Extend Method (GeometryEngine)

In This Topic

Performs the extend operation on a polyline using a polyline as the extender. The output polyline will have the first and last segment of each part extended to the extender if the segments can be interpolated to intersect the extender. In the case that the segments can be extended to multiple segments of the extender, the shortest extension is chosen. Only end points for parts that are not shared by the end points of other parts will be extended. If the polyline cannot be extended by the input extender, then a null will be returned.

Syntax

C#
Visual Basic (Declaration)

public Polyline Extend( 
   Polyline polyline,
   Polyline extender,
   ExtendFlags extendFlags
)

Public Function Extend( _
   ByVal polyline As Polyline, _
   ByVal extender As Polyline, _
   ByVal extendFlags As ExtendFlags _
) As Polyline

Parameters

polyline: The polyline to be extended.
extender: The polyline to extend to.
extendFlags: The type of extend operation to perform.

Return Value

The extended polyline.

Exceptions

Exception	Description
System.ArgumentNullException	Either polyline or extender or both are null or empty.
System.InvalidOperationException	Incompatible spatial references between the input geometries.
System.InvalidOperationException	Throws InvalidOperationException if both ExtendFlags.NoEndAttributes and ExtendFlags.KeepEndAttributes flags are sent together.

Remarks

Equivalent to IConstructCurve.ConstructExtended

Example

Extend a polyline

// build a polyline
var polyline = PolylineBuilderEx.CreatePolyline(new[]
{
  MapPointBuilderEx.CreateMapPoint(1, 1, 10, 20),
  MapPointBuilderEx.CreateMapPoint(0, 0, 10, 20),
  MapPointBuilderEx.CreateMapPoint(1, -1, 10, 20)
});

// build the extender line
var extender = PolylineBuilderEx.CreatePolyline(new[]
{
  MapPointBuilderEx.CreateMapPoint(2, 2),
  MapPointBuilderEx.CreateMapPoint(2, -2),
});

// extend
var result = GeometryEngine.Instance.Extend(polyline, extender, ExtendFlags.KeepEndAttributes);
Polyline extendedLine = result as Polyline;
// result.Parts[0].Points[0] = 2, 2, 10, 20
// result.parts[0].Points[1] = 1, 1, 10, 20
// result.Parts[0].Points[2] = 0, 0, 10, 20
// result.Parts[0].Points[3] = 1, -1, 10, 20
// result.Parts[0].Points[4] = 2, -2, 10, 20

// change the flags
result = GeometryEngine.Instance.Extend(polyline, extender, ExtendFlags.NoEndAttributes);
extendedLine = result as Polyline;
// result.Parts[0].Points[0] = 2, 2, 0
// result.parts[0].Points[1] = 1, 1, 10, 20
// result.Parts[0].Points[2] = 0, 0, 10, 20
// result.Parts[0].Points[3] = 1, -1, 10, 20
// result.Parts[0].Points[4] = 2, -2, 0

// extend
result = GeometryEngine.Instance.Extend(polyline, extender, ExtendFlags.KeepEndAttributes | ExtendFlags.NoExtendAtTo);
extendedLine = result as Polyline;
// result.Parts[0].Points[0] = 2, 2, 10, 20
// result.parts[0].Points[1] = 1, 1, 10, 20
// result.Parts[0].Points[2] = 0, 0, 10, 20
// result.Parts[0].Points[3] = 1, -1, 10, 20

// extend with no intersection 

polyline = PolylineBuilderEx.CreatePolyline(new[]
{
  MapPointBuilderEx.CreateMapPoint(1, 1),
  MapPointBuilderEx.CreateMapPoint(3, 1)
});

extender = PolylineBuilderEx.CreatePolyline(new[]
{
  MapPointBuilderEx.CreateMapPoint(1, 4),
  MapPointBuilderEx.CreateMapPoint(3, 4)
});

result = GeometryEngine.Instance.Extend(polyline, extender, ExtendFlags.Default);
// result = null

Requirements

Target Platforms: Windows 11, Windows 10, Windows 8.1

Reference

GeometryEngine Class
GeometryEngine Members
ExtendFlags Enumeration

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