geos::operation::buffer::OffsetCurveBuilder Class Reference

Computes the raw offset curve for a single Geometry component (ring, line or point). More...

#include <OffsetCurveBuilder.h>

Public Member Functions
	OffsetCurveBuilder (const geom::PrecisionModel *newPrecisionModel, const BufferParameters &nBufParams)
const BufferParameters &	getBufferParameters () const
	Gets the buffer parameters being used to generate the curve. More...
bool	isLineOffsetEmpty (double distance)
void	getLineCurve (const geom::CoordinateSequence *inputPts, double distance, std::vector< geom::CoordinateSequence * > &lineList)
	This method handles single points as well as lines. More...
void	getSingleSidedLineCurve (const geom::CoordinateSequence *inputPts, double distance, std::vector< geom::CoordinateSequence * > &lineList, bool leftSide, bool rightSide)
	This method handles single points as well as lines. More...
void	getRingCurve (const geom::CoordinateSequence *inputPts, int side, double distance, std::vector< geom::CoordinateSequence * > &lineList)
	This method handles the degenerate cases of single points and lines, as well as rings. More...
void	getOffsetCurve (const geom::CoordinateSequence *inputPts, double p_distance, std::vector< geom::CoordinateSequence * > &lineList)

Detailed Description

Computes the raw offset curve for a single Geometry component (ring, line or point).

A raw offset curve line is not noded - it may contain self-intersections (and usually will). The final buffer polygon is computed by forming a topological graph of all the noded raw curves and tracing outside contours. The points in the raw curve are rounded to a given geom::PrecisionModel.

Member Function Documentation

getBufferParameters()

const BufferParameters & geos::operation::buffer::OffsetCurveBuilder::getBufferParameters ( ) const

inline

Gets the buffer parameters being used to generate the curve.

Returns

the buffer parameters being used

getLineCurve()

void geos::operation::buffer::OffsetCurveBuilder::getLineCurve	(	const geom::CoordinateSequence *	inputPts,
		double	distance,
		std::vector< geom::CoordinateSequence * > &	lineList
	)

This method handles single points as well as lines.

Lines are assumed to not be closed (the function will not fail for closed lines, but will generate superfluous line caps).

Parameters

inputPts	input points
distance	offset distance
lineList	the std::vector to which the newly created CoordinateSequences will be pushed_back. Caller is responsible to delete these new elements.

getRingCurve()

void geos::operation::buffer::OffsetCurveBuilder::getRingCurve	(	const geom::CoordinateSequence *	inputPts,
		int	side,
		double	distance,
		std::vector< geom::CoordinateSequence * > &	lineList
	)

This method handles the degenerate cases of single points and lines, as well as rings.

Parameters

inputPts	input points
side	a Position
distance	offset distance
lineList	the std::vector to which CoordinateSequences will be pushed_back

getSingleSidedLineCurve()

void geos::operation::buffer::OffsetCurveBuilder::getSingleSidedLineCurve	(	const geom::CoordinateSequence *	inputPts,
		double	distance,
		std::vector< geom::CoordinateSequence * > &	lineList,
		bool	leftSide,
		bool	rightSide
	)

This method handles single points as well as lines.

Lines are assumed to not be closed (the function will not fail for closed lines, but will generate superfluous line caps).

Parameters

inputPts	input points
distance	offset distance
lineList	the std::vector to which newly created CoordinateSequences will be pushed_back. Caller will be responsible to delete them.
leftSide	indicates that the left side buffer will be obtained/skipped
rightSide	indicates that the right side buffer will be obtained/skipped

Note

This is a GEOS extension.

isLineOffsetEmpty()

bool geos::operation::buffer::OffsetCurveBuilder::isLineOffsetEmpty

(

double

distance

)

Tests whether the offset curve for line or point geometries at the given offset distance is empty (does not exist). This is the case if:

• the distance is zero,
• the distance is negative, except for the case of singled-sided buffers

Parameters

distance

the offset curve distance

Returns

true if the offset curve is empty

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

• OffsetCurveBuilder.h