How to find a feature programmatically

This sample code searches for a feature by looping through all of the map layers. The sample uses a UITool control to provide the MouseDown event and search point location. The search point is buffered using IEnvelope::Expand to increase the search tolerance and likelyhood of finding a feature. The FindFeature function below, returns the first feature found.
If you are using the Editor extension, you can alternatively use IEditor::CreateSearchShape to automatically expand the point envelope. See the sample "Find a Feature Programmatically While Editing" to see an example implementation.

How to use

  1. Add a custom UIToolControl onto any toolbar and make sure the names of the control match the code. This sample assumes the control is called UIToolControl1.
  2. Paste the code into VBA.
  3. Select the tool and then click on a feature.
[VBA] 
Private Sub UIToolControl1_MouseDown(ByVal button As Long, ByVal shift As Long, ByVal x As Long, ByVal y As Long)
    Dim pMxDoc As IMxDocument
    Dim pActiveView As IActiveView
    Dim pPoint As IPoint
    Dim pFeature As IFeature
    
    Set pMxDoc = Application.Document
    Set pActiveView = pMxDoc.FocusMap
    'Create a search point
    Set pPoint = pActiveView.ScreenDisplay.DisplayTransformation.ToMapPoint(x, y)
    'Pass the point to the FindFeature function along with the Map and search tolerance
    Set pFeature = FindFeature(pMxDoc.SearchTolerance, pPoint, pMxDoc.FocusMap)
    'Message box the feature ID and feature class alias name
    If Not pFeature Is Nothing Then MsgBox pFeature.OID & " " & pFeature.Class.AliasName
End Sub

Private Function FindFeature(SearchTol As Double, pPoint As IPoint, pMap As IMap) As IFeature
    Dim pEnvelope As IEnvelope
    Dim pSpatialFilter As ISpatialFilter
    Dim pEnumLayer As IEnumLayer
    Dim pFeatureLayer As IFeatureLayer
    Dim pFeatureClass As IFeatureClass
    Dim pFeatureCursor As IFeatureCursor
    Dim pFeature As IFeature
    Dim pUID As New UID
    Dim ShapeFieldName As String
    
    If pMap.LayerCount = 0 Then Exit Function
    
    'Expand the points envelope to give better search results
    Set pEnvelope = pPoint.Envelope
    pEnvelope.Expand SearchTol, SearchTol, False
    
    'Create a new spatial filter and use the new envelope as the geometry
    Set pSpatialFilter = New SpatialFilter
    Set pSpatialFilter.Geometry = pEnvelope
    pSpatialFilter.SpatialRel = esriSpatialRelIntersects
    
    'Search each selectable feature layer for a feature
    'Return the first feature found
    pUID = "{40A9E885-5533-11D0-98BE-00805F7CED21}" 'IFeatureLayer
    Set pEnumLayer = pMap.Layers(pUID, False)
    pEnumLayer.Reset
    Set pFeatureLayer = pEnumLayer.Next
    Do While Not pFeatureLayer Is Nothing
        'Only search the selectable layers
        If pFeatureLayer.Selectable Then
            ShapeFieldName = pFeatureLayer.FeatureClass.ShapeFieldName
            Set pSpatialFilter.OutputSpatialReference(ShapeFieldName) = pMap.SpatialReference
            pSpatialFilter.GeometryField = pFeatureLayer.FeatureClass.ShapeFieldName
            Set pFeatureClass = pFeatureLayer.FeatureClass
            Set pFeatureCursor = pFeatureClass.Search(pSpatialFilter, False) 'Do the search
            Set pFeature = pFeatureCursor.NextFeature 'Get the first feature
            If Not pFeature Is Nothing Then
                Set FindFeature = pFeature 'Exit if feature is valid
                Exit Do
            End If
        End If
        Set pFeatureLayer = pEnumLayer.Next
    Loop
    
End Function