在拖动期间，Recyclerview单元格的阴影被剪裁

Question

当要拖动一个单元格时，我使用cardView.setCardElevation api增加代码中的高程。当拖动开始时，由于某种原因，高程阴影会被剪裁。当一个单元被丢弃并且我在降低它之前检查高程时，它看起来没问题。因此即使高度很好，阴影也会因某种原因而被削减。我试图在recyclerview上添加填充到单元格和clipChildren = false，但它没有任何区别。有什么想法吗？

RecyclerView：

    <?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <android.support.v7.widget.RecyclerView
        android:id="@+id/blrtMediaSelector_recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/white"
        android:scrollbars="vertical" />
    <android.support.design.widget.FloatingActionButton
        android:id="@+id/blrtMediaSelector_addBtn"
        app:layout_behavior="blrtapp.droid.mediaPicker.AddButtonBehaviour"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        android:layout_margin="16dp"
        app:fabSize="normal"
        android:src="@drawable/ic_plus" />
</android.support.design.widget.CoordinatorLayout>

细胞：

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/mediaSelectorCell_cardView"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="2dp"
    card_view:cardUseCompatPadding="true"
    card_view:cardCornerRadius="2dp"
    android:foreground="?android:attr/selectableItemBackground"
    android:clickable="true">
    <RelativeLayout
        android:id="@+id/mediaSelectorCell_parentLayout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:padding="2dp"
        android:background="@color/white">
    <!-- thumbnail -->
        <ImageView
            android:id="@+id/mediaSelectorCell_thumbnail"
            android:layout_width="@dimen/blrtMediaSelectorCell_size"
            android:layout_height="@dimen/blrtMediaSelectorCell_size"
            android:layout_alignParentStart="true"
            android:layout_alignParentTop="true"
            android:scaleType="centerCrop"
            android:src="@drawable/splash" />
    <!-- select icon -->
        <ImageView
            android:id="@+id/mediaSelectorCell_selectIcon"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignEnd="@id/mediaSelectorCell_thumbnail"
            android:layout_alignBottom="@id/mediaSelectorCell_thumbnail"
            android:layout_marginEnd="2dp"
            android:layout_marginBottom="2dp" />
    <!-- container for text fields -->
        <LinearLayout
            android:id="@+id/mediaSelectorCell_textContainer"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerVertical="true"
            android:layout_toRightOf="@id/mediaSelectorCell_thumbnail"
            android:paddingStart="6dp"
            android:paddingEnd="2dp"
            android:orientation="vertical">
        <!-- primary text -->
            <TextView
                android:id="@+id/mediaSelectorCell_primaryTex"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:textColor="@color/charcoal"
                android:ellipsize="end"
                android:maxLines="1"
                android:text="Primary text"
                android:textSize="14sp" />
        <!-- secondary text -->
            <TextView
                android:id="@+id/mediaSelectorCell_secondaryText"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:ellipsize="end"
                android:maxLines="1"
                android:textColor="@color/gray4"
                android:text="secondary text"
                android:textSize="12sp" />
        </LinearLayout>
    <!-- anchor to drag the cell -->
        <ImageButton
            android:id="@+id/mediaSelectorCell_dragAnchorButton"
            android:layout_width="44dp"
            android:layout_height="44dp"
            android:layout_alignParentEnd="true"
            android:layout_marginEnd="8dp"
            android:scaleType="center"
            android:background="@color/white"
            android:src="@drawable/media_drag"
            android:layout_centerVertical="true" />
    </RelativeLayout>
</android.support.v7.widget.CardView>