GEOS
3.8.0dev

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 Geometry
s, which is sufficient for algorithms for binary operations.
More...
#include <Label.h>
Public Member Functions  
Label (int onLoc)  
Construct a Label with a single location for both Geometries.  
Label (int geomIndex, int onLoc)  
Construct a Label with the location specified for the given Geometry. More...  
Label (int onLoc, int leftLoc, int rightLoc)  
Construct a Label with On, Left and Right locations for both Geometries. More...  
Label (const Label &l)  
Copy ctor.  
Label &  operator= (const Label &l) 
Label ()  
Initialize both locations to Location::UNDEF. More...  
Label (int geomIndex, int onLoc, int leftLoc, int rightLoc)  
Construct a Label with On, Left and Right locations for the given Geometries. Initialize the locations for the other Geometry to Location::UNDEF.  
void  flip () 
int  getLocation (int geomIndex, int posIndex) const 
int  getLocation (int geomIndex) const 
void  setLocation (int geomIndex, int posIndex, int location) 
void  setLocation (int geomIndex, int location) 
void  setAllLocations (int geomIndex, int location) 
void  setAllLocationsIfNull (int geomIndex, int location) 
void  setAllLocationsIfNull (int location) 
void  merge (const Label &lbl) 
Merge this label with another one. More...  
int  getGeometryCount () const 
bool  isNull () const 
bool  isNull (int geomIndex) const 
bool  isAnyNull (int geomIndex) const 
bool  isArea () const 
bool  isArea (int geomIndex) const 
bool  isLine (int geomIndex) const 
bool  isEqualOnSide (const Label &lbl, int side) const 
bool  allPositionsEqual (int geomIndex, int loc) const 
void  toLine (int 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) More...  
Friends  
std::ostream &  operator<< (std::ostream &, const Label &) 
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 Geometry
s, 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 Geometry
s. 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 TopologyLocation
s with specific geometries.
geos::geomgraph::Label::Label  (  int  geomIndex, 
int  onLoc  
) 
Construct a Label with the location specified for the given Geometry.
Other geometry location will be set to Location::UNDEF.
geos::geomgraph::Label::Label  (  int  onLoc, 
int  leftLoc,  
int  rightLoc  
) 
Construct a Label with On, Left and Right locations for both Geometries.
Initialize the locations for both Geometries to the given values.
geos::geomgraph::Label::Label  (  ) 
Initialize both locations to Location::UNDEF.
isNull() should return true after this kind of construction
void geos::geomgraph::Label::merge  (  const Label &  lbl  ) 
Merge this label with another one.
Merging updates any null attributes of this label with the attributes from lbl
Converts a Label to a Line label (that is, one with no side Locations)