ArcGIS Engine Developer Guide

THE V ISUAL BASIC 6 DEVELOPMENT ENVIRONMENT
SETTING REFERENCES TO THE ESRI OBJECT LIBRARIES
The principal difference between working with the VBA development environment
embedded in the applications and working with Visual Basic is that the
latter environment requires that you load the appropriate object libraries so that
any object variables that you declare can be found. If you don’t add the reference,
you’ll get the error message shown on the left. In addition, the global variables
ThisDocument and Application are not available to you.
Adding a reference to an object library
Depending on what you want your code to do, you may need to add several ESRI
object and extension libraries. You can determine what library an object belongs
to by reviewing the object model diagrams in the developer help or by using the
LibraryLocator tool located in the Tools directory of your developer kit.
To display the References dialog box in which you can set the references you
need, select References in the Visual Basic Project menu.
After you set a reference to an object library by selecting the check box next to its
name, you can find a specific object and its methods and properties in the object
browser.
If you are not using any objects in a referenced library, you should clear the check
box for that reference to minimize the number of object references Visual Basic
must resolve, thus reducing the time it takes your project to compile. You should
not remove a reference for an item that is used in your project.
You can’t remove the “Visual Basic for Applications” and “Visual Basic objects
and procedures” references because they are necessary for running Visual Basic.
After the applicable ESRI object libraries are
referenced, all the types contained within them
are available in Visual Basic. IntelliSense will also
work with the contents of the object libraries.
REFERRING TO A DOCUMENT
Each VBA project (Normal, Project, TemplateProject) has a class called
ThisDocument, which represents the document object. Anywhere you write code
in VBA you can reference the document as ThisDocument. Further, if you are
writing your code in the ThisDocument code window, you have direct access to all
the methods and properties on IDocument. This is not available in Visual Basic.
You must first refer to the Application, then the document. When adding both
extensions and commands to ArcGIS applications, a pointer to the IApplication
interface is provided.
Implements IExtension
Private m_pApp As IApplication
Private Sub IExtension_Startup(ByRef initializationData As Variant)
Set m_pApp = initializationData ' Assign IApplication.
End Sub
Implements ICommand
Private m_pApp As IApplication
Private Sub ICommand_OnCreate(ByVal hook As Object)
Set m_pApp = hook
' QI for IApplication.
End Sub
94 • ArcGIS Engine Developer Guide