Check approximately how many downloadable tiles are within a specified DownloadableRegion
This does not take into account sea tile removal or redownload prevention, as these are handled in the download area of the code.
int which is the number of tiles.
Future<int> check(DownloadableRegion region) => compute( region.type == RegionType.rectangle ? TilesCounter.rectangleTiles : region.type == RegionType.circle ? TilesCounter.circleTiles : TilesCounter.lineTiles, region, );