Package org.locationtech.jts.operation

Class IsSimpleOp

  • public class IsSimpleOp
extends java.lang.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

    • Field Detail

      • isClosedEndpointsInInterior

        private boolean isClosedEndpointsInInterior

      • nonSimpleLocation

        private Coordinate nonSimpleLocation

    • Constructor Detail

      • IsSimpleOp

        public IsSimpleOp()
        Deprecated.
        use IsSimpleOp(Geometry)
        Creates a simplicity checker using the default SFS Mod-2 Boundary Node Rule

      • IsSimpleOp

        public IsSimpleOp​(Geometry geom)
        Creates a simplicity checker using the default SFS Mod-2 Boundary Node Rule
        Parameters:
        geom - the geometry to test

      • IsSimpleOp

        public IsSimpleOp​(Geometry geom,
                  BoundaryNodeRule boundaryNodeRule)
        Creates a simplicity checker using a given BoundaryNodeRule
        Parameters:
        geom - the geometry to test
        boundaryNodeRule - the rule to use.

    • Method Detail

      • isSimple

        public boolean isSimple()
        Tests whether the geometry is simple.
        Returns:
        true if the geometry is simple

      • computeSimple

        private boolean computeSimple​(Geometry geom)

      • getNonSimpleLocation

        public Coordinate 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​(LineString geom)
        Deprecated.
        use isSimple()
        Reports whether a LineString is simple.
        Parameters:
        geom - the lineal geometry to test
        Returns:
        true if the geometry is simple

      • isSimple

        public boolean isSimple​(MultiLineString geom)
        Deprecated.
        use isSimple()
        Reports whether a MultiLineString geometry is simple.
        Parameters:
        geom - the lineal geometry to test
        Returns:
        true if the geometry is simple

      • isSimple

        public boolean isSimple​(MultiPoint mp)
        Deprecated.
        use isSimple()
        A MultiPoint is simple iff it has no repeated points

      • isSimpleMultiPoint

        private boolean isSimpleMultiPoint​(MultiPoint mp)

      • isSimplePolygonal

        private boolean isSimplePolygonal​(Geometry geom)
        Computes simplicity for polygonal geometries. Polygonal geometries are simple if and only if all of their component rings are simple.
        Parameters:
        geom - a Polygonal geometry
        Returns:
        true if the geometry is simple

      • isSimpleGeometryCollection

        private boolean isSimpleGeometryCollection​(Geometry geom)
        Semantics for GeometryCollection is simple iff all components are simple.
        Parameters:
        geom -
        Returns:
        true if the geometry is simple

      • isSimpleLinearGeometry

        private boolean isSimpleLinearGeometry​(Geometry geom)

      • hasNonEndpointIntersection

        private boolean hasNonEndpointIntersection​(GeometryGraph graph)
        For all edges, check if there are any intersections which are NOT at an endpoint. The Geometry is not simple if there are intersections not at endpoints.

      • hasClosedEndpointIntersection

        private boolean hasClosedEndpointIntersection​(GeometryGraph graph)
        Tests that no edge intersection is the endpoint of a closed line. This ensures that closed lines are not touched at their endpoint, which is an interior point according to the Mod-2 rule To check this we compute the degree of each endpoint. The degree of endpoints of closed lines must be exactly 2.

      • addEndpoint

        private void addEndpoint​(java.util.Map endPoints,
                         Coordinate p,
                         boolean isClosed)
        Add an endpoint to the map, creating an entry for it if none exists