title: How does Android choose which small/normal/large resource folder?
body: <p>I've a 7 inch tablet but Android select the <code>normal/</code> resource folder, and it's wrong for me.</p>
  
  <p>I found that I can get the diagonal with some calculations:</p>
  
  <pre><code>DisplayMetrics dm = new DisplayMetrics();
  getWindowManager().getDefaultDisplay().getMetrics(dm);
  double x = Math.pow(dm.widthPixels / dm.xdpi, 2);
  double y = Math.pow(dm.heightPixels / dm.ydpi, 2);
  double screenInches = Math.sqrt(x + y);
  Log.d("debug", "Screen inches : " + screenInches); 
  </code></pre>
  
  <p>When choosing the resource folder, what Android does? </p>
  
  <ol>
  <li><strong>Make this kind of calculation</strong> or </li>
  <li><strong>get screen size from <em>build.prop</em>?</strong></li>
  </ol>