GeometryTransformer class

A framework for processes which transform an input {@link Geometry} into an output {@link Geometry}, possibly changing its structure and type(s). 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 geometry types, while allowing unhandled types to be simply copied. Also, the framework ensures 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 class that transforms 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 {@link #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.

All transformX methods may return null, to avoid creating empty or invalid geometry 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 {@link #transform(Geometry)} method itself will always return a non-null Geometry object (but this may be empty).

@version 1.7

@see GeometryEditor

Implementers

Constructors

GeometryTransformer()

Properties

factory ↔ GeometryFactory
getter/setter pair
hashCode → int
The hash code for this object.
no setterinherited
inputGeom ↔ Geometry
Possible extensions: getParent() method to return immediate parent e.g. of LinearRings in Polygons
getter/setter pair
preserveCollections ↔ bool
true if the output from a collection argument should still be a collection
getter/setter pair
preserveGeometryCollectionType ↔ bool
true if a homogenous collection result from a {@link GeometryCollection} should still be a general GeometryCollection
getter/setter pair
preserveType ↔ bool
true if the type of the input should be preserved
getter/setter pair
pruneEmptyGeometry ↔ bool
true if empty geometries should not be included in the result
getter/setter pair
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited

Methods

copy(CoordinateSequence seq) → CoordinateSequence
Convenience method which provides a standard way of copying {@link CoordinateSequence}s @param seq the sequence to copy @return a deep copy of the sequence
createCoordinateSequence(List<Coordinate> coords) → CoordinateSequence
Convenience method which provides standard way of creating a {@link CoordinateSequence}
getInputGeometry() → Geometry
Utility function to make input geometry available
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
toString() → String
A string representation of this object.
inherited
transform(Geometry inputGeom) → Geometry
transformCoordinates(CoordinateSequence coords, Geometry parent) → CoordinateSequence
Transforms a {@link 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.
transformGeometryCollection(GeometryCollection geom, Geometry parent) → Geometry
transformLinearRing(LinearRing geom, Geometry parent) → 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)
transformLineString(LineString geom, Geometry parent) → Geometry
Transforms a {@link LineString} geometry.
transformMultiLineString(MultiLineString geom, Geometry parent) → Geometry
transformMultiPoint(MultiPoint geom, Geometry parent) → Geometry
transformMultiPolygon(MultiPolygon geom, Geometry parent) → Geometry
transformPoint(Point geom, Geometry parent) → Geometry
transformPolygon(Polygon geom, Geometry parent) → Geometry

Operators

operator ==(Object other) → bool
The equality operator.
inherited