///<summary>
///For given region, target precision and extension size,
///returns region boundary that gives available ranges of latitude/longitude
///for regions of target precision, overlapping with extension of given region
/// </summary>
/// <param name="region">Source <see cref="Region"/></param>
/// <param name="extension">Size of region extension (in precision-aligned steps)</param>
/// <param name="precision"> Target precision parameter. Any integer value.</param>
/// <returns>Region boundary rb. Every region with Lat/Lon of corresponding RegionBoundary's min
/// belonging to rb overlaps with extension of given region <see cref="Region"/> objects</returns>
public static RegionBoundary GetConnectedRegionsRange(Region region, int extension, int precision)
{
RegionBoundary rb = RegionHelper.GetRegionBoundary(region);
double step = PrecisionHelper.GetStep(precision);
rb.Min.Latitude -= extension * step;
rb.Min.Longitude -= extension * step;
rb.Max.Latitude += (extension - 1) * step;
rb.Max.Latitude += (extension - 1) * step;
return rb;
}
/// <summary>
/// Enumerates all regions of given precisions range connected with given <see cref="Region"/>/>
/// Being connected means either intersects with the region extended by overlap amount of precision-aligned grids
/// </summary>
/// <param name="region">Source <see cref="Region"/></param>
/// <param name="extension">Size of region extension (in precision-aligned steps)</param>
/// <param name="precisionStart"> Start precision parameter. Any integer value.</param>
/// <param name="precisionCount"> Count of precision parameters to include. Any non-negative integer value.</param>
/// <returns>Collection of connected <see cref="Region"/> objects</returns>
public static IEnumerable<Region> GetConnectedRegions(Region region, int extension, int precisionStart, int precisionCount = 1)
{
RegionBoundary rb = GetRegionBoundary(region);
for (int precision = precisionStart; precision < precisionStart + precisionCount; ++precision)
{
double step = PrecisionHelper.GetStep(precision);
for (double lat = rb.Min.Latitude - extension * step; lat < rb.Max.Latitude + extension * step; lat += step)
{
for (double lon = rb.Min.Longitude - extension * step; lon < rb.Max.Longitude + extension * step; lon += step)
{
yield return new Region
{
LatitudePrefix = lat,
LongitudePrefix = lon,
Precision = precision
};
}
}
}
}
private static IEnumerable <Region> GetRegionCoveragePositive(Coordinates location, float radiusMeters, int precision)
{
int latMax = (int)Coordinates.MAX_LATITUDE;
int lonMax = (int)Coordinates.MAX_LONGITUDE;
int step = PrecisionHelper.GetStep(precision);
int latCurrent = PrecisionHelper.Round(location.Latitude, precision);
int latNext = Math.Min(latCurrent + step, latMax);
int lonCurrent = PrecisionHelper.Round(location.Longitude, precision);
int lonNext = Math.Min(lonCurrent + step, lonMax);
//region itself
yield return(new Region(latCurrent, lonCurrent, precision));
if (precision > 0)
{
if (latCurrent > 0)
{
// South-West
if (lonCurrent > 0 && GeoHelper.DistanceMeters(location, new Coordinates {
Latitude = (float)latCurrent, Longitude = (float)lonCurrent
}) < radiusMeters)
{
yield return(new Region(latCurrent - step, lonCurrent - step, precision));
}
// South
if (GeoHelper.DistanceMeters(location, new Coordinates {
Latitude = (float)latCurrent, Longitude = location.Longitude
}) < radiusMeters)
{
yield return(new Region(latCurrent - step, lonCurrent, precision));
}
// South-East
if (GeoHelper.DistanceMeters(location, new Coordinates {
Latitude = (float)latCurrent, Longitude = (float)lonNext
}) < radiusMeters)
{
yield return(new Region(latCurrent - step, lonNext == lonMax ? -lonCurrent : lonNext, precision));
}
}
if (lonCurrent > 0)
{
// West
if (GeoHelper.DistanceMeters(location, new Coordinates {
Latitude = location.Latitude, Longitude = (float)lonCurrent
}) < radiusMeters)
{
yield return(new Region(latCurrent, lonCurrent - step, precision));
}
//North-West
if (latNext < latMax && GeoHelper.DistanceMeters(location, new Coordinates {
Latitude = (float)latNext, Longitude = (float)lonCurrent
}) < radiusMeters)
{
yield return(new Region(latNext, lonCurrent - step, precision));
}
}
if (latNext < latMax)
{
//North
if (GeoHelper.DistanceMeters(location, new Coordinates {
Latitude = (float)latNext, Longitude = location.Longitude
}) < radiusMeters)
{
yield return(new Region(latNext, lonCurrent, precision));
}
//North-East
if (GeoHelper.DistanceMeters(location, new Coordinates {
Latitude = (float)latNext, Longitude = (float)lonNext
}) < radiusMeters)
{
yield return(new Region(latNext, lonNext == lonMax ? -lonCurrent : lonNext, precision));
}
}
//East
if (GeoHelper.DistanceMeters(location, new Coordinates {
Latitude = location.Latitude, Longitude = (float)lonNext
}) < radiusMeters)
{
if (lonNext < lonMax)
{
yield return(new Region(latCurrent, lonNext, precision));
}
else if (lonCurrent > 0)
{
yield return(new Region(latCurrent, -lonCurrent, precision));
}
}
}
}