Fixes that notifications were sometimes clipped on the lockscreen

When dragging down a notification into the bottom, the top notification
could become clipped.

Test: add notifications, pull down on last notification on lockscreen
Bug: 32437839
Change-Id: Ibb58d1aa7575fbe9d84b8542ac57ffae494bb127

packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java

@@ -4558,6 +4558,7 @@ public class PhoneStatusBar extends BaseStatusBar implements DemoMode,
         mGroupManager.setStatusBarState(state);
         mFalsingManager.setStatusBarState(state);
         mStatusBarWindowManager.setStatusBarState(state);
+        mStackScroller.setStatusBarState(state);
         updateReportRejectedTouchVisibility();
         updateDozing();
     }

packages/SystemUI/src/com/android/systemui/statusbar/stack/AmbientState.java

@@ -22,6 +22,7 @@ import android.view.View;
 import com.android.systemui.R;
 import com.android.systemui.statusbar.ActivatableNotificationView;
 import com.android.systemui.statusbar.NotificationShelf;
+import com.android.systemui.statusbar.StatusBarState;
 import com.android.systemui.statusbar.policy.HeadsUpManager;
 
 import java.util.ArrayList;
@@ -53,6 +54,7 @@ public class AmbientState {
     private int mMaxLayoutHeight;
     private ActivatableNotificationView mLastVisibleBackgroundChild;
     private float mCurrentScrollVelocity;
+    private int mStatusBarState;
 
     public AmbientState(Context context) {
         reload(context);
@@ -250,4 +252,12 @@ public class AmbientState {
     public float getCurrentScrollVelocity() {
         return mCurrentScrollVelocity;
     }
+
+    public boolean isOnKeyguard() {
+        return mStatusBarState == StatusBarState.KEYGUARD;
+    }
+
+    public void setStatusBarState(int statusBarState) {
+        mStatusBarState = statusBarState;
+    }
 }

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

@@ -357,6 +357,7 @@ public class NotificationStackScrollLayout extends ViewGroup
     private Rect mRequestedClipBounds;
     private boolean mInHeadsUpPinnedMode;
     private boolean mHeadsUpAnimatingAway;
+    private int mStatusBarState;
 
     public NotificationStackScrollLayout(Context context) {
         this(context, null);
@@ -1187,7 +1188,7 @@ public class NotificationStackScrollLayout extends ViewGroup
     }
 
     private boolean onKeyguard() {
-        return mPhoneStatusBar.getBarState() == StatusBarState.KEYGUARD;
+        return mStatusBarState == StatusBarState.KEYGUARD;
     }
 
     private void setSwipingInProgress(boolean isSwiped) {
@@ -2124,7 +2125,7 @@ public class NotificationStackScrollLayout extends ViewGroup
             top = mTopPadding;
             bottom = top;
         }
-        if (mPhoneStatusBar.getBarState() != StatusBarState.KEYGUARD) {
+        if (mStatusBarState != StatusBarState.KEYGUARD) {
             top = (int) Math.max(mTopPadding + mStackTranslation, top);
         } else {
             // otherwise the animation from the shade to the keyguard will jump as it's maxed
@@ -2358,7 +2359,7 @@ public class NotificationStackScrollLayout extends ViewGroup
                 }
                 break;
             case MotionEvent.ACTION_UP:
-                if (mPhoneStatusBar.getBarState() != StatusBarState.KEYGUARD && mTouchIsClick &&
+                if (mStatusBarState != StatusBarState.KEYGUARD && mTouchIsClick &&
                         isBelowLastNotification(mInitialTouchX, mInitialTouchY)) {
                     mOnEmptySpaceClickListener.onEmptySpaceClicked(mInitialTouchX, mInitialTouchY);
                 }
@@ -3981,6 +3982,11 @@ public class NotificationStackScrollLayout extends ViewGroup
         updateClipping();
     }
 
+    public void setStatusBarState(int statusBarState) {
+        mStatusBarState = statusBarState;
+        mAmbientState.setStatusBarState(statusBarState);
+    }
+
     /**
      * A listener that is notified when some child locations might have changed.
      */

packages/SystemUI/src/com/android/systemui/statusbar/stack/StackScrollAlgorithm.java

@@ -124,7 +124,8 @@ public class StackScrollAlgorithm {
 
     private void updateClipping(StackScrollState resultState,
             StackScrollAlgorithmState algorithmState, AmbientState ambientState) {
-        float drawStart = ambientState.getTopPadding() + ambientState.getStackTranslation();
+        float drawStart = !ambientState.isOnKeyguard() ? ambientState.getTopPadding()
+                + ambientState.getStackTranslation() : 0;
         float previousNotificationEnd = 0;
         float previousNotificationStart = 0;
         int childCount = algorithmState.visibleChildren.size();