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.venv/lib/python3.12/site-packages/ezdxf/dynblkhelper.py

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+#  Copyright (c) 2023, Manfred Moitzi
+#  License: MIT License
+"""
+This module provides helper tools to work with dynamic blocks.
+
+The current state supports only reading information from dynamic blocks, it does not
+support the creation of new dynamic blocks nor the modification of them.
+
+"""
+from __future__ import annotations
+from typing import TYPE_CHECKING, Optional
+from ezdxf.entities import Insert
+from ezdxf.lldxf import const
+
+if TYPE_CHECKING:
+    from ezdxf.document import Drawing
+    from ezdxf.layouts import BlockLayout
+    from ezdxf.entities import BlockRecord
+
+AcDbDynamicBlockGUID = "AcDbDynamicBlockGUID"
+AcDbBlockRepBTag = "AcDbBlockRepBTag"
+
+
+def get_dynamic_block_definition(
+    insert: Insert, doc: Optional[Drawing] = None
+) -> Optional[BlockLayout]:
+    """Returns the dynamic block definition if the given block reference is
+    referencing a dynamic block direct or indirect via an anonymous block.
+    Returns ``None`` otherwise.
+    """
+    if doc is None:
+        doc = insert.doc
+        if doc is None:
+            return None
+
+    block = doc.blocks.get(insert.dxf.name)
+    if block is None:
+        return None
+
+    block_record = block.block_record
+    if is_dynamic_block_definition(block_record):
+        return block  # direct dynamic block reference
+
+    # is indirect dynamic block reference?
+    handle = get_dynamic_block_record_handle(block_record)
+    if not handle:
+        return None  # lost reference to dynamic block definition
+    dyn_block_record = doc.entitydb.get(handle)
+    if dyn_block_record:
+        return doc.blocks.get(dyn_block_record.dxf.name)
+    return None
+
+
+def is_dynamic_block_definition(block_record: BlockRecord) -> bool:
+    """Return ``True`` if the given block record is a dynamic block definition."""
+    return block_record.has_xdata(AcDbDynamicBlockGUID)
+
+
+def get_dynamic_block_record_handle(block_record: BlockRecord) -> str:
+    """Returns handle of the dynamic block record for an indirect dynamic block
+    reference. Returns an empty string if the block record do not reference a dynamic
+    block or the handle was not found.
+
+    """
+    try:  # check for indirect dynamic block reference
+        xdata = block_record.get_xdata(AcDbBlockRepBTag)
+    except const.DXFValueError:
+        return ""  # not a dynamic block reference
+    # get handle of dynamic block definition
+    return xdata.get_first_value(1005, "")