/* The starting month and year that values are plotted against. If month is

	 * 0xFF, use x_values_start and x_values_increment below instead. */

	byte month;

	Year year;

	/* These values are used if the graph is being plotted against values

	 * rather than the dates specified by month and year. */

	uint16 x_values_start;

	uint16 x_values_increment;

	int graph_widget;

	StringID format_str_y_axis;

	byte colours[GRAPH_MAX_DATASETS];

	OverflowSafeInt64 cost[GRAPH_MAX_DATASETS][GRAPH_NUM_MONTHS]; ///< Stored costs for the last #GRAPH_NUM_MONTHS months

	/**

	 * Get the interval that contains the graph's data. Excluded data is ignored to show smaller values in

	 * better detail when disabling higher ones.

	 * @param num_hori_lines Number of horizontal lines to be drawn.

	 * @return Highest and lowest values of the graph (ignoring disabled data).

	 */

	ValuesInterval GetValuesInterval(int num_hori_lines) const

	{

		ValuesInterval current_interval;

		current_interval.highest = INT64_MIN;

		current_interval.lowest  = INT64_MAX;

		for (int i = 0; i < this->num_dataset; i++) {

			if (HasBit(this->excluded_data, i)) continue;

			for (int j = 0; j < this->num_on_x_axis; j++) {

				OverflowSafeInt64 datapoint = this->cost[i][j];

				if (datapoint != INVALID_DATAPOINT) {

					current_interval.highest = max(current_interval.highest, datapoint);

					current_interval.lowest  = min(current_interval.lowest, datapoint);

				}

			}

		}

		/* Prevent showing values too close to the graph limits. */

		current_interval.highest = (11 * current_interval.highest) / 10;

		current_interval.lowest =  (11 * current_interval.lowest) / 10;

		/* Always include zero in the shown range. */

		double abs_lower  = (current_interval.lowest > 0) ? 0 : (double)abs(current_interval.lowest);

		double abs_higher = (current_interval.highest < 0) ? 0 : (double)current_interval.highest;