I have been tasked with translating an AutoCAD plugin from VBA to VB.NET, and I'm currently a bit stuck.
The command I'm working on creates a new layer (or select it as the active layer if it already exist), then executes 2 "-INSERT" commands giving a point selected by the user, and a dwg-file. Then, the previous active layer is reset as the active layer.
The insert-command looks something like this:
-INSERT
C:\path\to\file.dwg
<point.x>,<point.y>,<point.z>
<documentScale>
Note: All the line-breaks in the command are added as vbCR (not vbCrLf).
My question is, how can I achieve the same result in .NET against ObjectARX? I can't use SendStringToExecute because it is async (with no callback), so in other words, I can't reset the current layer once it's done executing. There has to be some way to replicate this functionality in pure .NET code, probably using the BlockTable, but I have no idea how.
I've tried following the article found here: http://through-the-interface.typepad.com/through_the_interface/2006/08/import_blocks_f.html, but that had no visible effect on the document at all. I also tried to use myDatabase.Insert(transform, otherDatabase, False) and the command-prompt said something about blocks already existing and thus beeing skipped, yet I still saw no changes. I have no idea how much magic the "-INSERT" command actually does behind the scenes, but would it be viable to replicate it in .NET? Or is it somehow availible to be called as a normal method (not as a text-command sent to be processed by AutoCAD)?
The code example in the Through the Interface post, imports the blocks, but does not insert them into the drawing. You have to create a BlockReference and add it to the model space. It also inserts all the blocks from the file, not the file as a single block.
Here is the code I use to import a file as a whole block. This function returns a block reference you can insert into your drawing.
Private Shared Function InsertFile(ByVal FileName as String, ByVal dwgdb As Database, ByVal tr As Transaction) As BlockReference
Dim br As BlockReference
Dim id As ObjectId
'use a temporary database
Using TempDB As New Database(False, True)
'Get block table
Dim bt As BlockTable = tr.GetObject(dwgdb.BlockTableId, OpenMode.ForWrite, False)
'Create unique block name
Dim BlockName As String = FileName.Replace("\", "").Replace(":", "").Replace(".", "")
'check if block already exists
If Not bt.Has(BlockName) Then
'check if file exists
If IO.File.Exists(FileName) Then
'read in the file into the temp database
TempDB.ReadDwgFile(FileName, IO.FileShare.Read, True, Nothing)
'insert the tempdb into the current drawing db, id is the new block id
id = dwgdb.Insert(BlockName, TempDB, True)
Else
'Throw exception for missing file
Throw New System.Exception(String.Format("File {0} is not found for library item {1}", FileName, item.PartNo))
End If
Else
id = bt.Item(BlockName)
End If
'create a new block reference
br = New BlockReference(New Point3d(0, 0, 0), id)
End Using
Return br
End Function
Here would be the example of using that function to insert a block into the file. In this example I use a jig, which allows the user to drop the object onto a location they want, otherwise you could just set the position.
' Get Editor
Dim ed As Editor = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument.Editor
' Get Database
Dim dwg As Database = ed.Document.Database
'Lock document
Using dl As DocumentLock = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument.LockDocument()
'### Changed Try Finally to using, try was hiding errors
'Begin Transaction
Using trans As Transaction = dwg.TransactionManager.StartTransaction()
Dim blockRef As BlockReference = InsertFile(FileName, dwg, trans)
'check if layer exists/create
AcadUtil.AcadFunctions.CheckLayer(LayerName, trans, dwg)
blockRef.Layer = LayerName
'set focus to the editor
Autodesk.AutoCAD.Internal.Utils.SetFocusToDwgView()
'have the user pick insert point
Dim BlockMove As New AcadJigs.JigBlockMove(blockRef, False, 0)
ed.Drag(BlockMove)
'optionally you could just set the .Position of the block reference
' add it to the current space, first open the current space for write
Dim btr As BlockTableRecord = trans.GetObject(dwg.CurrentSpaceId, OpenMode.ForWrite, True, True)
' Add block reference to current space
btr.AppendEntity(blockRef)
'Capture the handle
handle = blockRef.Handle.Value.ToString
' remember to tell the transaction about the new block reference so that the transaction can autoclose it
trans.AddNewlyCreatedDBObject(blockRef, True)
'commit the transaction
trans.Commit()
End Using
End Using
And here is also the CheckLayer function I called.
Public Shared Sub CheckLayer(ByVal Name As String, ByVal tr As Transaction, ByVal dwg As Database)
Dim lt As LayerTable = CType(tr.GetObject(dwg.LayerTableId, OpenMode.ForWrite), LayerTable)
If lt.Has(Name) Then
Return
Else
Dim ly As New LayerTableRecord
ly.Name = Name
lt.Add(ly)
tr.AddNewlyCreatedDBObject(ly, True)
End If
End Sub
Just as a note, Kean's blog is a great resources, I pretty much learned all of the above code from there.
For completeness sake, here is the Jig class i reference in the insert code,
Class JigBlockMove
Inherits EntityJig
Private _CenterPt As Point3d
Private _ActualPoint As Point3d
Private _LockZ As Boolean
Private _Z As Double
Public ReadOnly Property SelectedPoint() As Point3d
Get
Return _ActualPoint
End Get
End Property
Public Sub New(ByVal BlockRef As BlockReference, ByVal LockZ As Boolean, ByVal Z As Double)
MyBase.New(BlockRef)
_CenterPt = BlockRef.Position
_LockZ = LockZ
_Z = Z
End Sub
Protected Overloads Overrides Function Sampler(ByVal prompts As JigPrompts) As SamplerStatus
Dim jigOpts As New JigPromptPointOptions()
jigOpts.UserInputControls = (UserInputControls.Accept3dCoordinates Or UserInputControls.NoZeroResponseAccepted Or UserInputControls.NoNegativeResponseAccepted)
jigOpts.Message = vbLf & "Enter insert point: "
Dim dres As PromptPointResult = prompts.AcquirePoint(jigOpts)
If _ActualPoint = dres.Value Then
Return SamplerStatus.NoChange
Else
_ActualPoint = dres.Value
End If
Return SamplerStatus.OK
End Function
Protected Overloads Overrides Function Update() As Boolean
If _LockZ Then
_CenterPt = New Point3d(_ActualPoint.X, _ActualPoint.Y, _Z)
Else
_CenterPt = _ActualPoint
End If
Try
DirectCast(Entity, BlockReference).Position = _CenterPt
Catch generatedExceptionName As System.Exception
Return False
End Try
Return True
End Function
Public Function GetEntity() As Entity
Return Entity
End Function
End Class
One note regarding working in .NET ObjectARX, there is a an issue with the single threaded nature of AutoCAD, and the fact that the .NET garbage collector runs on a separate thread. If you create any temporary AutoCAD objects that do not get added to the database, you must explicity call .Dispose() on them, or AutoCAD may crash! The crash will seem random too, since it will be triggered by the garbage collector thread. See this post, http://through-the-interface.typepad.com/through_the_interface/2008/06/cleaning-up-aft.html.