Making Overlaid image transparent on touch in Android?

Question

I need help on making the touched areas of bitmap image transparent(seems like erasing) while I am moving my finger on that image.

I am having a PNG file with Alpha

Answer 1

ImageView has a setAlpha method which takes an integer between 0 and 255. I don't know which is transparent and which is opaque but it shouldn't take a long time to try :P