# geos::operation::polygonize::PolygonizeGraph Class Reference

Represents a planar graph of edges that can be used to compute a polygonization, and implements the algorithms to compute the EdgeRings formed by the graph. More...

`#include <PolygonizeGraph.h>`

Inheritance diagram for geos::operation::polygonize::PolygonizeGraph:

List of all members.

## Public Member Functions

| PolygonizeGraph (const geom::GeometryFactory *newFactory)
| Create a new polygonization graph.
| ~PolygonizeGraph ()
| Destroy a polygonization graph.
void | addEdge (const geom::LineString *line)
| Add a LineString forming an edge of the polygon graph.
void | getEdgeRings (std::vector< EdgeRing * > &edgeRingList)
| Computes the EdgeRings formed by the edges in this graph.
void | deleteCutEdges (std::vector< const geom::LineString * > &cutLines)
| Finds and removes all cut edges from the graph.
void | deleteDangles (std::vector< const geom::LineString * > &dangleLines)
| Marks all edges from the graph which are "dangles".

## Static Public Member Functions

static void | deleteAllEdges (planargraph::Node *node)
| Deletes all edges at a node.

## Detailed Description

Represents a planar graph of edges that can be used to compute a polygonization, and implements the algorithms to compute the EdgeRings formed by the graph.

The marked flag on DirectedEdge is used to indicate that a directed edge has be logically deleted from the graph.

## Member Function Documentation

void geos::operation::polygonize::PolygonizeGraph::addEdge | ( | const geom::LineString * | line ) |

Add a LineString forming an edge of the polygon graph.

Parameters:

  line | the line to add

void geos::operation::polygonize::PolygonizeGraph::deleteCutEdges | ( | std::vector< const geom::LineString * > & | cutLines ) |

Finds and removes all cut edges from the graph.

Parameters:

  cutLines | : the list of the LineString forming the removed cut edges will be pushed here.

TODO: document ownership of the returned LineStrings

void geos::operation::polygonize::PolygonizeGraph::deleteDangles | ( | std::vector< const geom::LineString * > & | dangleLines ) |

Marks all edges from the graph which are "dangles".

Dangles are which are incident on a node with degree 1. This process is recursive, since removing a dangling edge may result in another edge becoming a dangle. In order to handle large recursion depths efficiently, an explicit recursion stack is used

Parameters:

  dangleLines | : the LineStrings that formed dangles will be push_back'ed here

void geos::operation::polygonize::PolygonizeGraph::getEdgeRings | ( | std::vector< EdgeRing * > & | edgeRingList ) |

Computes the EdgeRings formed by the edges in this graph.

Parameters:

  edgeRingList | : the EdgeRing found by the polygonization process will be pushed here.

The documentation for this class was generated from the following file:

- PolygonizeGraph.h