Analysing nested Xref in drawings

CSharpBoy

When a drawing has nested external references to other drawings, you may want to know the Xref dependencies that exist within the Xref nodes. For example :  Consider three drawings A, B and C where A is the main drawing, B is an external reference in A and C is an external reference in B. In this case, traversing the Xref graph of A will provide Xref graph nodes for A, B and C, but you may need to be able to get that B is the parent of C and is inserted in A.

Here is a sample code :

<CommandMethod("AnalyseXrefGraph")> _
       Public Shared Sub AnalyseXRefGraphMethod()
    Dim relations As Dictionary(Of [String], [String]) = NewDictionary(Of String, String)()
    AnalyseXref("c:\Temp\Test.dwg", "Test", relations)

    ' Print the results
    Dim ed As Editor = Application.DocumentManager.MdiActiveDocument.Editor
    For Each kv As KeyValuePair(Of [String], [String]) In relations
        ed.WriteMessage([String].Format(vbLf & "{0} - {1}", kv.Key, kv.Value))
    Next
End Sub

Public Shared Sub AnalyseXref(ByVal drawingFilePath As [String], ByValbaseNodeName As [String], ByRef relations As Dictionary(Of [String], [String]))
    Dim doc As Document = Application.DocumentManager.MdiActiveDocument
    Dim ed As Editor = doc.Editor

    Using db As New Database(False, True)
        db.ReadDwgFile(drawingFilePath, FileOpenMode.OpenForReadAndWriteNoShare, False, "")
        db.ResolveXrefs(True, False)

        Using tr As Transaction = db.TransactionManager.StartTransaction()
            Dim xg As XrefGraph = db.GetHostDwgXrefGraph(True)
            Dim root As GraphNode = xg.RootNode

            Dim numOfNodes As Integer = xg.NumNodes

            For cnt As Integer = 0 To xg.NumNodes - 1
                Dim node As XrefGraphNode =TryCast(xg.GetXrefNode(cnt), XrefGraphNode)
                If Not node.Database.Filename.Equals(drawingFilePath)Then
                    AnalyseXref(node.Database.Filename, node.Name, relations)
                End If

                If Not node.IsNested Then
                    If Not relations.ContainsKey(node.Name) Then
                        relations.Add(node.Name, baseNodeName)
                    End If
                End If
            Next
            tr.Commit()
        End Using
    End Using
End Sub

Consider a drawing "Test.dwg" that has external references to other drawings as shown in this graph.

The above code snippet will then print the Xref dependencies as :