title: Fading the image border in an imageview
body: <p>I need to add a fading effect on a <code>ImageView</code>.
  In my situation I have a <code>RelativeLayout</code>, the relative background in yellow and in the center of that background there is a <code>ImageView</code>. Now I need to apply a fade affect on the edge of the <code>ImageView</code>. Is this possible? (<code>Android api 11+</code>)</p>
  
  <p>I tried:</p>
  
  <pre><code>android:requiresFadingEdge="horizontal"
  android:fadingEdge="horizontal"
  android:fadingEdge="vertical"
  android:fadingEdgeLength="40px"
  </code></pre>
  
  <p>but doesn't work..</p>
  
  <p><img src="https://i.stack.imgur.com/ivP8I.png" alt="enter image description here"></p>
  
  <p>This is an example of what I want. Like you can see the <strong>top and the left</strong> are fading, the right and bottom edge, instead, are not fading..</p>
  
  <p>Thanks a lot!</p>