Function BuildLandLegend

src/smallmap_gui.cpp:290–336

* (Re)build the colour tables for the legends. */

 * (Re)build the colour tables for the legends.
 */
void BuildLandLegend()
{
	/* The smallmap window has never been initialized, so no need to change the legend. */
	if (_heightmap_schemes[0].height_colours.empty()) return;

	/*
	 * The general idea of this function is to fill the legend with an appropriate evenly spaced
	 * selection of height levels. All entries with STR_TINY_BLACK_HEIGHT are reserved for this.
	 * At the moment there are twelve of these.
	 *
	 * The table below defines up to which height level a particular delta in the legend should be
	 * used. One could opt for just dividing the maximum height and use that as delta, but that
	 * creates many "ugly" legend labels, e.g. once every 950 meter. As a result, this table will
	 * reduce the number of deltas to 7: every 100m, 200m, 300m, 500m, 750m, 1000m and 1250m. The
	 * deltas are closer together at the lower numbers because going from 12 entries to just 4, as
	 * would happen when replacing 200m and 300m by 250m, would mean the legend would be short and
	 * that might not be considered appropriate.
	 *
	 * The current method yields at least 7 legend entries and at most 12. It can be increased to
	 * 8 by adding a 150m and 400m option, but especially 150m creates ugly heights.
	 *
	 * It tries to evenly space the legend items over the two columns that are there for the legend.
	 */

	/* Table for delta; if max_height is less than the first column, use the second column as value. */
	uint deltas[][2] = { { 24, 2 }, { 48, 4 }, { 72, 6 }, { 120, 10 }, { 180, 15 }, { 240, 20 }, { MAX_TILE_HEIGHT + 1, 25 }};
	uint i = 0;
	for (; _settings_game.construction.map_height_limit >= deltas[i][0]; i++) {
		/* Nothing to do here. */
	}
	uint delta = deltas[i][1];

	int total_entries = (_settings_game.construction.map_height_limit / delta) + 1;
	int rows = CeilDiv(total_entries, 2);
	int j = 0;

	for (i = 0; i < lengthof(_legend_land_contours) - 1 && j < total_entries; i++) {
		if (_legend_land_contours[i].legend != STR_TINY_BLACK_HEIGHT) continue;

		_legend_land_contours[i].col_break = j % rows == 0;
		_legend_land_contours[i].end = false;
		_legend_land_contours[i].height = j * delta;
		_legend_land_contours[i].colour = PixelColour{static_cast<uint8_t>(_heightmap_schemes[_settings_client.gui.smallmap_land_colour].height_colours[_legend_land_contours[i].height])};
		j++;
	}
	_legend_land_contours[i].end = true;
}

/**
 * Completes the array for the owned property legend.