ArcEngine 10 .Net 4 c#

I'm currently allowing user to select a point on a polyline and creating a point on the line. I am using snapping tool.

I just want to make sure that when the user clicks on the screen, the point feedback that I get lies on top of the polyline.

I was wondering if there is a method that I can check if the IPOINT is ON any of the polylines in the polyline layer.

  • 2
    Sadly I think you mean .NET 3.5. 4.0 is not supported with ArcEngine
    – patrick
    Jun 14, 2011 at 15:46
  • 1
    Do you mean on the polyline or on the symbology used to draw the polyline? Jun 14, 2011 at 18:21

3 Answers 3


There's probably an easier way to do it but this is what I do.

//layer is what layer you are checking
ESRI.ArcGIS.Carto.IIdentify identify1 = layer as IIdentify; 

//idGeo is IGeometry you want to query -in your case a point, but I'm using a square here    
IArray array = identify1.Identify(idGeo);  

if (array != null)
    object obj = array.get_Element(0);
    IFeatureIdentifyObj fobj = obj as IFeatureIdentifyObj;
    IRowIdentifyObject irow = fobj as IRowIdentifyObject;
    IFeature feature = irow.Row as IFeature;
    IGeometry geometry1 = feature.Shape;
    IPointCollection pc = geometry1 as IPointCollection;
    if(pc != null && pc.PointCount > 0) //then its a polyline

You could probably use the iHitTest interface for this. http://help.arcgis.com/en/sdk/10.0/arcobjects_net/componenthelp/index.html#//002m0000021v000000

I only use VB so I don't have an example handy. Here is a version 9.3 example: http://resources.esri.com/help/9.3/ArcGISEngine/arcobjects/esriGeometry/IHittest_HitTest_Example.htm


If you are using arcgis, simply create a new topology layer, set the rule as points are covered by line, then the topology tool will validate the data you provided and show errors if there is one

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