Function ReadHeightmapBMP

src/heightmap.cpp:262–298

* Reads the heightmap and/or size of the heightmap from a BMP file. * If map == nullptr only the size of the BMP is read, otherwise a map * with greyscale pixels is allocated and assigned to *map. */

 * with greyscale pixels is allocated and assigned to *map.
 */
static bool ReadHeightmapBMP(std::string_view filename, uint *x, uint *y, std::vector<uint8_t> *map)
{
	auto f = FioFOpenFile(filename, "rb", HEIGHTMAP_DIR);
	if (!f.has_value()) {
		ShowErrorMessage(GetEncodedString(STR_ERROR_BMPMAP), GetEncodedString(STR_ERROR_PNGMAP_FILE_NOT_FOUND), WL_ERROR);
		return false;
	}

	RandomAccessFile file(filename, HEIGHTMAP_DIR);
	BmpInfo info{};
	BmpData data{};

	if (!BmpReadHeader(file, info, data)) {
		ShowErrorMessage(GetEncodedString(STR_ERROR_BMPMAP), GetEncodedString(STR_ERROR_BMPMAP_IMAGE_TYPE), WL_ERROR);
		return false;
	}

	if (!IsValidHeightmapDimension(info.width, info.height)) {
		ShowErrorMessage(GetEncodedString(STR_ERROR_BMPMAP), GetEncodedString(STR_ERROR_HEIGHTMAP_TOO_LARGE), WL_ERROR);
		return false;
	}

	if (map != nullptr) {
		if (!BmpReadBitmap(file, info, data)) {
			ShowErrorMessage(GetEncodedString(STR_ERROR_BMPMAP), GetEncodedString(STR_ERROR_BMPMAP_IMAGE_TYPE), WL_ERROR);
			return false;
		}

		map->resize(static_cast<size_t>(info.width) * info.height);
		ReadHeightmapBMPImageData(*map, info, data);
	}

	*x = info.width;
	*y = info.height;

	return true;
}

/**
 * Converts a given greyscale map to something that fits in OTTD map system