image cropper implementation
// start picker to get image for cropping and then use the image in cropping activity
CropImage.activity()
.setGuidelines(CropImageView.Guidelines.ON)
.start(this);
// start cropping activity for pre-acquired image saved on the device
CropImage.activity(imageUri)
.start(this);
// for fragment (DO NOT use `getActivity()`)
CropImage.activity()
.start(getContext(), this);