public CropState getCroppedBitmapAsync(final CropperCallback callback) {
        if (isGestureInProgess) {
            return CropState.FAILURE_GESTURE_IN_PROCESS;
        }

        CropperTask task = new CropperTask(callback);
        Cropper cropper = new Cropper(mImageView.getCropInfo(), mImageView.getLoadedBitmap());
        task.execute(cropper);
        return CropState.STARTED;
    }
Crop bitmap async
@param callback {@link CropperCallback}
@return State STARTED if cropping will start else FAILURE_GESTURE_IN_PROCESS
if cropping can not be started because the user is in the middle of a gesture.
nocropper/src/main/java/com/fenchtose/nocropper/CropperView.java