com.revolsys.jts.operation

Class IsSimpleOp

java.lang.Object

com.revolsys.jts.operation.IsSimpleOp

public class IsSimpleOp
extends Object

Tests whether a Geometry is simple. In general, the SFS specification of simplicity follows the rule:

• A Geometry is simple if and only if the only self-intersections are at boundary points.

Simplicity is defined for each Geometry type as follows:

• Polygonal geometries are simple by definition, so isSimple trivially returns true. (Note: this means that isSimple cannot be used to test for (invalid) self-intersections in Polygons. In order to check if a Polygonal geometry has self-intersections, use Geometry.isValid()).
• Linear geometries are simple iff they do not self-intersect at interior points (i.e. points other than boundary points). This is equivalent to saying that no two linear components satisfy the SFS Geometry.touches(Geometry) predicate.
• Zero-dimensional (point) geometries are simple if and only if they have no repeated points.
• Empty geometries are always simple, by definition

For Lineal geometries the evaluation of simplicity can be customized by supplying a BoundaryNodeRule to define how boundary points are determined. The default is the SFS-standard BoundaryNodeRule.MOD2_BOUNDARY_RULE. Note that under the Mod-2 rule, closed LineStrings (rings) will never satisfy the touches predicate at their endpoints, since these are interior points, not boundary points. If it is required to test whether a set of LineStrings touch only at their endpoints, use IsSimpleOp with BoundaryNodeRule.ENDPOINT_BOUNDARY_RULE. For example, this can be used to validate that a set of lines form a topologically valid linear network.

Version:

1.7

See Also:

BoundaryNodeRule

Constructor Summary

Constructors

Constructor and Description
IsSimpleOp(Geometry geometry) Creates a simplicity checker using the default SFS Mod-2 Boundary Node Rule
IsSimpleOp(Geometry geometry, boolean shortCircuit)

Method Summary

Methods

Modifier and Type	Method and Description
List<GeometryValidationError>	getErrors()
Point	getNonSimpleLocation() Gets a coordinate for the location where the geometry fails to be simple.
boolean	isSimple() Tests whether the geometry is simple.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

IsSimpleOp

public IsSimpleOp(Geometry geometry)

Creates a simplicity checker using the default SFS Mod-2 Boundary Node Rule

Parameters:

geometry - the geometry to test

IsSimpleOp

public IsSimpleOp(Geometry geometry,
          boolean shortCircuit)

Method Detail

getErrors

public List<GeometryValidationError> getErrors()

getNonSimpleLocation

public Point getNonSimpleLocation()

Gets a coordinate for the location where the geometry fails to be simple. (i.e. where it has a non-boundary self-intersection). isSimple() must be called before this method is called.

Returns:

a coordinate for the location of the non-boundary self-intersection or null if the geometry is simple

isSimple

public boolean isSimple()

Tests whether the geometry is simple.

Returns:

true if the geometry is simple