PhotoView aims to help produce an easily usable implementation of a zooming Android ImageView.
Out of the box zooming, using multi-touch and double-tap.
Scrolling, with smooth scrolling fling.
Works perfectly when using used in a scrolling parent (such as ViewPager).
Allows the application to be notified when the displayed Matrix has changed. Useful for when you need to update your UI based on the current zoom/scroll position.
Allows the application to be notified when the user taps on the Photo.
PhotoView GitHub site