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Application.MarkerEvent Event (Visio)

Published: July 16, 2012

Caused by calling the QueueMarkerEvent method.

Version Added: Visio 5.0

Private Sub expression _MarkerEvent(ByVal app As [IVAPPLICATION], ByVal SequenceNum As Long, ByVal ContextString As String)

expression A variable that represents an Application object.

Parameters

Name

Required/Optional

Data Type

Description

app

Required

[IVAPPLICATION]

The active instance of Microsoft Visio.

SequenceNum

Required

Long

The ordinal position of this event with respect to past events.

ContextString

Required

String

Context string passed by the QueueMarkerEvent method.

Unlike other events that Visio fires, the MarkerEvent event is fired by a client program. A client program receives the MarkerEvent event only if the client program called the QueueMarkerEvent method.

By using the MarkerEvent event in conjunction with the QueueMarkerEvent method, a client program can queue an event to itself. The client program receives the MarkerEvent event after Visio fires all the events present in its event queue at the time of the QueueMarkerEvent call.

The MarkerEvent event passes both the context string that was passed by the QueueMarkerEvent method and the sequence number of the MarkerEvent event to the MarkerEvent event handler. Either of these values can be used to correlate QueueMarkerEvent calls with MarkerEvent events. In this way, a client program can distinguish events it caused from those it did not cause.

For example, a client program that changes the values of Visio cells may only want to respond to the CellChanged events that it did not cause. The client program can first call the QueueMarkerEvent method and pass a context string for later use to bracket the scope of its processing:

 
vsoObject.QueueMarkerEvent "ScopeStart" 
 <My program changes cells here> 
vsoObject.QueueMarkerEvent "ScopeEnd" 

Then, in the MarkerEvent event handler, the client program could use the context string passed to the QueueMarkerEvent method to identify the CellChanged events that it caused:

 
Dim blsICausedCellChanges as Boolean 
 
Private Sub vsoObject_MarkerEvent (ByVal vsoApplication As Visio.IVApplication, _ 
 ByVal lngSequenceNum As Long, ByVal strContextString As String) 
 
 If strContextString = "ScopeStart" Then 
 blsICausedCellChanges = True 
 ElseIf strContextString = "ScopeEnd" Then 
 blsICausedCellChanges = "False" 
 End If 
 
End Sub 
 
Private Sub vsoObject_CellChanged (ByVal Cell As Visio.IVCell) 
 
 'Respond only if this client didn't cause a cell change. 
 If blsICausedCellChanges = False Then 
 <respond to the cell changes> 
 End If 
 
End Sub 

If you're using Microsoft Visual Basic or Visual Basic for Applications (VBA), the syntax in this topic describes a common, efficient way to handle events.

If you want to create your own Event objects, use the Add or AddAdvise method. To create an Event object that runs an add-on, use the Add method as it applies to the EventList collection. To create an Event object that receives notification, use the AddAdvise method. To find an event code for the event you want to create, see Event codes.

If you are handling this event from a program that receives a notification, the MarkerEvent event is one of one of a group of events that record extra information in the EventInfo property of the Application object.

The EventInfo property returns ContextString as described above. The varMoreInfo argument to VisEventProc will be empty.

This example shows how to use the MarkerEvent event to mark an event in the event queue.

Paste this example code into the ThisDocument code window and then run UseMarker. The output will be displayed in the Immediate window.

 
Dim WithEvents vsoApplication As Visio.Application 
 
Private Sub vsoApplication_MarkerEvent(ByVal app As Visio.IVApplication, _ 
 ByVal lngSequenceNum As Long, ByVal strContextString As String) 
 Debug.Print "Marker: " & app.EventInfo(0) 
 
End Sub 
 
Private Sub vsoApplication_ShapeAdded(ByVal vsoShape As Visio.IVShape) 
 Debug.Print " ShapeAdded: " & vsoShape.Name 
 
End Sub 
 
Public Sub UseMarker() 
 
 Set vsoApplication = ThisDocument.Application 
 
 'MarkerEvent events can be used to comment a segment 
 'of events in the queue. 
 vsoApplication.QueueMarkerEvent "I am starting..." 
 ActivePage.DrawRectangle 0, 0, 3, 3 
 vsoApplication.QueueMarkerEvent "I am finished..." 
 
End Sub 

The output in the Immediate window looks like this:

Marker: I am starting...

ShapeAdded: Sheet.1

Marker: I am finished...

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