How to get the X,Y Coordinates vertices of selected polygon feature in C#

worlanyo

I need help with a sample code to get the X,Y Coordinates of the vertices of a selected polygon feature. I intend to pass this to text elements on the pagelayout control. Any help will be greatly appreciated.

 

Thank you

Worlanyo

BrentHoskisson

Here is a sample that gets you from an IFeature (from a cursor) to a List of all the points (type PointF)...

Hope it helps.

Brent Hoskisson

		private void GetVertices(IFeature f)
		{
			IPolygon4 parcel = f.Shape as IPolygon4;
			if (parcel != null)
			{
				List<List<System.Drawing.PointF>> polycoll = new List<List<System.Drawing.PointF>>();
				if (parcel.ExteriorRingCount > 0)
				{
					IGeometryBag exteriorRings = parcel.ExteriorRingBag;
					IEnumGeometry exteriorRingsEnum = exteriorRings as IEnumGeometry;
					exteriorRingsEnum.Reset();
					int ering = 0;
					IRing currentExteriorRing = exteriorRingsEnum.Next() as IRing;
					int extrings = parcel.ExteriorRingCount;
					while (extrings > 0 && currentExteriorRing != null)
					{
						ering++;
						ISegmentCollection segments = currentExteriorRing as ISegmentCollection;

						List<System.Drawing.PointF> spc = ProcessRing(segments);
						if (spc != null)
							polycoll.Add(spc);

						IGeometryBag interiorRings = parcel.InteriorRingBag[currentExteriorRing];
						IEnumGeometry interiorRingsEnum = exteriorRings as IEnumGeometry;
						interiorRingsEnum.Reset();
						int iring = 0;
						IRing currentInteriorRing = exteriorRingsEnum.Next() as IRing;
						int intrings = parcel.InteriorRingCount[currentExteriorRing];
						while (intrings > 0 && currentInteriorRing != null)
						{
							iring++;
							ISegmentCollection insegments = currentInteriorRing as ISegmentCollection;
							List<System.Drawing.PointF> inspc = ProcessRing(insegments);
							if (inspc != null)
								polycoll.Add(inspc);

							currentInteriorRing = interiorRingsEnum.Next() as IRing;
							if (iring >= intrings)
								break;
						}
						currentExteriorRing = exteriorRingsEnum.Next() as IRing;
						if (ering >= extrings)
							break;
					}
				}
			}
			//do something with polycoll...
		}

		private List<System.Drawing.PointF> ProcessRing(ISegmentCollection segments)
		{
			int segcount = segments.SegmentCount;
			IEnumSegment enumsegment = segments.EnumSegments as IEnumSegment;
			if (enumsegment == null)
			{
				return null;
			}
			enumsegment.Reset();
			int partIndex = 0;
			int segIndex = 0;
			ISegment querySeg;
			enumsegment.Next(out querySeg, ref partIndex, ref segIndex);

			List<System.Drawing.PointF> spc = new List<System.Drawing.PointF>();
			while (querySeg != null && !querySeg.IsEmpty)
			{
				if (querySeg is Line)
				{
					//no additional information.
				}
				else
				{
					//Circle, Ellipse, Bezier...
					//get additional information to store about the line.
				}
				System.Drawing.PointF labpt = new System.Drawing.PointF((float)Math.Round(querySeg.FromPoint.X, 2, MidpointRounding.AwayFromZero),
					(float)Math.Round(querySeg.FromPoint.Y, 2, MidpointRounding.AwayFromZero));
				spc.Add(labpt);
				enumsegment.Next(out querySeg, ref partIndex, ref segIndex);
				if (segIndex == 0)
					break;
			}
			if (spc != null)
			{
				spc.Add(spc[0]);  //close the loop by adding the first point to the end...
				return spc;
			}
			else
			{
				return null;
			}
		}