/// <summary>
/// Gets the convex hull for the given geometry.
/// </summary>
/// <param name="geometry"></param>
/// <returns></returns>
public Geometry GetConvexHull(Geometry geometry)
{
this._geometry = geometry;
UniqueCoordinateArrayFilter filter = new UniqueCoordinateArrayFilter();
geometry.Apply(filter);
Coordinates pts = filter.GetCoordinates();
if (pts.Count == 0)
{
return new GeometryCollection(new Geometry[]{},
geometry.PrecisionModel, geometry.GetSRID());
}
if (pts.Count == 1)
{
return new Point(pts[0], geometry.PrecisionModel, geometry.GetSRID());
}
if (pts.Count == 2)
{
return new LineString(pts, geometry.PrecisionModel, geometry.GetSRID());
}
// sort points for Graham scan.
Coordinates pspts;
if (pts.Count > 10)
{
//Probably should be somewhere between 50 and 100?
Coordinates rpts = Reduce(pts);
pspts = PreSort(rpts);
}
else
{
pspts = PreSort(pts);
}
// Use Graham scan to find convex hull.
Stack cHS = GrahamScan(pspts);
// Convert stack to an array.
Coordinates cH = ToCoordinateArray(cHS);
// Convert array to linear ring.
//awcreturn lineOrPolygon(cH);
return LineOrPolygon(cH);
}
public static ArrayList GetLines(Geometry geom)
{
ArrayList lines = new ArrayList();
geom.Apply(new LineExtracterFilter(lines));
return lines;
}
public static ArrayList GetPoints(Geometry geom)
{
ArrayList pts = new ArrayList();
geom.Apply(new PointExtracterFilter(pts));
return pts;
}
public static ArrayList GetPolygons(Geometry geom)
{
ArrayList comps = new ArrayList();
geom.Apply(new PolygonExtracterFilter(comps));
return comps;
}
public static ArrayList GetCoordinates(Geometry geom)
{
ArrayList pts = new ArrayList();
geom.Apply(new ConnectedElementPointFilter(pts));
return pts;
}