Merge "Fix "No Notification" text not gradually showing on LockScreen" into tm-qpr-dev am: 0162aec6c8 am: d9b74e5bfe

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/19606335

Change-Id: I8f39628c2d3cf957c714569bac8441aaf47baec8
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

9 files changed, 251 insertions, 64 deletions

diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/EmptyShadeView.java b/packages/SystemUI/src/com/android/systemui/statusbar/EmptyShadeView.java
index b9684fcb8a01..3d161d9bfa75 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/EmptyShadeView.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/EmptyShadeView.java
@@ -24,6 +24,8 @@ import android.util.AttributeSet;
 import android.view.View;
 import android.widget.TextView;
 
+import androidx.annotation.NonNull;
+
 import com.android.systemui.R;
 import com.android.systemui.statusbar.notification.row.StackScrollerDecorView;
 import com.android.systemui.statusbar.notification.stack.ExpandableViewState;
@@ -73,6 +75,7 @@ public class EmptyShadeView extends StackScrollerDecorView {
     }
 
     @Override
+    @NonNull
     public ExpandableViewState createExpandableViewState() {
         return new EmptyShadeViewState();
     }
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/NotificationShelf.java b/packages/SystemUI/src/com/android/systemui/statusbar/NotificationShelf.java
index 221428747558..cea3debe6379 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/NotificationShelf.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/NotificationShelf.java
@@ -29,6 +29,8 @@ import android.view.accessibility.AccessibilityNodeInfo;
 import android.view.animation.Interpolator;
 import android.view.animation.PathInterpolator;
 
+import androidx.annotation.NonNull;
+
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.policy.SystemBarUtils;
 import com.android.systemui.R;
@@ -153,6 +155,7 @@ public class NotificationShelf extends ActivatableNotificationView implements
     }
 
     @Override
+    @NonNull
     public ExpandableViewState createExpandableViewState() {
         return new ShelfState();
     }
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/notification/row/ExpandableNotificationRow.java b/packages/SystemUI/src/com/android/systemui/statusbar/notification/row/ExpandableNotificationRow.java
index 855390d75ff8..8574f872ad9c 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/notification/row/ExpandableNotificationRow.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/notification/row/ExpandableNotificationRow.java
@@ -25,8 +25,6 @@ import android.animation.Animator;
 import android.animation.AnimatorListenerAdapter;
 import android.animation.ObjectAnimator;
 import android.animation.ValueAnimator.AnimatorUpdateListener;
-import android.annotation.NonNull;
-import android.annotation.Nullable;
 import android.app.INotificationManager;
 import android.app.Notification;
 import android.app.NotificationChannel;
@@ -68,6 +66,9 @@ import android.widget.Chronometer;
 import android.widget.FrameLayout;
 import android.widget.ImageView;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.logging.MetricsLogger;
 import com.android.internal.logging.nano.MetricsProto.MetricsEvent;
@@ -3247,6 +3248,7 @@ public class ExpandableNotificationRow extends ActivatableNotificationView
     }
 
     @Override
+    @NonNull
     public ExpandableViewState createExpandableViewState() {
         return new NotificationViewState();
     }
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/notification/row/ExpandableView.java b/packages/SystemUI/src/com/android/systemui/statusbar/notification/row/ExpandableView.java
index 8f73b802271d..1e09b8a37645 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/notification/row/ExpandableView.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/notification/row/ExpandableView.java
@@ -29,6 +29,7 @@ import android.view.ViewGroup;
 import android.view.ViewParent;
 import android.widget.FrameLayout;
 
+import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
 import com.android.systemui.Dumpable;
@@ -66,7 +67,7 @@ public abstract class ExpandableView extends FrameLayout implements Dumpable {
     protected float mContentTransformationAmount;
     protected boolean mIsLastChild;
     protected int mContentShift;
-    private final ExpandableViewState mViewState;
+    @NonNull private final ExpandableViewState mViewState;
     private float mContentTranslation;
     protected boolean mLastInSection;
     protected boolean mFirstInSection;
@@ -610,6 +611,7 @@ public abstract class ExpandableView extends FrameLayout implements Dumpable {
 
     public void setActualHeightAnimating(boolean animating) {}
 
+    @NonNull
     protected ExpandableViewState createExpandableViewState() {
         return new ExpandableViewState();
     }
@@ -642,7 +644,12 @@ public abstract class ExpandableView extends FrameLayout implements Dumpable {
         return mViewState;
     }
 
-    @Nullable public ExpandableViewState getViewState() {
+    /**
+     * Get the {@link ExpandableViewState} associated with the view.
+     *
+     * @return the ExpandableView's view state.
+     */
+    @NonNull public ExpandableViewState getViewState() {
         return mViewState;
     }
 
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/notification/row/FooterView.java b/packages/SystemUI/src/com/android/systemui/statusbar/notification/row/FooterView.java
index e43ecf70a308..49dc6550a51f 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/notification/row/FooterView.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/notification/row/FooterView.java
@@ -23,6 +23,8 @@ import android.util.AttributeSet;
 import android.util.IndentingPrintWriter;
 import android.view.View;
 
+import androidx.annotation.NonNull;
+
 import com.android.systemui.R;
 import com.android.systemui.statusbar.notification.stack.ExpandableViewState;
 import com.android.systemui.statusbar.notification.stack.ViewState;
@@ -142,6 +144,7 @@ public class FooterView extends StackScrollerDecorView {
     }
 
     @Override
+    @NonNull
     public ExpandableViewState createExpandableViewState() {
         return new FooterViewState();
     }
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/NotificationStackScrollLayout.java b/packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/NotificationStackScrollLayout.java
index cc87499d39cb..1fb265fea0b1 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/NotificationStackScrollLayout.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/NotificationStackScrollLayout.java
@@ -4460,8 +4460,7 @@ public class NotificationStackScrollLayout extends ViewGroup implements Dumpable
     }
 
     private void updateVisibility() {
-        boolean shouldShow = !mAmbientState.isFullyHidden() || !onKeyguard();
-        setVisibility(shouldShow ? View.VISIBLE : View.INVISIBLE);
+        mController.updateVisibility(!mAmbientState.isFullyHidden() || !onKeyguard());
     }
 
     @ShadeViewRefactor(RefactorComponent.STATE_RESOLVER)
@@ -4526,17 +4525,21 @@ public class NotificationStackScrollLayout extends ViewGroup implements Dumpable
     }
 
     @ShadeViewRefactor(RefactorComponent.SHADE_VIEW)
-    void updateEmptyShadeView(boolean visible, boolean notifVisibleInShade) {
+    void updateEmptyShadeView(boolean visible, boolean areNotificationsHiddenInShade) {
         mEmptyShadeView.setVisible(visible, mIsExpanded && mAnimationsEnabled);
 
         int oldTextRes = mEmptyShadeView.getTextResource();
-        int newTextRes = notifVisibleInShade
+        int newTextRes = areNotificationsHiddenInShade
                 ? R.string.dnd_suppressing_shade_text : R.string.empty_shade_text;
         if (oldTextRes != newTextRes) {
             mEmptyShadeView.setText(newTextRes);
         }
     }
 
+    public boolean isEmptyShadeViewVisible() {
+        return mEmptyShadeView.isVisible();
+    }
+
     @ShadeViewRefactor(RefactorComponent.SHADE_VIEW)
     public void updateFooterView(boolean visible, boolean showDismissView, boolean showHistory) {
         if (mFooterView == null) {
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/NotificationStackScrollLayoutController.java b/packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/NotificationStackScrollLayoutController.java
index e6eceb555897..ec1e6207ef8f 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/NotificationStackScrollLayoutController.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/NotificationStackScrollLayoutController.java
@@ -177,7 +177,6 @@ public class NotificationStackScrollLayoutController {
     private NotificationStackScrollLayout mView;
     private boolean mFadeNotificationsOnDismiss;
     private NotificationSwipeHelper mSwipeHelper;
-    private boolean mShowEmptyShadeView;
     @Nullable private Boolean mHistoryEnabled;
     private int mBarState;
     private HeadsUpAppearanceController mHeadsUpAppearanceController;
@@ -1173,8 +1172,21 @@ public class NotificationStackScrollLayoutController {
     }
 
     /**
-     * Update whether we should show the empty shade view (no notifications in the shade).
-     * If so, send the update to our view.
+     * Set the visibility of the view, and propagate it to specific children.
+     *
+     * @param visible either the view is visible or not.
+     */
+    public void updateVisibility(boolean visible) {
+        mView.setVisibility(visible ? View.VISIBLE : View.INVISIBLE);
+
+        if (mView.getVisibility() == View.VISIBLE) {
+            // Synchronize EmptyShadeView visibility with the parent container.
+            updateShowEmptyShadeView();
+        }
+    }
+
+    /**
+     * Update whether we should show the empty shade view ("no notifications" in the shade).
      *
      * When in split mode, notifications are always visible regardless of the state of the
      * QuickSettings panel. That being the case, empty view is always shown if the other conditions
@@ -1182,18 +1194,31 @@ public class NotificationStackScrollLayoutController {
      */
     public void updateShowEmptyShadeView() {
         Trace.beginSection("NSSLC.updateShowEmptyShadeView");
-        mShowEmptyShadeView = mStatusBarStateController.getCurrentOrUpcomingState() != KEYGUARD
+
+        final boolean shouldShow = getVisibleNotificationCount() == 0
                 && !mView.isQsFullScreen()
-                && getVisibleNotificationCount() == 0;
+                // Hide empty shade view when in transition to Keyguard.
+                // That avoids "No Notifications" to blink when transitioning to AOD.
+                // For more details, see: b/228790482
+                && !isInTransitionToKeyguard();
+
+        mView.updateEmptyShadeView(shouldShow, mZenModeController.areNotificationsHiddenInShade());
 
-        mView.updateEmptyShadeView(
-                mShowEmptyShadeView,
-                mZenModeController.areNotificationsHiddenInShade());
         Trace.endSection();
     }
 
+    /**
+     * @return true if {@link StatusBarStateController} is in transition to the KEYGUARD
+     *         and false otherwise.
+     */
+    private boolean isInTransitionToKeyguard() {
+        final int currentState = mStatusBarStateController.getState();
+        final int upcomingState = mStatusBarStateController.getCurrentOrUpcomingState();
+        return (currentState != upcomingState && upcomingState == KEYGUARD);
+    }
+
     public boolean isShowingEmptyShadeView() {
-        return mShowEmptyShadeView;
+        return mView.isEmptyShadeViewVisible();
     }
 
     public void setHeadsUpAnimatingAway(boolean headsUpAnimatingAway) {
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/StackScrollAlgorithm.java b/packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/StackScrollAlgorithm.java
index 6d513d0da5c1..353355bef7bb 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/StackScrollAlgorithm.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/StackScrollAlgorithm.java
@@ -120,11 +120,64 @@ public class StackScrollAlgorithm {
         updateClipping(algorithmState, ambientState);
         updateSpeedBumpState(algorithmState, speedBumpIndex);
         updateShelfState(algorithmState, ambientState);
+        updateAlphaState(algorithmState, ambientState);
         getNotificationChildrenStates(algorithmState, ambientState);
     }
 
+    private void updateAlphaState(StackScrollAlgorithmState algorithmState,
+            AmbientState ambientState) {
+        for (ExpandableView view : algorithmState.visibleChildren) {
+            final ViewState viewState = view.getViewState();
+
+            final boolean isHunGoingToShade = ambientState.isShadeExpanded()
+                    && view == ambientState.getTrackedHeadsUpRow();
+
+            if (isHunGoingToShade) {
+                // Keep 100% opacity for heads up notification going to shade.
+                viewState.alpha = 1f;
+            } else if (ambientState.isOnKeyguard()) {
+                // Adjust alpha for wakeup to lockscreen.
+                viewState.alpha = 1f - ambientState.getHideAmount();
+            } else if (ambientState.isExpansionChanging()) {
+                // Adjust alpha for shade open & close.
+                float expansion = ambientState.getExpansionFraction();
+                viewState.alpha = ambientState.isBouncerInTransit()
+                        ? BouncerPanelExpansionCalculator.aboutToShowBouncerProgress(expansion)
+                        : ShadeInterpolation.getContentAlpha(expansion);
+            }
+
+            // For EmptyShadeView if on keyguard, we need to control the alpha to create
+            // a nice transition when the user is dragging down the notification panel.
+            if (view instanceof EmptyShadeView && ambientState.isOnKeyguard()) {
+                final float fractionToShade = ambientState.getFractionToShade();
+                viewState.alpha = ShadeInterpolation.getContentAlpha(fractionToShade);
+            }
+
+            NotificationShelf shelf = ambientState.getShelf();
+            if (shelf != null) {
+                final ViewState shelfState = shelf.getViewState();
+
+                // After the shelf has updated its yTranslation, explicitly set alpha=0 for view
+                // below shelf to skip rendering them in the hardware layer. We do not set them
+                // invisible because that runs invalidate & onDraw when these views return onscreen,
+                // which is more expensive.
+                if (shelfState.hidden) {
+                    // When the shelf is hidden, it won't clip views, so we don't hide rows
+                    return;
+                }
+
+                final float shelfTop = shelfState.yTranslation;
+                final float viewTop = viewState.yTranslation;
+                if (viewTop >= shelfTop) {
+                    viewState.alpha = 0;
+                }
+            }
+        }
+    }
+
     /**
      * How expanded or collapsed notifications are when pulling down the shade.
+     *
      * @param ambientState Current ambient state.
      * @return 0 when fully collapsed, 1 when expanded.
      */
@@ -208,22 +261,6 @@ public class StackScrollAlgorithm {
         }
 
         shelf.updateState(algorithmState, ambientState);
-
-        // After the shelf has updated its yTranslation, explicitly set alpha=0 for view below shelf
-        // to skip rendering them in the hardware layer. We do not set them invisible because that
-        // runs invalidate & onDraw when these views return onscreen, which is more expensive.
-        if (shelf.getViewState().hidden) {
-            // When the shelf is hidden, it won't clip views, so we don't hide rows
-            return;
-        }
-        final float shelfTop = shelf.getViewState().yTranslation;
-
-        for (ExpandableView view : algorithmState.visibleChildren) {
-            final float viewTop = view.getViewState().yTranslation;
-            if (viewTop >= shelfTop) {
-                view.getViewState().alpha = 0;
-            }
-        }
     }
 
     private void updateClipping(StackScrollAlgorithmState algorithmState,
@@ -473,21 +510,6 @@ public class StackScrollAlgorithm {
         ExpandableViewState viewState = view.getViewState();
         viewState.location = ExpandableViewState.LOCATION_UNKNOWN;
 
-        final boolean isHunGoingToShade = ambientState.isShadeExpanded()
-                && view == ambientState.getTrackedHeadsUpRow();
-        if (isHunGoingToShade) {
-            // Keep 100% opacity for heads up notification going to shade.
-        } else if (ambientState.isOnKeyguard()) {
-            // Adjust alpha for wakeup to lockscreen.
-            viewState.alpha = 1f - ambientState.getHideAmount();
-        } else if (ambientState.isExpansionChanging()) {
-            // Adjust alpha for shade open & close.
-            float expansion = ambientState.getExpansionFraction();
-            viewState.alpha = ambientState.isBouncerInTransit()
-                    ? BouncerPanelExpansionCalculator.aboutToShowBouncerProgress(expansion)
-                    : ShadeInterpolation.getContentAlpha(expansion);
-        }
-
         final float expansionFraction = getExpansionFractionWithoutShelf(
                 algorithmState, ambientState);
 
diff --git a/packages/SystemUI/tests/src/com/android/systemui/statusbar/notification/stack/StackScrollAlgorithmTest.kt b/packages/SystemUI/tests/src/com/android/systemui/statusbar/notification/stack/StackScrollAlgorithmTest.kt
index 8fd6842911de..35d2363b1c2a 100644
--- a/packages/SystemUI/tests/src/com/android/systemui/statusbar/notification/stack/StackScrollAlgorithmTest.kt
+++ b/packages/SystemUI/tests/src/com/android/systemui/statusbar/notification/stack/StackScrollAlgorithmTest.kt
@@ -3,19 +3,21 @@ package com.android.systemui.statusbar.notification.stack
 import android.annotation.DimenRes
 import android.widget.FrameLayout
 import androidx.test.filters.SmallTest
+import com.android.keyguard.BouncerPanelExpansionCalculator.aboutToShowBouncerProgress
 import com.android.systemui.R
 import com.android.systemui.SysuiTestCase
+import com.android.systemui.animation.ShadeInterpolation.getContentAlpha
 import com.android.systemui.dump.DumpManager
 import com.android.systemui.statusbar.EmptyShadeView
+import com.android.systemui.statusbar.NotificationShelf
+import com.android.systemui.statusbar.StatusBarState
 import com.android.systemui.statusbar.notification.row.ExpandableNotificationRow
 import com.android.systemui.statusbar.notification.row.ExpandableView
-import com.android.systemui.statusbar.notification.stack.StackScrollAlgorithm.BypassController
-import com.android.systemui.statusbar.notification.stack.StackScrollAlgorithm.SectionProvider
 import com.android.systemui.statusbar.phone.StatusBarKeyguardViewManager
 import com.google.common.truth.Truth.assertThat
+import junit.framework.Assert.assertEquals
 import junit.framework.Assert.assertFalse
 import junit.framework.Assert.assertTrue
-import junit.framework.Assert.assertEquals
 import org.junit.Before
 import org.junit.Test
 import org.mockito.Mockito.mock
@@ -26,17 +28,20 @@ class StackScrollAlgorithmTest : SysuiTestCase() {
 
     private val hostView = FrameLayout(context)
     private val stackScrollAlgorithm = StackScrollAlgorithm(context, hostView)
-    private val expandableViewState = ExpandableViewState()
     private val notificationRow = mock(ExpandableNotificationRow::class.java)
     private val dumpManager = mock(DumpManager::class.java)
     private val mStatusBarKeyguardViewManager = mock(StatusBarKeyguardViewManager::class.java)
+    private val notificationShelf = mock(NotificationShelf::class.java)
+    private val emptyShadeView = EmptyShadeView(context, /* attrs= */ null).apply {
+        layout(/* l= */ 0, /* t= */ 0, /* r= */ 100, /* b= */ 100)
+    }
 
     private val ambientState = AmbientState(
-        context,
-        dumpManager,
-        SectionProvider { _, _ -> false },
-        BypassController { false },
-        mStatusBarKeyguardViewManager
+            context,
+            dumpManager,
+            /* sectionProvider */ { _, _ -> false },
+            /* bypassController */ { false },
+            mStatusBarKeyguardViewManager
     )
 
     private val testableResources = mContext.orCreateTestableResources
@@ -49,7 +54,9 @@ class StackScrollAlgorithmTest : SysuiTestCase() {
 
     @Before
     fun setUp() {
-        whenever(notificationRow.viewState).thenReturn(expandableViewState)
+        whenever(notificationShelf.viewState).thenReturn(ExpandableViewState())
+        whenever(notificationRow.viewState).thenReturn(ExpandableViewState())
+
         hostView.addView(notificationRow)
     }
 
@@ -60,7 +67,8 @@ class StackScrollAlgorithmTest : SysuiTestCase() {
 
         stackScrollAlgorithm.resetViewStates(ambientState, 0)
 
-        assertThat(expandableViewState.yTranslation).isEqualTo(stackScrollAlgorithm.mHeadsUpInset)
+        assertThat(notificationRow.viewState.yTranslation)
+                .isEqualTo(stackScrollAlgorithm.mHeadsUpInset)
     }
 
     @Test
@@ -75,15 +83,12 @@ class StackScrollAlgorithmTest : SysuiTestCase() {
         stackScrollAlgorithm.resetViewStates(ambientState, 0)
 
         // top margin presence should decrease heads up translation up to minHeadsUpTranslation
-        assertThat(expandableViewState.yTranslation).isEqualTo(minHeadsUpTranslation)
+        assertThat(notificationRow.viewState.yTranslation).isEqualTo(minHeadsUpTranslation)
     }
 
     @Test
     fun resetViewStates_emptyShadeView_isCenteredVertically() {
         stackScrollAlgorithm.initView(context)
-        val emptyShadeView = EmptyShadeView(context, /* attrs= */ null).apply {
-            layout(/* l= */ 0, /* t= */ 0, /* r= */ 100, /* b= */ 100)
-        }
         hostView.removeAllViews()
         hostView.addView(emptyShadeView)
         ambientState.layoutMaxHeight = 1280
@@ -98,6 +103,121 @@ class StackScrollAlgorithmTest : SysuiTestCase() {
     }
 
     @Test
+    fun resetViewStates_hunGoingToShade_viewBecomesOpaque() {
+        whenever(notificationRow.isAboveShelf).thenReturn(true)
+        ambientState.isShadeExpanded = true
+        ambientState.trackedHeadsUpRow = notificationRow
+        stackScrollAlgorithm.initView(context)
+
+        stackScrollAlgorithm.resetViewStates(ambientState, /* speedBumpIndex= */ 0)
+
+        assertThat(notificationRow.viewState.alpha).isEqualTo(1f)
+    }
+
+    @Test
+    fun resetViewStates_isExpansionChanging_viewBecomesTransparent() {
+        whenever(mStatusBarKeyguardViewManager.isBouncerInTransit).thenReturn(false)
+        ambientState.isExpansionChanging = true
+        ambientState.expansionFraction = 0.25f
+        stackScrollAlgorithm.initView(context)
+
+        stackScrollAlgorithm.resetViewStates(ambientState, /* speedBumpIndex= */ 0)
+
+        val expected = getContentAlpha(0.25f)
+        assertThat(notificationRow.viewState.alpha).isEqualTo(expected)
+    }
+
+    @Test
+    fun resetViewStates_isExpansionChangingWhileBouncerInTransit_viewBecomesTransparent() {
+        whenever(mStatusBarKeyguardViewManager.isBouncerInTransit).thenReturn(true)
+        ambientState.isExpansionChanging = true
+        ambientState.expansionFraction = 0.25f
+        stackScrollAlgorithm.initView(context)
+
+        stackScrollAlgorithm.resetViewStates(ambientState, /* speedBumpIndex= */ 0)
+
+        val expected = aboutToShowBouncerProgress(0.25f)
+        assertThat(notificationRow.viewState.alpha).isEqualTo(expected)
+    }
+
+    @Test
+    fun resetViewStates_isOnKeyguard_viewBecomesTransparent() {
+        ambientState.setStatusBarState(StatusBarState.KEYGUARD)
+        ambientState.hideAmount = 0.25f
+        stackScrollAlgorithm.initView(context)
+
+        stackScrollAlgorithm.resetViewStates(ambientState, /* speedBumpIndex= */ 0)
+
+        assertThat(notificationRow.viewState.alpha).isEqualTo(1f - ambientState.hideAmount)
+    }
+
+    @Test
+    fun resetViewStates_isOnKeyguard_emptyShadeViewBecomesTransparent() {
+        ambientState.setStatusBarState(StatusBarState.KEYGUARD)
+        ambientState.fractionToShade = 0.25f
+        stackScrollAlgorithm.initView(context)
+        hostView.removeAllViews()
+        hostView.addView(emptyShadeView)
+
+        stackScrollAlgorithm.resetViewStates(ambientState, /* speedBumpIndex= */ 0)
+
+        val expected = getContentAlpha(ambientState.fractionToShade)
+        assertThat(emptyShadeView.viewState.alpha).isEqualTo(expected)
+    }
+
+    @Test
+    fun resetViewStates_isOnKeyguard_emptyShadeViewBecomesOpaque() {
+        ambientState.setStatusBarState(StatusBarState.SHADE)
+        ambientState.fractionToShade = 0.25f
+        stackScrollAlgorithm.initView(context)
+        hostView.removeAllViews()
+        hostView.addView(emptyShadeView)
+
+        stackScrollAlgorithm.resetViewStates(ambientState, /* speedBumpIndex= */ 0)
+
+        assertThat(emptyShadeView.viewState.alpha).isEqualTo(1f)
+    }
+
+    @Test
+    fun resetViewStates_hiddenShelf_viewAlphaDoesNotChange() {
+        val expected = notificationShelf.viewState.alpha
+        notificationShelf.viewState.hidden = true
+        ambientState.shelf = notificationShelf
+        stackScrollAlgorithm.initView(context)
+
+        stackScrollAlgorithm.resetViewStates(ambientState, /* speedBumpIndex= */ 0)
+
+        assertThat(notificationShelf.viewState.alpha).isEqualTo(expected)
+    }
+
+    @Test
+    fun resetViewStates_shelfTopLessThanViewTop_hidesView() {
+        notificationRow.viewState.yTranslation = 10f
+        notificationShelf.viewState.yTranslation = 0.9f
+        notificationShelf.viewState.hidden = false
+        ambientState.shelf = notificationShelf
+        stackScrollAlgorithm.initView(context)
+
+        stackScrollAlgorithm.resetViewStates(ambientState, /* speedBumpIndex= */ 0)
+
+        assertThat(notificationRow.viewState.alpha).isEqualTo(0f)
+    }
+
+    @Test
+    fun resetViewStates_shelfTopGreaterOrEqualThanViewTop_viewAlphaDoesNotChange() {
+        val expected = notificationRow.viewState.alpha
+        notificationRow.viewState.yTranslation = 10f
+        notificationShelf.viewState.yTranslation = 10f
+        notificationShelf.viewState.hidden = false
+        ambientState.shelf = notificationShelf
+        stackScrollAlgorithm.initView(context)
+
+        stackScrollAlgorithm.resetViewStates(ambientState, /* speedBumpIndex= */ 0)
+
+        assertThat(notificationRow.viewState.alpha).isEqualTo(expected)
+    }
+
+    @Test
     fun getGapForLocation_onLockscreen_returnsSmallGap() {
         val gap = stackScrollAlgorithm.getGapForLocation(
                 /* fractionToShade= */ 0f, /* onKeyguard= */ true)
@@ -267,7 +387,6 @@ class StackScrollAlgorithmTest : SysuiTestCase() {
         assertEquals(10f, expandableViewState.yTranslation)
     }
 
-
     @Test
     fun clampHunToTop_viewYFarAboveVisibleStack_heightCollapsed() {
         val expandableViewState = ExpandableViewState()