title: Setting src and background for FloatingActionButton
body: <p>When I use background and src in android.support.design.FloatingActionbutton it is not set correctly. Instead it is displayed as</p>
  
  <p><a href="https://i.stack.imgur.com/0SOlI.png" rel="noreferrer"><img src="https://i.stack.imgur.com/0SOlI.png" alt="enter image description here"></a></p>
  
  <pre><code>&lt;android.support.design.widget.FloatingActionButton
  android:id="@+id/fab"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:background="@drawable/pink"
  android:src="@drawable/ic_action_barcode_2"
  android:layout_gravity="bottom|right"
  android:layout_marginBottom="16dp"
  android:layout_marginRight="16dp" /&gt;
  </code></pre>
  
  <p>but when I use ImageView it appears correctly as </p>
  
  <p><a href="https://i.stack.imgur.com/vh5tv.png" rel="noreferrer"><img src="https://i.stack.imgur.com/vh5tv.png" alt="enter image description here"></a></p>
  
  <pre><code>&lt;ImageView
  android:id="@+id/fab"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:background="@drawable/pink"
  android:src="@drawable/ic_action_barcode_2"
  android:layout_gravity="bottom|right"
  android:layout_marginBottom="16dp"
  android:layout_marginRight="16dp" /&gt;
  </code></pre>
  
  <p>why is FloatingActionButton is not displayed correctly? What should I change in my code?</p>