title: Android: animate circular progress drawable
body: <p>I need a drawable that looks like the rotating progress circle. That drawable I want to use for instance in an ImageView inside a GridView etc.</p>
  
  <p>So, according to other posts I took the progress_medium_holo.xml from the folder \sdk\platforms\android-xx\data\res\drawable which looks like this. And I also copied the PNG files which are used by this drawable.</p>
  
  <pre><code>&lt;layer-list xmlns:android="http://schemas.android.com/apk/res/android"&gt;
      &lt;item&gt;
          &lt;rotate
               android:drawable="@drawable/spinner_48_outer_holo"
               android:pivotX="50%"
               android:pivotY="50%"
               android:fromDegrees="0"
               android:toDegrees="1080" /&gt;
      &lt;/item&gt;
      &lt;item&gt;
          &lt;rotate
               android:drawable="@drawable/spinner_48_inner_holo"
               android:pivotX="50%"
               android:pivotY="50%"
               android:fromDegrees="720"
               android:toDegrees="0" /&gt;
      &lt;/item&gt;
  &lt;/layer-list&gt;
  </code></pre>
  
  <p>Within my layout I then used for instance this ImageView which is used the progress-drawable.</p>
  
  <pre><code>&lt;ImageView
      android:id="@+id/element_image"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:layout_gravity="center"
      android:paddingBottom="5dp"
      android:paddingTop="5dp"
      android:src="@drawable/progress_medium_holo" /&gt;
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/WoRNk.png" alt="static progress circle"></p>
  
  <p>But the result is a static circle-progress. Is there a way to animate that one by XML definition and using no code?</p>