74 lines
2.3 KiB
C
74 lines
2.3 KiB
C
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/**********************************************************************
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*
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* GEOS - Geometry Engine Open Source
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* http://geos.osgeo.org
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*
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* Copyright (C) 2022 ISciences LLC
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*
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* This is free software; you can redistribute and/or modify it under
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* the terms of the GNU Lesser General Public Licence as published
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* by the Free Software Foundation.
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* See the COPYING file for more information.
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*
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**********************************************************************/
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#pragma once
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#include <geos/export.h>
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#include <geos/operation/cluster/AbstractClusterFinder.h>
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#include <geos/operation/cluster/GeometryFlattener.h>
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#include <geos/geom/Geometry.h>
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#include <geos/geom/GeometryFactory.h>
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namespace geos {
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namespace operation {
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namespace cluster {
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class GEOS_DLL DisjointOperation {
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public:
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DisjointOperation(AbstractClusterFinder& finder) : m_finder(finder), m_split_inputs(false) {}
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/** Splits multipart geometries into their underlying components before identifying
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* disjoint subsets.
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*/
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void setSplitInputs(bool b) {
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m_split_inputs = b;
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}
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/** Decompose a geometry into disjoint subsets using the provided `ClusterFinder`,
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* process each subset using `f`, and combine/flatten the results. It is assumed that
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* the processed results of each subset will also be disjoint; therefore, this
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* algorithm may not be suitable for operations such as buffering.
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*
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* @brief process
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* @param g a geometry to be processed
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* @param f function taking a single argument of `const Geometry&`
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*/
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template<typename Function>
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std::unique_ptr<geom::Geometry> processDisjointSubsets(const geom::Geometry& g, Function&& f) {
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if (g.getNumGeometries() == 1) {
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return f(g);
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}
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auto flattened = m_split_inputs ? operation::cluster::GeometryFlattener::flatten(g.clone()) : g.clone();
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auto clustered = m_finder.clusterToVector(std::move(flattened));
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for (auto& subset : clustered) {
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subset = f(*subset);
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}
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auto coll = g.getFactory()->createGeometryCollection(std::move(clustered));
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return operation::cluster::GeometryFlattener::flatten(std::move(coll));
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}
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private:
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AbstractClusterFinder& m_finder;
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bool m_split_inputs;
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};
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}
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}
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}
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