Class OffsetCurve

Computes an offset curve from a geometry. The offset curve is a linear geometry which is offset a specified distance from the input. If the offset distance is positive the curve lies on the left side of the input; if it is negative the curve is on the right side.

For a LineString the offset curve is a line.
For a Point the offset curve is an empty LineString.
For a Polygon the offset curve is the boundary of the polygon buffer (which may be a MultiLineString).
For a collection the output is a MultiLineString containing the element offset curves.

The offset curve is computed as a single contiguous section of the geometry buffer boundary. In some geometric situations this definition is ill-defined. This algorithm provides a "best-effort" interpretation. In particular:

For self-intersecting lines, the buffer boundary includes offset lines for both left and right sides of the input line. Only a single contiguous portion on the specified side is returned.
If the offset corresponds to buffer holes, only the largest hole is used.

Offset curves support setting the number of quadrant segments, the join style, and the mitre limit(if applicable) via the BufferParameters.

Inheritance

Object

OffsetCurve

Inherited Members

Object.Equals(Object)

Object.Equals(Object, Object)

Object.GetHashCode()

Object.GetType()

Object.MemberwiseClone()

Object.ReferenceEquals(Object, Object)

Object.ToString()

Namespace: NetTopologySuite.Operation.Buffer

Assembly: NetTopologySuite.dll

Syntax

public class OffsetCurve

Constructors

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OffsetCurve(Geometry, Double)

Creates a new instance for computing an offset curve for a geometryat a given distance. with default quadrant segments(DefaultQuadrantSegments and join style (DefaultJoinStyle).

Declaration

public OffsetCurve(Geometry geom, double distance)

Parameters

Type	Name	Description
Geometry	geom	The geometry
Double	distance	A distance value

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OffsetCurve(Geometry, Double, BufferParameters)

Declaration

public OffsetCurve(Geometry geom, double distance, BufferParameters bufParams)

Parameters

Type	Name	Description
Geometry	geom
Double	distance
BufferParameters	bufParams

Methods

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GetCurve()

Gets the computed offset curve.

Declaration

public Geometry GetCurve()

Returns

Type	Description
Geometry	The offset curve geometry

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GetCurve(Geometry, Double)

Computes the offset curve of a geometry at a given distance.

Declaration

public static Geometry GetCurve(Geometry geom, double distance)

Parameters

Type	Name	Description
Geometry	geom	A geometry
Double	distance	the offset distance (positive = left, negative = right)

Returns

Type	Description
Geometry	The offset curve

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GetCurve(Geometry, Double, Int32, JoinStyle, Double)

Computes the offset curve of a geometry at a given distance, and for a specified quadrant segments, join style and mitre limit.

Declaration

public static Geometry GetCurve(Geometry geom, double distance, int quadSegs = -1, JoinStyle joinStyle = JoinStyle.Round, double mitreLimit = -1)

Parameters

Type	Name	Description
Geometry	geom	A geometry
Double	distance	The offset distance (positive = left, negative = right)
Int32	quadSegs	The quadrant segments
JoinStyle	joinStyle	The join style
Double	mitreLimit	The mitre limit

Returns

Type	Description
Geometry	The offset curve

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RawOffset(LineString, Double)

Gets the raw offset line, with default buffer parameters.

Declaration

public static Coordinate[] RawOffset(LineString geom, double distance)

Parameters

Type	Name	Description
LineString	geom	The `LineString` to offset
Double	distance	The offset distance

Returns

Type	Description
Coordinate[]	The raw offset line

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RawOffset(LineString, Double, BufferParameters)

Gets the raw offset line. The quadrant segments and join style and mitre limit to be set via BufferParameters.

The raw offset line may contain loops and other artifacts which are not present in the true offset curve. The raw offset line is matched to the buffer ring (which is clean) to extract the offset curve.

Declaration

public static Coordinate[] RawOffset(LineString geom, double distance, BufferParameters bufParams)

Parameters

Type	Name	Description
LineString	geom	The `LineString` to offset
Double	distance	The offset distance
BufferParameters	bufParams	The buffer parameters to use

Returns

Type	Description
Coordinate[]	The raw offset line