Communicate with ArcMap from standalone Visual Basic application

Summary

Memory address errors can occur when passing objects from a standalone application (vb.exe) to ArcMap.

This is because the standalone application is in a different address space than ArcMap. Passing objects across this boundary, can lead to unexpected behavior.

To pass an object from a vb.exe to ArcMap, use the IObjectFactory interface. This interface contains members that allow automation clients to create arbitrary objects within the application's process space.

Procedure

1. Start ArcMap.
2. Switch to page layout view.
3. Create a new Visual Basic standard exe application.
4. Click Project > References and select ESRI Object Library to add a reference to esriCore.olb.
5. Add a button to the form.
6. Paste the following code into the button's click event.
   
   
   Dim doc As IDocument
   Dim app As IApplication
   Dim pmxdoc As IMxDocument
   Dim pobjectFactory As IObjectFactory
   Dim rot As AppROT
   Dim strName As String
   
   Set rot = New AppROT
   Set app = rot.Item(0)
   Set pobjectFactory = app
   Set pmxdoc = app.Document
   Dim pmxapp As IMxApplication
   Set pmxapp = app
   
   Dim pav As IActiveView
   Set pav = pmxdoc.ActiveView
   
   ''''Here is the ObjectFactory assignment********************
   Dim ppointcoll As IPointCollection
   Dim ppoly As IPolygon
   Set ppoly = pobjectFactory.Create("esricore.polygon")
   Set ppointcoll = ppoly
   
   Dim pt1 As IPoint
   Set pt1 = New Point
   pt1.X = 1
   pt1.Y = 1
   
   Dim pt2 As IPoint
   Set pt2 = New Point
   pt2.X = 1
   pt2.Y = 4
   
   Dim pt3 As IPoint
   Set pt3 = New Point
   pt3.X = 4
   pt3.Y = 4
   
   Dim pt4 As IPoint
   Set pt4 = New Point
   pt4.X = 4
   pt4.Y = 1
   
   ppointcoll.AddPoint pt1
   ppointcoll.AddPoint pt2
   ppointcoll.AddPoint pt3
   ppointcoll.AddPoint pt4
   
   '''Here is the ObjectFactory assignment********************
   Dim psym As ISimpleFillSymbol
   Set psym = pobjectFactory.Create("esricore.SimplefillSymbol")
   
   Dim pcolor As IRgbColor
   Set pcolor = New RgbColor
   pcolor.Blue = 255
   pcolor.Red = 0
   pcolor.Green = 0
   
   psym.Color = pcolor
   
   pav.ScreenDisplay.StartDrawing 0, esriNoScreenCache
   pav.ScreenDisplay.SetSymbol psym
   pav.ScreenDisplay.DrawPolygon ppoly
   pav.ScreenDisplay.FinishDrawing
   
   
   
   
7. Save and run the application.
   
   

   Note:
   This code sample adds a polygon to the page layout screen display. This polygon is temporary and any refresh will erase the polgyon. Therefore make sure the page layout view is visible before running the code.