H3Error H3_EXPORT()

in h3_polyfill.c [732:781]
31 lines of code
6 McCabe index (conditional complexity)

H3Error H3_EXPORT(maxPolygonToCellsSizeExperimental)(const GeoPolygon *polygon,
                                                     int res, uint32_t flags,
                                                     int64_t *out) {
    // Special case: 0-vertex polygon
    if (polygon->geoloop.numVerts == 0) {
        *out = 0;
        return E_SUCCESS;
    }

    // Initialize the iterator without stepping, so we can adjust the res and
    // flags (after they are validated by the initialization) before we start
    IterCellsPolygonCompact iter = _iterInitPolygonCompact(polygon, res, flags);

    if (iter.error) {
        return iter.error;
    }

    // Ignore the requested flags and use the faster overlapping-bbox mode
    iter._flags = CONTAINMENT_OVERLAPPING_BBOX;

    // Get a (very) rough area of the polygon bounding box
    BBox *polygonBBox = &iter._bboxes[0];
    double polygonBBoxAreaKm2 =
        bboxHeightRads(polygonBBox) * bboxWidthRads(polygonBBox) /
        cos(fmin(fabs(polygonBBox->north), fabs(polygonBBox->south))) *
        EARTH_RADIUS_KM * EARTH_RADIUS_KM;

    // Determine the res for the size estimate, based on a (very) rough estimate
    // of the number of cells at various resolutions that would fit in the
    // polygon. All we need here is a general order of magnitude.
    while (iter._res > 0 &&
           polygonBBoxAreaKm2 / getAverageCellArea(iter._res - 1) >
               MAX_SIZE_CELL_THRESHOLD) {
        iter._res--;
    }

    // Now run the polyfill, counting the output in the target res.
    // We have to take the first step outside the loop, to get the first
    // valid output cell
    iterStepPolygonCompact(&iter);

    *out = 0;
    int64_t childrenSize;
    for (; iter.cell; iterStepPolygonCompact(&iter)) {
        H3_EXPORT(cellToChildrenSize)(iter.cell, res, &childrenSize);
        *out += childrenSize;
    }

    return iter.error;
}