title: Display image button from external source
body: <p>I'm working on a project where I need to display image buttons with some images saved in the sd card or from an Url. How can I do this? Or what's best practice?
  The objective is to change the image on the button only replacing the file in the sd card.
  There are other solutions if I don't know which images will be displayed in future?
  THX</p>