title: android ImageView with level-list do not work
body: <p>start_background.xml</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;level-list xmlns:android="http://schemas.android.com/apk/res/android"&gt;
  &lt;item
      android:drawable="@color/grey"
      android:maxLevel="1"
      /&gt;
  &lt;item
      android:drawable="@color/grey"
      android:maxLevel="2"
      /&gt;
  &lt;item
      android:drawable="@color/grey"
      android:maxLevel="3"
      /&gt;
  
  &lt;/level-list&gt;
  </code></pre>
  
  <p>start_activity.xml</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical" android:layout_width="match_parent"
  android:layout_height="match_parent"
  
  android:id="@+id/page"
  &gt;
  &lt;ImageView
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:background="@drawable/start_background"
      android:id="@+id/start"
      /&gt;
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p>Java Code</p>
  
  <pre><code>ImageView image= (ImageView)findViewById(R.id.start);
  LevelListDrawable background=(LevelListDrawable)image.getBackground();
  background.setLevel(3);
  </code></pre>
  
  <p>but it can not change the background, I have try to change android:background to android:src, it didn't work also.</p>
  
  <p>logcat:</p>
  
  <pre><code>2690-2705/com.jifa.runandcatch2 W/EGL_emulation﹕     eglSurfaceAttrib not implemented
  2690-2705/com.jifa.runandcatch2 W/OpenGLRenderer﹕ Failed to set EGL_SWAP_BEHAVIOR on surface 0xae0e1de0, error=EGL_SUCCESS
  </code></pre>
  
  <p>how to solve it, thanks.</p>