topic Re: Erase last object in .NET Forum

Erase last object

Anonymous — Tue, 20 Mar 2012 19:27:10 GMT

Hey everyone, In AutoCAD, i can type "erase" and then "last" into the commandline and it will automatically select and erase the last object i created. How is this accomplished in C#? I'm generating a polyline to automatically calculate areas, but i would like that polyline to vanish once the area has been measured. Thanks Vince

Re: Erase last object

hgasty1001 — Tue, 20 Mar 2012 20:20:15 GMT

Hi,

There is a SelectLast option:

PromptSelectionResult acSSPrompt;
Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;
acSSPrompt = ed.SelectLast();

Gaston Nunez

Re: Erase last object

Anonymous — Tue, 20 Mar 2012 20:42:49 GMT

Ok that helps, what would i use to delete what i selected with the editor?

Thanks

Vince

Re: Erase last object

hgasty1001 — Tue, 20 Mar 2012 21:22:44 GMT

Hi,

You should start a transaction, get the last object (as entity) erase it (entity.erase), and commit the transaction and that's it. Like this (not tested, and translated from VB)

[CommandMethod("ELAST")]
public void EraseObj()
{
	Document acDoc = Application.DocumentManager.MdiActiveDocument;
	Database acCurDb = acDoc.Database;
	Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;

	using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction()) {
		PromptSelectionResult acSSPrompt;
		acSSPrompt = ed.SelectLast;
		Entity ent;
		SelectionSet ss = acSSPrompt.Value;

		if (ss.Count > 0) {
			ent = acTrans.GetObject(ss.Item(0).ObjectId, OpenMode.ForWrite);
			ent.Erase();
		}
		acTrans.Commit();
	}
}

Gaston Nunez

Re: Erase last object

jeff — Tue, 20 Mar 2012 23:48:26 GMT

I have not used it and of course 'not supported' but maybe you can search for

Autodesk.AutoCAD.Internal.Utils.EntLast();

and see if people have had success

Re: Erase last object

Anonymous — Wed, 21 Mar 2012 12:49:36 GMT

Thanks for this sample, i'm having an issue with the line:

ent = acTrans.GetObject(ss.(0).ObjectId, OpenMode.ForWrite);

Visual Studio 2010 and AutoCAD 2012 are telling me that there is no definition for ss.item and thus i cannot compile. As i missing a reference?

Thanks

Vince

using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.Colors;

Re: Erase last object

Anonymous — Wed, 21 Mar 2012 12:49:59 GMT

Thanks jeff, i'll have a look into this as well.

Cheers

Vince

Re: Erase last object

hgasty1001 — Wed, 21 Mar 2012 13:12:34 GMT

Hi,

SelectionSet it's part of the EditorInput, and I see you are "using" it, so I have no idea why VS is telling you that. Any way the correct sintax is : ss(index).ObjectId without a dot after ss.

Gaston Nunez

Re: Erase last object

Anonymous — Wed, 21 Mar 2012 13:20:10 GMT

Ok, so i've got this now:

using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
{
PromptSelectionResult acSSPrompt;
acSSPrompt = ed.SelectLast();
Entity ent;
SelectionSet ss = acSSPrompt.Value;

if (ss.Count > 0)
{
ent = acTrans.GetObject(ss(0).ObjectId, OpenMode.ForWrite);
ent.Erase();
}
acTrans.Commit();
}
}
}
}

But the error I have is 'ss' is a 'variable' but is used like a 'method'

Re: Erase last object

hgasty1001 — Wed, 21 Mar 2012 13:25:10 GMT

Hi,

My mistake (i'm a vb guy), just change ss(0) by ss[0].

Gaston Nunez

Re: Erase last object

Anonymous — Wed, 21 Mar 2012 13:30:03 GMT

Haha didn't even notice that. Now when i change it to ss[0], i get

Error 1 Cannot implicitly convert type 'Autodesk.AutoCAD.DatabaseServices.DBObject' to 'Autodesk.AutoCAD.DatabaseServices.Entity'. An explicit conversion exists (are you missing a cast?) C:\Users\user\Dropbox\Programming\Cad\Cad\TheProgram\Drawing Commands\Copy of AREA.cs 28 27 Commands

if (ss.Count > 0)
{
ent = acTrans.GetObject(ss[0].ObjectId, OpenMode.ForWrite);
ent.Erase();
}
acTrans.Commit();

Re: Erase last object

Anonymous — Wed, 21 Mar 2012 13:47:31 GMT

Scratch that, fixed it 😉

public void EraseObj()
{
Document acDoc = Application.DocumentManager.MdiActiveDocument;
Database acCurDb = acDoc.Database;
Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;

using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
{
PromptSelectionResult acSSPrompt;
acSSPrompt = ed.SelectLast();
Entity ent;
SelectionSet ss = acSSPrompt.Value;

if (ss.Count > 0)
{
ent = acTrans.GetObject(ss[0].ObjectId, OpenMode.ForWrite) as Entity;
ent.Erase();
}
acTrans.Commit();
}
}
}
}

Thanks a million for your help!

Re: Erase last object

hgasty1001 — Wed, 21 Mar 2012 14:02:22 GMT

Hi,

Glad to help you, sorry the mistake, i feel much comfortable with vb 'cause I'd like to see "End this", "End That"... instead of a lot of brackets at the end of a block of code.

Gaston Nunez

Re: Erase last object

Anonymous — Wed, 21 Mar 2012 14:11:43 GMT

No worries, thanks again!