Get all entities inside a blockreference

[哀家爆]

Hi, I've had some problems trying to get all entities inside a blockreference. As the following pic, there are 4 lines and another blockreference inside a blockreference.

var entities = new List<Entity>();
var objects = new DBObjectCollection();
block.Explode(objects);

the objects returns me only 4 lines but no blockreference.

What is amazing is that when I mirror the whole blockreference and execute the code again, I can get 4 lines and a blockreference from the mirrored blockreference.

Is there sth wrong with my code, or is there a better way to get all entities inside a blockreference.

Thanks.

[_gile]

Hi,

A block reference (BlockReference) does not contain entities, it is just a reference to a block definition (BlockTableRecord) which does contain entities.

You can get the ObjectId of the block definition using the BlockReference.BlockTableRecord property, open the BlockTablerecord for read and iterate through its contents.

[哀家爆]

Thanks for your answer. 

How am I supposed to understand that we can obtain the DBObjectCollection by using :

blockReference.Explode();

And I did get what I wanted by using the 'Explode()' method in most cases.

In the example above, the blockReference consists of four lines and another blockReference. In general, I can get what I want. Just this time I do not know what reason cause the 'Explode()' method to lose a blockReference.

[hosneyalaa]

Hi

Please look at this is

https://forums.autodesk.com/t5/net/how-to-get-poin-center-of-circle-in-block/m-p/10354555

Change this 

id.ObjectClass.DxfName.ToUpper() == "CIRCLE")

To

id.ObjectClass.DxfName.ToUpper() == "line")

[哀家爆]

Hi, _gile

var blockTableRecordId = block.BlockTableRecord;
BlockTableRecord blockTableRecord = null;
using (var ts = block.Database.TransactionManager.StartTransaction())
{
    blockTableRecord = ts.GetObject(blockTableRecordId, OpenMode.ForRead) as BlockTableRecord;
    foreach (var id in blockTableRecord)
    {
        var ent = (Entity)ts.GetObject(id, OpenMode.ForRead);
        ent.TransformBy(block.BlockTransform);
        entities.Add(ent);
     }
}

Now I use your way to get all entities from a blockreference (throuth the blocktablerecord), and get the correct result.

But the following statement :

ent.TransformBy(block.BlockTransform);

throw a exception :

Autodesk.AutoCAD.Runtime.Exception:“eMissingSymbolTableRec”

What is wrong with this?

Best regards!~

[哀家爆]

Hi, _gile

Now I use your way to get all entities from a blockreference (throuth the blocktablerecord), and get the correct result.

var blockTableRecordId = block.BlockTableRecord;
BlockTableRecord blockTableRecord = null;
using (var ts = block.Database.TransactionManager.StartTransaction())
{
    blockTableRecord = ts.GetObject(blockTableRecordId, OpenMode.ForRead) as BlockTableRecord;
    foreach (var id in blockTableRecord)
    {
        var ent = (Entity)ts.GetObject(id, OpenMode.ForRead);
        ent.TransformBy(block.BlockTransform);
        entities.Add(ent);
     }
}

But the following statement :

 ent.TransformBy(block.BlockTransform); 

throw a exception : Autodesk.AutoCAD.Runtime.Exception:“eMissingSymbolTableRec”

What is wrong with this? Best regards!~

[_gile]

I was just trying to reply to your question : "is there a better way to get all entities inside a blockreference."

        private static IEnumerable<Entity> GetEntitiesWithinBlock(BlockReference br) =>
            ((BlockTableRecord)br.BlockTableRecord.GetObject(OpenMode.ForRead))
            .Cast<ObjectId>()
            .Select(id => (Entity)id.GetObject(OpenMode.ForRead));

[_gile · Accepted solution]

You should not tranform the entity within the block definition, you should clone it and transform the clone.

        private static IEnumerable<Entity> GetEntitiesWithinBlock(BlockReference br)
        {
            var btr = (BlockTableRecord)br.BlockTableRecord.GetObject(OpenMode.ForRead);
            var ids = new ObjectIdCollection(btr.Cast<ObjectId>().ToArray());
            var mapping = new IdMapping();
            br.Database.DeepCloneObjects(ids, br.OwnerId, mapping, false);
            foreach (IdPair pair in mapping)
            {
                if (pair.IsCloned && pair.IsPrimary)
                {
                    var entity = (Entity)pair.Value.GetObject(OpenMode.ForWrite);
                    entity.TransformBy(br.BlockTransform);
                    yield return entity;
                }
            }
        }

[哀家爆]

thanks a lot，I will try again.

[哀家爆]

What if I want to get all entities recursively?

public static void GetEntitiesWithinBlock(BlockReference br, Document doc, ref List<Entity> entities)
        {
            using (var ts = doc.Database.TransactionManager.StartTransaction())
            {
                var btr = (BlockTableRecord)br.BlockTableRecord.GetObject(OpenMode.ForRead);
                var ids = new ObjectIdCollection(btr.Cast<ObjectId>().ToArray());
                var mapping = new IdMapping();
                br.Database.DeepCloneObjects(ids, br.OwnerId, mapping, false);
                var asd = br.BlockTransform;
                foreach (IdPair pair in mapping)
                {
                    if (pair.IsCloned && pair.IsPrimary)
                    {
                        var entity = (Entity)ts.GetObject(pair.Value, OpenMode.ForWrite);
                        if (entity is BlockReference blockReference)
                        {
                            GetEntitiesWithinBlock(blockReference, doc, ref entities);
                        }
                        else
                        {
                            entity.TransformBy(br.BlockTransform);
                            entities.Add(entity);
                        }
                    }
                }
            }
        }

And the statement: entity.TransformBy(br.BlockTransform); throw a new exception: eCannotScaleNonUniformly.

Thanks a lot!

[_gile]

        private static IEnumerable<Entity> GetEntitiesWithinBlock(BlockReference br)
        {
            var btr = (BlockTableRecord)br.BlockTableRecord.GetObject(OpenMode.ForRead);
            var ids = new ObjectIdCollection(btr.Cast<ObjectId>().ToArray());
            var mapping = new IdMapping();
            br.Database.DeepCloneObjects(ids, br.OwnerId, mapping, false);
            foreach (IdPair pair in mapping)
            {
                if (pair.IsCloned && pair.IsPrimary)
                {
                    var entity = (Entity)pair.Value.GetObject(OpenMode.ForWrite);
                    if (entity is BlockReference)
                    {
                        entity.TransformBy(br.BlockTransform);
                        foreach (var ent in GetEntitiesWithinBlock((BlockReference)entity))
                        {
                            yield return ent;
                        }
                        entity.Erase();
                    }
                    else
                    {
                        entity.TransformBy(br.BlockTransform);
                        yield return entity;
                    }
                }
            }
        }

[哀家爆]

When the entity is BlockReference, 

entity.TransformBy(br.BlockTransform);

throw the exception: eMissingSymbolTableRec.

It seems that AutoCAD doesn't allow us to transform a blockReference which is within another blockReference .

[_gile]

---

@哀家爆  a écrit :

When the entity is BlockReference, 

entity.TransformBy(br.BlockTransform);

throw the exception: eMissingSymbolTableRec.

It seems that AutoCAD doesn't allow us to transform a blockReference which is within another blockReference .

---

We do not transform the block reference which is within the block definition, we transform the clone.

The upper code works for me.

[哀家爆]

Could you please help me to test the attached dwg file.

I've no idea why the exception happens in my test.

Thank you very much !

[_gile · Accepted solution]

In the "blocktest"drawing, the block is not uniformy scaled.

[NSJamieLiu]

hi there: I am facing the same problem. I want to transform inner objects within a non uniformy scaled blockrefernce. So what should I do if the blockrefernce is not uniform scaled?

all the best