private GeometryCollection EditGeometryCollection(GeometryCollection collection,
IGeometryEdit operation)
{
GeometryCollection newCollection =
(GeometryCollection)operation.Edit(collection, m_objFactory);
GeometryList geometries = new GeometryList();
for (int i = 0; i < newCollection.NumGeometries; i++)
{
Geometry geometry = Edit(newCollection.GetGeometry(i), operation);
if (geometry.IsEmpty)
{
continue;
}
geometries.Add(geometry);
}
GeometryType geomType = newCollection.GeometryType;
if (geomType == GeometryType.MultiPoint)
{
return(m_objFactory.CreateMultiPoint(geometries.ToPointArray()));
}
if (geomType == GeometryType.MultiLineString)
{
return(m_objFactory.CreateMultiLineString(
geometries.ToLineStringArray()));
}
if (geomType == GeometryType.MultiPolygon)
{
return(m_objFactory.CreateMultiPolygon(geometries.ToPolygonArray()));
}
return(m_objFactory.CreateGeometryCollection(geometries.ToArray()));
}
/// <summary>
/// Build an appropriate Geometry, MultiGeometry, or GeometryCollection
/// to contain the <see cref="Geometry"/> instances in it.
/// </summary>
/// <param name="geometryList"> the <see cref="Geometry"/> instances to combine
/// </param>
/// <returns> a Geometry of the "smallest", "most
/// type-specific" class that can contain the elements of geomList.
/// </returns>
/// <remarks>
/// For example:
/// <list type="number">
/// <item>
/// <description>
/// If geomList Contains a single Polygon, the Polygon is returned.
/// </description>
/// </item>
/// <item>
/// <description>
/// If geomList Contains several Polygons, a MultiPolygon is returned.
/// </description>
/// </item>
/// <item>
/// <description>
/// If geomList Contains some Polygons and some LineStrings, a GeometryCollection is
/// returned.
/// </description>
/// </item>
/// <item>
/// <description>
/// If geomList is empty, an empty GeometryCollection is returned.
/// </description>
/// </item>
/// </list>
/// Note that this method does not "flatten" Geometries in the input, and hence if
/// any MultiGeometries are contained in the input a GeometryCollection containing
/// them will be returned.
/// </remarks>
public virtual Geometry BuildGeometry(GeometryList geometryList)
{
if (geometryList == null)
{
throw new ArgumentNullException("geometryList");
}
GeometryType geomClass = GeometryType.None;
bool isHeterogeneous = false;
int nCount = geometryList.Count;
for (int i = 0; i < nCount; i++)
{
Geometry geom = geometryList[i];
GeometryType partClass = geom.GeometryType;
if (geomClass == GeometryType.None)
{
geomClass = partClass;
}
if (partClass != geomClass)
{
isHeterogeneous = true;
}
}
// for the empty geometry, return an empty GeometryCollection
if (geomClass == GeometryType.None)
{
return(CreateGeometryCollection(null));
}
if (isHeterogeneous)
{
return(CreateGeometryCollection(geometryList.ToArray()));
}
// at this point we know the collection is hetereogenous.
// Determine the type of the result from the first Geometry in the list
// this should always return a geometry, since otherwise an empty collection would have already been returned
// IGeometryEnumerator iTemp = geometryList.GetEnumerator();
// iTemp.MoveNext();
// Geometry geom0 = iTemp.Current;
Geometry geom0 = geometryList[0];
bool isCollection = nCount > 1;
if (isCollection)
{
GeometryType geomType = geom0.GeometryType;
if (geomType == GeometryType.Polygon)
{
return(CreateMultiPolygon(geometryList.ToPolygonArray()));
}
else if (geomType == GeometryType.LineString ||
geomType == GeometryType.LinearRing)
{
return(CreateMultiLineString(geometryList.ToLineStringArray()));
}
else if (geomType == GeometryType.Point)
{
return(CreateMultiPoint(geometryList.ToPointArray()));
}
Debug.Assert(false, "Should never reach here");
}
return(geom0);
}