About Converting the VBA Code to VB (VBA/ActiveX)

To update a code example for use with VB, you must first reference the AutoCAD type library.

To do this in VB, select the References option from the Project menu to launch the References dialog box. From the References dialog box, choose the type library for AutoCAD, and then click OK.

Next, in the code example, replace all references to ThisDrawing with a user-specified variable referencing the active document. To do this, define a variable for the AutoCAD application (acadApp) and for the current document (acadDoc). Then, set the application variable to the current AutoCAD application.

If AutoCAD is running, the VB GetObject function retrieves the AutoCAD Application object when you specify the AutoCAD version number. If AutoCAD is not running, an error occurs that (in this example) is trapped, then cleared. The CreateObject function then attempts to create an AutoCAD Application object. If it succeeds, AutoCAD is started; if it fails, a message box displays a description of the error.

When running multiple sessions of AutoCAD, the GetObject function will return the first instance of AutoCAD in the Windows Running Object Table. See the Microsoft VBA documentation on the Running Object Table (ROT) and the GetObject function for more information on verifying the session returned by GetObject.

You must set the AutoCAD application's Visible property to TRUE in order to display the AutoCAD drawing window.

If GetObject creates a new instance of AutoCAD (that is, AutoCAD was not already running when you issued GetObject), failure to set Visible to TRUE results in an invisible AutoCAD application; AutoCAD will not even appear on the Windows taskbar.

Note: Use version-dependent ProgIDs. If a CreateObject or GetObject function uses a version-independent ProgID, change the function to use a version-dependent ProgID. For example, if you are using CreateObject, you change CreateObject("AutoCAD.Application") to CreateObject("AutoCAD.Application.20.1"). Additionally, if a GetInterfaceObject method uses a version-independent ProgID, the method must be changed to use a version-dependent ProgID.

Connect to AutoCAD from Visual Basic 6

The following code example uses the Clear and Description properties of Err. If your coding environment does not support these properties, you will need to modify the example appropriately: 

Sub Ch2_ConnectToAcad()
    Dim acadApp As AcadApplication
    On Error Resume Next

    Set acadApp = GetObject(, "AutoCAD.Application.20.1")
    If Err Then
        Err.Clear
        Set acadApp = CreateObject("AutoCAD.Application.20.1")
        If Err Then
 MsgBox Err.Description
 Exit Sub
        End If
    End If
    MsgBox "Now running " + acadApp.Name + _
 " version " + acadApp.Version
End Sub

Next, set the document variable to the Document object in the AutoCAD application. The Document object is returned by the ActiveDocument property of the Application object. 

Dim acadDoc as AcadDocument
Set acadDoc = acadApp.ActiveDocument

From this point on, use the acadDoc variable to reference the current AutoCAD drawing.

VBA versus VB Comparison Code Example

The following code example demonstrates creating a line in both VBA and VB.

Creating a line using VBA: 

Sub Ch2_AddLineVBA()
    ' This example adds a line
    ' in model space
    Dim lineObj As AcadLine
    Dim startPoint(0 To 2) As Double
    Dim endPoint(0 To 2) As Double

    ' Define the start and end
    ' points for the line
    startPoint(0) = 1
    startPoint(1) = 1
    startPoint(2) = 0
    endPoint(0) = 5
    endPoint(1) = 5
    endPoint(2) = 0

    ' Create the line in model space
    Set lineObj = ThisDrawing. _
        ModelSpace.AddLine _
        (startPoint, endPoint)

    ' Zoom in on the newly created line
    ZoomAll
End Sub

Creating a line using VB: 

Sub Ch2_AddLineVB()
    On Error Resume Next

    ' Connect to the AutoCAD application
    Dim acadApp As AcadApplication
    Set acadApp = GetObject _
 (, "AutoCAD.Application.20.1")
    If Err Then
        Err.Clear
        Set acadApp = CreateObject _
 ("AutoCAD.Application.20.1")
        If Err Then
 MsgBox Err.Description
 Exit Sub
        End If
    End If

    ' Connect to the AutoCAD drawing
    Dim acadDoc As AcadDocument
    Set acadDoc = acadApp.ActiveDocument

    ' Establish the endpoints of the line
    Dim lineObj As AcadLine
    Dim startPoint(0 To 2) As Double
    Dim endPoint(0 To 2) As Double
    startPoint(0) = 1
    startPoint(1) = 1
    startPoint(2) = 0
    endPoint(0) = 5
    endPoint(1) = 5
    endPoint(2) = 0
    ' Create a Line object in model space
    Set lineObj = acadDoc.ModelSpace.AddLine _
 (startPoint, endPoint)
    ZoomAll
    acadApp.visible = True
End Sub

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