ConstructPolygonsFromPolylines Method (IGeometryEngine)

In This Topic

Generates polygons from a set of polylines.

Syntax

C#
Visual Basic (Declaration)

IReadOnlyList<Polygon> ConstructPolygonsFromPolylines( 
   IEnumerable<Polyline> polylines
)

Function ConstructPolygonsFromPolylines( _
   ByVal polylines As IEnumerable(Of Polyline) _
) As IReadOnlyList(Of Polygon)

Parameters

polylines: The set of polylines to create polygons from. If a polyline has curves, a densified copy of it is used to construct the polygons.

Return Value

Returns the polygons. If none are created, then the collection returned is empty.

Exceptions

Exception	Description
System.ArgumentNullException	The polylines is null.

Remarks

The polylines may cross rather than be connected from end to end.

ConstructPolygonsFromPolylines

Example

Construct a Polygon from a set of Polylines

List<Coordinate2D> firstLinePts = new List<Coordinate2D>();
firstLinePts.Add(new Coordinate2D(1.0, 1.0));
firstLinePts.Add(new Coordinate2D(1.0, 4.0));

List<Coordinate2D> secondLinePts = new List<Coordinate2D>();
secondLinePts.Add(new Coordinate2D(4.0, 4.0));
secondLinePts.Add(new Coordinate2D(4.0, 1.0));

List<Coordinate2D> thirdLinePts = new List<Coordinate2D>();
thirdLinePts.Add(new Coordinate2D(0.0, 2.0));
thirdLinePts.Add(new Coordinate2D(5.0, 2.0));
      
List<Coordinate2D> fourthLinePts = new List<Coordinate2D>();
fourthLinePts.Add(new Coordinate2D(0.0, 3.0));
fourthLinePts.Add(new Coordinate2D(5.0, 3.0));

// build the polylines
List<Polyline> polylines = new List<Polyline>();
polylines.Add(PolylineBuilderEx.CreatePolyline(firstLinePts));
polylines.Add(PolylineBuilderEx.CreatePolyline(secondLinePts));
polylines.Add(PolylineBuilderEx.CreatePolyline(thirdLinePts));
polylines.Add(PolylineBuilderEx.CreatePolyline(fourthLinePts));

// construct polygons from the polylines
var polygons = GeometryEngine.Instance.ConstructPolygonsFromPolylines(polylines);

// polygons.Count = 1
// polygon coordinates are (1.0, 2.0), (1.0, 3.0), (4.0, 3.0), (4.0, 2.0)

Requirements

Target Platforms: Windows 11, Windows 10, Windows 8.1

Reference

IGeometryEngine Interface
IGeometryEngine Members

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