I hope you are doing well.it often happens with all when they want to add new functionality in your app then normally they all search for libraries which are not good tactic because you don`t know what kind of code is in that libabry. so I always prefer to fork the libraries and add the useful classes and methods in my application code.
so when I stuck with the same issue, I make lots of much R&D then I find a class which gives the ability to zoomIn ,zoomOut and pinIn and out. so you can see that class here..
so as I told before, it is a single class. so you can put this class anywhere in your projects like utils folder.and put below lines into your XML files like:
<your_packege_name.TouchImageView
android:id="@+id/frag_imageview"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scaleType="fitCenter"
android:src="@drawable/default_flag"
android:transitionName="@string/transition_name_phone" />
and you can find that image view in your respected activity, as you did for all views like -:
TouchImageView tv=(TouchImageView)findViewById(R.id.frag_imageview);
tv.setImageResource(R.drawable.ic_play);
that's it for TouchImageView.
enjoy our code :)