title: How to add shadow to a imageview?
body: <p>I'm trying to add a border and a shadow to my imageview, which is placed in a ConstraintLayout.
  I tried to use a 9 patch image, but it not work at all!</p>
  
  <p>Below, is the layout that contains the imageview.</p>
  
  <pre><code>&lt;android.support.constraint.ConstraintLayout
      xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto"
      xmlns:tools="http://schemas.android.com/tools"
      android:layout_width="match_parent"
      android:layout_height="match_parent"&gt;
  
      &lt;android.support.constraint.Guideline
          android:id="@+id/guideline_vertical_start"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:orientation="vertical"
          app:layout_constraintGuide_percent="0.04" /&gt;
  
      &lt;ImageView
          android:id="@+id/list_item_google_cards_media_image"
          android:layout_width="0dp"
          android:layout_height="200dp"
          app:layout_constraintDimensionRatio="w,400:576"
          app:layout_constraintStart_toStartOf="@+id/guideline_vertical_start"
          app:layout_constraintTop_toTopOf="parent"
          app:layout_constraintVertical_bias="0.8"
          android:layout_marginTop="8dp"
          android:scaleType="centerCrop"
          android:src="@drawable/default_image"
          android:contentDescription="@string/cd_main_image" /&gt;
  
  &lt;/android.support.constraint.ConstraintLayout&gt;
  </code></pre>
  
  <p>I wish to have something similar to the image below.
  <a href="https://i.stack.imgur.com/Um16V.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Um16V.png" alt="Result Expected"></a></p>