Package org.locationtech.jts.operation.buffer

Class BufferBuilder

  • class BufferBuilder
extends java.lang.Object
    Builds the buffer geometry for a given input geometry and precision model. Allows setting the level of approximation for circular arcs, and the precision model in which to carry out the computation.

    When computing buffers in floating point double-precision it can happen that the process of iterated noding can fail to converge (terminate). In this case a TopologyException will be thrown. Retrying the computation in a fixed precision can produce more robust results.

    Version:
    1.7

    • Constructor Detail

      • BufferBuilder

        public BufferBuilder​(BufferParameters bufParams)
        Creates a new BufferBuilder

    • Method Detail

      • depthDelta

        private static int depthDelta​(Label label)
        Compute the change in depth as an edge is crossed from R to L

      • setWorkingPrecisionModel

        public void setWorkingPrecisionModel​(PrecisionModel pm)
        Sets the precision model to use during the curve computation and noding, if it is different to the precision model of the Geometry. If the precision model is less than the precision of the Geometry precision model, the Geometry must have previously been rounded to that precision.
        Parameters:
        pm - the precision model to use

      • setNoder

        public void setNoder​(Noder noder)
        Sets the Noder to use during noding. This allows choosing fast but non-robust noding, or slower but robust noding.
        Parameters:
        noder - the noder to use

      • computeNodedEdges

        private void computeNodedEdges​(java.util.List bufferSegStrList,
                               PrecisionModel precisionModel)

      • insertUniqueEdge

        protected void insertUniqueEdge​(Edge e)
        Inserted edges are checked to see if an identical edge already exists. If so, the edge is not inserted, but its label is merged with the existing edge.

      • createSubgraphs

        private java.util.List createSubgraphs​(PlanarGraph graph)

      • buildSubgraphs

        private void buildSubgraphs​(java.util.List subgraphList,
                            PolygonBuilder polyBuilder)
        Completes the building of the input subgraphs by depth-labelling them, and adds them to the PolygonBuilder. The subgraph list must be sorted in rightmost-coordinate order.
        Parameters:
        subgraphList - the subgraphs to build
        polyBuilder - the PolygonBuilder which will build the final polygons

      • convertSegStrings

        private static Geometry convertSegStrings​(java.util.Iterator it)

      • createEmptyResultGeometry

        private Geometry createEmptyResultGeometry()
        Gets the standard result for an empty buffer. Since buffer always returns a polygonal result, this is chosen to be an empty polygon.
        Returns:
        the empty result geometry