title: How to get ascender/descender and x height for a given font
body: <p>I need to get a <a href="http://en.wikipedia.org/wiki/Ascender_%28typography%29" rel="noreferrer">ascender</a>/<a href="http://en.wikipedia.org/wiki/Descender" rel="noreferrer">descender</a> and <a href="http://en.wikipedia.org/wiki/X-height" rel="noreferrer">x-height</a>..</p>
  
  <p>By using following code I can find the descender and the total height:</p>
  
  <pre><code>descender_height = paint.descent();
  total_height = descender_height - paint.ascent();
  //ascender = ?; is this always equal to descender height?
  //x_height = ?; total_height - 2*descender_height ?
  </code></pre>
  
  <p>Thanks</p>