Get center visible item of RecycleView when scrolling

I made something just like this. I can do exactly what you need.
First of all, this is how is my alogrithm work

This is my recyclerView Adapter

public class DateAdapter extends RecyclerView.Adapter<DateAdapter.DateViewHolder> {
private ArrayList<LabelerDate> dateDataList;


private static final int VIEW_TYPE_PADDING = 1;
private static final int VIEW_TYPE_ITEM = 2;
private int paddingWidthDate = 0;

private int selectedItem = -1;

public DateAdapter(ArrayList<LabelerDate> dateData, int paddingWidthDate) {
    this.dateDataList = dateData;
    this.paddingWidthDate = paddingWidthDate;

}


@Override
public DateViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    if (viewType == VIEW_TYPE_ITEM) {
        final View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_date,
                parent, false);
        return new DateViewHolder(view);
    } else {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_padding,
                parent, false);

        RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) view.getLayoutParams();
        layoutParams.width = paddingWidthDate;
        view.setLayoutParams(layoutParams);
        return new DateViewHolder(view);
    }
}

@Override
public void onBindViewHolder(DateViewHolder holder, int position) {
    LabelerDate labelerDate = dateDataList.get(position);
    if (getItemViewType(position) == VIEW_TYPE_ITEM) {
        if(labelerDate.dateType.equals(BirthDayActivity.DateType.C31))
                holder.tvDate.setText(String.valueOf(labelerDate.valueDate));
                holder.tvDate.setVisibility(View.VISIBLE);
                holder.imgSmall.setVisibility(View.VISIBLE);

        if (position == selectedItem) {
            holder.tvDate.setTextColor(Color.parseColor("#094673"));
            holder.tvDate.setTextSize(35);
            holder.imgSmall.setBackgroundResource(R.color.textviewbold);

        } else {
            holder.tvDate.setTextColor(Color.GRAY);
            holder.tvDate.setTextSize(35);
            holder.imgSmall.setBackgroundResource(R.color.gray);
        }
    }
}

public void setSelecteditem(int selecteditem) {
    this.selectedItem = selecteditem;
    notifyDataSetChanged();
}

@Override
public int getItemCount() {
    return dateDataList.size();
}

@Override
public int getItemViewType(int position) {
    LabelerDate labelerDate = dateDataList.get(position);
    if (labelerDate.dateType.equals(BirthDayActivity.DateType.NONE)) {
        return VIEW_TYPE_PADDING;
    }
    return VIEW_TYPE_ITEM;
}


public class DateViewHolder extends RecyclerView.ViewHolder {
    public TextView tvDate;
    public ImageView imgSmall;

    public DateViewHolder(View itemView) {
        super(itemView);
        tvDate = (TextView) itemView.findViewById(R.id.tvNumberDate);
        imgSmall = (ImageView) itemView.findViewById(R.id.small_marked_dob);
    }
}}

This is most important alogrithm:

public void getRecyclerviewDate() {
    recyclerViewDate = (RecyclerView) findViewById(R.id.recyclerViewDay);
    ViewTreeObserver vtoDate = recyclerViewDate.getViewTreeObserver();
    vtoDate.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
        @Override
        public boolean onPreDraw() {
            recyclerViewDate.getViewTreeObserver().removeOnPreDrawListener(this);
            finalWidthDate = recyclerViewDate.getMeasuredWidth();
            itemWidthDate = getResources().getDimension(R.dimen.item_dob_width);
            paddingDate = (finalWidthDate - itemWidthDate) / 2;
            firstItemWidthDate = paddingDate ;
            allPixelsDate = 0;

            final LinearLayoutManager dateLayoutManager = new LinearLayoutManager(getApplicationContext());
            dateLayoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);
            recyclerViewDate.setLayoutManager(dateLayoutManager);
            recyclerViewDate.addOnScrollListener(new RecyclerView.OnScrollListener() {
                @Override
                public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                    super.onScrollStateChanged(recyclerView, newState);
                    synchronized (this) {
                         if(newState == RecyclerView.SCROLL_STATE_IDLE){           
                            calculatePositionAndScrollDate(recyclerView);
                        }
                    }

                }

                @Override
                public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                    super.onScrolled(recyclerView, dx, dy);
                    allPixelsDate += dx;
                }
            });
            if (labelerDates == null)
                labelerDates = new ArrayList<>();
            labelerDates.addAll(genLabelerDate(currentMonth, currentYear));
            dateAdapter = new DateAdapter(labelerDates, (int) firstItemWidthDate);
            recyclerViewDate.setAdapter(dateAdapter);
            return true;
        }
    });
}
/* this if most important, if expectedPositionDate < 0 recyclerView will return to nearest item*/

private void calculatePositionAndScrollDate(RecyclerView recyclerView) {
    int expectedPositionDate = Math.round((allPixelsDate + paddingDate - firstItemWidthDate) / itemWidthDate);

    if (expectedPositionDate == -1) {
        expectedPositionDate = 0;
    } else if (expectedPositionDate >= recyclerView.getAdapter().getItemCount() - 2) {
        expectedPositionDate--;
    }
    scrollListToPositionDate(recyclerView, expectedPositionDate);

}
/* this if most important, if expectedPositionDate < 0 recyclerView will return to nearest item*/
private void scrollListToPositionDate(RecyclerView recyclerView, int expectedPositionDate) {
    float targetScrollPosDate = expectedPositionDate * itemWidthDate + firstItemWidthDate - paddingDate;
    float missingPxDate = targetScrollPosDate - allPixelsDate;
    if (missingPxDate != 0) {
        recyclerView.smoothScrollBy((int) missingPxDate, 0);
    }
}
private void setDateValue() {
    int expectedPositionDateColor = Math.round((allPixelsDate + paddingDate - firstItemWidthDate) / itemWidthDate);
    setColorDate = expectedPositionDateColor + 1;
    //set color here
    dateAdapter.setSelecteditem(setColorDate);
}
 @Override
protected void onRestoreInstanceState(@NonNull Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);   
    allPixelsDate = savedInstanceState.getFloat(BUNDLE_LIST_PIXELS_DATE);
    allPixelsDateChanged = savedInstanceState.getFloat(BUNDLE_LIST_PIXELS_DATE_CHANGED);
}

@Override
protected void onSaveInstanceState(@NonNull Bundle outState) {
    super.onSaveInstanceState(outState);
    outState.putFloat(BUNDLE_LIST_PIXELS_DATE, allPixelsDate);
    outState.putFloat(BUNDLE_LIST_PIXELS_DATE_CHANGED, allPixelsDateChanged);
}

And this is my result:

Look at this video link, this is my app demo