title: Blue highlight over an ImageView when the user taps it
body: <p>I have a LinearLayout "card" with an ImageView and a TextView. I want the card to be highlighted when the user taps it. See <a href="http://www.youtube.com/watch?v=Yx1l9Y7GIk8&amp;feature=share&amp;t=15m17s" rel="noreferrer">http://www.youtube.com/watch?v=Yx1l9Y7GIk8&amp;feature=share&amp;t=15m17s</a> for an example.</p>
  
  <p>This is easily done for the TextView by setting <code>android:background="@drawable/blue_highlight"</code>. Below is res/drawable/blue_highlight.xml:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;selector xmlns:android="http://schemas.android.com/apk/res/android"&gt;
    &lt;item android:state_selected="true" android:drawable="@color/selected"/&gt;
    &lt;item android:state_pressed="true" android:drawable="@color/pressed"/&gt;
    &lt;item android:drawable="@color/bg_window"/&gt;
  &lt;/selector&gt;
  </code></pre>
  
  <p>But this does not work for the ImageView because the image is in front and the background is not visible. How can I have the touch highlight effect with a semi-transparent color for an ImageView?</p>