Public Class BlockModel
    Inherits ACADObjectModel
    Implements IDisposable

    Public Event BlockModified()

    Public Sub New(ObjID As ObjectId)
        MyBase.New(ObjID)
        AddHandlers()
    End Sub

    Private Sub RemoveHandlers()
        Try
            Dim doc As Document = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.GetDocument(ObjID.Database)
            Using tran As Transaction = doc.TransactionManager.StartTransaction()
                Dim item As BlockReference = ObjID.GetObject(OpenMode.ForRead)
                RemoveHandler item.Modified, AddressOf OnBlockModified
            End Using
        Catch ex As Exception
            'TODO: Handle
        End Try
    End Sub

    Private Sub AddHandlers()
        Try
            Dim doc As Document = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.GetDocument(ObjID.Database)
            Using tran As Transaction = doc.TransactionManager.StartTransaction()
                Dim item As BlockReference = ObjID.GetObject(OpenMode.ForRead)
                AddHandler item.Modified, AddressOf OnBlockModified
            End Using
        Catch ex As Exception
            'TODO: Handle
        End Try
    End Sub

    Protected Sub OnBlockModified(ByVal Sender As Object, e As EventArgs)
        RaiseEvent BlockModified()
    End Sub

    Public Overrides Function GetState() As ACADObjectState
        Return BlockStateFactory.BuildBlockState(ObjID)
    End Function

    Public Overrides Sub SetState(State As ACADObjectState)
        If Not State.GetType() Is GetType(BlockState) Then Throw New ArgumentException("State Type is Invalid.")
        Dim blkState As BlockState = State
        RemoveHandlers()
        DynamicBlockHelper.UpdateAttributeValues(ObjID, blkState.Attributes)
        For Each bprop As BlockProperty In blkState.Properties
            Select Case bprop.PropertyType
                Case 1
                    'numeric (double)
                    Dim n As Double
                    If Not Double.TryParse(bprop.SelectedValue, n) Then Throw New InvalidOperationException("BlockDefID " + bprop.BlockDefID + " PropertyDefID " + bprop.PropertyDefID + " Value " + bprop.SelectedValue + " Should be Numeric but isn't.")
                    DynamicBlockHelper.SetParameter(ObjID, bprop.Name, n)
                Case 3
                    'boolean
                    Dim b As Short
                    If Not Short.TryParse(bprop.SelectedValue, b) AndAlso (b = 0 OrElse b = 1) Then Throw New InvalidOperationException("BlockDefID " + bprop.BlockDefID + " PropertyDefID " + bprop.PropertyDefID + " Value " + bprop.SelectedValue + " Should be Boolean but isn't.")
                    DynamicBlockHelper.SetParameter(ObjID, bprop.Name, b)
                Case Else
                    'assume string
                    DynamicBlockHelper.SetParameter(ObjID, bprop.Name, bprop.SelectedValue)
            End Select
        Next
        AddHandlers()
    End Sub

#Region "IDisposable Support"
    Private disposedValue As Boolean ' To detect redundant calls

    ' IDisposable
    Protected Overridable Sub Dispose(disposing As Boolean)
        If Not Me.disposedValue Then
            If disposing Then
                Try
                    RemoveHandlers()
                Catch ex As Exception

                End Try
                _ObjID = Nothing
            End If

            ' TODO: free unmanaged resources (unmanaged objects) and override Finalize() below.
            ' TODO: set large fields to null.
        End If
        Me.disposedValue = True
    End Sub

    ' TODO: override Finalize() only if Dispose(ByVal disposing As Boolean) above has code to free unmanaged resources.
    'Protected Overrides Sub Finalize()
    '    ' Do not change this code.  Put cleanup code in Dispose(ByVal disposing As Boolean) above.
    '    Dispose(False)
    '    MyBase.Finalize()
    'End Sub

    ' This code added by Visual Basic to correctly implement the disposable pattern.
    Public Sub Dispose() Implements IDisposable.Dispose
        ' Do not change this code.  Put cleanup code in Dispose(ByVal disposing As Boolean) above.
        Dispose(True)
        GC.SuppressFinalize(Me)
    End Sub
#End Region

End Class


Public Shared Function SetParameter(ByVal BlockID As ObjectId, ByVal ParameterName As String, ByVal Value As String) As Boolean
    Using dl As DocumentLock = Application.DocumentManager.MdiActiveDocument.LockDocument(DocumentLockMode.ProtectedAutoWrite, Nothing, Nothing, True)
        Using myTrans As Transaction = BlockID.Database.TransactionManager.StartTransaction
            Dim myBRef As BlockReference = BlockID.GetObject(OpenMode.ForWrite)
            For Each myDynamProp As DynamicBlockReferenceProperty In _
               myBRef.DynamicBlockReferencePropertyCollection
                If myDynamProp.PropertyName.Equals( _
                   ParameterName, StringComparison.OrdinalIgnoreCase) = True Then
                    myDynamProp.Value = Value
                    myTrans.Commit()
                    Return True
                End If
            Next
            Return False
        End Using
    End Using
End Function