geos::operation::overlayng::OverlayLabel Class Reference

#include <OverlayLabel.h>

Public Types
enum	{   DIM_UNKNOWN = -1 , DIM_NOT_PART = -1 , DIM_LINE = 1 , DIM_BOUNDARY = 2 ,   DIM_COLLAPSE = 3 }

Public Member Functions
	OverlayLabel (uint8_t p_index)
	OverlayLabel (uint8_t p_index, Location p_locLeft, Location p_locRight, bool p_isHole)
int	dimension (uint8_t index) const
void	initBoundary (uint8_t index, Location locLeft, Location locRight, bool p_isHole)
void	initCollapse (uint8_t index, bool p_isHole)
void	initLine (uint8_t index)
void	initNotPart (uint8_t index)
void	setLocationLine (uint8_t index, Location loc)
void	setLocationAll (uint8_t index, Location loc)
void	setLocationCollapse (uint8_t index)
bool	isLine () const
bool	isLine (uint8_t index) const
bool	isLinear (uint8_t index) const
bool	isKnown (uint8_t index) const
bool	isNotPart (uint8_t index) const
bool	isBoundaryEither () const
bool	isBoundaryBoth () const
bool	isBoundaryCollapse () const
bool	isBoundaryTouch () const
bool	isBoundary (uint8_t index) const
bool	isLineLocationUnknown (int index) const
bool	isBoundarySingleton () const
bool	isLineInArea (int8_t index) const
bool	isHole (uint8_t index) const
bool	isCollapse (uint8_t index) const
Location	getLineLocation (uint8_t index) const
bool	isInteriorCollapse () const
bool	isCollapseAndNotPartInterior () const
bool	isLineInterior (uint8_t index) const
Location	getLocationBoundaryOrLine (uint8_t index, int position, bool isForward) const
Location	getLocation (uint8_t index) const
Location	getLocation (uint8_t index, int position, bool isForward) const
bool	hasSides (uint8_t index) const
OverlayLabel	copy () const
void	toString (bool isForward, std::ostream &os) const

Static Public Attributes
static constexpr Location	LOC_UNKNOWN = Location::NONE

Friends
std::ostream &	operator<< (std::ostream &os, const OverlayLabel &ol)

Detailed Description

A label for a pair of OverlayEdges which records the topological information for the edge in the OverlayGraph containing it. The label is shared between both OverlayEdges of a symmetric pair. Accessors for orientation-sensitive information require the orientation of the containing OverlayEdge.

A label contains the topological geom::Locations for the two overlay input geometries. A labelled input geometry may be either a Line or an Area. In both cases, the label locations are populated with the locations for the edge geom::Positions once they are computed by topological evaluation. The label also records the dimension of each geometry, and in the case of area boundary edges, the role of the originating ring (which allows determination of the edge role in collapse cases).

For each input geometry, the label indicates that an edge is in one of the following states (identified by the "dim" field). Each state has some additional information about the edge.

• A Boundary edge of an input Area (polygon)
  • dim = DIM_BOUNDARY
  • locLeft, locRight : the locations of the edge sides for the input Area
  • isHole : whether the edge was in a shell or a hole
• A Collapsed edge of an input Area (which had two or more parent edges)
  • dim = DIM_COLLAPSE
  • locLine : the location of the edge relative to the input Area
  • isHole : whether some contributing edge was in a shell (false), or otherwise that all were in holes (true)
• An edge from an input Line
  • dim = DIM_LINE
  • locLine : initialized to LOC_UNKNOWN, to simplify logic.
• An edge which is Not Part of an input geometry (and thus must be part of the other geometry).
  • dim = NOT_PART

Note that:

• an edge cannot be both a Collapse edge and a Line edge in the same input geometry, because each input geometry must be homogeneous.
• an edge may be an Boundary edge in one input geometry and a Line or Collapse edge in the other input.

Author

Martin Davis

Member Function Documentation

getLocation()

Location geos::operation::overlayng::OverlayLabel::getLocation ( uint8_t  index ) const

inline

Gets the linear location for the given source.

Parameters

index

the source index

Returns

the linear location for the source

getLocationBoundaryOrLine()

Location geos::operation::overlayng::OverlayLabel::getLocationBoundaryOrLine ( uint8_t  index, int  position, bool  isForward  ) const

inline

Gets the location for this label for either a Boundary or a Line edge. This supports a simple determination of whether the edge should be included as a result edge.

Parameters

index	the source index
position	the position for a boundary label
isForward	the direction for a boundary label

Returns

the location for the specified position

isBoundaryCollapse()

bool geos::operation::overlayng::OverlayLabel::isBoundaryCollapse ( ) const

inline

Tests if the label is for a collapsed edge of an area which is coincident with the boundary of the other area.

Returns

true if the label is for a collapse coincident with a boundary

isBoundarySingleton()

bool geos::operation::overlayng::OverlayLabel::isBoundarySingleton ( ) const

inline

Tests whether a label is for an edge which is a boundary of one geometry and not part of the other.

isBoundaryTouch()

bool geos::operation::overlayng::OverlayLabel::isBoundaryTouch ( ) const

inline

Tests if a label is for an edge where two area touch along their boundary.

References geos::geom::Position::RIGHT.

isCollapseAndNotPartInterior()

bool geos::operation::overlayng::OverlayLabel::isCollapseAndNotPartInterior

(

)

const

Tests if a label is a Collapse and NotPart with location INTERIOR for the other geometry.

isInteriorCollapse()

bool geos::operation::overlayng::OverlayLabel::isInteriorCollapse ( ) const

inline

Tests if a label is a Collapse has location INTERIOR, to at least one source geometry.

isLineInArea()

bool geos::operation::overlayng::OverlayLabel::isLineInArea ( int8_t  index ) const

inline

Tests if a line edge is inside

Parameters

index

Returns

isLineInterior()

bool geos::operation::overlayng::OverlayLabel::isLineInterior ( uint8_t  index ) const

inline

Tests if a line is in the interior of a source geometry.

Parameters

index

source geometry

Returns

true if the label is a line and is interior

setLocationLine()

void geos::operation::overlayng::OverlayLabel::setLocationLine	(	uint8_t	index,
		Location	loc
	)

Sets the line location.

This is used to set the locations for linear edges encountered during area label propagation.

Parameters

index	source to update
loc	location to set

---

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

• OverlayLabel.h