void setMonthCount(int monthCount) {
        if (this.monthCount == monthCount) {
            return;
        }

        this.monthCount = monthCount;
        if (adapter != null) {
            adapter.notifyDataSetChanged();
        }
    }
Color when month is before the current selected month
library/src/main/java/com/github/badoualy/datepicker/MonthView.java