GEOS: geos::linearref::LocationIndexedLine Class Reference

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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 *linearGeom)
| Constructs an object which allows linear referencing along a given linear Geometry. More...
geom::Coordinate | extractPoint (const LinearLocation &index) const
| Computes the Coordinate for the point on the line at the given index. More...
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. More...
geom::Geometry * | extractLine (const LinearLocation &startIndex, const LinearLocation &endIndex) const
| Computes the LineString for the interval on the line between the given indices. More...
LinearLocation | indexOf (const geom::Coordinate &pt) const
| Computes the index for a given point on the line. More...
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. More...
LinearLocation * | indicesOf (const geom::Geometry *subLine) const
| Computes the indices for a subline of the line. More...
LinearLocation | project (const geom::Coordinate &pt) const
| Computes the index for the closest point on the line to the given point. More...
LinearLocation | getStartIndex () const
| Returns the index of the start of the line. More...
LinearLocation | getEndIndex () const
| Returns the index of the end of the line. More...
bool | isValidIndex (const LinearLocation &index) const
| Tests whether an index is in the valid index range for the line. More...
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. More...

## Detailed Description

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

## Constructor & Destructor Documentation

geos::linearref::LocationIndexedLine::LocationIndexedLine | ( | const geom::Geometry * | linearGeom | ) |
| inline

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

Parameters

  linearGeom | the linear geometry to reference along

## Member Function Documentation

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().

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

References geos::linearref::ExtractLineByLocation::extract().

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().

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().

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

Returns the index of the end of the line.

Returns
  the end index

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

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

Returns the index of the start of the line.

Returns
  the start index

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

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

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.

References geos::linearref::LocationIndexOfLine::indicesOf().

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

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

Parameters

  length | the index to test

Returns
  `true` if the index is in the valid range

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

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

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

- LocationIndexedLine.h