How do I zoom to the overall extent of two (or more) selected features from two layers?

Question

I am creating an application where the user picks a value from a combo box, the application then selects that feature and then selects the corresponding features from a second layer, (both selections are in a different colour). What I want to do is as soon as the selection is made, the map will zoom to the envelope of the selected features. I know how to zoom to 2 individual layers (using pEnvlope.union...), but i need to do it on features.

Has anyone got any idea of the best way to do this? (I'm using ArcGIS 9.3.1 and VBA).

Thanks

Answer 1

You could just use the ArcMap Command, Zoom To Selected Features.

  Dim pUID As New UID
  Dim pCmdItem As ICommandItem
  ' Use the GUID of the Save command
  ' Zoom to all selected features
  pUID.Value = "{AB073B49-DE5E-11D1-AA80-00C04FA37860}"
  ' or you can use the ProgID
  ' pUID.Value = "esriArcMapUI.ZoomToSelectedCommand"
  pUID.SubType = 3
  Set pCmdItem = Application.Document.CommandBars.Find(pUID)
  pCmdItem.Execute

Answer 2

If you are outside of arcmap you would get the features geometries and use the IToplogicalOperator's union and zoom to the extent of the unioned geometry.

Answer 3

If you have info about the object, you know it's min/max X and Y's, so it's a matter of building some logic in the code tozoom to that envelope, taking into account scaling etc