Delete block from Autocad Drawing.

[Anonymous]

Hello everyone,

  i need to delete a block from my autocad drawing.

  Is there any way i can search for a block in the drawing(by its name for example-'Terminal1') and delete it from the drawing??

  I am able to check if a certain block name (ex-terminal1) is present in the current drawing or not,but i do not know how to remove that portion from the   drawing.If anyone can give a solution it will be of great help.

Regards

Aaditya

[SENL1362 · Accepted solution]

This might help you to get started. Don't ever erase a Block when there are references to prevent drawing corruption.

        [CommandMethod("TestEraseBlk")]
        public void TestEraseBlk()
        {
            Document doc = Application.DocumentManager.MdiActiveDocument;
            Database db = doc.Database;
            Editor ed = doc.Editor;

            var blkName = "Terminal1";

            try
            {
                var blkId = GetBlkId(db, blkName);
                if (blkId.IsNull)
                    throw new System.Exception(string.Format("\n Block not found: {0}", blkName));

                if (!EraseBlkRefs(blkId))
                    throw new System.Exception(string.Format("\n Failed to Erase BlockReferences for: {0}", blkName));

                if (!EraseBlk(blkId))
                    throw new System.Exception(string.Format("\n Failed to Erase Block: {0}", blkName));

                ed.WriteMessage("\n Block Erased: {0}", blkName);
            }
            catch (System.Exception ex)
            {
                ed.WriteMessage(ex.Message);
            }
        }


        public static ObjectId GetBlkId(Database db, string blkName)
        {

            ObjectId blkId = ObjectId.Null;

            if (db == null)
                return ObjectId.Null;

            if (string.IsNullOrWhiteSpace(blkName))
                return ObjectId.Null;

            using (Transaction tr = db.TransactionManager.StartTransaction())
            {
                BlockTable bt = (BlockTable)tr.GetObject(db.BlockTableId, OpenMode.ForRead);
                if (bt.Has(blkName))
                    blkId = bt[blkName];
                tr.Commit();
            }
            return blkId;
        }


        public static bool EraseBlkRefs(ObjectId blkId)
        {
            bool blkRefsErased = false;

            if (blkId.IsNull)
                return false;

            Database db = blkId.Database;
            if (db == null)
                return false;

            using (Transaction tr = db.TransactionManager.StartTransaction())
            {
                BlockTableRecord blk = (BlockTableRecord)tr.GetObject(blkId, OpenMode.ForRead);
                var blkRefs = blk.GetBlockReferenceIds(true, true);
                if (blkRefs != null && blkRefs.Count > 0)
                {
                    foreach (ObjectId blkRefId in blkRefs)
                    {
                        BlockReference blkRef = (BlockReference)tr.GetObject(blkRefId, OpenMode.ForWrite);
                        blkRef.Erase();
                    }
                    blkRefsErased = true;
                }
                tr.Commit();
            }
            return blkRefsErased;
        }



        public static bool EraseBlk(ObjectId blkId)
        {
            bool blkIsErased = false;

            if (blkId.IsNull)
                return false;

            Database db = blkId.Database;
            if (db == null)
                return false;

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

                BlockTableRecord blk = (BlockTableRecord)tr.GetObject(blkId, OpenMode.ForRead);
                var blkRefs = blk.GetBlockReferenceIds(true, true);
                if (blkRefs == null || blkRefs.Count == 0)
                {
                    blk.UpgradeOpen();
                    blk.Erase();
                    blkIsErased = true;
                }
                tr.Commit();
            }
            return blkIsErased;
        }

[Anonymous]

Thanks for the reply.

This solution works like dream!!Absolutely perfect for my problem!! 

Simple and efficient solution!!

Regards

Aaditya Aggarwal