How to Highlight Attributes of a "given" block

[william.klawitter]

I'm working on an AutoCAD .net application that lists all block definitions in the active drawing in a TreeView Control with the attributes of that block listed a child nodes (AutoCAD 2015).  When the user selects a block definition my code will highlight each block instance within the drawing.  I also want it to Hihglight ONLY the attribute if an Attribute node is selected.  Here is my code - for some reason the attributes are not being highlighted.  Any assistance would be greatly appreciated.

    Private Sub BlocksUltraTree_AfterSelect(sender As Object, e As Infragistics.Win.UltraWinTree.SelectEventArgs) Handles BlocksUltraTree.AfterSelect
        acActiveDocument = acDocumentManager.MdiActiveDocument
        acActiveDocumentDatabase = acActiveDocument.Database

        Dim acTrans As Transaction = acActiveDocumentDatabase.TransactionManager.StartTransaction
        Using acTrans
            'clear any existing entity highlights
            Dim acBlockTable As BlockTable = acTrans.GetObject(acActiveDocumentDatabase.BlockTableId, OpenMode.ForRead)
            For Each acBlockTableRecordId As ObjectId In acBlockTable
                Dim acBlockTableRecord As BlockTableRecord = CType(acTrans.GetObject(acBlockTableRecordId, OpenMode.ForRead), BlockTableRecord)
                For Each acEntityId As ObjectId In acBlockTableRecord
                    Dim myEnt As Entity = TryCast(acTrans.GetObject(acEntityId, OpenMode.ForRead), Entity)
                    myEnt.Unhighlight()
                Next
            Next
            'highlight selected blocks in the drawing
            Dim UserSelectedNode As Infragistics.Win.UltraWinTree.UltraTreeNode = Me.BlocksUltraTree.SelectedNodes(0)
            Dim acActiveDocumentEditor As Editor = acActiveDocument.Editor
            If UserSelectedNode.Tag = "Block" Then
                Dim acTypValAr(0) As TypedValue
                acTypValAr.SetValue(New TypedValue(DxfCode.BlockName, UserSelectedNode.Text), 0)
                Dim acSelFtr As SelectionFilter = New SelectionFilter(acTypValAr)
                Dim acSSPromptRslt As PromptSelectionResult
                acSSPromptRslt = acActiveDocumentEditor.SelectAll(acSelFtr)
                If acSSPromptRslt.Status = PromptStatus.OK Then
                    For i = 0 To acSSPromptRslt.Value.Count - 1
                        Dim myBlk As BlockReference = TryCast(acTrans.GetObject(acSSPromptRslt.Value(i).ObjectId, OpenMode.ForRead), BlockReference)
                        myBlk.Highlight()
                    Next
                End If
            End If
            'highlight selected attributes within the blocks in the drawing
            If UserSelectedNode.Tag = "Attribute" Then
                Dim acTypValAr(0) As TypedValue
                acTypValAr.SetValue(New TypedValue(DxfCode.BlockName, UserSelectedNode.Parent.Text), 0)
                Dim acSelFtr As SelectionFilter = New SelectionFilter(acTypValAr)
                Dim acSSPromptRslt As PromptSelectionResult
                acSSPromptRslt = acActiveDocumentEditor.SelectAll(acSelFtr)
                If acSSPromptRslt.Status = PromptStatus.OK Then
                    For i = 0 To acSSPromptRslt.Value.Count - 1
                        Dim myBlk As BlockReference = TryCast(acTrans.GetObject(acSSPromptRslt.Value(i).ObjectId, OpenMode.ForRead), BlockReference)
                        Dim attCol As AttributeCollection = myBlk.AttributeCollection
                        For Each attObjId As ObjectId In attCol
                            Dim att As AttributeReference = TryCast(acTrans.GetObject(attObjId, OpenMode.ForRead), AttributeReference)
                            If Not att Is Nothing Then
                                If att.Tag = UserSelectedNode.Text Then
                                    MsgBox(att.TextString)
                                    att.Highlight()
                                End If
                            End If
                        Next
                    Next
                End If
            End If
        End Using 'acTrans
    End Sub

Note that the msgbox (att.TextString) line is simply there to know I was indeed getting each seperate instance of that attribute within the drawing.

[norman.yuan · Accepted solution]

It looks like AttributeReference.Highlight() method has its own implementation rather than inherits Entity.Highlight(). In order so find a vailable solution to your question, I did a bit research and code practice, and I believe I have a fairly "OK" solution. Since the code and some description on my solution is a bit long to be post here as the reply to your question, I post it in my blog here:

http://drive-cad-with-code.blogspot.ca/2015/09/highlight-attributes-in-blockreference.html

HTH

[william.klawitter · Accepted solution]

norman.yuan

Thank you for your reply.  I've implemented your solution into my project.  I had to change it a bit because I only need a certain attribute within certain blocks highlighted.  Here is my final code.

Imports Autodesk.AutoCAD.GraphicsInterface
Imports Autodesk.AutoCAD.Geometry
Imports Autodesk.AutoCAD.DatabaseServices
Imports System.Linq
Imports System.Collections.Generic
Imports System

Public Class AttributeHighlighter
    Implements IDisposable
    Private _tManager As TransientManager = TransientManager.CurrentTransientManager
    Private _entities As New List(Of Drawable)()

    Public Sub Dispose() Implements IDisposable.Dispose
        DisposeDrawables()
    End Sub

    Public Sub Highlight(db As Database, blkId As ObjectId, attTag As String)
        DisposeDrawables()
        CollectDrawables(db, blkId, attTag)
        For Each ent In _entities
            _tManager.AddTransient(ent, TransientDrawingMode.Highlight, 128, New IntegerCollection())
        Next
    End Sub

    Public Sub Unhighlight()
        _tManager.EraseTransients(TransientDrawingMode.Highlight, 128, New IntegerCollection())
    End Sub

    Private Sub DisposeDrawables()
        For Each ent In _entities
            ent.Dispose()
        Next
        _entities.Clear()
    End Sub

    Private Sub CollectDrawables(db As Database, id As ObjectId, attTag As String)
        Using tran As Object = db.TransactionManager.StartTransaction()
            Dim bref As BlockReference = TryCast(tran.GetObject(id, OpenMode.ForRead), BlockReference)
            If bref Is Nothing Then
            Else
                For Each attId As ObjectId In bref.AttributeCollection
                    Dim att As AttributeReference = CType(tran.GetObject(attId, OpenMode.ForRead), AttributeReference)
                    If att.Tag = attTag Then
                        _entities.Add(TryCast(att.Clone(), Drawable))
                    End If
                Next
            End If
            tran.Commit()
        End Using
    End Sub
End Class

            'highlight selected attributes within the blocks in the drawing
            If UserSelectedNode.Tag = "Attribute" Then
                Dim acTypValAr(0) As TypedValue
                acTypValAr.SetValue(New TypedValue(DxfCode.BlockName, UserSelectedNode.Parent.Text), 0)
                Dim acSelFtr As SelectionFilter = New SelectionFilter(acTypValAr)
                Dim acSSPromptRslt As PromptSelectionResult
                acSSPromptRslt = acActiveDocumentEditor.SelectAll(acSelFtr)
                If acSSPromptRslt.Status = PromptStatus.OK Then
                    For i = 0 To acSSPromptRslt.Value.Count - 1
                        Dim myBlk As BlockReference = TryCast(acTrans.GetObject(acSSPromptRslt.Value(i).ObjectId, OpenMode.ForRead), BlockReference)
                        Dim attCol As AttributeCollection = myBlk.AttributeCollection
                        For Each attObjId As ObjectId In attCol
                            Dim att As AttributeReference = TryCast(acTrans.GetObject(attObjId, OpenMode.ForRead), AttributeReference)
                            If Not att Is Nothing Then
                                If att.Tag = UserSelectedNode.Text Then
                                    Dim hl As New AttributeHighlighter()
                                    hl.Highlight(acActiveDocumentDatabase, myBlk.ObjectId, att.Tag)
                                    acActiveDocumentEditor.UpdateScreen()
                                End If
                            End If
                        Next
                    Next
                End If