topic Re: unwanted zoom in loop command in .NET Forum

unwanted zoom in loop command

Anonymous — Tue, 12 Feb 2013 14:02:08 GMT

I have a portion of my routine below. Basically I need the user to continue to loop through the command. They are picking Circles or blocks in the drawing and I get the insertion point, then insert a new block. However, whenever they try and use a transparent zoom or pan to move around the drawing when the promptentityresult is hit, it zooms back to the original location. How do I stop it from doing that? Any help or direction is much appreciated. Here is a code....

CommandMethod("getpnt", CommandFlags.Session)> _

Sub findpnt()

Dim cnt AsInteger = 0

Dim NEWPNT AsPoint3d = GetInsPoint()

While cnt < 3

NEWPNT = GetInsPoint()

' other code is inserted here...

cnt = cnt + 1

EndWhile

EndSub

Public Function GetInsPoint()

Dim inspnt AsPoint3d

Dim acdoced AsDocument = Application.DocumentManager.MdiActiveDocument

Dim myed AsEditor = acdoced.Editor

Dim db AsDatabase = HostApplicationServices.WorkingDatabase

Using mytrans2 AsTransaction = db.TransactionManager.StartTransaction()

Dim myPEO AsNewPromptEntityOptions(vbLf & "Select Circle or Block: ")

myPEO.SetRejectMessage(

"You must select a Circle or Block.")

myPEO.AddAllowedClass(

GetType(Circle), True)

myPEO.AddAllowedClass(

GetType(BlockReference), True)

myPEO.AllowNone =

False

Dim symbolent AsPromptEntityResult = myed.GetEntity(myPEO)

If symbolent.Status = PromptStatus.OK Then

Dim Objid AsObjectId = symbolent.ObjectId

Dim ent AsEntity = CType(mytrans2.GetObject(Objid, OpenMode.ForRead), Entity)

Dim enttype1 AsString = ent.GetType().ToString

Dim enttype AsString = Objid.ObjectClass.DxfName

SelectCase enttype

Case"CIRCLE"

Dim circleobj AsCircle = mytrans2.GetObject(Objid, OpenMode.ForRead)

inspnt = circleobj.Center

Case"INSERT"

Dim blockent AsBlockReference = mytrans2.GetObject(Objid, OpenMode.ForRead)

inspnt = blockent.Position

EndSelect

EndIf

EndUsing

Return inspnt

EndFunction

Re: unwanted zoom in loop command

Norman_Yuan — Tue, 12 Feb 2013 16:12:15 GMT

This is an interesting issue I have not noticed before and did not know current view seems associated with a new started transaction.

The reason AutoCAD always restore back to original view after each pick is that you did not commit the Transaction in the GetInsPoint() function.

As rule of thumb, one should always EXPLICITLY complete the transaction, either commit it, or abort it. If a transaction is wrapped in Using ... End Using, when End Using is reached, if the transaction has not been commited, it will be aborted before being disposed, which may not be what you want, as your code behaves.

So, you need to add mytrans2.Commit() right before End Using.

Re: unwanted zoom in loop command

Anonymous — Tue, 12 Feb 2013 16:15:52 GMT

thanks! I will make that change. maybe that will resolve the issue.

Re: unwanted zoom in loop command

Norman_Yuan — Tue, 12 Feb 2013 16:18:16 GMT

I forgot to mention: I actually tried your code.

Not "maybe". It IS because of the transaction not being commited.

Re: unwanted zoom in loop command

Anonymous — Tue, 12 Feb 2013 16:25:20 GMT

That was it.....found a couple other locations that I did not commit my transactions. Still learning .NET as you can tell.

Once I got those cleared up, the routine is working like it should and is not zooming automatically!

Thanks so much for your help.

Re: unwanted zoom in loop command

Alexander.Rivilis — Tue, 12 Feb 2013 20:26:37 GMT

Excellent, Norman!

I thought that this is due to CommandFlags.Session, but you're absolutely right.

Re: unwanted zoom in loop command

FRFR1426 — Sat, 08 Aug 2015 15:56:04 GMT

I dug up this discussion because I find it's extremely annoying. It does not work like built-in commands. For example, if I start a LINE command and zoom on a specific part of my drawing, I stay where I am if I cancel the command. If I do the same in a .NET command with a transaction started, the transaction is aborted (to cancel changes done on the drawing) and I go back to the location I was before starting the command. Of course, I can handle it with nested transactions, but I found this behavior very strange...

Workaround:

// Top transaction (records view changes)
using (Transaction tr = db.TransactionManager.StartTransaction())
{
  try {

    // Retrieve entities, read-only operations

    using (Transaction writeTr = db.TransactionManager.StartTransaction())
    {

      // Change database here. If something goes wrong or user cancels
      // the command, throw an exception and abort the writeTr transaction.

      writeTr.Commit();
    }
  } 
  finally
  { 
    // Always commit to preserve view changes
    tr.Commit();
  }
}