Adjust the position of playback queue list items

This CL adds an ItemDecoration above the first item of playback queue. As a result
the normal list items are moved a bit downward when the queue is not scrolled.

Fixes: 132653118
Test: manual
Change-Id: Ie13626a592b216fce4390b3a65364e86814c722c

2 files changed, 29 insertions, 0 deletions

diff --git a/res/values/dimens.xml b/res/values/dimens.xml
index 633d1b3..d3fb9d1 100644
--- a/res/values/dimens.xml
+++ b/res/values/dimens.xml
@@ -152,6 +152,9 @@
     <dimen name="fragment_metadata_margin_x">@*android:dimen/car_margin</dimen>
     <dimen name="playback_title_margin_end">@*android:dimen/car_padding_3</dimen>
 
+    <!-- PlaybackFragment.java -->
+    <dimen name="playback_queue_list_padding_top">@*android:dimen/car_padding_4</dimen>
+
     <!-- queue_list_item.xml -->
     <dimen name="queue_list_item_height">116dp</dimen>
     <dimen name="queue_list_item_padding_x">@*android:dimen/car_keyline_1</dimen>
diff --git a/src/com/android/car/media/PlaybackFragment.java b/src/com/android/car/media/PlaybackFragment.java
index d869b5b..5b0dd56 100644
--- a/src/com/android/car/media/PlaybackFragment.java
+++ b/src/com/android/car/media/PlaybackFragment.java
@@ -19,6 +19,7 @@ package com.android.car.media;
 import android.annotation.Nullable;
 import android.content.Context;
 import android.content.res.ColorStateList;
+import android.graphics.Rect;
 import android.os.Bundle;
 import android.util.Log;
 import android.view.LayoutInflater;
@@ -215,6 +216,25 @@ public class PlaybackFragment extends Fragment {
         }
     }
 
+    private class QueueTopItemDecoration extends RecyclerView.ItemDecoration {
+        int mHeight;
+        int mDecorationPosition;
+
+        QueueTopItemDecoration(int height, int decorationPosition) {
+            mHeight = height;
+            mDecorationPosition = decorationPosition;
+        }
+
+        @Override
+        public void getItemOffsets(Rect outRect, View view, RecyclerView parent,
+                RecyclerView.State state) {
+            super.getItemOffsets(outRect, view, parent, state);
+            if (parent.getChildAdapterPosition(view) == mDecorationPosition) {
+                outRect.top = mHeight;
+            }
+        }
+    }
+
     @Override
     public View onCreateView(@NonNull LayoutInflater inflater, final ViewGroup container,
             Bundle savedInstanceState) {
@@ -298,6 +318,12 @@ public class PlaybackFragment extends Fragment {
         mPlaybackQueueBackgroundAlpha = getResources().getFloat(
                 R.dimen.playback_queue_background_alpha);
 
+        int decorationHeight = getResources().getDimensionPixelSize(
+                R.dimen.playback_queue_list_padding_top);
+        // Put the decoration above the first item.
+        int decorationPosition = 0;
+        mQueue.addItemDecoration(new QueueTopItemDecoration(decorationHeight, decorationPosition));
+
         mQueue.setVerticalFadingEdgeEnabled(
                 getResources().getBoolean(R.bool.queue_fading_edge_length_enabled));
         mQueueAdapter = new QueueItemsAdapter();