title: add image to my layout with size proportional to dimension of screen android
body: <p>In my application i have an image that should have 25% width and height of screen.
  I hope this is clear. This is what i'm already tried but doesn't work. Thank you.</p>
  
  <pre><code>&lt;ImageView
          android:layout_width="fill_parent"
          android:layout_height="fill_parent"
          android:layout_weight="0.25"
          android:src="@drawable/fish"
          android:scaleType="fitCenter"
          /&gt;
  </code></pre>