title: Android Creating a masking activity
body: <p>I'm attempting to create an activity which allows a user to mask out part of an image. The way I'm trying to achieve this (yes trying, because it still isn't working for me, please see my other SO questions), is by painting a color over the base image using the canvas. I saw an app this morning which basically does exactly what I need and I thought I'd ask here if anyone knows how the app is doing the hard work and if there is a good tutorial or documentation somewhere for this concept?</p>
  
  <p>Basically you press part of the image and it automatically masks out to the edges of the object in the image, you press again to add more, and press to remove. </p>
  
  <p>the app is called "AThumb Cut" and hope its ok to link to it here <a href="https://play.google.com/store/apps/details?id=com.instacut2" rel="nofollow">https://play.google.com/store/apps/details?id=com.instacut2</a></p>