title: How to create a post-processing effect to render on top of the screen in Android?
body: <p>I would like to create a global post-processing effect to render as an overlay on the screen in Android, in other words, I want to access the pixels on the screen and change them in realtime to create the desired effect, however I could not find anything about this in the documentation, any help?</p>
  <p>The effect should draw on top of everything else, not just inside the app.</p>