Document.AddUndoUnit Method

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Visio Automation Reference

Adds an object that supports the IOleUndoUnit or IVBUndoUnit interface to the Microsoft Office Visio undo queue.

Version Information
 Version Added:  Visio 2000

Syntax

expression.AddUndoUnit(pUndoUnit)

expression   A variable that represents a Document object.

Parameters

Name Required/Optional Data Type Description
pUndoUnit Required [UNKNOWN] A reference to an object that supports the IOleUndoUnit or IVBUndoUnit interface.

Return Value
Nothing

Remarks

For information about implementing the IOleUndoUnit interface on your object, see the Microsoft Platform SDK on MSDN, the Microsoft Developer Network. For information about implementing the IVBUndoUnit interface, see Developing Microsoft Visio Solutions on MSDN.

Example

The following procedure shows how to use the AddUndoUnit method to add an object to the Visio undo queue. When a shape is added to the active document, the procedure checks to see if it was added as a result of an undo or redo action, and if not, it adds an Undo unit.

This procedure is a member of class clsParticipateInUndo, which is defined in one of two related class modules in the Code Librarian in the Visio SDK, and is not intended to be run independently. (The other class module defines class clsVBUndoUnits.) For more information on these class modules, see the Visio SDK on MSDN.

Visual Basic for Applications 
  
Private Sub mvsoDocument_ShapeAdded(ByVal vsoShape As IVShape) 

Dim VBUndoUnit As clsVBUndoUnits 

On Error GoTo mvsoDocument_ShapeAdded_Err 

If Not (mvsoApplication Is Nothing) Then

    If Not msvoApplication.IsUndoingOrRedoing Then
 
        'Increment the count of undoable actions. 
        IncrementModuleVar 
        Debug.Print "Original Do: GetModuleVar = " & GetModuleVar 

        'Instantiate clsVBUndoUnit, a
        'class that implements Visio.IVBUndoUnit.
        Set VBUndoUnit = New clsVBUndoUnits 

        'Pass the current instance of the class 
        'of which this procedure is a member, 
        'clsParticipateInUndo, to the Undo unit. 
        VBUndoUnit.SetModelObject Me 

        'Add an Undo unit. 
        mvsoApplication.AddUndoUnit VBUndoUnit 

    End If  

 End If  



Exit Sub


mvsoDocument_ShapeAdded_Err:


MsgBox Err.Description 



End Sub

See Also