendering() && view.getLayerType() != View.LAYER_TYPE_HARDWARE) {
+            view.animate().withLayer();
+        }
+    }
+
     public static void fadeIn(View view, float fadeInAmount) {
         fadeIn(view, fadeInAmount, false /* remap */);
     }
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/notification/icon/ui/viewbinder/NotificationIconContainerViewBinder.kt b/packages/SystemUI/src/com/android/systemui/statusbar/notification/icon/ui/viewbinder/NotificationIconContainerViewBinder.kt
index c6d7e2193a23..a78fd9dfca43 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/notification/icon/ui/viewbinder/NotificationIconContainerViewBinder.kt
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/notification/icon/ui/viewbinder/NotificationIconContainerViewBinder.kt
@@ -15,8 +15,11 @@
  */
 package com.android.systemui.statusbar.notification.icon.ui.viewbinder
 
+import android.animation.Animator
+import android.animation.AnimatorListenerAdapter
 import android.graphics.Rect
 import android.view.View
+import android.view.ViewPropertyAnimator
 import android.widget.FrameLayout
 import androidx.collection.ArrayMap
 import androidx.lifecycle.Lifecycle
@@ -46,6 +49,9 @@ import com.android.systemui.util.children
 import com.android.systemui.util.kotlin.mapValuesNotNullTo
 import com.android.systemui.util.kotlin.sample
 import com.android.systemui.util.kotlin.stateFlow
+import com.android.systemui.util.ui.isAnimating
+import com.android.systemui.util.ui.stopAnimating
+import com.android.systemui.util.ui.value
 import javax.inject.Inject
 import kotlinx.coroutines.DisposableHandle
 import kotlinx.coroutines.coroutineScope
@@ -73,14 +79,22 @@ object NotificationIconContainerViewBinder {
             repeatOnLifecycle(Lifecycle.State.CREATED) {
                 launch { viewModel.animationsEnabled.collect(view::setAnimationsEnabled) }
                 launch {
-                    viewModel.isDozing.collect { (isDozing, animate) ->
-                        val animateIfNotBlanking = animate && !dozeParameters.displayNeedsBlanking
-                        view.setDozing(
-                            /* dozing = */ isDozing,
-                            /* fade = */ animateIfNotBlanking,
-                            /* delay = */ 0,
-                            /* endRunnable = */ viewModel::completeDozeAnimation,
-                        )
+                    viewModel.isDozing.collect { isDozing ->
+                        if (isDozing.isAnimating) {
+                            val animate = !dozeParameters.displayNeedsBlanking
+                            view.setDozing(
+                                /* dozing = */ isDozing.value,
+                                /* fade = */ animate,
+                                /* delay = */ 0,
+                                /* endRunnable = */ isDozing::stopAnimating,
+                            )
+                        } else {
+                            view.setDozing(
+                                /* dozing = */ isDozing.value,
+                                /* fade= */ false,
+                                /* delay= */ 0,
+                            )
+                        }
                     }
                 }
                 // TODO(b/278765923): this should live where AOD is bound, not inside of the NIC
@@ -92,7 +106,6 @@ object NotificationIconContainerViewBinder {
                         configuration,
                         featureFlags,
                         screenOffAnimationController,
-                        onAnimationEnd = viewModel::completeVisibilityAnimation,
                     )
                 }
                 launch {
@@ -225,33 +238,38 @@ object NotificationIconContainerViewBinder {
         configuration: ConfigurationState,
         featureFlags: FeatureFlagsClassic,
         screenOffAnimationController: ScreenOffAnimationController,
-        onAnimationEnd: () -> Unit,
     ): Unit = coroutineScope {
         val iconAppearTranslation =
             configuration.getDimensionPixelSize(R.dimen.shelf_appear_translation).stateIn(this)
         val statusViewMigrated = featureFlags.isEnabled(Flags.MIGRATE_KEYGUARD_STATUS_VIEW)
-        viewModel.isVisible.collect { (isVisible, animate) ->
+        viewModel.isVisible.collect { isVisible ->
             view.animate().cancel()
+            val animatorListener =
+                object : AnimatorListenerAdapter() {
+                    override fun onAnimationEnd(animation: Animator) {
+                        isVisible.stopAnimating()
+                    }
+                }
             when {
-                !animate -> {
+                !isVisible.isAnimating -> {
                     view.alpha = 1f
                     if (!statusViewMigrated) {
                         view.translationY = 0f
                     }
-                    view.visibility = if (isVisible) View.VISIBLE else View.INVISIBLE
+                    view.visibility = if (isVisible.value) View.VISIBLE else View.INVISIBLE
                 }
                 featureFlags.isEnabled(Flags.NEW_AOD_TRANSITION) -> {
                     animateInIconTranslation(view, statusViewMigrated)
-                    if (isVisible) {
-                        CrossFadeHelper.fadeIn(view, onAnimationEnd)
+                    if (isVisible.value) {
+                        CrossFadeHelper.fadeIn(view, animatorListener)
                     } else {
-                        CrossFadeHelper.fadeOut(view, onAnimationEnd)
+                        CrossFadeHelper.fadeOut(view, animatorListener)
                     }
                 }
-                !isVisible -> {
+                !isVisible.value -> {
                     // Let's make sure the icon are translated to 0, since we cancelled it above
                     animateInIconTranslation(view, statusViewMigrated)
-                    CrossFadeHelper.fadeOut(view, onAnimationEnd)
+                    CrossFadeHelper.fadeOut(view, animatorListener)
                 }
                 view.visibility != View.VISIBLE -> {
                     // No fading here, let's just appear the icons instead!
@@ -262,14 +280,14 @@ object NotificationIconContainerViewBinder {
                         animate = screenOffAnimationController.shouldAnimateAodIcons(),
                         iconAppearTranslation.value,
                         statusViewMigrated,
+                        animatorListener,
                     )
-                    onAnimationEnd()
                 }
                 else -> {
                     // Let's make sure the icons are translated to 0, since we cancelled it above
                     animateInIconTranslation(view, statusViewMigrated)
                     // We were fading out, let's fade in instead
-                    CrossFadeHelper.fadeIn(view, onAnimationEnd)
+                    CrossFadeHelper.fadeIn(view, animatorListener)
                 }
             }
         }
@@ -280,18 +298,20 @@ object NotificationIconContainerViewBinder {
         animate: Boolean,
         iconAppearTranslation: Int,
         statusViewMigrated: Boolean,
+        animatorListener: Animator.AnimatorListener,
     ) {
         if (animate) {
             if (!statusViewMigrated) {
                 view.translationY = -iconAppearTranslation.toFloat()
             }
             view.alpha = 0f
-            animateInIconTranslation(view, statusViewMigrated)
             view
                 .animate()
                 .alpha(1f)
                 .setInterpolator(Interpolators.LINEAR)
                 .setDuration(AOD_ICONS_APPEAR_DURATION)
+                .apply { if (statusViewMigrated) animateInIconTranslation() }
+                .setListener(animatorListener)
                 .start()
         } else {
             view.alpha = 1.0f
@@ -303,15 +323,13 @@ object NotificationIconContainerViewBinder {
 
     private fun animateInIconTranslation(view: View, statusViewMigrated: Boolean) {
         if (!statusViewMigrated) {
-            view
-                .animate()
-                .setInterpolator(Interpolators.DECELERATE_QUINT)
-                .translationY(0f)
-                .setDuration(AOD_ICONS_APPEAR_DURATION)
-                .start()
+            view.animate().animateInIconTranslation().setDuration(AOD_ICONS_APPEAR_DURATION).start()
         }
     }
 
+    private fun ViewPropertyAnimator.animateInIconTranslation(): ViewPropertyAnimator =
+        setInterpolator(Interpolators.DECELERATE_QUINT).translationY(0f)
+
     private const val AOD_ICONS_APPEAR_DURATION: Long = 200
 
     private val View.viewBounds: Rect
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/notification/icon/ui/viewmodel/NotificationIconContainerAlwaysOnDisplayViewModel.kt b/packages/SystemUI/src/com/android/systemui/statusbar/notification/icon/ui/viewmodel/NotificationIconContainerAlwaysOnDisplayViewModel.kt
index 885f449ecd19..e6788fb858bf 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/notification/icon/ui/viewmodel/NotificationIconContainerAlwaysOnDisplayViewModel.kt
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/notification/icon/ui/viewmodel/NotificationIconContainerAlwaysOnDisplayViewModel.kt
@@ -41,9 +41,9 @@ import com.android.systemui.util.kotlin.sample
 import com.android.systemui.util.ui.AnimatableEvent
 import com.android.systemui.util.ui.AnimatedValue
 import com.android.systemui.util.ui.toAnimatedValueFlow
+import com.android.systemui.util.ui.zip
 import javax.inject.Inject
 import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.distinctUntilChanged
 import kotlinx.coroutines.flow.map
@@ -65,9 +65,6 @@ constructor(
     shadeInteractor: ShadeInteractor,
 ) : NotificationIconContainerViewModel {
 
-    private val onDozeAnimationComplete = MutableSharedFlow<Unit>(extraBufferCapacity = 1)
-    private val onVisAnimationComplete = MutableSharedFlow<Unit>(extraBufferCapacity = 1)
-
     override val iconColors: Flow<ColorLookup> =
         configuration.getColorAttr(R.attr.wallpaperTextColor, DEFAULT_AOD_ICON_COLOR).map { tint ->
             ColorLookup { IconColorsImpl(tint) }
@@ -96,7 +93,7 @@ constructor(
                 AnimatableEvent(isDozing, animate)
             }
             .distinctUntilChanged()
-            .toAnimatedValueFlow(completionEvents = onDozeAnimationComplete)
+            .toAnimatedValueFlow()
 
     override val isVisible: Flow<AnimatedValue<Boolean>> =
         combine(
@@ -106,37 +103,36 @@ constructor(
                 isPulseExpandingAnimated(),
             ) {
                 onKeyguard: Boolean,
-                bypassEnabled: Boolean,
-                (notifsFullyHidden: Boolean, isAnimatingHide: Boolean),
-                (pulseExpanding: Boolean, isAnimatingPulse: Boolean),
+                isBypassEnabled: Boolean,
+                notifsFullyHidden: AnimatedValue<Boolean>,
+                pulseExpanding: AnimatedValue<Boolean>,
                 ->
-                val isAnimating = isAnimatingHide || isAnimatingPulse
                 when {
                     // Hide the AOD icons if we're not in the KEYGUARD state unless the screen off
                     // animation is playing, in which case we want them to be visible if we're
                     // animating in the AOD UI and will be switching to KEYGUARD shortly.
                     !onKeyguard && !screenOffAnimationController.shouldShowAodIconsWhenShade() ->
-                        AnimatedValue(false, isAnimating = false)
-                    // If we're bypassing, then we're visible
-                    bypassEnabled -> AnimatedValue(true, isAnimating)
-                    // If we are pulsing (and not bypassing), then we are hidden
-                    pulseExpanding -> AnimatedValue(false, isAnimating)
-                    // If notifs are fully gone, then we're visible
-                    notifsFullyHidden -> AnimatedValue(true, isAnimating)
-                    // Otherwise, we're hidden
-                    else -> AnimatedValue(false, isAnimating)
+                        AnimatedValue.NotAnimating(false)
+                    else ->
+                        zip(notifsFullyHidden, pulseExpanding) {
+                            areNotifsFullyHidden,
+                            isPulseExpanding,
+                            ->
+                            when {
+                                // If we're bypassing, then we're visible
+                                isBypassEnabled -> true
+                                // If we are pulsing (and not bypassing), then we are hidden
+                                isPulseExpanding -> false
+                                // If notifs are fully gone, then we're visible
+                                areNotifsFullyHidden -> true
+                                // Otherwise, we're hidden
+                                else -> false
+                            }
+                        }
                 }
             }
             .distinctUntilChanged()
 
-    override fun completeDozeAnimation() {
-        onDozeAnimationComplete.tryEmit(Unit)
-    }
-
-    override fun completeVisibilityAnimation() {
-        onVisAnimationComplete.tryEmit(Unit)
-    }
-
     override val iconsViewData: Flow<IconsViewData> =
         iconsInteractor.aodNotifs.map { entries ->
             IconsViewData(
@@ -150,7 +146,7 @@ constructor(
             .pairwise(initialValue = null)
             // If pulsing changes, start animating, unless it's the first emission
             .map { (prev, expanding) -> AnimatableEvent(expanding, startAnimating = prev != null) }
-            .toAnimatedValueFlow(completionEvents = onVisAnimationComplete)
+            .toAnimatedValueFlow()
     }
 
     /** Are notifications completely hidden from view, are we animating in response? */
@@ -176,7 +172,7 @@ constructor(
                     }
                 AnimatableEvent(fullyHidden, animate)
             }
-            .toAnimatedValueFlow(completionEvents = onVisAnimationComplete)
+            .toAnimatedValueFlow()
     }
 
     private class IconColorsImpl(override val tint: Int) : IconColors {
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/notification/icon/ui/viewmodel/NotificationIconContainerShelfViewModel.kt b/packages/SystemUI/src/com/android/systemui/statusbar/notification/icon/ui/viewmodel/NotificationIconContainerShelfViewModel.kt
index 38eae24d98b9..b8e0b5828831 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/notification/icon/ui/viewmodel/NotificationIconContainerShelfViewModel.kt
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/notification/icon/ui/viewmodel/NotificationIconContainerShelfViewModel.kt
@@ -31,11 +31,10 @@ class NotificationIconContainerShelfViewModel
 constructor(
     interactor: NotificationIconsInteractor,
 ) : NotificationIconContainerViewModel {
+
     override val animationsEnabled: Flow<Boolean> = flowOf(true)
     override val isDozing: Flow<AnimatedValue<Boolean>> = emptyFlow()
     override val isVisible: Flow<AnimatedValue<Boolean>> = emptyFlow()
-    override fun completeDozeAnimation() {}
-    override fun completeVisibilityAnimation() {}
     override val iconColors: Flow<ColorLookup> = emptyFlow()
 
     override val iconsViewData: Flow<IconsViewData> =
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/notification/icon/ui/viewmodel/NotificationIconContainerStatusBarViewModel.kt b/packages/SystemUI/src/com/android/systemui/statusbar/notification/icon/ui/viewmodel/NotificationIconContainerStatusBarViewModel.kt
index cdbabb601da9..046d364a407b 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/notification/icon/ui/viewmodel/NotificationIconContainerStatusBarViewModel.kt
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/notification/icon/ui/viewmodel/NotificationIconContainerStatusBarViewModel.kt
@@ -68,8 +68,6 @@ constructor(
 
     override val isDozing: Flow<AnimatedValue<Boolean>> = emptyFlow()
     override val isVisible: Flow<AnimatedValue<Boolean>> = emptyFlow()
-    override fun completeDozeAnimation() {}
-    override fun completeVisibilityAnimation() {}
 
     override val iconsViewData: Flow<IconsViewData> =
         iconsInteractor.statusBarNotifs.map { entries ->
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/notification/icon/ui/viewmodel/NotificationIconContainerViewModel.kt b/packages/SystemUI/src/com/android/systemui/statusbar/notification/icon/ui/viewmodel/NotificationIconContainerViewModel.kt
index 0e8dfea76319..236a2371d9dd 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/notification/icon/ui/viewmodel/NotificationIconContainerViewModel.kt
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/notification/icon/ui/viewmodel/NotificationIconContainerViewModel.kt
@@ -46,18 +46,6 @@ interface NotificationIconContainerViewModel {
     val iconsViewData: Flow<IconsViewData>
 
     /**
-     * Signal completion of the [isDozing] animation; if [isDozing]'s [AnimatedValue.isAnimating]
-     * property was `true`, calling this method will update it to `false`.
-     */
-    fun completeDozeAnimation()
-
-    /**
-     * Signal completion of the [isVisible] animation; if [isVisible]'s [AnimatedValue.isAnimating]
-     * property was `true`, calling this method will update it to `false`.
-     */
-    fun completeVisibilityAnimation()
-
-    /**
      * Lookup the colors to use for the notification icons based on the bounds of the icon
      * container. A result of `null` indicates that no color changes should be applied.
      */
diff --git a/packages/SystemUI/src/com/android/systemui/util/ui/AnimatedValue.kt b/packages/SystemUI/src/com/android/systemui/util/ui/AnimatedValue.kt
index 51d2afabd7f9..1112d6f4f25c 100644
--- a/packages/SystemUI/src/com/android/systemui/util/ui/AnimatedValue.kt
+++ b/packages/SystemUI/src/com/android/systemui/util/ui/AnimatedValue.kt
@@ -17,26 +17,58 @@
 
 package com.android.systemui.util.ui
 
+import com.android.systemui.util.ui.AnimatedValue.Animating
+import com.android.systemui.util.ui.AnimatedValue.NotAnimating
+import kotlinx.coroutines.CompletableDeferred
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.firstOrNull
-import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.transformLatest
 
 /**
  * A state comprised of a [value] of type [T] paired with a boolean indicating whether or not the
  * [value] [isAnimating] in the UI.
  */
-data class AnimatedValue<T>(
-    val value: T,
-    val isAnimating: Boolean,
-)
+sealed interface AnimatedValue<out T> {
+
+    /** A [state][value] that is not actively animating in the UI. */
+    data class NotAnimating<out T>(val value: T) : AnimatedValue<T>
+
+    /**
+     * A [state][value] that is actively animating in the UI. Invoking [onStopAnimating] will signal
+     * the source of the state to stop animating.
+     */
+    data class Animating<out T>(
+        val value: T,
+        val onStopAnimating: () -> Unit,
+    ) : AnimatedValue<T>
+}
+
+/** The state held in this [AnimatedValue]. */
+inline val <T> AnimatedValue<T>.value: T
+    get() =
+        when (this) {
+            is Animating -> value
+            is NotAnimating -> value
+        }
+
+/** Returns whether or not this [AnimatedValue] is animating or not. */
+inline val <T> AnimatedValue<T>.isAnimating: Boolean
+    get() = this is Animating<T>
+
+/**
+ * If this [AnimatedValue] [isAnimating], then signal that the animation should be stopped.
+ * Otherwise, do nothing.
+ */
+@Suppress("NOTHING_TO_INLINE")
+inline fun AnimatedValue<*>.stopAnimating() {
+    if (this is Animating) onStopAnimating()
+}
 
 /**
  * An event comprised of a [value] of type [T] paired with a [boolean][startAnimating] indicating
  * whether or not this event should start an animation.
  */
-data class AnimatableEvent<T>(
+data class AnimatableEvent<out T>(
     val value: T,
     val startAnimating: Boolean,
 )
@@ -47,16 +79,87 @@ data class AnimatableEvent<T>(
  * [AnimatableEvent.startAnimating] value is `true`. When [completionEvents] emits a value, the
  * [AnimatedValue.isAnimating] will flip to `false`.
  */
-fun <T> Flow<AnimatableEvent<T>>.toAnimatedValueFlow(
-    completionEvents: Flow<Any?>,
-): Flow<AnimatedValue<T>> = transformLatest { (value, startAnimating) ->
-    emit(AnimatedValue(value, isAnimating = startAnimating))
-    if (startAnimating) {
-        // Wait for a completion now that we've started animating
-        completionEvents
-            .map { Unit } // replace the event so that it's never `null`
-            .firstOrNull() // `null` indicates an empty flow
-            // emit the new state if the flow was not empty.
-            ?.run { emit(AnimatedValue(value, isAnimating = false)) }
+fun <T> Flow<AnimatableEvent<T>>.toAnimatedValueFlow(): Flow<AnimatedValue<T>> =
+    transformLatest { (value, startAnimating) ->
+        if (startAnimating) {
+            val onCompleted = CompletableDeferred<Unit>()
+            emit(Animating(value) { onCompleted.complete(Unit) })
+            // Wait for a completion now that we've started animating
+            onCompleted.await()
+        }
+        emit(NotAnimating(value))
+    }
+
+/**
+ * Zip two [AnimatedValue]s together into a single [AnimatedValue], using [block] to combine the
+ * [value]s of each.
+ *
+ * If either [AnimatedValue] [isAnimating], then the result is also animating. Invoking
+ * [stopAnimating] on the result is equivalent to invoking [stopAnimating] on each input.
+ */
+inline fun <A, B, Z> zip(
+    valueA: AnimatedValue<A>,
+    valueB: AnimatedValue<B>,
+    block: (A, B) -> Z,
+): AnimatedValue<Z> {
+    val zippedValue = block(valueA.value, valueB.value)
+    return when (valueA) {
+        is Animating ->
+            when (valueB) {
+                is Animating ->
+                    Animating(zippedValue) {
+                        valueA.onStopAnimating()
+                        valueB.onStopAnimating()
+                    }
+                is NotAnimating -> Animating(zippedValue, valueA.onStopAnimating)
+            }
+        is NotAnimating ->
+            when (valueB) {
+                is Animating -> Animating(zippedValue, valueB.onStopAnimating)
+                is NotAnimating -> NotAnimating(zippedValue)
+            }
     }
 }
+
+/**
+ * Flattens a nested [AnimatedValue], the result of which holds the [value] of the inner
+ * [AnimatedValue].
+ *
+ * If either the outer or inner [AnimatedValue] [isAnimating], then the flattened result is also
+ * animating. Invoking [stopAnimating] on the result is equivalent to invoking [stopAnimating] on
+ * both the outer and inner values.
+ */
+@Suppress("NOTHING_TO_INLINE")
+inline fun <T> AnimatedValue<AnimatedValue<T>>.flatten(): AnimatedValue<T> = flatMap { it }
+
+/**
+ * Returns an [AnimatedValue], the [value] of which is the result of the given [value] applied to
+ * [block].
+ */
+inline fun <A, B> AnimatedValue<A>.map(block: (A) -> B): AnimatedValue<B> =
+    when (this) {
+        is Animating -> Animating(block(value), ::stopAnimating)
+        is NotAnimating -> NotAnimating(block(value))
+    }
+
+/**
+ * Returns an [AnimatedValue] from the result of [block] being invoked on the [value] original
+ * [AnimatedValue].
+ *
+ * If either the input [AnimatedValue] or the result of [block] [isAnimating], then the flattened
+ * result is also animating. Invoking [stopAnimating] on the result is equivalent to invoking
+ * [stopAnimating] on both values.
+ */
+inline fun <A, B> AnimatedValue<A>.flatMap(block: (A) -> AnimatedValue<B>): AnimatedValue<B> =
+    when (this) {
+        is NotAnimating -> block(value)
+        is Animating ->
+            when (val inner = block(value)) {
+                is Animating ->
+                    Animating(inner.value) {
+                        onStopAnimating()
+                        inner.onStopAnimating()
+                    }
+                is NotAnimating -> Animating(inner.value, onStopAnimating)
+            }
+    }
diff --git a/packages/SystemUI/tests/src/com/android/systemui/statusbar/notification/icon/ui/viewmodel/NotificationIconContainerAlwaysOnDisplayViewModelTest.kt b/packages/SystemUI/tests/src/com/android/systemui/statusbar/notification/icon/ui/viewmodel/NotificationIconContainerAlwaysOnDisplayViewModelTest.kt
index 31efebbc5b60..41c7071a616d 100644
--- a/packages/SystemUI/tests/src/com/android/systemui/statusbar/notification/icon/ui/viewmodel/NotificationIconContainerAlwaysOnDisplayViewModelTest.kt
+++ b/packages/SystemUI/tests/src/com/android/systemui/statusbar/notification/icon/ui/viewmodel/NotificationIconContainerAlwaysOnDisplayViewModelTest.kt
@@ -44,7 +44,9 @@ import com.android.systemui.statusbar.phone.ScreenOffAnimationController
 import com.android.systemui.statusbar.policy.data.repository.FakeDeviceProvisioningRepository
 import com.android.systemui.user.domain.UserDomainLayerModule
 import com.android.systemui.util.mockito.whenever
-import com.android.systemui.util.ui.AnimatedValue
+import com.android.systemui.util.ui.isAnimating
+import com.android.systemui.util.ui.stopAnimating
+import com.android.systemui.util.ui.value
 import com.google.common.truth.Truth.assertThat
 import dagger.BindsInstance
 import dagger.Component
@@ -243,6 +245,7 @@ class NotificationIconContainerAlwaysOnDisplayViewModelTest : SysuiTestCase() {
                 )
             )
             val animationsEnabled by collectLastValue(underTest.animationsEnabled)
+            runCurrent()
 
             keyguardRepository.setKeyguardShowing(true)
             keyguardRepository.setKeyguardOccluded(false)
@@ -266,6 +269,7 @@ class NotificationIconContainerAlwaysOnDisplayViewModelTest : SysuiTestCase() {
     fun isDozing_startAodTransition() =
         scope.runTest {
             val isDozing by collectLastValue(underTest.isDozing)
+            runCurrent()
             keyguardTransitionRepository.sendTransitionStep(
                 TransitionStep(
                     from = KeyguardState.GONE,
@@ -274,13 +278,15 @@ class NotificationIconContainerAlwaysOnDisplayViewModelTest : SysuiTestCase() {
                 )
             )
             runCurrent()
-            assertThat(isDozing).isEqualTo(AnimatedValue(true, isAnimating = true))
+            assertThat(isDozing?.value).isTrue()
+            assertThat(isDozing?.isAnimating).isTrue()
         }
 
     @Test
     fun isDozing_startDozeTransition() =
         scope.runTest {
             val isDozing by collectLastValue(underTest.isDozing)
+            runCurrent()
             keyguardTransitionRepository.sendTransitionStep(
                 TransitionStep(
                     from = KeyguardState.GONE,
@@ -289,13 +295,15 @@ class NotificationIconContainerAlwaysOnDisplayViewModelTest : SysuiTestCase() {
                 )
             )
             runCurrent()
-            assertThat(isDozing).isEqualTo(AnimatedValue(true, isAnimating = false))
+            assertThat(isDozing?.value).isTrue()
+            assertThat(isDozing?.isAnimating).isFalse()
         }
 
     @Test
     fun isDozing_startDozeToAodTransition() =
         scope.runTest {
             val isDozing by collectLastValue(underTest.isDozing)
+            runCurrent()
             keyguardTransitionRepository.sendTransitionStep(
                 TransitionStep(
                     from = KeyguardState.DOZING,
@@ -304,13 +312,15 @@ class NotificationIconContainerAlwaysOnDisplayViewModelTest : SysuiTestCase() {
                 )
             )
             runCurrent()
-            assertThat(isDozing).isEqualTo(AnimatedValue(true, isAnimating = true))
+            assertThat(isDozing?.value).isTrue()
+            assertThat(isDozing?.isAnimating).isTrue()
         }
 
     @Test
     fun isNotDozing_startAodToGoneTransition() =
         scope.runTest {
             val isDozing by collectLastValue(underTest.isDozing)
+            runCurrent()
             keyguardTransitionRepository.sendTransitionStep(
                 TransitionStep(
                     from = KeyguardState.AOD,
@@ -319,13 +329,15 @@ class NotificationIconContainerAlwaysOnDisplayViewModelTest : SysuiTestCase() {
                 )
             )
             runCurrent()
-            assertThat(isDozing).isEqualTo(AnimatedValue(false, isAnimating = true))
+            assertThat(isDozing?.value).isFalse()
+            assertThat(isDozing?.isAnimating).isTrue()
         }
 
     @Test
     fun isDozing_stopAnimation() =
         scope.runTest {
             val isDozing by collectLastValue(underTest.isDozing)
+            runCurrent()
             keyguardTransitionRepository.sendTransitionStep(
                 TransitionStep(
                     from = KeyguardState.AOD,
@@ -335,7 +347,8 @@ class NotificationIconContainerAlwaysOnDisplayViewModelTest : SysuiTestCase() {
             )
             runCurrent()
 
-            underTest.completeDozeAnimation()
+            assertThat(isDozing?.isAnimating).isEqualTo(true)
+            isDozing?.stopAnimating()
             runCurrent()
 
             assertThat(isDozing?.isAnimating).isEqualTo(false)
@@ -345,6 +358,7 @@ class NotificationIconContainerAlwaysOnDisplayViewModelTest : SysuiTestCase() {
     fun isNotVisible_pulseExpanding() =
         scope.runTest {
             val isVisible by collectLastValue(underTest.isVisible)
+            runCurrent()
             notifsKeyguardRepository.setPulseExpanding(true)
             runCurrent()
 
@@ -355,6 +369,7 @@ class NotificationIconContainerAlwaysOnDisplayViewModelTest : SysuiTestCase() {
     fun isNotVisible_notOnKeyguard_dontShowAodIconsWhenShade() =
         scope.runTest {
             val isVisible by collectLastValue(underTest.isVisible)
+            runCurrent()
             keyguardTransitionRepository.sendTransitionStep(
                 TransitionStep(
                     to = KeyguardState.GONE,
@@ -364,13 +379,15 @@ class NotificationIconContainerAlwaysOnDisplayViewModelTest : SysuiTestCase() {
             whenever(screenOffAnimController.shouldShowAodIconsWhenShade()).thenReturn(false)
             runCurrent()
 
-            assertThat(isVisible).isEqualTo(AnimatedValue(false, isAnimating = false))
+            assertThat(isVisible?.value).isFalse()
+            assertThat(isVisible?.isAnimating).isFalse()
         }
 
     @Test
     fun isVisible_bypassEnabled() =
         scope.runTest {
             val isVisible by collectLastValue(underTest.isVisible)
+            runCurrent()
             deviceEntryRepository.setBypassEnabled(true)
             runCurrent()
 
@@ -381,6 +398,7 @@ class NotificationIconContainerAlwaysOnDisplayViewModelTest : SysuiTestCase() {
     fun isNotVisible_pulseExpanding_notBypassing() =
         scope.runTest {
             val isVisible by collectLastValue(underTest.isVisible)
+            runCurrent()
             notifsKeyguardRepository.setPulseExpanding(true)
             deviceEntryRepository.setBypassEnabled(false)
             runCurrent()
@@ -398,26 +416,30 @@ class NotificationIconContainerAlwaysOnDisplayViewModelTest : SysuiTestCase() {
             notifsKeyguardRepository.setNotificationsFullyHidden(true)
             runCurrent()
 
-            assertThat(isVisible).isEqualTo(AnimatedValue(true, isAnimating = true))
+            assertThat(isVisible?.value).isTrue()
+            assertThat(isVisible?.isAnimating).isTrue()
         }
 
     @Test
     fun isVisible_notifsFullyHidden_bypassDisabled_aodDisabled() =
         scope.runTest {
             val isVisible by collectLastValue(underTest.isVisible)
+            runCurrent()
             notifsKeyguardRepository.setPulseExpanding(false)
             deviceEntryRepository.setBypassEnabled(false)
             whenever(dozeParams.alwaysOn).thenReturn(false)
             notifsKeyguardRepository.setNotificationsFullyHidden(true)
             runCurrent()
 
-            assertThat(isVisible).isEqualTo(AnimatedValue(true, isAnimating = false))
+            assertThat(isVisible?.value).isTrue()
+            assertThat(isVisible?.isAnimating).isFalse()
         }
 
     @Test
     fun isVisible_notifsFullyHidden_bypassDisabled_displayNeedsBlanking() =
         scope.runTest {
             val isVisible by collectLastValue(underTest.isVisible)
+            runCurrent()
             notifsKeyguardRepository.setPulseExpanding(false)
             deviceEntryRepository.setBypassEnabled(false)
             whenever(dozeParams.alwaysOn).thenReturn(true)
@@ -425,7 +447,8 @@ class NotificationIconContainerAlwaysOnDisplayViewModelTest : SysuiTestCase() {
             notifsKeyguardRepository.setNotificationsFullyHidden(true)
             runCurrent()
 
-            assertThat(isVisible).isEqualTo(AnimatedValue(true, isAnimating = false))
+            assertThat(isVisible?.value).isTrue()
+            assertThat(isVisible?.isAnimating).isFalse()
         }
 
     @Test
@@ -440,13 +463,15 @@ class NotificationIconContainerAlwaysOnDisplayViewModelTest : SysuiTestCase() {
             notifsKeyguardRepository.setNotificationsFullyHidden(true)
             runCurrent()
 
-            assertThat(isVisible).isEqualTo(AnimatedValue(true, isAnimating = true))
+            assertThat(isVisible?.value).isTrue()
+            assertThat(isVisible?.isAnimating).isTrue()
         }
 
     @Test
     fun isVisible_stopAnimation() =
         scope.runTest {
             val isVisible by collectLastValue(underTest.isVisible)
+            runCurrent()
             notifsKeyguardRepository.setPulseExpanding(false)
             deviceEntryRepository.setBypassEnabled(false)
             whenever(dozeParams.alwaysOn).thenReturn(true)
@@ -454,7 +479,8 @@ class NotificationIconContainerAlwaysOnDisplayViewModelTest : SysuiTestCase() {
             notifsKeyguardRepository.setNotificationsFullyHidden(true)
             runCurrent()
 
-            underTest.completeVisibilityAnimation()
+            assertThat(isVisible?.isAnimating).isEqualTo(true)
+            isVisible?.stopAnimating()
             runCurrent()
 
             assertThat(isVisible?.isAnimating).isEqualTo(false)
diff --git a/packages/SystemUI/tests/src/com/android/systemui/util/ui/AnimatedValueTest.kt b/packages/SystemUI/tests/src/com/android/systemui/util/ui/AnimatedValueTest.kt
index 6e3a732aa8ec..94100fe7f4c4 100644
--- a/packages/SystemUI/tests/src/com/android/systemui/util/ui/AnimatedValueTest.kt
+++ b/packages/SystemUI/tests/src/com/android/systemui/util/ui/AnimatedValueTest.kt
@@ -24,8 +24,6 @@ import com.android.systemui.coroutines.collectLastValue
 import com.google.common.truth.Truth.assertThat
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.MutableSharedFlow
-import kotlinx.coroutines.flow.emptyFlow
-import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.test.runCurrent
 import kotlinx.coroutines.test.runTest
 import org.junit.Test
@@ -38,64 +36,193 @@ class AnimatedValueTest : SysuiTestCase() {
     @Test
     fun animatableEvent_updatesValue() = runTest {
         val events = MutableSharedFlow<AnimatableEvent<Int>>()
-        val values = events.toAnimatedValueFlow(completionEvents = emptyFlow())
+        val values = events.toAnimatedValueFlow()
         val value by collectLastValue(values)
         runCurrent()
 
         events.emit(AnimatableEvent(value = 1, startAnimating = false))
 
-        assertThat(value).isEqualTo(AnimatedValue(value = 1, isAnimating = false))
+        assertThat(value?.value).isEqualTo(1)
+        assertThat(value?.isAnimating).isFalse()
     }
 
     @Test
     fun animatableEvent_startAnimation() = runTest {
         val events = MutableSharedFlow<AnimatableEvent<Int>>()
-        val values = events.toAnimatedValueFlow(completionEvents = emptyFlow())
+        val values = events.toAnimatedValueFlow()
         val value by collectLastValue(values)
         runCurrent()
 
         events.emit(AnimatableEvent(value = 1, startAnimating = true))
 
-        assertThat(value).isEqualTo(AnimatedValue(value = 1, isAnimating = true))
+        assertThat(value?.value).isEqualTo(1)
+        assertThat(value?.isAnimating).isTrue()
     }
 
     @Test
     fun animatableEvent_startAnimation_alreadyAnimating() = runTest {
         val events = MutableSharedFlow<AnimatableEvent<Int>>()
-        val values = events.toAnimatedValueFlow(completionEvents = emptyFlow())
+        val values = events.toAnimatedValueFlow()
         val value by collectLastValue(values)
         runCurrent()
 
         events.emit(AnimatableEvent(value = 1, startAnimating = true))
         events.emit(AnimatableEvent(value = 2, startAnimating = true))
 
-        assertThat(value).isEqualTo(AnimatedValue(value = 2, isAnimating = true))
+        assertThat(value?.value).isEqualTo(2)
+        assertThat(value?.isAnimating).isTrue()
     }
 
     @Test
     fun animatedValue_stopAnimating() = runTest {
         val events = MutableSharedFlow<AnimatableEvent<Int>>()
-        val stopEvent = MutableSharedFlow<Unit>()
-        val values = events.toAnimatedValueFlow(completionEvents = stopEvent)
+        val values = events.toAnimatedValueFlow()
         val value by collectLastValue(values)
         runCurrent()
 
         events.emit(AnimatableEvent(value = 1, startAnimating = true))
-        stopEvent.emit(Unit)
+        assertThat(value?.isAnimating).isTrue()
+        value?.stopAnimating()
 
-        assertThat(value).isEqualTo(AnimatedValue(value = 1, isAnimating = false))
+        assertThat(value?.value).isEqualTo(1)
+        assertThat(value?.isAnimating).isFalse()
     }
 
     @Test
-    fun animatedValue_stopAnimating_notAnimating() = runTest {
+    fun animatedValue_stopAnimatingPrevValue_doesNothing() = runTest {
         val events = MutableSharedFlow<AnimatableEvent<Int>>()
-        val stopEvent = MutableSharedFlow<Unit>()
-        val values = events.toAnimatedValueFlow(completionEvents = stopEvent)
-        values.launchIn(backgroundScope)
+        val values = events.toAnimatedValueFlow()
+        val value by collectLastValue(values)
         runCurrent()
 
-        events.emit(AnimatableEvent(value = 1, startAnimating = false))
+        events.emit(AnimatableEvent(value = 1, startAnimating = true))
+        val prevValue = value
+        assertThat(prevValue?.isAnimating).isTrue()
+
+        events.emit(AnimatableEvent(value = 2, startAnimating = true))
+        assertThat(value?.isAnimating).isTrue()
+        prevValue?.stopAnimating()
+
+        assertThat(value?.value).isEqualTo(2)
+        assertThat(value?.isAnimating).isTrue()
+    }
+
+    @Test
+    fun zipValues_applyTransform() {
+        val animating = AnimatedValue.Animating(1) {}
+        val notAnimating = AnimatedValue.NotAnimating(2)
+        val sum = zip(animating, notAnimating) { a, b -> a + b }
+        assertThat(sum.value).isEqualTo(3)
+    }
+
+    @Test
+    fun zipValues_firstIsAnimating_resultIsAnimating() {
+        var stopped = false
+        val animating = AnimatedValue.Animating(1) { stopped = true }
+        val notAnimating = AnimatedValue.NotAnimating(2)
+        val sum = zip(animating, notAnimating) { a, b -> a + b }
+        assertThat(sum.isAnimating).isTrue()
+
+        sum.stopAnimating()
+        assertThat(stopped).isTrue()
+    }
+
+    @Test
+    fun zipValues_secondIsAnimating_resultIsAnimating() {
+        var stopped = false
+        val animating = AnimatedValue.Animating(1) { stopped = true }
+        val notAnimating = AnimatedValue.NotAnimating(2)
+        val sum = zip(notAnimating, animating) { a, b -> a + b }
+        assertThat(sum.isAnimating).isTrue()
+
+        sum.stopAnimating()
+        assertThat(stopped).isTrue()
+    }
+
+    @Test
+    fun zipValues_bothAnimating_resultIsAnimating() {
+        var firstStopped = false
+        var secondStopped = false
+        val first = AnimatedValue.Animating(1) { firstStopped = true }
+        val second = AnimatedValue.Animating(2) { secondStopped = true }
+        val sum = zip(first, second) { a, b -> a + b }
+        assertThat(sum.isAnimating).isTrue()
+
+        sum.stopAnimating()
+        assertThat(firstStopped).isTrue()
+        assertThat(secondStopped).isTrue()
+    }
 
-        assertThat(stopEvent.subscriptionCount.value).isEqualTo(0)
+    @Test
+    fun zipValues_neitherAnimating_resultIsNotAnimating() {
+        val first = AnimatedValue.NotAnimating(1)
+        val second = AnimatedValue.NotAnimating(2)
+        val sum = zip(first, second) { a, b -> a + b }
+        assertThat(sum.isAnimating).isFalse()
+    }
+
+    @Test
+    fun mapAnimatedValue_isAnimating() {
+        var stopped = false
+        val animating = AnimatedValue.Animating(3) { stopped = true }
+        val squared = animating.map { it * it }
+        assertThat(squared.value).isEqualTo(9)
+        assertThat(squared.isAnimating).isTrue()
+        squared.stopAnimating()
+        assertThat(stopped).isTrue()
+    }
+
+    @Test
+    fun mapAnimatedValue_notAnimating() {
+        val notAnimating = AnimatedValue.NotAnimating(3)
+        val squared = notAnimating.map { it * it }
+        assertThat(squared.value).isEqualTo(9)
+        assertThat(squared.isAnimating).isFalse()
+    }
+
+    @Test
+    fun flattenAnimatingValue_neitherAnimating() {
+        val nested = AnimatedValue.NotAnimating(AnimatedValue.NotAnimating(10))
+        val flattened = nested.flatten()
+        assertThat(flattened.value).isEqualTo(10)
+        assertThat(flattened.isAnimating).isFalse()
+    }
+
+    @Test
+    fun flattenAnimatingValue_outerAnimating() {
+        var stopped = false
+        val inner = AnimatedValue.NotAnimating(10)
+        val nested = AnimatedValue.Animating(inner) { stopped = true }
+        val flattened = nested.flatten()
+        assertThat(flattened.value).isEqualTo(10)
+        assertThat(flattened.isAnimating).isTrue()
+        flattened.stopAnimating()
+        assertThat(stopped).isTrue()
+    }
+
+    @Test
+    fun flattenAnimatingValue_innerAnimating() {
+        var stopped = false
+        val inner = AnimatedValue.Animating(10) { stopped = true }
+        val nested = AnimatedValue.NotAnimating(inner)
+        val flattened = nested.flatten()
+        assertThat(flattened.value).isEqualTo(10)
+        assertThat(flattened.isAnimating).isTrue()
+        flattened.stopAnimating()
+        assertThat(stopped).isTrue()
+    }
+
+    @Test
+    fun flattenAnimatingValue_bothAnimating() {
+        var innerStopped = false
+        var outerStopped = false
+        val inner = AnimatedValue.Animating(10) { innerStopped = true }
+        val nested = AnimatedValue.Animating(inner) { outerStopped = true }
+        val flattened = nested.flatten()
+        assertThat(flattened.value).isEqualTo(10)
+        assertThat(flattened.isAnimating).isTrue()
+        flattened.stopAnimating()
+        assertThat(innerStopped).isTrue()
+        assertThat(outerStopped).isTrue()
     }
 }