Interface ICoordinateSequenceFilter

An interface for classes which process the coordinates in a CoordinateSequence. A filter can either record information about each coordinate, or change the value of the coordinate. Filters can be used to implement operations such as coordinate transformations, centroid and envelope computation, and many other functions. Geometry classes support the concept of applying a CoordinateSequenceFilter to each CoordinateSequences they contain.

For maximum efficiency, the execution of filters can be short-circuited by using the Done property.

Namespace: NetTopologySuite.Geometries

Assembly: NetTopologySuite.dll

Syntax

public interface ICoordinateSequenceFilter

Remarks

CoordinateSequenceFilter is an example of the Gang-of-Four Visitor pattern.

Note: In general, it is preferable to treat Geometrys as immutable. Mutation should be performed by creating a new Geometry object (see GeometryEditor and GeometryTransformer for convenient ways to do this). An exception to this rule is when a new Geometry has been created via Copy(). In this case mutating the Geometry will not cause aliasing issues, and a filter is a convenient way to implement coordinate transformation.

Properties

Done

Reports whether the application of this filter can be terminated.

Declaration

bool Done { get; }

Property Value

Type	Description
bool

Remarks

Once this method returns true, it must continue to return true on every subsequent call.

GeometryChanged

Reports whether the execution of this filter has modified the coordinates of the geometry. If so, GeometryChanged() will be executed after this filter has finished being executed.

Declaration

bool GeometryChanged { get; }

Property Value

Type	Description
bool

Remarks

Most filters can simply return a constant value reflecting whether they are able to change the coordinates.

Methods

Filter(CoordinateSequence, int)

Performs an operation on a coordinate in a CoordinateSequence.

Declaration

void Filter(CoordinateSequence seq, int i)

Parameters

Type	Name	Description
CoordinateSequence	seq	the CoordinateSequence to which the filter is applied
int	i	i the index of the coordinate to apply the filter to

See Also

Apply(ICoordinateFilter)

GeometryTransformer