Define a snapping environment in ArcMap using VBA

Summary

ISnapEnvironment can reference the properties of SnapAgent FeatureSnap objects.

Procedure

1. Get a reference to the ESRI Object Editor and start editing in the desired workspace.
   
   

   Code:
   Dim pUID As UID
   Dim pEditor As IEditor
   Set pUID = New UID
   pUID = "esricore.Editor"
   Set pEditor = Application.FindExtensionByCLSID(pUID)
   pEditor.StartEditing pWorkspace

   
   
   

   Note:
   This code example assumes the pWorkspace variable has been defined as an IWorkspace and has been set to a valid workspace.  

   
   
2. Define the snap environment. The following is an example of snapping to a feature class edge (such as a polygon edge) using the esriGeometryHitPartType of esriGeometryPartBoundary. This will snap to edges in the given feature class.
   
   

   Code:
   Dim pSnapEnvironment As ISnapEnvironment
   Dim pFeatureSnapagent As IFeatureSnapAgent
   Set pSnapEnvironment = pEditor
   Set pFeatureSnapAgent = New FeatureSnap
   Set pFeatureSnapAgent.FeatureClass = pFeatureClass
   pFeatureSnapAgent.HitType = esriGeometryPartBoundary
   pSnapEnvironment.ClearSnapAgents
   pSnapEnvironment.AddSnapAgent pFeatureSnapagent
   pSnapEnvironment.SnapToleranceUnits = esriSnapTolerancePixels
   pSnapEnvironment.SnapTolerance = 5

   
   

   Note:
   This code example assumes the pFeatureClass variable has been defined as an IFeatureClass and has been set to a feature class with edges (such as polygons). 

   
   
3. Snap some sketch points to the feature class edges.
   
   

   Code:
   Dim pPoint1 As IPoint
   Dim pPoint2 As IPoint
   Set pPoint1 = New Point
   Set pPoint2 = New Point
   pPoint1.X = 413188.31
   pPoint1.Y = 1124061.78
   pPoint2.X = 438944.57
   pPoint2.Y = 1123086.17
   pSnapEnvironment.SnapPoint pPoint1
   pSnapEnvironment.SnapPoint pPoint2

   
   
4. Start a new feature sketch using the snapped points.
   
   

   Code:
   Dim pSketchOperation As ISketchOperation
   Dim pEditSketch As IEditSketch
   pEditor.StartOperation
   Set pSketchOperation = New SketchOperation
   pSketchOperation.Start pEditor
   Set pEditSketch = pEditor
   pEditSketch.AddPoint pPoint1, True
   pEditSketch.AddPoint pPoint2, True
   pEditSketch.FinishSketch
   pEnvelope.Expand 1.2, 1.2, True
   pSketchOperation.Finish pEnvelope

   
   

   Note:
   This code assumes the pEnvelope was defined as IEnvelope and has the extent of the feature currently selected and being edited.