How to Crop a image via finger touch in Android App?

Question

[ORIGINAL]

I am working on a project in which i need to create summary of book (combination of images). Summary includes parts of image masked by finger. I found an example for android i.e fingercrop-image-tutorial but it is not what i want. What i want is here for an Ionic app.

Can someone tell me how to do this in android?

[NOTE : before down-voting, please check provided link of ionic app and press "run code snippet" button below code to see what i want]

[EDITED]

tried something and now getting this. Can someone help me to crop whole marked part.I am using same code as fingercrop-image-tutorial. changes made in initcanvas() method are :

1. paint.setColor(Color.YELLOW);
2. paint.setStrokeWidth(60);
3. paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DARKEN));

crop() function is same.