Fixing split shade going full black when changing density

The source of issue was status bar height defined in px while shelf height is defined in dp. When changing density, shelf height value in px decreases but status bar height remains the same. When density is low enough it means status bar height ends up bigger than shelf height and that messes up the calculation of NSSL's min expansion height.

Fixes: 210476328
Test: When having some notifications, change Display size to "Small" in settings -> expand split shade and check it's visible
Change-Id: I1e2506f9cf8b21f776a3698f58863ed868da07ba

packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/NotificationStackScrollLayout.java

@@ -411,7 +411,7 @@ public class NotificationStackScrollLayout extends ViewGroup implements Dumpable
     private NotificationShelf mShelf;
     private int mMaxDisplayedNotifications = -1;
     private float mKeyguardBottomPadding = -1;
-    private int mStatusBarHeight;
+    @VisibleForTesting int mStatusBarHeight;
     private int mMinInteractionHeight;
     private final Rect mClipRect = new Rect();
     private boolean mIsClipped;
@@ -4849,8 +4849,12 @@ public class NotificationStackScrollLayout extends ViewGroup implements Dumpable
 
     @ShadeViewRefactor(RefactorComponent.COORDINATOR)
     public int getMinExpansionHeight() {
+        // shelf height is defined in dp but status bar height can be defined in px, that makes
+        // relation between them variable - sometimes one might be bigger than the other when
+        // changing density. That’s why we need to ensure we’re not subtracting negative value below
         return mShelf.getIntrinsicHeight()
-                - (mShelf.getIntrinsicHeight() - mStatusBarHeight + mWaterfallTopInset) / 2
+                - Math.max(0,
+                (mShelf.getIntrinsicHeight() - mStatusBarHeight + mWaterfallTopInset) / 2)
                 + mWaterfallTopInset;
     }
 

packages/SystemUI/tests/src/com/android/systemui/statusbar/notification/stack/NotificationStackScrollLayoutTest.java

@@ -22,6 +22,7 @@ import static android.view.View.GONE;
 import static com.android.systemui.statusbar.notification.stack.NotificationStackScrollLayout.ROWS_ALL;
 import static com.android.systemui.statusbar.notification.stack.NotificationStackScrollLayout.ROWS_GENTLE;
 
+import static com.google.common.truth.Truth.assertThat;
 import static com.google.common.truth.Truth.assertWithMessage;
 
 import static junit.framework.Assert.assertEquals;
@@ -103,6 +104,7 @@ public class NotificationStackScrollLayoutTest extends SysuiTestCase {
     @Mock private NotificationSwipeHelper mNotificationSwipeHelper;
     @Mock private NotificationStackScrollLayoutController mStackScrollLayoutController;
     @Mock private UnlockedScreenOffAnimationController mUnlockedScreenOffAnimationController;
+    @Mock private NotificationShelf mNotificationShelf;
 
     @Before
     @UiThreadTest
@@ -124,13 +126,13 @@ public class NotificationStackScrollLayoutTest extends SysuiTestCase {
         mDependency.injectTestDependency(GroupMembershipManager.class, mGroupMembershipManger);
         mDependency.injectTestDependency(GroupExpansionManager.class, mGroupExpansionManager);
         mDependency.injectTestDependency(AmbientState.class, mAmbientState);
+        mDependency.injectTestDependency(NotificationShelf.class, mNotificationShelf);
         mDependency.injectTestDependency(
                 UnlockedScreenOffAnimationController.class, mUnlockedScreenOffAnimationController);
 
         NotificationShelfController notificationShelfController =
                 mock(NotificationShelfController.class);
-        NotificationShelf notificationShelf = mock(NotificationShelf.class);
-        when(notificationShelfController.getView()).thenReturn(notificationShelf);
+        when(notificationShelfController.getView()).thenReturn(mNotificationShelf);
         when(mNotificationSectionsManager.createSectionsForBuckets()).thenReturn(
                 new NotificationSection[]{
                         mNotificationSection
@@ -160,7 +162,7 @@ public class NotificationStackScrollLayoutTest extends SysuiTestCase {
                         anyBoolean());
         doNothing().when(mGroupExpansionManager).collapseGroups();
         doNothing().when(mExpandHelper).cancelImmediately();
-        doNothing().when(notificationShelf).setAnimationsEnabled(anyBoolean());
+        doNothing().when(mNotificationShelf).setAnimationsEnabled(anyBoolean());
     }
 
     @Test
@@ -203,21 +205,43 @@ public class NotificationStackScrollLayoutTest extends SysuiTestCase {
 
     @Test
     @UiThreadTest
-    public void testSetExpandedHeight_blockingHelperManagerReceivedCallbacks() {
-        final float[] expectedHeight = {0f};
-        final float[] expectedAppear = {0f};
+    public void testSetExpandedHeight_listenerReceivedCallbacks() {
+        final float expectedHeight = 0f;
 
         mStackScroller.addOnExpandedHeightChangedListener((height, appear) -> {
-            Assert.assertEquals(expectedHeight[0], height, 0);
-            Assert.assertEquals(expectedAppear[0], appear, .1);
+            Assert.assertEquals(expectedHeight, height, 0);
         });
-        expectedHeight[0] = 1f;
-        expectedAppear[0] = 1f;
-        mStackScroller.setExpandedHeight(expectedHeight[0]);
+        mStackScroller.setExpandedHeight(expectedHeight);
+    }
 
-        expectedHeight[0] = 100f;
-        expectedAppear[0] = 0f;
-        mStackScroller.setExpandedHeight(expectedHeight[0]);
+    @Test
+    public void testAppearFractionCalculation() {
+        // appear start position
+        when(mNotificationShelf.getIntrinsicHeight()).thenReturn(100);
+        // because it's the same as shelf height, appear start position equals shelf height
+        mStackScroller.mStatusBarHeight = 100;
+        // appear end position
+        when(mEmptyShadeView.getHeight()).thenReturn(200);
+
+        assertEquals(0f, mStackScroller.calculateAppearFraction(100));
+        assertEquals(1f, mStackScroller.calculateAppearFraction(200));
+        assertEquals(0.5f, mStackScroller.calculateAppearFraction(150));
+    }
+
+    @Test
+    public void testAppearFractionCalculationIsNotNegativeWhenShelfBecomesSmaller() {
+        // this situation might occur if status bar height is defined in pixels while shelf height
+        // in dp and screen density changes - appear start position
+        // (calculated in NSSL#getMinExpansionHeight) that is adjusting for status bar might
+        // increase and become bigger that end position, which should be prevented
+
+        // appear start position
+        when(mNotificationShelf.getIntrinsicHeight()).thenReturn(80);
+        mStackScroller.mStatusBarHeight = 100;
+        // appear end position
+        when(mEmptyShadeView.getHeight()).thenReturn(90);
+
+        assertThat(mStackScroller.calculateAppearFraction(100)).isAtLeast(0);
     }
 
     @Test