Class OverlayOp

Computes the geometric overlay of two Geometrys. The overlay can be used to determine any bool combination of the geometries.

Inheritance

object

GeometryGraphOperation

OverlayOp

Inherited Members

GeometryGraphOperation.lineIntersector

GeometryGraphOperation.resultPrecisionModel

GeometryGraphOperation.arg

GeometryGraphOperation.GetArgGeometry(int)

GeometryGraphOperation.ComputationPrecision

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: NetTopologySuite.Operation.Overlay

Assembly: NetTopologySuite.dll

Syntax

public class OverlayOp : GeometryGraphOperation

Constructors

OverlayOp(Geometry, Geometry)

Constructs an instance to compute a single overlay operation for the given geometries.

Declaration

public OverlayOp(Geometry g0, Geometry g1)

Parameters

Type	Name	Description
Geometry	g0	The first geometry argument
Geometry	g1	The second geometry argument

Properties

Graph

Gets the graph constructed to compute the overlay.

Declaration

public PlanarGraph Graph { get; }

Property Value

Type	Description
PlanarGraph

NodingValidatorDisabled

Disable EdgeNodingValidator when an intersection is made (ComputeOverlay(SpatialFunction)), so performances are dramatically improved but failures are not managed.

Declaration

public static bool NodingValidatorDisabled { get; set; }

Property Value

Type	Description
bool

Remarks

Use ay your own risk!

Methods

CreateEmptyResult(SpatialFunction, Geometry, Geometry, GeometryFactory)

Creates an empty result geometry of the appropriate dimension, based on the given overlay operation and the dimensions of the inputs. The created geometry is always an atomic geometry, not a collection.

The empty result is constructed using the following rules:

• Intersection - result has the dimension of the lowest input dimension
• Union - result has the dimension of the highest input dimension
• Difference - result has the dimension of the left-hand input
• SymDifference - result has the dimension of the highest input dimension (since symDifference is the union of the differences).

Declaration

public static Geometry CreateEmptyResult(SpatialFunction overlayOpCode, Geometry a, Geometry b, GeometryFactory geomFact)

Parameters

Type	Name	Description
SpatialFunction	overlayOpCode	The overlay operation being performed
Geometry	a	An input geometry
Geometry	b	An input geometry
GeometryFactory	geomFact	The geometry factory being used for the operation

Returns

Type	Description
Geometry	An empty atomic geometry of the appropriate dimension

GetResultGeometry(SpatialFunction)

Gets the result of the overlay for a given overlay operation.

Note: this method can be called once only.

Declaration

public Geometry GetResultGeometry(SpatialFunction overlayOpCode)

Parameters

Type	Name	Description
SpatialFunction	overlayOpCode	The code of the overlay operation to perform

Returns

Type	Description
Geometry	The computed result geometry

Exceptions

Type	Condition
TopologyException	Thrown if a robustness problem is encountered

InsertUniqueEdge(Edge)

Insert an edge from one of the noded input graphs. Checks edges that are inserted to see if an identical edge already exists. If so, the edge is not inserted, but its label is merged with the existing edge.

Declaration

protected void InsertUniqueEdge(Edge e)

Parameters

Type	Name	Description
Edge	e	The edge to insert

IsCoveredByA(Coordinate)

Tests if an L edge should be included in the result or not.

Declaration

public bool IsCoveredByA(Coordinate coord)

Parameters

Type	Name	Description
Coordinate	coord	The point coordinate

Returns

Type	Description
bool	true if the coordinate point is covered by a result Area geometry.

IsCoveredByLA(Coordinate)

Tests if a point node should be included in the result or not.

Declaration

public bool IsCoveredByLA(Coordinate coord)

Parameters

Type	Name	Description
Coordinate	coord	The point coordinate

Returns

Type	Description
bool	true if the coordinate point is covered by a result Line or Area geometry.

IsResultOfOp(Location, Location, SpatialFunction)

Tests whether a point with given Locations relative to two geometries is contained in the result of overlaying the geometries using a given overlay operation.

The method handles arguments of Null correctly

Declaration

public static bool IsResultOfOp(Location loc0, Location loc1, SpatialFunction overlayOpCode)

Parameters

Type	Name	Description
Location	loc0	the code for the location in the first geometry
Location	loc1	the code for the location in the second geometry
SpatialFunction	overlayOpCode	the code for the overlay operation to test

Returns

Type	Description
bool	true if the locations correspond to the overlayOpCode.

IsResultOfOp(Label, SpatialFunction)

Tests whether a point with a given topological Label relative to two geometries is contained in the result of overlaying the geometries using a given overlay operation.

The method handles arguments of Null correctly

Declaration

public static bool IsResultOfOp(Label label, SpatialFunction overlayOpCode)

Parameters

Type	Name	Description
Label	label	The topological label of the point
SpatialFunction	overlayOpCode	The code for the overlay operation to test

Returns

Type	Description
bool	true if the label locations correspond to the overlayOpCode

Overlay(Geometry, Geometry, SpatialFunction)

Computes an overlay operation for the given geometry arguments.

Declaration

public static Geometry Overlay(Geometry geom0, Geometry geom1, SpatialFunction opCode)

Parameters

Type	Name	Description
Geometry	geom0	The first geometry argument
Geometry	geom1	The second geometry argument
SpatialFunction	opCode	The code for the desired overlay operation

Returns

Type	Description
Geometry	The result of the overlay operation

Exceptions

Type	Condition
TopologyException	Thrown if a robustness problem is encountered.