Controlling the scroll bar in scroll mode while changing orientation

I have a bookshelf that is implemented like this:

I have a ScrollView that contains a nested TableLayout that acts as a container for dynamically generated tables.

   <com.test.bookshelf.CustomScrollView
        android:id="@+id/scrollview"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/newHeader"
        android:overScrollMode="never"
        android:fadingEdge="none" >

        <TableLayout
            android:id="@+id/tblLayout"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:padding="0dp" >
        </TableLayout>
    </com.test.bookshelf.CustomScrollView>

      

        
        
        
      

    

Custom scroll code:

public class CustomScrollView extends ScrollView {

    private boolean enableScrolling = true;
    private ScrollViewListener scrollViewListener = null;

    public interface OnEndScrollListener {
        public void onEndScroll();
    }

    private OnEndScrollListener mOnEndScrollListener;

    public boolean isEnableScrolling() {
        return enableScrolling;
    }

    public void setEnableScrolling(boolean enableScrolling) {
        this.enableScrolling = enableScrolling;
    }

    public CustomScrollView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    public CustomScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public CustomScrollView(Context context) {
        super(context);
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {

        if (isEnableScrolling()) {
            return super.onInterceptTouchEvent(ev);
        } else {
            return false;
        }
    }

    public void setScrollViewListener(ScrollViewListener scrollViewListener) {
        this.scrollViewListener = scrollViewListener;
    }

    @Override
    protected void onScrollChanged(int x, int y, int oldx, int oldy) {
        super.onScrollChanged(x, y, oldx, oldy);
        if(scrollViewListener != null) {
            scrollViewListener.onScrollChanged(this, x, y, oldx, oldy);
        }
    }

    public OnEndScrollListener getOnEndScrollListener() {
        return mOnEndScrollListener;
    }

    public void setOnEndScrollListener(OnEndScrollListener mOnEndScrollListener) {
        this.mOnEndScrollListener = mOnEndScrollListener;
    }
}

      

        
        
        
      

    

Each row of the table consists of a fixed number of columns, which is dynamically calculated based on the total number of books. When you change the orientation, the entire layout is re-created.

When the bookshelf is created, I store the total number of rows in a static variable.

When the user clicks on any book, he takes them to the details page. I keep the current scroll position during the click event:

public static currentScrollPosition = 0;

imageviewobj.setOnClickListener(new View.OnClickListener() 
{
   @Override
   public void onClick(View v) 
   {
      currentScrollPosition = scrollviewObj.getScrollY();

      

        
        
        
      

    

....

When the user returns to this screen, I restored the scroll position using this value.

scrollviewObj.post(new Runnable() {
        @Override
        public void run() {
            scrollviewObj.scrollTo(0, currentScrollPosition);
        } 
    });

      

        
        
        
      

    

But how do you calculate the equivalent scroll position during orientation change? The vertical offset (scroll position) of a book in portrait mode is different from landscape mode because the number of rows and columns is different.

Any thoughts on this?