Method GetValuesInterval

src/graph_gui.cpp:277–340

* 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). */

	 * @return Highest and lowest values of the graph (ignoring disabled data).
	 */
	ValuesInterval GetValuesInterval(int num_hori_lines) const
	{
		assert(num_hori_lines > 0);

		ValuesInterval current_interval;
		current_interval.highest = INT64_MIN;
		current_interval.lowest  = INT64_MAX;

		for (const DataSet &dataset : this->data) {
			if (HasBit(this->excluded_data, dataset.exclude_bit)) continue;
			if (HasBit(this->excluded_range, dataset.range_bit)) continue;

			for (const OverflowSafeInt64 &datapoint : this->GetDataSetRange(dataset)) {
				if (datapoint != INVALID_DATAPOINT) {
					current_interval.highest = std::max(current_interval.highest, datapoint);
					current_interval.lowest  = std::min(current_interval.lowest, datapoint);
				}
			}
		}

		/* 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;

		/* Prevent showing values too close to the graph limits. */
		abs_higher = (11.0 * abs_higher) / 10.0;
		abs_lower = (11.0 * abs_lower) / 10.0;

		int num_pos_grids;
		OverflowSafeInt64 grid_size;

		if (abs_lower != 0 || abs_higher != 0) {
			/* The number of grids to reserve for the positive part is: */
			num_pos_grids = (int)floor(0.5 + num_hori_lines * abs_higher / (abs_higher + abs_lower));

			/* If there are any positive or negative values, force that they have at least one grid. */
			if (num_pos_grids == 0 && abs_higher != 0) num_pos_grids++;
			if (num_pos_grids == num_hori_lines && abs_lower != 0) num_pos_grids--;

			/* Get the required grid size for each side and use the maximum one. */

			OverflowSafeInt64 grid_size_higher = 0;
			if (abs_higher > 0) {
				grid_size_higher = abs_higher > INT64_MAX_IN_DOUBLE ? INT64_MAX : static_cast<int64_t>(abs_higher);
				grid_size_higher = (grid_size_higher + num_pos_grids - 1) / num_pos_grids;
			}

			OverflowSafeInt64 grid_size_lower = 0;
			if (abs_lower > 0) {
				grid_size_lower = abs_lower > INT64_MAX_IN_DOUBLE ? INT64_MAX : static_cast<int64_t>(abs_lower);
				grid_size_lower = (grid_size_lower + num_hori_lines - num_pos_grids - 1) / (num_hori_lines - num_pos_grids);
			}

			grid_size = std::max(grid_size_higher, grid_size_lower);
		} else {
			/* If both values are zero, show an empty graph. */
			num_pos_grids = num_hori_lines / 2;
			grid_size = 1;