Moving widget padding to drawable instead of using itemDecorator

ItemDecorator uses item position which is not stable during animations.
Moving it to the background allows the padding to be stable

Bug: 236961658
Test: Verified that the app doesn't crash.
Change-Id: Ied12077de4097e827c5c4157f5196346a301f185

res/layout/widgets_list_row_header.xml

@@ -19,7 +19,6 @@
     android:id="@+id/widgets_list_header"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
-    android:paddingVertical="@dimen/widget_list_header_view_vertical_padding"
     android:orientation="horizontal"
     android:importantForAccessibility="yes"
     android:focusable="true"

src/com/android/launcher3/widget/picker/WidgetsListDrawableFactory.java

@@ -27,6 +27,7 @@ import android.content.res.ColorStateList;
 import android.content.res.Resources;
 import android.graphics.drawable.Drawable;
 import android.graphics.drawable.GradientDrawable;
+import android.graphics.drawable.InsetDrawable;
 import android.graphics.drawable.RippleDrawable;
 import android.graphics.drawable.StateListDrawable;
 
@@ -40,6 +41,8 @@ final class WidgetsListDrawableFactory {
     private final float mMiddleCornerRadius;
     private final ColorStateList mSurfaceColor;
     private final ColorStateList mRippleColor;
+    private final int mVerticalPadding;
+    private final int mHeaderMargin;
 
     WidgetsListDrawableFactory(Context context) {
         Resources res = context.getResources();
@@ -48,6 +51,9 @@ final class WidgetsListDrawableFactory {
         mSurfaceColor = context.getColorStateList(R.color.surface);
         mRippleColor = ColorStateList.valueOf(
                 Themes.getAttrColor(context, android.R.attr.colorControlHighlight));
+        mVerticalPadding =
+                res.getDimensionPixelSize(R.dimen.widget_list_header_view_vertical_padding);
+        mHeaderMargin = res.getDimensionPixelSize(R.dimen.widget_list_entry_spacing);
     }
 
     /**
@@ -74,7 +80,10 @@ final class WidgetsListDrawableFactory {
         stateList.addState(
                 LAST.mStateSet,
                 createRoundedRectDrawable(mMiddleCornerRadius, mTopBottomCornerRadius));
-        return new RippleDrawable(mRippleColor, /* content= */ stateList, /* mask= */ stateList);
+        RippleDrawable ripple =
+                new RippleDrawable(mRippleColor, /* content= */ stateList, /* mask= */ stateList);
+        ripple.setPadding(0, mVerticalPadding, 0, mVerticalPadding);
+        return new InsetDrawable(ripple, 0, mHeaderMargin, 0, 0);
     }
 
     /**

src/com/android/launcher3/widget/picker/WidgetsRecyclerView.java

@@ -16,18 +16,12 @@
 
 package com.android.launcher3.widget.picker;
 
-import static com.android.launcher3.widget.picker.WidgetsListAdapter.VIEW_TYPE_WIDGETS_HEADER;
-import static com.android.launcher3.widget.picker.WidgetsListAdapter.VIEW_TYPE_WIDGETS_SEARCH_HEADER;
-
 import android.content.Context;
 import android.graphics.Point;
-import android.graphics.Rect;
 import android.util.AttributeSet;
 import android.util.SparseIntArray;
 import android.view.MotionEvent;
-import android.view.View;
 
-import androidx.annotation.NonNull;
 import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
 import androidx.recyclerview.widget.RecyclerView.OnItemTouchListener;
@@ -55,7 +49,6 @@ public class WidgetsRecyclerView extends FastScrollRecyclerView implements OnIte
      * VIEW_TYPE_WIDGETS_LIST is not visible on the screen.
      */
     private final SparseIntArray mCachedSizes = new SparseIntArray();
-    private final SpacingDecoration mSpacingDecoration;
 
     public WidgetsRecyclerView(Context context) {
         this(context, null);
@@ -70,9 +63,6 @@ public class WidgetsRecyclerView extends FastScrollRecyclerView implements OnIte
         super(context, attrs, defStyleAttr);
         mScrollbarTop = getResources().getDimensionPixelSize(R.dimen.dynamic_grid_edge_margin);
         addOnItemTouchListener(this);
-
-        mSpacingDecoration = new SpacingDecoration(context);
-        addItemDecoration(mSpacingDecoration);
     }
 
     @Override
@@ -183,7 +173,7 @@ public class WidgetsRecyclerView extends FastScrollRecyclerView implements OnIte
     @Override
     protected int getItemsHeight(int untilIndex) {
         // Initialize cache
-        int childCount = getChildCount();
+        int childCount = Math.min(getChildCount(), getAdapter().getItemCount());
         int startPosition;
         if (childCount > 0
                 && ((startPosition = getChildAdapterPosition(getChildAt(0))) != NO_POSITION)) {
@@ -200,7 +190,7 @@ public class WidgetsRecyclerView extends FastScrollRecyclerView implements OnIte
         int totalItemsHeight = 0;
         for (int i = 0; i < untilIndex; i++) {
             int type = mAdapter.getItemViewType(i);
-            totalItemsHeight += mCachedSizes.get(type) + mSpacingDecoration.getSpacing(i, type);
+            totalItemsHeight += mCachedSizes.get(type);
         }
         return totalItemsHeight;
     }
@@ -216,31 +206,4 @@ public class WidgetsRecyclerView extends FastScrollRecyclerView implements OnIte
          */
         int getHeaderViewHeight();
     }
-
-    private static class SpacingDecoration extends RecyclerView.ItemDecoration {
-
-        private final int mSpacingBetweenEntries;
-
-        SpacingDecoration(@NonNull Context context) {
-            mSpacingBetweenEntries =
-                    context.getResources().getDimensionPixelSize(R.dimen.widget_list_entry_spacing);
-        }
-
-        @Override
-        public void getItemOffsets(
-                @NonNull Rect outRect,
-                @NonNull View view,
-                @NonNull RecyclerView parent,
-                @NonNull RecyclerView.State state) {
-            super.getItemOffsets(outRect, view, parent, state);
-            int position = parent.getChildAdapterPosition(view);
-            outRect.top += getSpacing(position, parent.getAdapter().getItemViewType(position));
-        }
-
-        public int getSpacing(int position, int type) {
-            boolean isHeader = type == VIEW_TYPE_WIDGETS_SEARCH_HEADER
-                    || type == VIEW_TYPE_WIDGETS_HEADER;
-            return position > 0 && isHeader ? mSpacingBetweenEntries : 0;
-        }
-    }
 }