Selecting point feature on Mouse click using ArcObjects?

Question

How do I select point feature on mouse click?

I can select polygon feature but I cannot select apoint feature.

ESRI.ArcGIS.Carto.IIdentify identifyLayer = (IIdentify)iLayer;
IArray array = identifyLayer.Identify(identifyPoint);

Answer 1

The first step is to convert your clicked point into map coordinates, on your event the X and Y are screen coordinates which need to be converted with IDisplayTransformation:

In your OnMouseDown event:

IPoint pQueryPoint = new PointClass();
pQueryPoint = gDoc.ActiveView.ScreenDisplay.DisplayTransformation.ToMapPoint(arg.X, arg.Y);

gDoc is of type IMxDocument. Then buffer the query point to a query geometry, this example is in pixels to map coordinates:

int PxTol = 6; // 6 pixels to select by
IPoint pNextPoint = gDoc.ActiveView.ScreenDisplay.DisplayTransformation.ToMapPoint(arg.X + PxTol, arg.Y);
double pSrchDist = pNextPoint.X - pQueryPoint.X; // measure the distance between points PxTol apart
ITopologicalOperator pTopOp = (ITopologicalOperator)pQueryPoint;
IGeometry pSrchGeom = pTopOp.Buffer(pSrchDist);

If your feature class has a spatial reference other than the FocusMap you will need to project the points first before creating the buffer. Then setup a spatial filter:

ISpatialFilter pSF = new SpatialFilterClass();
pSF.Geometry = pSrchGeom;
pSF.SpatialRel = esriSpatialRelEnum.esriSpatialRelIntersects;

Now search from the ILayer as IFeatureLayer to return a cursor:

IFeatureCursor pDestCur = (YourLayer as IFeatureLayer).FeatureClass.Search(pSF, true); 
// recycling cursor, use non-recycling if you're going to modify any part of the feature

which you can iterate through:

IFeature pFeat = pDestCur.NextFeature();
do
{
 // do something with pFeat
 pFeat = pDestCur.NextFeature();
} while (pFeat != null);

Or you can select to get an ISelectionSet:

ISelectionSet pSelSet = (YourLayer as IFeatureLayer).FeatureClass.Select(
pSF,
esriSelectionType.esriSelectionTypeHybrid,
esriSelectionOption.esriSelectionOptionNormal,
YourWorkspace);

• riki: I could select point feature.. thank you very much..

Answer 2

You didn't post much code but I'm going to assume that identifyPoint is an IPoint in map coordinates.

IGeometry buffer = (identifyPoint as ITopologicalOperator).Buffer(1);
map.SelectByShape(buffer, null, true);

First you buffer the point you are using to search. The buffer will be in the units of the current geometry. So if I'm in UTM, the buffer would buffer 1 meter out. (doc)

Now I can take my current map and use select by shape. This will select anything within the buffer that is currently on the map. (doc)