GetExteriorRing Method

In This Topic

Gets the specified exterior ring in this polygon.

Syntax

C#
Visual Basic (Declaration)

public Polygon GetExteriorRing( 
   int index,
   bool setSpatialReference
)

Public Function GetExteriorRing( _
   ByVal index As Integer, _
   Optional ByVal setSpatialReference As Boolean _
) As Polygon

Parameters

index: The index of the exterior ring. Note that this is not the index of the part in the polygon. Use ExteriorRingCount to determine the number of exterior rings in this polygon.
setSpatialReference: (Optional) Determines if the spatial reference should be set in each of the returned polygons. If setSpatialReference is set to true, then the spatial reference in each polygon is inherited from this polygon. If setSpatialReference is set to false, then the spatial reference in each polygon is set to null. The default value is true.

Return Value

A polygon representing the exterior ring.

Exceptions

Exception	Description
System.ArgumentOutOfRangeException	The index is negative or is greater than or equal to the number of external rings in this polygon.

Remarks

An exterior ring is a part that is oriented clockwise.

Example

Get the exterior rings of a polygon - polygon.GetExteriorRing

public void GetExteriorRings(Polygon inputPolygon)
{
  if (inputPolygon == null || inputPolygon.IsEmpty)
    return;

  // polygon part count
  int partCount = inputPolygon.PartCount;
  // polygon exterior ring count
  int numExtRings = inputPolygon.ExteriorRingCount;
  // get set of exterior rings for the polygon
  IList<Polygon> extRings = inputPolygon.GetExteriorRings();

  // test each part for "exterior ring"
  for (int idx = 0; idx < partCount; idx++)
  {
    bool isExteriorRing = inputPolygon.IsExteriorRing(idx);
    var ring = inputPolygon.GetExteriorRing(idx);
  }
}

Requirements

Target Platforms: Windows 11, Windows 10, Windows 8.1

Reference

Polygon Class
Polygon Members

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