How to get BLKREFS from a BLOCK_RECORD

[iakovos-panourgias]

Hi,

First of all many thanks for this great library.

I have a DWG file, which I have converted to a DXF.

The DXF file has (amongst other entries) BLOCK_RECORDs with a list of BLKREFS which references INSERTs.

My goal is to get the list of the handles of the INSERTs in the BLKREFS section of a BLOCK_RECORD .

The BLOCK_RECORD and the corresponding start BLOCK have the same name.
(BLOCK: Group codes 2 and 3 **and ** BLOCK_RECORD: Group code 2 are all the same)

I've done the following:

A.
I can get the BLOCK_RECORD (BlockRecord in EZDXF terminology) by using the following line:

block_record = doc.block_records.get("NAME_OF_BLOCK_RECORD_AND_BLOCK") # (this is an ezdxf.entities.blockrecord.BlockRecord)

From there I can get the start and end BLOCKs:

block_record.block
block_record.endblk

The objects (LINE, ARC, etc) between the START and END BLOCKS are the ones that I expect; but the owner handle points back to the BLOCK_RECORD (which is kinda correct)

I can also use this to get the same list of objects (LINE, ARC, etc) using:

for entity in block_record.entity_space:
    print(entity)

The list contains the correct objects; but I can't get a reference back to the INSERTs.

The BLOCK_RECORD dictionary looks like this:

{'doc': <ezdxf.document.Drawing object at X>, 'dxf': <ezdxf.entities.dxfns.DXFNamespace object at Y>, 'appdata': None, 'reactors': None, 'extension_dict': None, 'xdata': <ezdxf.entities.xdata.XData object at Z>, 'proxy_graphic': None, 'entity_space': <ezdxf.entitydb.EntitySpace object at A>, 'block': <class 'ezdxf.entities.block.Block'> BLOCK(#31A92), 'endblk': <class 'ezdxf.entities.block.EndBlk'> ENDBLK(#31B24), 'block_layout': <ezdxf.layouts.blocklayout.BlockLayout object at B>}

The BLOCK_RECORD has no appdata and it has xdata; but the BLKREFs are not part of the xdata.

B.
I can get something (BlockLayout in EZDXF terminology) by using the following line:

block_layout = doc.blocks.get("NAME_OF_BLOCK_RECORD_AND_BLOCK") (this is an ezdxf.layouts.blocklayout.BlockLayout)

From there I can get the start BLOCK using:

block_layout.block

I can also use this one; but it only returns the INSERTs that have as onwer the BlockLayout / BLOCK_RECORD. The INSERTs referenced in BLKREFS are not there ...

for entity in block_layout.query('INSERT'):

So my question: "is there a way of getting the INSERTs referenced in the BLKREFS section of a BLOCK_RECORD?"

I can see them when I browse the file using "ezdxf browse"; so there must be a way ...

Thanks,
Iakovos

[mozman]

TLDR; I don't know why you are dealing with BLOCK_RECORDS, here is a tutorial how to use BLOCK layouts and block references (INSERT entities): https://ezdxf.mozman.at/docs/tutorials/blocks.html

[iakovos-panourgias]

Apologies for the long post and many thanks for the reply.

I wish I didn't have to deal with BLOCK_RECORDS at all.

The document has nested BLOCK (INSERT entities). The query returns either the first level of INSERTs or nothing:

This one returns nothing:

for flag_ref in msp.query('INSERT[name=="AN_ACTUAL_INSERT_NAME"]'):

This one returns the first level of INSERTs (just five objects from a 10000+ object DXF document):

for flag_ref in msp.query('INSERT'):

This one returns the correct BLOCK (INSERT entity):

for flag_ref in msp.query('INSERT[name=="AN_ACTUAL_INSERT_NAME_OF_THE_0TH_LEVEL"]'):

Using the "ezdxf browse" application, I can see the relationships between a BLOCK_RECORD and the various INSERTs.

I will have a look at the "ezdxf browse" code to see how the relationships are formed.

Many thanks,
Iakovos

[mozman]

This function maybe can help: https://ezdxf.mozman.at/docs/disassemble.html#ezdxf.disassemble.recursive_decompose

Recursive decomposition of the given DXF entity collection into a flat stream of DXF entities. All block references (INSERT) and entities which provide a virtual_entities() method will be disassembled into simple DXF sub-entities, therefore the returned entity stream does not contain any INSERT entity.

And if this implementation doesn't fit your needs, look at the source code and make your own function:

ezdxf/src/ezdxf/disassemble.py

Line 542 in 4f5e04a

def recursive_decompose(entities: Iterable[DXFEntity]) -> Iterable[DXFEntity]:

[iakovos-panourgias]

Many thanks for the suggestion.

My point of entry used to be this line:

msp = doc.modelspace()
for e in msp:

I have now changed it to:

for dxfentity in doc.chain_layouts_and_blocks():

and I get to see everything (or at least all the objects that I am interested in).

I'll also try your suggestion.

Thanks for the support