Class GeometryTransformer

Namespace

NetTopologySuite.Geometries.Utilities

Assembly

NetTopologySuite.dll

A framework for processes which transform an input Geometry into an output Geometry, possibly changing its structure and type(s).

public class GeometryTransformer

Inheritance

object

GeometryTransformer

Inherited Members

object.GetType()

object.MemberwiseClone()

object.ToString()

object.Equals(object)

object.Equals(object, object)

object.ReferenceEquals(object, object)

object.GetHashCode()

Remarks

This class is a framework for implementing subclasses which perform transformations on various different Geometry subclasses.

It provides an easy way of applying specific transformations to given point types, while allowing unhandled types to be simply copied. Also, the framework handles ensuring that if subcomponents change type the parent geometries types change appropriately to maintain valid structure. Subclasses will override whichever TransformX methods they need to to handle particular Geometry types.

A typically usage would be a transformation that may transform Polygons into Polygons, LineStrings or Points, depending on the geometry of the input (For instance, a simplification operation). This class would likely need to override the TransformMultiPolygon(MultiPolygon, Geometry) method to ensure that if input Polygons change type the result is a GeometryCollection, not a MultiPolygon.

The default behaviour of this class is simply to recursively transform each Geometry component into an identical object by deep copying down to the level of, but not including, coordinates.

Note that all TransformXXX methods may return null, to avoid creating empty point objects. This will be handled correctly by the transformer. TransformXXX methods should always return valid geometry - if they cannot do this they should return null (for instance, it may not be possible for a transformLineString implementation to return at least two points - in this case, it should return null). The Transform(Geometry) method itself will always return a non-null Geometry object (but this may be empty).

Constructors

GeometryTransformer()

public GeometryTransformer()

Fields

Factory

The geometry factory

protected GeometryFactory Factory

Field Value

GeometryFactory

Properties

InputGeometry

Makes the input geometry available

public Geometry InputGeometry { get; }

Property Value

Geometry

Methods

Copy(CoordinateSequence)

Convenience method which provides a standard way of copying CoordinateSequences.

protected virtual CoordinateSequence Copy(CoordinateSequence seq)

Parameters

seq CoordinateSequence

The sequence to copy.

Returns

CoordinateSequence

A deep copy of the sequence.

CreateCoordinateSequence(Coordinate[])

Convenience method which provides standard way of creating a CoordinateSequence.

protected virtual CoordinateSequence CreateCoordinateSequence(Coordinate[] coords)

Parameters

coords Coordinate[]

The coordinate array to copy.

Returns

CoordinateSequence

A coordinate sequence for the array.

Transform(Geometry)

public Geometry Transform(Geometry inputGeom)

Parameters

inputGeom Geometry

Returns

Geometry

TransformCoordinates(CoordinateSequence, Geometry)

Transforms a CoordinateSequence. This method should always return a valid coordinate list for the desired result type. (E.g. a coordinate list for a LineString must have 0 or at least 2 points). If this is not possible, return an empty sequence - this will be pruned out.

protected virtual CoordinateSequence TransformCoordinates(CoordinateSequence coords, Geometry parent)

Parameters

coords CoordinateSequence

The coordinates to transform

parent Geometry

The parent geometry

Returns

CoordinateSequence

The transformed coordinates

TransformGeometryCollection(GeometryCollection, Geometry)

Transforms a GeometryCollection geometry.

protected virtual Geometry TransformGeometryCollection(GeometryCollection geom, Geometry parent)

Parameters

geom GeometryCollection

The GeometryCollection to transform

parent Geometry

The parent geometry

Returns

Geometry

A GeometryCollection

TransformLineString(LineString, Geometry)

Transforms a LineString geometry.

protected virtual Geometry TransformLineString(LineString geom, Geometry parent)

Parameters

geom LineString

The LineString to transform

parent Geometry

The parent geometry

Returns

Geometry

A LineString

TransformLinearRing(LinearRing, Geometry)

Transforms a LinearRing.

The transformation of a LinearRing may result in a coordinate sequence which does not form a structurally valid ring (i.e. a degenerate ring of 3 or fewer points). In this case a LineString is returned. Subclasses may wish to override this method and check for this situation (e.g.a subclass may choose to eliminate degenerate linear rings)

protected virtual Geometry TransformLinearRing(LinearRing geom, Geometry parent)

Parameters

geom LinearRing

The LinearRing to transform

parent Geometry

The parent geometry

Returns

Geometry

A LinearRing if the transformation resulted in a structurally valid ring, otherwise, if the transformation caused the LinearRing to collapse to 3 or fewer points, a LineString

TransformMultiLineString(MultiLineString, Geometry)

Transforms a MultiLineString geometry.

protected virtual Geometry TransformMultiLineString(MultiLineString geom, Geometry parent)

Parameters

geom MultiLineString

The MultiLineString to transform

parent Geometry

The parent geometry

Returns

Geometry

A MultiLineString

TransformMultiPoint(MultiPoint, Geometry)

Transforms a MultiPoint geometry.

protected virtual Geometry TransformMultiPoint(MultiPoint geom, Geometry parent)

Parameters

geom MultiPoint

The MultiPoint to transform

parent Geometry

The parent geometry

Returns

Geometry

A MultiPoint

TransformMultiPolygon(MultiPolygon, Geometry)

Transforms a MultiPolygon geometry.

protected virtual Geometry TransformMultiPolygon(MultiPolygon geom, Geometry parent)

Parameters

geom MultiPolygon

The MultiPolygon to transform

parent Geometry

The parent geometry

Returns

Geometry

A MultiPolygon

TransformPoint(Point, Geometry)

Transforms a Point geometry.

protected virtual Geometry TransformPoint(Point geom, Geometry parent)

Parameters

geom Point

The Point to transform

parent Geometry

The parent geometry

Returns

Geometry

A Point

TransformPolygon(Polygon, Geometry)

Transforms a Polygon geometry.

protected virtual Geometry TransformPolygon(Polygon geom, Geometry parent)

Parameters

geom Polygon

The Polygon to transform

parent Geometry

The parent geometry

Returns

Geometry

A Polygon