Page-curl animation by harism not working properly

Question

I am developing an epub reader and I use page-curl by harism to get the page-curl animation.

It works well for left to right side(When user reads forward) and loads the correct pages accordingly. But if I turn a page backwards, it's loading the previous page which is ok. Then if I further moves back then it loads a wrong page.

For example : I go through pages until 5, then go back it loads page 4. If I go to another page back it should load page 3. Instead it loads page 6.

I know this question has been asked eralier, but it gives some hints which I have already tried.

I tried with index value in updatePage method as well as mCurrentIndex in CurlView. But still can't figure out how to fix this issue.

This is the class I am dealing with

Any suggestions would be really appreciated. Thanks.