Add DoclingParseV3 backend implementation

Signed-off-by: Christoph Auer <cau@zurich.ibm.com>

tests/test_backend_docling_parse_v3.py

@@ -0,0 +1,76 @@
+from pathlib import Path
+
+import pytest
+
+from docling.backend.docling_parse_v3_backend import (
+    DoclingParseV3DocumentBackend,
+    DoclingParseV3PageBackend,
+)
+from docling.datamodel.base_models import BoundingBox, InputFormat
+from docling.datamodel.document import InputDocument
+
+
+@pytest.fixture
+def test_doc_path():
+    return Path("./tests/data/2206.01062.pdf")
+
+
+def _get_backend(pdf_doc):
+    in_doc = InputDocument(
+        path_or_stream=pdf_doc,
+        format=InputFormat.PDF,
+        backend=DoclingParseV3DocumentBackend,
+    )
+
+    doc_backend = in_doc._backend
+    return doc_backend
+
+
+def test_text_cell_counts():
+    pdf_doc = Path("./tests/data/redp5110_sampled.pdf")
+
+    doc_backend = _get_backend(pdf_doc)
+
+    for page_index in range(0, doc_backend.page_count()):
+        last_cell_count = None
+        for i in range(10):
+            page_backend: DoclingParseV3PageBackend = doc_backend.load_page(0)
+            cells = list(page_backend.get_text_cells())
+
+            if last_cell_count is None:
+                last_cell_count = len(cells)
+
+            if len(cells) != last_cell_count:
+                assert (
+                    False
+                ), "Loading page multiple times yielded non-identical text cell counts"
+            last_cell_count = len(cells)
+
+
+def test_get_text_from_rect(test_doc_path):
+    doc_backend = _get_backend(test_doc_path)
+    page_backend: DoclingParseV3PageBackend = doc_backend.load_page(0)
+
+    # Get the title text of the DocLayNet paper
+    textpiece = page_backend.get_text_in_rect(
+        bbox=BoundingBox(l=102, t=77, r=511, b=124)
+    )
+    ref = "DocLayNet: A Large Human-Annotated Dataset for Document-Layout Analysis"
+
+    assert textpiece.strip() == ref
+
+
+def test_crop_page_image(test_doc_path):
+    doc_backend = _get_backend(test_doc_path)
+    page_backend: DoclingParseV3PageBackend = doc_backend.load_page(0)
+
+    # Crop out "Figure 1" from the DocLayNet paper
+    im = page_backend.get_page_image(
+        scale=2, cropbox=BoundingBox(l=317, t=246, r=574, b=527)
+    )
+    # im.show()
+
+
+def test_num_pages(test_doc_path):
+    doc_backend = _get_backend(test_doc_path)
+    doc_backend.page_count() == 9