feat!: Docling v2 (#117)

---------

Signed-off-by: Christoph Auer <cau@zurich.ibm.com>
Signed-off-by: Maxim Lysak <mly@zurich.ibm.com>
Signed-off-by: Michele Dolfi <dol@zurich.ibm.com>
Signed-off-by: Panos Vagenas <35837085+vagenas@users.noreply.github.com>
Co-authored-by: Maxim Lysak <mly@zurich.ibm.com>
Co-authored-by: Michele Dolfi <dol@zurich.ibm.com>
Co-authored-by: Panos Vagenas <35837085+vagenas@users.noreply.github.com>

docling/backend/pdf_backend.py

@@ -0,0 +1,78 @@
+from abc import ABC, abstractmethod
+from io import BytesIO
+from pathlib import Path
+from typing import Iterable, Optional, Set, Union
+
+from docling_core.types.doc import BoundingBox, Size
+from PIL import Image
+
+from docling.backend.abstract_backend import PaginatedDocumentBackend
+from docling.datamodel.base_models import Cell, InputFormat
+from docling.datamodel.document import InputDocument
+
+
+class PdfPageBackend(ABC):
+
+    @abstractmethod
+    def get_text_in_rect(self, bbox: BoundingBox) -> str:
+        pass
+
+    @abstractmethod
+    def get_text_cells(self) -> Iterable[Cell]:
+        pass
+
+    @abstractmethod
+    def get_bitmap_rects(self, float: int = 1) -> Iterable[BoundingBox]:
+        pass
+
+    @abstractmethod
+    def get_page_image(
+        self, scale: float = 1, cropbox: Optional[BoundingBox] = None
+    ) -> Image.Image:
+        pass
+
+    @abstractmethod
+    def get_size(self) -> Size:
+        pass
+
+    @abstractmethod
+    def is_valid(self) -> bool:
+        pass
+
+    @abstractmethod
+    def unload(self):
+        pass
+
+
+class PdfDocumentBackend(PaginatedDocumentBackend):
+
+    def __init__(self, in_doc: InputDocument, path_or_stream: Union[BytesIO, Path]):
+        super().__init__(in_doc, path_or_stream)
+
+        if self.input_format is not InputFormat.PDF:
+            if self.input_format is InputFormat.IMAGE:
+                buf = BytesIO()
+                img = Image.open(self.path_or_stream)
+                img.save(buf, "PDF")
+                buf.seek(0)
+                self.path_or_stream = buf
+            else:
+                raise RuntimeError(
+                    f"Incompatible file format {self.input_format} was passed to a PdfDocumentBackend."
+                )
+
+    @abstractmethod
+    def load_page(self, page_no: int) -> PdfPageBackend:
+        pass
+
+    @abstractmethod
+    def page_count(self) -> int:
+        pass
+
+    @classmethod
+    def supported_formats(cls) -> Set[InputFormat]:
+        return {InputFormat.PDF}
+
+    @classmethod
+    def supports_pagination(cls) -> bool:
+        return True