System.Windows.Forms.ListView.GetAdjustedIndex C# (CSharp) Method

		int GetAdjustedIndex (Keys key)
		{
			int result = -1;

			if (View == View.Details) {
				switch (key) {
				case Keys.Up:
					result = FocusedItem.DisplayIndex - 1;
					break;
				case Keys.Down:
					result = FocusedItem.DisplayIndex + 1;
					if (result == items.Count)
						result = -1;
					break;
				case Keys.PageDown:
					int last_index = LastVisibleIndex;
					Rectangle item_rect = new Rectangle (GetItemLocation (last_index), ItemSize);
					if (item_rect.Bottom > item_control.ClientRectangle.Bottom)
						last_index--;
					if (FocusedItem.DisplayIndex == last_index) {
						if (FocusedItem.DisplayIndex < Items.Count - 1) {
							int page_size = item_control.Height / ItemSize.Height - 1;
							result = FocusedItem.DisplayIndex + page_size - 1;
							if (result >= Items.Count)
								result = Items.Count - 1;
						}
					} else
						result = last_index;
					break;
				case Keys.PageUp:
					int first_index = FirstVisibleIndex;
					if (GetItemLocation (first_index).Y < 0)
						first_index++;
					if (FocusedItem.DisplayIndex == first_index) {
						if (first_index > 0) {
							int page_size = item_control.Height / ItemSize.Height - 1;
							result = first_index - page_size + 1;
							if (result < 0)
								result = 0;
						}
					} else
						result = first_index;
					break;
				}
				return result;
			}

			if (virtual_mode)
				return GetFixedAdjustedIndex (key);

			ItemMatrixLocation item_matrix_location = items_matrix_location [FocusedItem.DisplayIndex];
			int row = item_matrix_location.Row;
			int col = item_matrix_location.Col;

			int adjusted_index = -1;

			switch (key) {
			case Keys.Left:
				if (col == 0)
					return -1;
				adjusted_index = item_index_matrix [row, col - 1];
				break;

			case Keys.Right:
				if (col == (cols - 1))
					return -1;
				while (item_index_matrix [row, col + 1] == 0) {
					row--;
					if (row < 0)
						return -1;
				}
				adjusted_index = item_index_matrix [row, col + 1];
				break;

			case Keys.Up:
				if (row == 0)
					return -1;
				while (item_index_matrix [row - 1, col] == 0 && row != 1) {
					col--;
					if (col < 0)
						return -1;
				}
				adjusted_index = item_index_matrix [row - 1, col];
				break;

			case Keys.Down:
				if (row == (rows - 1) || row == Items.Count - 1)
					return -1;
				while (item_index_matrix [row + 1, col] == 0) {
					col--;
					if (col < 0)
						return -1;
				}
				adjusted_index = item_index_matrix [row + 1, col];
				break;

			default:
				return -1;
			}

			return items [adjusted_index].DisplayIndex;
		}