org.locationtech.jts.operation.buffer

Class OffsetCurveBuilder

java.lang.Object

org.locationtech.jts.operation.buffer.OffsetCurveBuilder

public class OffsetCurveBuilder
extends Object

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 PrecisionModel.

Note: this may not produce correct results if the input contains repeated or invalid points. Repeated points should be removed before calling. See CoordinateArrays.removeRepeatedOrInvalidPoints(Coordinate[]).

Version:

1.7

Constructor Summary

Constructors

Constructor and Description
OffsetCurveBuilder(PrecisionModel precisionModel, BufferParameters bufParams)

Method Summary

Modifier and Type	Method and Description
BufferParameters	getBufferParameters() Gets the buffer parameters being used to generate the curve.
Coordinate[]	getLineCurve(Coordinate[] inputPts, double distance) This method handles single points as well as LineStrings.
Coordinate[]	getOffsetCurve(Coordinate[] inputPts, double distance)
Coordinate[]	getRingCurve(Coordinate[] inputPts, int side, double distance) This method handles the degenerate cases of single points and lines, as well as valid rings.
boolean	isLineOffsetEmpty(double distance) Tests whether the offset curve for line or point geometries at the given offset distance is empty (does not exist).

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

OffsetCurveBuilder

public OffsetCurveBuilder(PrecisionModel precisionModel,
                          BufferParameters bufParams)

Method Detail

getBufferParameters

public BufferParameters getBufferParameters()

Gets the buffer parameters being used to generate the curve.

Returns:

the buffer parameters being used

getLineCurve

public Coordinate[] getLineCurve(Coordinate[] inputPts,
                                 double distance)

This method handles single points as well as LineStrings. LineStrings are assumed not to be closed (the function will not fail for closed lines, but will generate superfluous line caps).

Parameters:

inputPts - the vertices of the line to offset

distance - the offset distance

Returns:

a Coordinate array representing the curve or null if the curve is empty

isLineOffsetEmpty

public boolean 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

getRingCurve

public Coordinate[] getRingCurve(Coordinate[] inputPts,
                                 int side,
                                 double distance)

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

Parameters:

inputPts - the coordinates of the ring (must not contain repeated points)

side - side the side Position of the ring on which to construct the buffer line

distance - the positive distance at which to create the offset

Returns:

a Coordinate array representing the curve, or null if the curve is empty

getOffsetCurve

public Coordinate[] getOffsetCurve(Coordinate[] inputPts,
                                   double distance)