topic Re: Add Vertex to Polygon in ArcObjects SDK Questions

Add Vertex to Polygon

sonj — Tue, 01 Oct 2024 13:20:51 GMT

To add a vertex to the polygon, we are creating an application. After a few runs, the application displays the error message "Attempt to read and write protected memory."

IHitTest hitTest = polygon.ShapeCopy as IHitTest;
bool result = hitTest.HitTest(, searchRadius, esriGeometryHitPartType.esriGeometryPartBoundary, hitPoint, ref hitDist, ref hitPartIndex, ref hitSegmentIndex, ref bTrue);

if (result)
{
IGeometryCollection geometryCol = polygon.ShapeCopy as IGeometryCollection;
IPointCollection pathOrRingPointCollection = geometryCol.get_Geometry(hitPartIndex) as IPointCollection;

object hitSegmentIndexObject = new object();
hitSegmentIndexObject = hitSegmentIndex;

object partIndexObject = new object();
partIndexObject = hitPartIndex;

if(hitSegmentIndex == 0)
{
pathOrRingPointCollection.AddPoint(point, 1, Type.Missing);
}
else if(hitSegmentIndex > 0)
{
pathOrRingPointCollection.AddPoint(point, Type.Missing, hitSegmentIndexObject);
}

//remove the old PointCollection from the GeometryCollection and replace with the new one
geometryCol.RemoveGeometries(hitPartIndex, 1);
geometryCol.AddGeometry(pathOrRingPointCollection as IGeometry, ref partIndexObject, Type.Missing);

polygon.Shape = geometryCol as IGeometry;
invalidArea.Invalidate(2);
polygon.Store();

}

Any recommendations or an alternative interface would be much appreciated.

Re: Add Vertex to Polygon

sonj — Thu, 03 Oct 2024 06:19:44 GMT

Is anyone here to help 🤔

Re: Add Vertex to Polygon

DuncanHornby — Sat, 11 Jan 2025 01:04:46 GMT

I'm surprised the HitTest() even works as the help file indicates the first parameter is a point object which in your code you don't supply?

Re: Add Vertex to Polygon

sonj — Sat, 11 Jan 2025 03:19:59 GMT

I apologize; it was overlooked during copy and paste. Points are collected throughout the process, and each repetition will send a point. The polygon vertex count is approximately 8 to 9 million.

Re: Add Vertex to Polygon

DuncanHornby — Sun, 12 Jan 2025 00:54:15 GMT

Sorry are you saying you are trying to insert a vertex into a polygon that is composed of 8 million vertices? I would imagine any sort of spatial processing would be quite slow and you would need to dice up your data?