Split-out bambu-specific elements to their own 3MF 'variant'.

part of CURA-12099

plugins/3MFWriter/ThreeMFVariant.py

@@ -0,0 +1,74 @@
+#  Copyright (c) 2025 UltiMaker
+#  Cura is released under the terms of the LGPLv3 or higher.
+
+from abc import ABC, abstractmethod
+from typing import TYPE_CHECKING
+import xml.etree.ElementTree as ET
+import zipfile
+
+from PyQt6.QtGui import QImage
+from PyQt6.QtCore import QBuffer
+
+if TYPE_CHECKING:
+    from .ThreeMFWriter import ThreeMFWriter
+
+class ThreeMFVariant(ABC):
+    """Base class for 3MF format variants.
+    
+    Different vendors may have their own extensions to the 3MF format,
+    such as BambuLab's 3MF variant. This class provides an interface
+    for implementing these variants.
+    """
+    
+    def __init__(self, writer: 'ThreeMFWriter'):
+        """
+        :param writer: The ThreeMFWriter instance that will use this variant
+        """
+        self._writer = writer
+    
+    @property
+    @abstractmethod
+    def mime_type(self) -> str:
+        """The MIME type for this 3MF variant."""
+        pass
+
+    def handles_mime_type(self, mime_type: str) -> bool:
+        """Check if this variant handles the given MIME type.
+        
+        :param mime_type: The MIME type to check
+        :return: True if this variant handles the MIME type, False otherwise
+        """
+        return mime_type == self.mime_type
+    
+    def prepare_content_types(self, content_types: ET.Element) -> None:
+        """Prepare the content types XML element for this variant.
+        
+        :param content_types: The content types XML element
+        """
+        pass
+    
+    def prepare_relations(self, relations_element: ET.Element) -> None:
+        """Prepare the relations XML element for this variant.
+        
+        :param relations_element: The relations XML element
+        """
+        pass
+    
+    def process_thumbnail(self, snapshot: QImage, thumbnail_buffer: QBuffer, 
+                          archive: zipfile.ZipFile, relations_element: ET.Element) -> None:
+        """Process the thumbnail for this variant.
+        
+        :param snapshot: The snapshot image
+        :param thumbnail_buffer: Buffer containing the thumbnail data
+        :param archive: The zip archive to write to
+        :param relations_element: The relations XML element
+        """
+        pass
+
+    def add_extra_files(self, archive: zipfile.ZipFile, metadata_relations_element: ET.Element) -> None:
+        """Add any extra files required by this variant to the archive.
+        
+        :param archive: The zip archive to write to
+        :param metadata_relations_element: The metadata relations XML element
+        """
+        pass