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

You need to set the PorterDuff mode on a Paint object:

mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC)) 

and draw with Color.TRANSPARENT

Also see this thread in the Android developer group: http://groups.google.com/group/android-developers/browse_thread/thread/5b0a498664b17aa0/de4aab6fb7e97e38?lnk=gst&q=erase+transparent#