GEOS  3.13.0dev
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geos::geomgraph::Label Class Reference

A Label indicates the topological relationship of a component of a topology graph to a given Geometry. More...

#include <Label.h>

Public Member Functions

 Label (geom::Location onLoc)
 Construct a Label with a single location for both Geometries.
 
 Label (uint32_t geomIndex, geom::Location onLoc)
 Construct a Label with the location specified for the given Geometry. More...
 
 Label (geom::Location onLoc, geom::Location leftLoc, geom::Location rightLoc)
 Construct a Label with On, Left and Right locations for both Geometries. More...
 
 Label (const Label &l)
 Copy ctor.
 
 Label ()
 Initialize both locations to Location::NONE. More...
 
 Label (uint32_t geomIndex, geom::Location onLoc, geom::Location leftLoc, geom::Location rightLoc)
 Construct a Label with On, Left and Right locations for the given Geometries. Initialize the locations for the other Geometry to Location::NONE.
 
Labeloperator= (const Label &l)
 
void flip ()
 
void merge (const Label &lbl)
 Merge this label with another one. More...
 
int getGeometryCount () const
 
geom::Location getLocation (uint32_t geomIndex, uint32_t posIndex) const
 
geom::Location getLocation (uint32_t geomIndex) const
 
void setLocation (uint32_t geomIndex, uint32_t posIndex, geom::Location location)
 
void setLocation (uint32_t geomIndex, geom::Location location)
 
void setAllLocations (uint32_t geomIndex, geom::Location location)
 
void setAllLocationsIfNull (uint32_t geomIndex, geom::Location location)
 
void setAllLocationsIfNull (geom::Location location)
 
bool isNull (uint32_t geomIndex) const
 
bool isNull () const
 
bool isAnyNull (uint32_t geomIndex) const
 
bool isArea () const
 
bool isArea (uint32_t geomIndex) const
 
bool isLine (uint32_t geomIndex) const
 
bool isEqualOnSide (const Label &lbl, uint32_t side) const
 
bool allPositionsEqual (uint32_t geomIndex, geom::Location loc) const
 
void toLine (uint32_t geomIndex)
 Converts one GeometryLocation to a Line location.
 
std::string toString () const
 

Static Public Member Functions

static Label toLineLabel (const Label &label)
 Converts a Label to a Line label (that is, one with no side Locations)
 

Friends

std::ostream & operator<< (std::ostream &, const Label &)
 

Detailed Description

A Label indicates the topological relationship of a component of a topology graph to a given Geometry.

This class supports labels for relationships to two Geometrys, which is sufficient for algorithms for binary operations.

Topology graphs support the concept of labeling nodes and edges in the graph. The label of a node or edge specifies its topological relationship to one or more geometries. (In fact, since JTS operations have only two arguments labels are required for only two geometries). A label for a node or edge has one or two elements, depending on whether the node or edge occurs in one or both of the input Geometrys. Elements contain attributes which categorize the topological location of the node or edge relative to the parent Geometry; that is, whether the node or edge is in the interior, boundary or exterior of the Geometry. Attributes have a value from the set {Interior, Boundary, Exterior}. In a node each element has a single attribute <On>. For an edge each element has a triplet of attributes <Left, On, Right>.

It is up to the client code to associate the 0 and 1 TopologyLocations with specific geometries.

Constructor & Destructor Documentation

◆ Label() [1/3]

geos::geomgraph::Label::Label ( uint32_t  geomIndex,
geom::Location  onLoc 
)
inline

Construct a Label with the location specified for the given Geometry.

Other geometry location will be set to Location::NONE.

◆ Label() [2/3]

geos::geomgraph::Label::Label ( geom::Location  onLoc,
geom::Location  leftLoc,
geom::Location  rightLoc 
)
inline

Construct a Label with On, Left and Right locations for both Geometries.

Initialize the locations for both Geometries to the given values.

◆ Label() [3/3]

geos::geomgraph::Label::Label ( )
inline

Initialize both locations to Location::NONE.

isNull() should return true after this kind of construction

Member Function Documentation

◆ merge()

void geos::geomgraph::Label::merge ( const Label lbl)
inline

Merge this label with another one.

Merging updates any null attributes of this label with the attributes from lbl


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