topic Re: Iterate through each instance of a block type in .NET Forum

Iterate through each instance of a block type

Anonymous — Sat, 01 Apr 2017 18:53:25 GMT

Hi All

I am trying to get information from each inserted block in a drawing... Specificaly, the geometry extents of that instance. For example, I have inserted three of the same blocks into a drawing:

How would i go about getting the information from each of these? I have tried several different ways, but I just can't seem to extract this information. I hace managed to just get the whole block defenition from the drawing (just shows one instance).

Hope this makes sense!!!

Any help would be greatly appreciated!

Re: Iterate through each instance of a block type

_gile — Sat, 01 Apr 2017 20:00:37 GMT

Hi,

To get all inserted references, have a look at the BlockTableRecord.GetBlockReferenceIds() method.

        public ObjectIdCollection GetAllReferenceIds(string blockName, Database db)
        {
            var ids = new ObjectIdCollection();
            using (var tr = db.TransactionManager.StartOpenCloseTransaction())
            {
                var bt = (BlockTable)tr.GetObject(db.BlockTableId, OpenMode.ForRead);
                if (bt.Has(blockName))
                {
                    var btr = (BlockTableRecord)tr.GetObject(bt[blockName], OpenMode.ForRead);
                    foreach (ObjectId brId in btr.GetBlockReferenceIds(true, false))
                    {
                        ids.Add(brId);
                    }
                    if (btr.IsDynamicBlock)
                    {
                        foreach (ObjectId btrId in btr.GetAnonymousBlockIds())
                        {
                            var anonymousBtr = (BlockTableRecord)tr.GetObject(btrId, OpenMode.ForRead);
                            foreach (ObjectId brId in anonymousBtr.GetBlockReferenceIds(true, false))
                            {
                                ids.Add(brId);
                            }
                        }
                    }
                }
            }
            return ids;
        }

Re: Iterate through each instance of a block type

Anonymous — Sun, 02 Apr 2017 14:38:13 GMT

Thank you for your help. I have just implemented this and am getting some results... I am iterating through the blocks and trying to get th valuses like this:

            string blockName = "SAMPLE";
            ObjectIdCollection ids = GetAllReferenceIds(blockName, db);
            Matrix3d ucs = ed.CurrentUserCoordinateSystem;
            //get current UCS matrix
            try
            {
                using (DocumentLock docloc = doc.LockDocument())
                {
                    using (Transaction tr = db.TransactionManager.StartTransaction())
                    {
                        
                        doc.TransactionManager.EnableGraphicsFlush(true);

                        BlockTable bt = (BlockTable)tr.GetObject(db.BlockTableId, OpenMode.ForRead);
                                              
                         if (!bt.Has(blockName))
                            {
                                Autodesk.AutoCAD.ApplicationServices.Application.ShowAlertDialog("Block " + blockName + " does not exist.");
                                return;
                         }

                        var btr = (BlockTableRecord)tr.GetObject(bt[blockName], OpenMode.ForWrite);
                        foreach (ObjectId brId in btr.GetBlockReferenceIds(true, false))
                        {
                            ids.Add(brId);
                        }
                        if (btr.IsDynamicBlock)
                        {
                            foreach (ObjectId btrId in btr.GetAnonymousBlockIds())
                            {
                                var anonymousBr = (BlockTableRecord)tr.GetObject(btrId, OpenMode.ForRead);
                                foreach (ObjectId brId in anonymousBr.GetBlockReferenceIds(true, false))
                                {
                                    ids.Add(brId);
                                }
                            }
                        }

                            foreach (ObjectId id in ids)
                            {
                                Entity e = (Entity)tr.GetObject(id, OpenMode.ForWrite);
                                    System.Windows.Forms.MessageBox.Show(e.GeometricExtents.MinPoint.X.ToString() + e.BlockName + e.GeometricExtents.MinPoint.Y.ToString());
                             }

However, the messagebox shows the blockname as MODEL_SPACE? I also get a 'max readers' error if i try to run it again 😕

Re: Iterate through each instance of a block type

Anonymous — Sun, 02 Apr 2017 15:28:27 GMT

looks like the XY positions are correct... thats good enough for me 🙂 I'll work out how to fix the errors now!

Thanks a lot

Re: Iterate through each instance of a block type

ActivistInvestor — Mon, 03 Apr 2017 01:26:40 GMT

The Entity.BlockName property is the name of the block that contains the entity, not the name of the block that is referenced by the Entity/BlockReference.

You also should not be casting each ObjectId to Entity, you should be casting them to BlockReference, because that's what they all are.