ObjectModified & Properties Palette & Dynamic Blocks

[jamie.159739]

When I get these three things together in the same room, they fight and fuss and cause trouble.

I have the need to capture the change of a dynamic block's property such as Length (the property that stretches the block) when a user changes it using the built in AutoCAD 2008 Properties Palette.

The code I run works fine when I want to change the object on the screen from edit mode, but when I change it using properties palette, it cycles through too many times, and the third time the DynamicPropertiesCollection shows up emtpy (or with error) in the locals window, and the system crashes on simply trying to read the property's value.

The Object Modified event fires off for my watched block ref 3 times. First time the property reports no change. The second time the property shows the appropriate changed value. The third time AutoCAD crashes.

Is there some way to either filter the object's properties or turn off or on events to get this to work? I am only responding to the ObjectModified event.

Help!!

Thanks,

jamie

[bweir]

Not sure how you are capturing the change of the block. Are you using database events or something through the editor. Might what to watch the database.

[jamie.159739]

Private Sub callback_ObjectModified(ByVal sender As Object, ByVal e As ObjectEventArgs)
        If booIgnoreModified = True Then
            Return
        End If
        booIgnoreModified = True
        'Debug.Print(sender.ToString)
        Debug.Print("ObjectModified: " & e.DBObject.GetType.ToString)
        Select Case e.DBObject.GetType.ToString
            Case "Autodesk.AutoCAD.DatabaseServices.BlockReference"
                'If e.DBObject.IsModified = False Then
                Debug.Print("BlockReference")
                Try
                    Dim objCheck As Object = Me.Levels.ContainsHandle(e.DBObject.Handle)
                    If objCheck(0) Then
                        Me.ReactToChange(objCheck)
                    End If
                Catch ex As Exception
                    MsgBox("Error when running ObjectModified event: " & Err.Description)
                End Try
                'End If
        End Select
        booIgnoreModified = False
    End Sub

Moderator Note:

How to use [ CODE ] tags...

[bweir]

If booIgnoreModified = True Then
Return
End If

Instead of doing the above try...

If e.DBObject.IsWriteEnabled Then Exit Sub

If the object is opened for Write by one process it can not be opened for Write by another. Another operation could however open it for Read (at least that is my understanding).

I might approach the problem diffrently then what you have shown. I'm not sure what your Levels.Contains returns but I would have it return a boolean. Also I understand that transactions are the way to go, don't know what happens in the call to ReactToChange(). Here is a sample of how I might have approached it (hasn't been tested).

    Private Sub MyObjectModifiedCallback(ByVal sender As Object, ByVal e As Autodesk.AutoCAD.DatabaseServices.ObjectEventArgs)

        If e.DBObject.IsWriteEnabled Then Exit Sub
        If Not Me.Levels.ContainsHandle(e.DBObject.Handle) Then Exit Sub

        Dim Trans As Transaction = e.DBObject.Database.TransactionManager.StartTransaction
        Try
            Dim ObjCheck As Object = Trans.GetObject(e.DBObject.Id, Autodesk.AutoCAD.DatabaseServices.OpenMode.ForWrite)
            Select Case ObjCheck.GetType.Name
                Case GetType(Autodesk.AutoCAD.DatabaseServices.BlockReference).Name
                    Me.ReactToChange(ObjCheck)
            End Select
            Trans.Commit()
        Catch ex As Exception
            MsgBox("Error when running ObjectModified event. " & vbNewLine & ex.ToString)
        Finally
            Trans.Dispose()
        End Try
    End Sub

[jamie.159739]

Thanks for your help, however...
I added your line at top - If e.DBObject.IsWriteEnabled Then Exit Sub
Immediate window:

BlockReference
PanelRef c1560e2c-de48-436c-840d-c38942c71e19
BlockReference
PanelRef c1560e2c-de48-436c-840d-c38942c71e19
BlockReference
PanelRef c1560e2c-de48-436c-840d-c38942c71e19
A first chance exception of type 'System.Runtime.InteropServices.SEHException' occurred in AcdbMgd.dll
A first chance exception of type 'System.NullReferenceException' occurred in AcdbMgd.dll

Still crashes. For some reason changing the dynamic property its the object modified 3 times or more (crashed on 3rd time). The exact missing data (null reference) is the dynamic property collection...

The effect of crash is the combination of my ReactToChange and this object. In react to change I run this to get a dynamic property:

    Public ReadOnly Property XDictionary(ByVal classID As Guid, ByVal strDictName As String) As DBDictionary
        Get
            Dim dbd As DBDictionary = Nothing
            Dim dbdColl As DBDictionary = Nothing
            Dim trans As Transaction = db.TransactionManager.StartTransaction
            Dim NOD As DBDictionary
            Dim dbdObjTree As DBDictionary
            Try 'to get existing Dictionary
                NOD = trans.GetObject(db.NamedObjectsDictionaryId, OpenMode.ForRead)
                dbdObjTree = trans.GetObject(NOD.GetAt("srwlObjectTree"), OpenMode.ForRead)
                dbdColl = trans.GetObject(dbdObjTree.GetAt(strDictName), OpenMode.ForRead)
                If dbdColl.Contains(classID.ToString) Then
                    dbd = trans.GetObject(dbdColl.GetAt(classID.ToString), OpenMode.ForRead)
                Else
                    NOD.UpgradeOpen()
                    dbdObjTree.UpgradeOpen()
                    dbdColl.UpgradeOpen()
                    dbd = New DBDictionary
                    dbdColl.SetAt(classID.ToString, dbd)
                    trans.AddNewlyCreatedDBObject(dbd, True)
                End If
                trans.Commit()
            Catch 'create a new Dictionary instead
                MsgBox("Error creating a new " & strDictName & " Dictionary. " & Err.Description)
            Finally 'store a reference the dictionary in live memory
                trans.Dispose()
            End Try
            Return dbd
        End Get
    End Property

While running this, I am setting off the event again, but only for dynamic properties, not for other block properties. Any clue?

Thanks,

jamie

Moderator Note:

How to use [ CODE ] tags...

[jamie.159739]

oops wrong code snippet:

    Public Function GetDynProperty(ByVal bref As BlockReference, ByVal PropertyName As String) As Object
        Dim objProp As Object = Nothing
        Dim trans As Transaction = db.TransactionManager.StartTransaction
        Try
            Dim dpcPanel As DynamicBlockReferencePropertyCollection
            Dim dpPanel As DynamicBlockReferenceProperty
            If bref.IsDynamicBlock Then
                dpcPanel = bref.DynamicBlockReferencePropertyCollection
                For Each dpPanel In dpcPanel
                    Select Case dpPanel.PropertyName.ToUpper
                        Case PropertyName
                            objProp = dpPanel.Value
                            Exit For
                    End Select
                Next
            End If
            'trans.Commit()
        Finally
            trans.Dispose()
        End Try
        Return objProp
    End Function

Moderator Note:

How to use [ CODE ] tags...

[bweir]

Maybe instead of trying to make calls from within the ObjectModified event add the modified objects to a list of sorts. When all objects have finished being modified iterate the list and check for objects with your custom data. I believe that do be a safer method.

[jamie.159739]

Great Idea, but how do I know When all objects are done, in an Automatic environment. I don't want the user to have to press a 'calculate' button. I want calculations to take place automatically...