title: How can I write a Drawable resource to a File?
body: <p>I need to export some <code>Drawable</code> resources to a file. </p>
  
  <p>For example, I have a function that returns to me a <code>Drawable</code> object.  I want to write it out to a file in <code>/sdcard/drawable/newfile.png</code>. How can i do it?</p>