title: Set android:altSrc programmatically in ImageFilterView?
body: <p>this is my layout element.</p>
  
  <pre><code>&lt;android.support.constraint.utils.ImageFilterView
          android:id="@+id/start_track"
          android:layout_width="96dp" android:layout_height="49dp"
          android:src="@drawable/icons_copy_6"
          app:altSrc="@drawable/icons_copy_4"
          app:layout_constraintTop_toTopOf="parent"
          app:layout_constraintStart_toStartOf="parent"
          android:visibility="visible"/&gt;
  </code></pre>
  
  <p>and in Activity, I'm initializing this view as below.</p>
  
  <pre><code>ImageFilterView thumb = v.findViewById(R.id.start_thumb);
  </code></pre>
  
  <p>I'm able to set the image src as below</p>
  
  <pre><code>thumb.setImageDrawable(getResources().getDrawable(mThumbDisabled));
  </code></pre>
  
  <p><strong>How do I set <code>app:altSrc="@drawable/icons_copy_4"</code> Dynamically ?</strong></p>