private void getDateNames()
        {
            try
            {
                var coursePath = new DirectoryInfo(_corPath + "\\" + Courses[SelectedCourseIndex]);
                Dates = coursePath.GetDirectories().ToArray();

                DateNames.Clear();
                GraduateNames.Clear();

                foreach (var date in Dates)
                {
                    if (date != null)
                    {
                        DateNames.Add(date.Name);
                    }
                }

                _selectedNameIndex = -1;
                getGraduateNames();
            }
            catch
            {
            }
        }
        private void getCoursesNames()
        {
            try
            {
                Courses = _directoryPath.GetDirectories().ToArray();

                CourseNames.Clear();
                DateNames.Clear();
                GraduateNames.Clear();

                foreach (var course in Courses)
                {
                    if (course != null)
                    {
                        CourseNames.Add(course.Name);
                    }
                }

                _selectedDateIndex = -1;
                getDateNames();
            }
            catch
            {
            }
        }
        private void getGraduateNames()
        {
            try
            {
                if (_selectedDateIndex != -1)
                {
                    var datePath = new DirectoryInfo(_corPath + "\\" + Courses[SelectedCourseIndex] + "\\" + Dates[SelectedDateIndex]);
                    Images = datePath.GetFiles().Where(f => _extensions.Contains(f.Extension.ToLower())).ToArray();

                    GraduateNames.Clear();

                    foreach (var image in Images)
                    {
                        if (image != null)
                        {
                            GraduateNames.Add(image.Name);
                        }
                    }
                }
            }
            catch
            {
            }
        }