com.vividsolutions.jts.operation.overlay

Class OverlayOp


  • public class OverlayOp
extends GeometryGraphOperation
    Computes the geometric overlay of two Geometrys. The overlay can be used to determine any boolean combination of the geometries.

    • Field Detail

      • INTERSECTION

        public static final int INTERSECTION
        The code for the Intersection overlay operation.
        See Also:
        Constant Field Values

      • UNION

        public static final int UNION
        The code for the Union overlay operation.
        See Also:
        Constant Field Values

      • DIFFERENCE

        public static final int DIFFERENCE
        The code for the Difference overlay operation.
        See Also:
        Constant Field Values

      • SYMDIFFERENCE

        public static final int SYMDIFFERENCE
        The code for the Symmetric Difference overlay operation.
        See Also:
        Constant Field Values

    • Constructor Detail

      • OverlayOp

        public OverlayOp(Geometry g0,
                 Geometry g1)
        Constructs an instance to compute a single overlay operation for the given geometries.
        Parameters:
        g0 - the first geometry argument
        g1 - the second geometry argument

    • Method Detail

      • overlayOp

        public static Geometry overlayOp(Geometry geom0,
                                 Geometry geom1,
                                 int opCode)
        Computes an overlay operation for the given geometry arguments.
        Parameters:
        geom0 - the first geometry argument
        geom1 - the second geometry argument
        opCode - the code for the desired overlay operation
        Returns:
        the result of the overlay operation
        Throws:
        TopologyException - if a robustness problem is encountered

      • isResultOfOp

        public static boolean isResultOfOp(Label label,
                                   int opCode)
        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 Location.NONE correctly

        Parameters:
        label - the topological label of the point
        opCode - the code for the overlay operation to test
        Returns:
        true if the label locations correspond to the overlayOpCode

      • isResultOfOp

        public static boolean isResultOfOp(int loc0,
                                   int loc1,
                                   int overlayOpCode)
        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 Location.NONE correctly

        Parameters:
        loc0 - the code for the location in the first geometry
        loc1 - the code for the location in the second geometry
        overlayOpCode - the code for the overlay operation to test
        Returns:
        true if the locations correspond to the overlayOpCode

      • getResultGeometry

        public Geometry getResultGeometry(int overlayOpCode)
        Gets the result of the overlay for a given overlay operation.

        Note: this method can be called once only.

        Parameters:
        overlayOpCode - the overlay operation to perform
        Returns:
        the compute result geometry
        Throws:
        TopologyException - if a robustness problem is encountered

      • getGraph

        public PlanarGraph getGraph()
        Gets the graph constructed to compute the overlay.
        Returns:
        the overlay graph

      • insertUniqueEdge

        protected void insertUniqueEdge(Edge e)
        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.

      • isCoveredByLA

        public boolean isCoveredByLA(Coordinate coord)
        Tests if a point node should be included in the result or not.
        Parameters:
        coord - the point coordinate
        Returns:
        true if the coordinate point is covered by a result Line or Area geometry

      • isCoveredByA

        public boolean isCoveredByA(Coordinate coord)
        Tests if an L edge should be included in the result or not.
        Parameters:
        coord - the point coordinate
        Returns:
        true if the coordinate point is covered by a result Area geometry

      • createEmptyResult

        public static Geometry createEmptyResult(int overlayOpCode,
                                         Geometry a,
                                         Geometry b,
                                         GeometryFactory geomFact)
        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 the symmetric Difference is the union of the differences).
        Parameters:
        overlayOpCode - the code for the overlay operation being performed
        a - an input geometry
        b - an input geometry
        geomFact - the geometry factory being used for the operation
        Returns:
        an empty atomic geometry of the appropriate dimension