Split shade motion: improve expansion timing

In this CL the approach is the following:
1 - Define a minimum content height in NSSL for split shade
2 - Use the minimum height when computing Nssl#getEmptyBottomMargin()
3 - Components (Npvc) that calculate expansion fraction already use
    Nssl#getEmptyBottomMargin().

Bug: 213585177
Test: Manually
Change-Id: Id74531a95300ed093edb21c379b57b4ce6836771

2 files changed, 21 insertions, 1 deletions

diff --git a/packages/SystemUI/res/values/dimens.xml b/packages/SystemUI/res/values/dimens.xml
index f94031c73e3c..b35571c17db7 100644
--- a/packages/SystemUI/res/values/dimens.xml
+++ b/packages/SystemUI/res/values/dimens.xml
@@ -369,6 +369,13 @@
     <!-- The top margin of the panel that holds the list of notifications. -->
     <dimen name="notification_panel_margin_top">0dp</dimen>
 
+    <!-- The minimum content height for the split shade NSSL.
+         It is used because if the height is too small, the expansion motion is too fast.
+         Note that the value of 256dp is more or less a random value and can be changed to tweak
+         the expansion motion.
+    -->
+    <dimen name="nssl_split_shade_min_content_height">256dp</dimen>
+
     <!-- The bottom margin of the panel that holds the list of notifications. -->
     <dimen name="notification_panel_margin_bottom">0dp</dimen>
 
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 428334369e21..abf24a07db8a 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
@@ -202,6 +202,7 @@ public class NotificationStackScrollLayout extends ViewGroup implements Dumpable
     private int mBottomMargin;
     private int mBottomInset = 0;
     private float mQsExpansionFraction;
+    private final int mSplitShadeMinContentHeight;
 
     /**
      * The algorithm which calculates the properties for our children
@@ -583,6 +584,8 @@ public class NotificationStackScrollLayout extends ViewGroup implements Dumpable
                 .getDefaultColor();
         int minHeight = res.getDimensionPixelSize(R.dimen.notification_min_height);
         int maxHeight = res.getDimensionPixelSize(R.dimen.notification_max_height);
+        mSplitShadeMinContentHeight = res.getDimensionPixelSize(
+                R.dimen.nssl_split_shade_min_content_height);
         mExpandHelper = new ExpandHelper(getContext(), mExpandHelperCallback,
                 minHeight, maxHeight);
         mExpandHelper.setEventSource(this);
@@ -3886,7 +3889,17 @@ public class NotificationStackScrollLayout extends ViewGroup implements Dumpable
 
     @ShadeViewRefactor(RefactorComponent.COORDINATOR)
     int getEmptyBottomMargin() {
-        return Math.max(mMaxLayoutHeight - mContentHeight, 0);
+        int contentHeight;
+        if (mShouldUseSplitNotificationShade) {
+            // When in split shade and there are no notifications, the height can be too low, as
+            // it is based on notifications bottom, which is lower on split shade.
+            // Here we prefer to use at least a minimum height defined for split shade.
+            // Otherwise the expansion motion is too fast.
+            contentHeight = Math.max(mSplitShadeMinContentHeight, mContentHeight);
+        } else {
+            contentHeight = mContentHeight;
+        }
+        return Math.max(mMaxLayoutHeight - contentHeight, 0);
     }
 
     @ShadeViewRefactor(RefactorComponent.STATE_RESOLVER)