title: How to size an Android view based on its parent's dimensions
body: <p>How can I size a view based on the size of its parent layout. For example I have a <code>RelativeLayout</code> that fills the full screen, and I want a child view, say an <code>ImageView</code>, to take up the whole height, and 1/2 the width?</p>
  
  <p>I've tried overriding all on <code>onMeasure</code>, <code>onLayout</code>, <code>onSizeChanged</code>, etc and I couldn't get it to work....</p>