Detecting anonymous blocks (.NET C#)

Chuckie

I know how to detect if a given object is a polyline or a block reference. But how do I detect if an entity is an anonymous block?

// Examine the object
var ent = acTransNewDb.GetObject(id, _AcDb.OpenMode.ForRead) as _AcDb.Entity;

// Is it a polyline or block?
if (ent is _AcDb.Polyline || ent is _AcDb.BlockReference)
{
}

avc_programming

You can get the BTR of a block and check its IsAnonymous property.
In addition, all anonymous blocks have a name starting with an asterisk.

Chuckie

Thank you. I asked AI (CoPilot) how it would do it and I believe it used the principles you stated:

public bool IsAnonymousBlock(ObjectId objectId)
{
    using (Transaction transaction = objectId.Database.TransactionManager.StartTransaction())
    {
        BlockReference blockReference = transaction.GetObject(objectId, OpenMode.ForRead) as BlockReference;
        if (blockReference != null)
        {
            // Check the block name.
            string blockName = blockReference.Name;
            if (blockName.StartsWith("*U"))
                return true;

            // Check the block type flag.
            BlockTableRecord blockDef = transaction.GetObject(blockReference.BlockTableRecord, OpenMode.ForRead) as BlockTableRecord;
            if (blockDef != null && blockDef.IsAnonymous)
                return true;
        }
    }
    return false;
}

TorstenMoses

> if (blockName.StartsWith("*U"))

that is wrong/incomplete :-)
the only indicator of an anonymous block is the asteriks "*", not the sequence "*U" ...
because
a) also "*u" (lowercase) is valid, as block names are in generally case-insensitive
and
b) any "*" sequence like "*D" (seen with dimensions) or "*x" also indocates an anonymous block ...

So far for the "intelligence" - if the so-called AI "learns" from erroneous samples, and effectively has no clue what text pieces are clobbered together ... then you get such improper results;
in the end, such "CoPilot" mangles valid + invalid code, from whatever & whereever "CoPilot" finds on the web ...
no trace of intelligence, just plain statistics including valid + invalid samples, and (naturally !) not being able to distinguish between ...

In the end, it is *KNOWLEDGE* what matters, not blindly collecting any rubbish :-)
hope this helps a bit ...

Chuckie

@TorstenMoses I agree 100% and thanks for the clarification about anonymous blocks.

But, it brings me on to a related question about these blocks. My client sent me a drawing with a parametric array in it. If I list it in Bricscad it is an anonymous block. If I use the EXPLODE command in Bricscad it ends up as a series of LINE entities.

Yet, using .NET C# to explode the same entity with:

ent.Explode(objExplodedObjs);

(I have extra code to delete the old etc and just showing this line for brevity). Why is it that in the resulting file I do not have a series of LINE entities but another series of anonymous block entities? I can explode them in Bricscad and they turn to LINES again.

Why is it that BricsCAD exploded the parametric array directly to LINE entities whereas usigng .NET exploded it into a bunch of anonymous blocks?

avc_programming

A parametric array is a block consisting of block referenceses. You need to use the Explode command twice to get the lines.