geos::linearref::LocationIndexedLine Class Reference

Supports linear referencing along a linear Geometry using LinearLocations as the index. More...

#include <LocationIndexedLine.h>

Public Member Functions
	LocationIndexedLine (const geom::Geometry *p_linearGeom)
	Constructs an object which allows linear referencing along a given linear Geometry.
geom::Coordinate	extractPoint (const LinearLocation &index) const
	Computes the Coordinate for the point on the line at the given index.
geom::Coordinate	extractPoint (const LinearLocation &index, double offsetDistance) const
	Computes the Coordinate for the point on the line at the given index, offset by the given distance.
std::unique_ptr< geom::Geometry >	extractLine (const LinearLocation &startIndex, const LinearLocation &endIndex) const
	Computes the LineString for the interval on the line between the given indices.
LinearLocation	indexOf (const geom::Coordinate &pt) const
	Computes the index for a given point on the line.
LinearLocation	indexOfAfter (const geom::Coordinate &pt, const LinearLocation &minIndex) const
	Finds the index for a point on the line which is greater than the given index.
LinearLocation *	indicesOf (const geom::Geometry *subLine) const
	Computes the indices for a subline of the line.
LinearLocation	project (const geom::Coordinate &pt) const
	Computes the index for the closest point on the line to the given point.
LinearLocation	getStartIndex () const
	Returns the index of the start of the line.
LinearLocation	getEndIndex () const
	Returns the index of the end of the line.
bool	isValidIndex (const LinearLocation &index) const
	Tests whether an index is in the valid index range for the line.
LinearLocation	clampIndex (const LinearLocation &index) const
	Computes a valid index for this line by clamping the given index to the valid range of index values.

Detailed Description

Supports linear referencing along a linear Geometry using LinearLocations as the index.

Constructor & Destructor Documentation

LocationIndexedLine()

geos::linearref::LocationIndexedLine::LocationIndexedLine ( const geom::Geometry *  p_linearGeom )

inline

Constructs an object which allows linear referencing along a given linear Geometry.

Parameters

p_linearGeom

the linear geometry to reference along

Member Function Documentation

clampIndex()

LinearLocation geos::linearref::LocationIndexedLine::clampIndex ( const LinearLocation &  index ) const

inline

Computes a valid index for this line by clamping the given index to the valid range of index values.

Returns

a valid index value

References geos::linearref::LinearLocation::clamp().

extractLine()

std::unique_ptr< geom::Geometry > geos::linearref::LocationIndexedLine::extractLine ( const LinearLocation &  startIndex, const LinearLocation &  endIndex  ) const

inline

Computes the LineString for the interval on the line between the given indices.

If the endIndex lies before the startIndex, the computed geometry is reversed.

Parameters

startIndex	the index of the start of the interval
endIndex	the index of the end of the interval

Returns

the linear interval between the indices

extractPoint() [1/2]

geom::Coordinate geos::linearref::LocationIndexedLine::extractPoint ( const LinearLocation &  index ) const

inline

Computes the Coordinate for the point on the line at the given index.

If the index is out of range the first or last point on the line will be returned. The Z-ordinate of the computed point will be interpolated from the Z-ordinates of the line segment containing it, if they exist.

Parameters

index

the index of the desired point

Returns

the Coordinate at the given index

References geos::linearref::LinearLocation::getCoordinate().

extractPoint() [2/2]

geom::Coordinate geos::linearref::LocationIndexedLine::extractPoint ( const LinearLocation &  index, double  offsetDistance  ) const

inline

Computes the Coordinate for the point on the line at the given index, offset by the given distance.

If the index is out of range the first or last point on the line will be returned. The computed point is offset to the left of the line if the offset distance is positive, to the right if negative.

The Z-ordinate of the computed point will be interpolated from the Z-ordinates of the line segment containing it, if they exist.

Parameters

index	the index of the desired point
offsetDistance	the distance the point is offset from the segment (positive is to the left, negative is to the right)

Returns

the Coordinate at the given index

References geos::linearref::LinearLocation::getSegment(), and geos::linearref::LinearLocation::getSegmentFraction().

getEndIndex()

LinearLocation geos::linearref::LocationIndexedLine::getEndIndex ( ) const

inline

Returns the index of the end of the line.

Returns

the end index

getStartIndex()

LinearLocation geos::linearref::LocationIndexedLine::getStartIndex ( ) const

inline

Returns the index of the start of the line.

Returns

the start index

indexOf()

LinearLocation geos::linearref::LocationIndexedLine::indexOf ( const geom::Coordinate &  pt ) const

inline

Computes the index for a given point on the line.

The supplied point does not necessarily have to lie precisely on the line, but if it is far from the line the accuracy and performance of this function is not guaranteed. Use project to compute a guaranteed result for points which may be far from the line.

Parameters

pt	a point on the line

Returns

the index of the point

See also

project

indexOfAfter()

LinearLocation geos::linearref::LocationIndexedLine::indexOfAfter ( const geom::Coordinate &  pt, const LinearLocation &  minIndex  ) const

inline

Finds the index for a point on the line which is greater than the given index.

If no such index exists, returns minIndex. This method can be used to determine all indexes for a point which occurs more than once on a non-simple line. It can also be used to disambiguate cases where the given point lies slightly off the line and is equidistant from two different points on the line.

The supplied point does not necessarily have to lie precisely on the line, but if it is far from the line the accuracy and performance of this function is not guaranteed. Use project to compute a guaranteed result for points which may be far from the line.

Parameters

pt	a point on the line
minIndex	the value the returned index must be greater than

Returns

the index of the point greater than the given minimum index

See also

project

indicesOf()

LinearLocation * geos::linearref::LocationIndexedLine::indicesOf ( const geom::Geometry *  subLine ) const

inline

Computes the indices for a subline of the line.

(The subline must conform to the line; that is, all vertices in the subline (except possibly the first and last) must be vertices of the line and occur in the same order).

Parameters

subLine

a subLine of the line

Returns

a pair of indices for the start and end of the subline.

isValidIndex()

bool geos::linearref::LocationIndexedLine::isValidIndex ( const LinearLocation &  index ) const

inline

Tests whether an index is in the valid index range for the line.

Parameters

index

the index to test

Returns

true if the index is in the valid range

References geos::linearref::LinearLocation::isValid().

project()

LinearLocation geos::linearref::LocationIndexedLine::project ( const geom::Coordinate &  pt ) const

inline

Computes the index for the closest point on the line to the given point.

If more than one point has the closest distance the first one along the line is returned. (The point does not necessarily have to lie precisely on the line.)

Parameters

pt	a point on the line

Returns

the index of the point

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

• LocationIndexedLine.h