get the points of a polygon

BillLanza — Wed, 12 May 2010 16:42:07 GMT

I have a silverlight app where a user can draw a polygon on a map. I want a way to take the polygon and get the vertices. I can see how to get the envelope, but not the actual points. In arcobjects you can convert an Ipolygon to an IpointCollection, but that does not seem possible in the SL API. Any direction would be appreciated.

Re: get the points of a polygon

DominiqueBroux — Thu, 13 May 2010 09:43:23 GMT

Get the rings of the polygon, each ring is a collection of point.

For example, to get the points of the first ring of your polygon, you can use :

ESRI.ArcGIS.Client.Geometry.PointCollection points = myPolygon.Rings[0];

/Dominique

Re: get the points of a polygon

AvronPolakow — Thu, 20 May 2010 12:17:42 GMT

// This is how I do it:

// Here's how I do it creating an XML type output (you can create whatever output you like)

////////////////////////////////////////////////////////////////////////////
//             ldblTolerance ; Tolerance for the removal of proximal points
//             lbXML          ; XML output type:
//                                 true=short xml with attributes
//                                 false=long xml with tags
//             lbBrief         ; Points in single tag
////////////////////////////////////////////////////////////////////////////

StringBuilder lstrBuilder = new StringBuilder();
string        [] LPad        = ", , ,   ,    ,     ,      ,       ,        ,         ,          ".Split(',');

double ldblTolerance    = 0.000010; // For removal of proximal points. Usage: GetPoints()
bool    lbXML               = true;
bool    lbBrief               = true;

lstrBuilder.Append("");

if (lGraphic.Geometry is ESRI.ArcGIS.Client.Geometry.Polygon)
{
ESRI.ArcGIS.Client.Geometry.Polygon lPolygon = (ESRI.ArcGIS.Client.Geometry.Polygon) lGraphic.Geometry;
foreach (ESRI.ArcGIS.Client.Geometry.PointCollection lPoints in lPolygon.Rings)
{
lstrBuilder.Append(LPad[6] + "<ring>\n");
lstrBuilder = GetPoints(lstrBuilder, lbXML, lbBrief, ldblTolerance, LPad, lPoints);
lstrBuilder.Append(LPad[6] + "</ring>\n");
}

:
:
:

   return lstringBuilder.ToString();

//////////////////////////////////////////////////////////////////////
public static StringBuilder GetPoints(StringBuilder astrBuilder, bool abXML, bool abBrief, double adblTolerance, string[] LPad, ESRI.ArcGIS.Client.Geometry.PointCollection aPoints)
{
MapPoint lprevMapPoint = new MapPoint();
double   ldblX, ldblY;

lprevMapPoint.X = 0;
lprevMapPoint.Y = 0;

if (abBrief)
{
astrBuilder.Append(LPad[7] + "<points>");
if (abXML && !abBrief) {astrBuilder.Append("\n");}
}

foreach(MapPoint lMapPoint in aPoints)
{
ldblX = Math.Round(lMapPoint.X, 6);     // Math.Round(lMapPoint.X, 6);
ldblY = Math.Round(lMapPoint.Y, 6);     // Math.Round(lMapPoint.Y, 6);

if (Math.Abs(ldblX - lprevMapPoint.X) > adblTolerance && Math.Abs(ldblY - lprevMapPoint.Y) > adblTolerance)
{
   lprevMapPoint.X = ldblX;
   lprevMapPoint.Y = ldblY;

   // Brief
   if (abBrief)
   {
    if (abXML) {astrBuilder.Append(ldblX.ToString() + "," + ldblY.ToString() +",");}
    else
    {
     astrBuilder.Append(ldblX.ToString() + ",");
     astrBuilder.Append(ldblY.ToString() + "\n");
    }
   }
   else
   {
    if (abXML) {astrBuilder.Append(LPad[7] + "<point x=\"" + ldblX.ToString() + "\" y=\"" + ldblY.ToString() + "\" />\n");}
    else
    {
     astrBuilder.Append(LPad[7] + "<point>\n");
     astrBuilder.Append(LPad[8] + "<x>" + ldblX.ToString() + "</x>\n");
     astrBuilder.Append(LPad[8] + "<y>" + ldblY.ToString() + "</y>\n");
     astrBuilder.Append(LPad[7] + "</point>\n");
    }
   }
}
}
if (abBrief)
{
if (abXML && !abBrief) {astrBuilder.Append("\n" + LPad[7]);}
astrBuilder.Append("</points>\n");
}

return astrBuilder;
}

Re: get the points of a polygon

BrianBehling — Sun, 12 Dec 2021 05:42:47 GMT

                    ESRI.ArcGIS.Client.Geometry.Polygon polygon =   (ESRI.ArcGIS.Client.Geometry.Polygon)graphic.Geometry;

                    int ringCount = polygon.Rings.Count;

                    for (int i = 0; i < ringCount; i++)
                    {
                        ESRI.ArcGIS.Client.Geometry.PointCollection pc = polygon.Rings;

                        foreach (ESRI.ArcGIS.Client.Geometry.MapPoint mp in pc)
                        {
                            MapPoint coordinates = new MapPoint(mp.X, mp.Y);

                            
                        }
}

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